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					                     SECTION 4

                     Model Description




NAS101, Page 4 - 1
                     Model Description
                                             PAGE

     MSC.Nastran Input File                   13
     Introduction to the Bulk Data Section    16
     Format of Bulk Data                      17
     Sample Bulk Data Entry                   18
     Format of Bulk Data Entries              19
     Small Field Format                        23
     Free Field Format                         24
     Large Field Format                        25
     General Input Format Rules                27
     Continuation Entries                      29
     Input Generation (Replication)            32


NAS101, Page 4 - 2
              Model Description (cont.)
                                                  PAGE

     Generation of Continuation Entries            34
     Example of Replication                        35
     Bulk Data Generated by Replication Example    36
     Common Errors in Entry Format                 37
     GRID Points                                   38
     Displacement Coordinate System                39
     Format of the GRID Entry                      41
     The GRID Entry                                42
     Coordinate Systems                            43
     Rectangular Coordinate Systems                45
     Cylindrical Coordinate Systems                48
     Spherical Coordinate Systems                  51

NAS101, Page 4 - 3
              Model Description (cont.)
                                                PAGE

     Sample of Coordinate Systems                54
     Using Coordinate Systems on GRID Entries    59
     The SPOINT Entry                            63
     The GRDSET Entry                            64
     Constraints                                 65
     Constraints – SPC and SPC1                   68
     Constraints – The SPC Entry                 69
     Constraints – The SPC1 Entry                 70
     Constraints – SPC and SPC1                   71
     Constraints – SPCD                          72




NAS101, Page 4 - 4
              Model Description (cont.)
                                                      PAGE

     Workshop 4                                        74
        Coordinate Systems and Constraints
        Model for Workshop 4
        New and Modified Case Control and Bulk Data
          for Workshop 4
        Partial Input File for Workshop # 4
        F06 Output for Subcase 40
        Deformed Plot for Subcase 40
        Solution for Workshop # 4
     Material Properties                               85
     Material Properties – MAT1                        87
     Element Library                                   90

NAS101, Page 4 - 5
              Model Description (cont.)
                                      PAGE

     Commonly Used Elements                91
     Elements in MSC.Nastran               92
     Element Coordinate Systems            94
     One Dimensional Elements              96
     The BAR Element                      100
     The BEAM Element                     102
     BEAM Properties                      108
     BEAM Properties – The PBEAML         121
     BEAM Element Output                  124
     CBEAM Example                        127
     CBEAM Example – Output               132


NAS101, Page 4 - 6
              Model Description (cont.)
                                                             PAGE

     BEAM Element with Intermediate Output                    135
     BEAM Element with Intermediate Output – Results          138
     Two-Dimensional Elements (Plates and Shells)             141
     Two-Dimensional Elements in MSC.Nastran                   144
     The QUAD4 Element                                        146
     Sign Convention of Force Output for the QUAD4 Element     149
     QUAD4 Element Definition                                  151
     QUAD4 Element Coordinate System                           154
     QUAD4 Element Properties                                  157
     QUAD4 Example                                             165
     QUAD4 Alternate Property Definition                       171


NAS101, Page 4 - 7
              Model Description (cont.)
                                              PAGE

     Workshop 5                               172
       Partial Input File for Workshop # 5
       F06 Output for Workshop # 5
       Deformed Plot for Workshop # 5
       Von Mises Stresses for Plate Element
       Solution for Workshop # 5
     Solid Elements                           189
     Solid Elements – Example                 198
     Loading Entries                          204
     Force and Moment Entries                 206




NAS101, Page 4 - 8
              Model Description (cont.)
                                              PAGE

     Distributed Loads (PLOADi)               209
     The PLOAD1 Entry                         211
     The PLOAD1 Entry – Samples               213
     Workshop 6                               217
        Partial Input File for Workshop # 6
        F06 Output for Workshop # 6
        Deformed Plot for Snow Loading
        Solution File for Workshop # 6
     Combined Loadings – The LOAD Entry       226




NAS101, Page 4 - 9
             Model Description (cont.)
                                       PAGE

     Workshop 7 – Combined Loads         229
       F06 Output for Workshop 7
       Deformed Plot for Workshop 7
       Solution for Workshop 7
     Workshop 7a                         237
       Solution for Workshop 7A
     The Zero-Dimensional Elements       241
     Workshop 7B                         252
       Solution for Workshop 7B
       F06 Output for Workshop 7B
       Deformed Plot for Workshop 7B


NAS101, Page 4 - 10
              Model Description (cont.)
                                       PAGE

     CWELD Element                     260
     CWELD Connectivity Types          261
     CWELD Entry                       262
     PWELD Entry                       266
     CWELD Point to Point Definition   267
     CWELD ―ALIGN‖ Example             268
     CWELD Point to Patch              269
     CWELD ―GRIDID‖ Example            272
     CWELD Patch to Patch              273
     CWELD ―ELEMID‖ Example            274




NAS101, Page 4 - 11
             Model Description (cont.)
                                                   PAGE

     CWELD ―GRIDID‖ Example                         275
     CWELD Geometry                                 276
     PWELD Property Definition                      278
     Internal Representation of the WELD Element    279
     Weld to Patch Connection                       280
     Results Output                                 281
     Results of Testing                              282
     Benchmark Problems                              283
     CWELD Summary                                   284
     Sample Problem                                  285
     Sample Problem—Point-to-Point                   287
     Sample Problem—Patch-to-patch                   289

NAS101, Page 4 - 12
                MSC.Nastran Input File




NAS101, Page 4 - 13
         MSC.Nastran Input File (cont)
File Management Section (FMS):
        • Includes the "NASTRAN" statement (optional - determines overall program
          control for the current run

        • Allocates files, controls restarts and database operations

        • The goal of the File Management Section is to make the operating
          system invisible to the user

 Executive Control Section:
        • Solution type, time allowed, program modifications and system diagnostics

Case Control Section
        • Output requests and selects certain Bulk Data items such as loadings and
          constraints to be used
Bulk Data Section
        • Structural model definition and solution conditions

 NAS101, Page 4 - 14
        MSC.Nastran Input File (cont)
The Bulk Data section is where you provide the
 description of the model and the loading conditions and
 constraints

As mentioned in the previous section, the Executive
 Control section provides overall control of the solution
 and the Case Control provides the control of the individual
 loadings to be applied and the output requests




NAS101, Page 4 - 15
        Introduction to the Bulk Data
                   Section
The Bulk Data Section contains all data necessary for
 describing a structural model
Bulk Data definitions include
    Geometry
        • User-definable coordinate systems
        • Geometric locations of grid points
    Constraints
    Material Properties
    Element Properties
    Loads
The Bulk Data is not required to be input in any set order.
 It is automatically sorted (alphabetically) at the beginning
 of the analysis

NAS101, Page 4 - 16
                       Format of Bulk Data
 The format of the Bulk Data section is based each line:
    having 80 possible columns
    being divided into 10 fields
 Each item described in the Bulk Data section is called an ―Entry‖
 Each Entry may span multiple lines
 The format of each Entry is pre-defined - the format of each entry is
  described in the MSC.NASTRAN Quick Reference Guide (QRG), section
  5
 Only a few basic entries will be described in this set of notes
 Not all options will be discussed for each entry - for a full description,
  check the QRG




 NAS101, Page 4 - 17
               Sample Bulk Data Entry




NAS101, Page 4 - 18
          Format of Bulk Data Entries
Data in each field may be:
    Integer      5
    Real         1.0E+7
    BCD          (Character String)
Each field of the input has a pre-determined data type.
You must enter you data correctly
An integer number has no decimal point
Examples:
   1
   134
   267


NAS101, Page 4 - 19
 Format of Bulk Data Entries (cont.)
Real data has a decimal point and may have an exponent
There are several ways to represent real numbers
For example, the real value 123.45 might be represented
 using any of the following:
 123.45
 1.2345+2
 12.345E+01
 .12345E3
These all represent the same number



NAS101, Page 4 - 20
 Format of Bulk Data Entries (cont.)
BCD (or character) data is represented as a text string
It must start with a letter (A-Z)
It may contain numbers in the text (0-9)
It must be 8 or fewer characters long
No special characters or embedded blanks may be used
Examples:
 TEST123
 X32
 DUM1



NAS101, Page 4 - 21
 Format of Bulk Data Entries (cont.)
The first field of an entry is its name
All subsequent fields provide data as defined for that entry
 in the QRG
If an entry spans more than one line, then a ―continuation‖
 is needed
Each line of input will use one of three formats:
    Small Field
    Free Field
    Large Field




NAS101, Page 4 - 22
                      Small Field Format
When using Small Field, each line is divided into 10 fields
Each field is 8 columns long
This is the format used by most pre-processing programs
 when writing an input file for MSC.Nastran
Example Small Field Entry




When using small field, you must be sure to count the
 number of columns for each field
There is no requirement that numbers be right- or left-
 justified (the program handles this for you)
NAS101, Page 4 - 23
                      Free Field Format
This is similar to small field, but fields are separated by
 either a comma or a space (using commas is
 recommended)
Rules:
    To skip a field, use two commas in succession
    Integers or BCD fields with more than 8 characters will result in a
     FATAL error
    Real numbers with more than 8 characters will be rounded off to 8
     characters (therefore, some precision will be lost)
Example: (Same entry as on the previous page)
 GRID,10,,7.5,8.6,9.,,456


NAS101, Page 4 - 24
                      Large Field Format
Expands a line in the Bulk Data to 2 lines
When used:
    The first and last fields of each line are 8 columns
    The intermediate fields are 16 columns (there are only 4
     intermediate fields per line - resulting in each line being 80
     columns long)
Large Field is denoted by adding an asterisk (*) after the
 name in the first field of an entry and by an asterisk(*) in
 the first column of the second line of the entry
See next page for the format



NAS101, Page 4 - 25
            Large Field Format (cont.)
Sample Large Field Format Entry:




NAS101, Page 4 - 26
          General Input Format Rules
Errors result if data extends beyond its field into another
 field
Fields 1 and 10 must be left justified. Fields 2 through 9 do
 not have this requirement
Input items should not have embedded blanks




NAS101, Page 4 - 27
  General Input Format Rules (cont)
All Real numbers (including zero) must have a decimal
 point (This is a common error)
Many fields have a default value, if these fields are left
 blank, the default value will be used (See the QRG)




NAS101, Page 4 - 28
                      Continuation Entries
Many input entries require more than one line of input
If this is the case, then ―continuation‖ entries must be
 used
Continuation entries may be generated automatically
 when the entries are in sorted order. The parent entry
 must be blank in columns 74-80 (field 10), and the
 continuation entry must be blank in columns 2-8 (field 1).
 For small field entries, the first column of the continuation
 entry may be blank or contain a + symbol. For large field
 entries, the first column of the continuation entry must
 contain a * symbol



NAS101, Page 4 - 29
          Continuation Entries (cont.)
Input rules
    Unless you use automatic generation, a (+) or (*) is required in
     column 1, field 1 of a continuation entry. The remaining contents
     in field 1 of a continuation entry must be identical to the entry in
     field 10 (columns 2 through 8) of the parent entry (or the preceding
     continuation entry)
    Any entry in the first column of field 10 on the parent entry is
     ignored by the continuation entry
    Small field and large field continuation entries may be used
     together in defining a single data item entry
An example of this is shown on the next page




NAS101, Page 4 - 30
          Continuation Entries (cont.)




NAS101, Page 4 - 31
      Input Generation – Replication
To avoid the time-consuming input of each Bulk Data
 entry individually, repetitive fields can be generated from a
 single entry definition. Rules governing this capability
 are:
    Duplication of a field from the preceding entry is accomplished by
     coding the symbol = in the associated field
    Duplication of all remaining fields from the preceding entry is
     accomplished by coding the symbol == in the first of the fields to be
     repeated
    Generation of a incremented value from the previous entry is defined by
     coding *X or *(X) where X is the real or integer value of the increment
     (Note: Parentheses are optional)
    Repeated replication is indicated by coding =n or the optional =(n) in
     field 1, where n is the number of entry images to be generated using the
     values of the increments on the preceding generation entry


NAS101, Page 4 - 32
      Input Generation – Replication
                 (cont.)
Generation/replication rules apply to all Bulk Data entries
 unless denoted otherwise on specific entry definition
 pages in the QRG.
Preprocessing programs generally generate a separate
 entry for each item and do not use replication.
In this seminar and others, we often use replication as a
 method to shorten the file so that we can show the
 complete input, rather than just showing parts of it




NAS101, Page 4 - 33
 Generation of Continuation Entries
Continuation fields (fields 1 and 10) may be replicated
 using the following conventions
    Only letters of the alphabet and integers may be used. They are coded
     into a base 36 number. That is, the sequence of numbers is 0, 1, 2,...8,
     9, A, B,...Z.
    The first character in the field 1 or 10 is not incremented
    MSC.Nastran increments continuation fields by +1.
    The number of characters in an incremented field is not increased. For
     example, if the field in the first entry is “0”, the field in the 37th entry is
     also “0” resulting in an illegal duplicate entry. A method to solve this
     problem is to start a first entry with “00”. This will provide 36 squared
     unique fields
    See Section 3.5.1 of the MSC/NASTRAN Handbook for Linear Analysis
     for examples of continuation entries in small field and large field formats

NAS101, Page 4 - 34
                Example of Replication




NAS101, Page 4 - 35
               Bulk Data Generated by
                Replication Example




NAS101, Page 4 - 36
    Common Errors in Entry Format
The following are recommendations on how to avoid some
 commonly made errors in the input
    Failure to leave the proper number of fields blank when defining data
     values causes either a fatal error or wrong answers. Be sure to leave
     the proper number of blanks or include the correct number of commas
     to delimit data fields
    Be sure to use the correct format for integer numbers and real numbers.
     See individual entry format in the MSC/NASTRAN Quick Reference
     Guide for these specifications
    Be sure to define all the required fields for the Bulk Data entries




NAS101, Page 4 - 37
                        GRID Points
Now that we have discussed the format for input data, let
 us look at individual Entries and their format
Grid points are used to specify:
    Structural geometry
    Degrees of freedom of the structure
    Locations of points at which displacements are constrained or loads are
     applied
    Locations where output quantities are to be calculated
Each GRID entry refers to 2 coordinate systems. One for
 locating the grid point and the other for establishing the
 grid point displacement coordinate system, which defines
 for the given grid point the directions of the nodal
 displacements (degrees of freedom), constraints, and
 solution vectors
NAS101, Page 4 - 38
  Displacement Coordinate System
The motion of each GRID point is defined using 6 dof
 identified as 1,2,3,4,5,6




NAS101, Page 4 - 39
  Displacement Coordinate System
              (cont.)
Commonly used nomenclature for the components of
 motion at a GRID point




Each GRID point may use a different coordinate system to
 measure its motion
The associated terms (T1-R3) are in the selected
 displacement system for the GRID point
NAS101, Page 4 - 40
                 Format of the GRID Entry
  Grid Entry Definition

     1             2      3      4      5       6      7      8      9      10
  GRID            ID     CP     X1      X2     X3     CD     PS     SEID
  GRID           101      0     5.0    10.0    2.0     1     123

         Field                                 Contents
    ID                 Grid point identification number
    CP                 Identification number of coordinate system in which
                       the location of the grid point is defined (integer  0 or
                       blank) (default = basic coordinate system)
    X1, X2, X3         Location of grid point in coordinate system CP (real)
     CD                Identification number of coordinate system in which
                       displacements, degrees of freedom, constraints, and
                       solution vectors are defined at the grid point (integer 
                       0 or blank, default = basic coordinate system)
     PS                Permanent single-point constraints associated with
                       grid point (any of the digits 1-6 with no embedded
                       blanks)
    SEID               Superelement ID
NAS101, Page 4 - 41
                 The GRID Entry (cont)
Note that there are two coordinate systems on the GRID
 entry
    CP = ―position‖ coordinate system - used to define the location in
     space
    CD = ―displacement‖ coordinate system - used to measure the
     motion of the point and to define constraints at the point
These may be rectangular, cylindrical, or spherical
 systems
These coordinate systems are defined using CORD1R,
 CORD2R, CORD1S,CORD2S, CORD1C, and CORD2C
 entries
On the CORDxx entries, R=rectangular, C=cylindrical,
 S=spherical
NAS101, Page 4 - 42
                       Coordinate Systems
Coordinate systems are required to define the locations of
 grid points in space and to orient each grid point’s
 displacement vector
In MSC.Nastran the following coordinate systems may be
 used
    Basic Coordinate System - Implicitly defined reference rectangular
     coordinate system (Coordinate System 0). Orientation of this system is
     defined by the user through specifying the components of grid point
     locations. This is the default system
    Alternate (local) Coordinate Systems - Alternate systems can be defined
     to facilitate geometric input. Each local system must be related directly
     or indirectly to the basic coordinate system.
Matrices, constraints, and GRID-related output in
 MSC.Nastran use the GLOBAL (or “displacement”)
 coordinate system.

 NAS101, Page 4 - 43
           Coordinate Systems (cont.)
The CORD1i entries define a local coordinate system by
 referencing three grid points. Beware that if the model is
 modified and any of these reference grid point locations
 change, the coordinate system orientation will also change
The CORD2i entries define a local coordinate system by
 specifying the locations of three reference points
Global System - Collection of all displacement coordinate
 systems referenced on all grid entries. (Note that some
 finite element codes use the term “global coordinate
 system” to refer to the equivalent of MSC.Nastran’s Basic
 Coordinate System
All angular coordinates are input in degrees. Output
 associated with these coordinates is in radians

 NAS101, Page 4 - 44
   Rectangular Coordinate Systems
Are defined using either a CORD1R or CORD2R
Locations A, B, and C are used to define the local
 coordinate system (see next page)




NAS101, Page 4 - 45
   Rectangular Coordinate Systems
               (cont.)




                      A




NAS101, Page 4 - 46
   Rectangular Coordinate Systems
               (cont.)
If the location of a GRID is defined using this system, the
 locations (X1, X2, and X3) will be in the local X, Y, and Z
 directions of this system (measured from its origin).

If this system is used as CD for a GRID, then the local U1,
 U2, and U3 are simply parallel to the X-, Y-, and Z-axes of
 this system




NAS101, Page 4 - 47
     Cylindrical Coordinate Systems
Are defined using either a CORD1C or CORD2C
Locations A, B, and C are used to define the local
 coordinate system (see next page)




NAS101, Page 4 - 48
     Cylindrical Coordinate Systems
                  (cont.)




NAS101, Page 4 - 49
     Cylindrical Coordinate Systems
                  (cont.)
If the location of a GRID is defined using this system, the
 locations (X1, X2, and X3) will be in the local R, q, and Z
 directions of this system (measured from its origin).
If this system is used as CD for a GRID, then the local U1,
 U2, and U3 are defined as follows:
    U1 is parallel to the radius vector
    U3 is parallel to the local Z axis
    U2 is defined by the right-hand rule (in the positive theta direction)
This means that if a cylindrical system is used, the
 Displacement system may be different at each point



NAS101, Page 4 - 50
      Spherical Coordinate Systems
Are defined using either a CORD1S or CORD2S
Locations A, B, and C are used to define the local
 coordinate system (see next page)




NAS101, Page 4 - 51
      Spherical Coordinate Systems
                 (cont.)




NAS101, Page 4 - 52
      Spherical Coordinate Systems
                 (cont.)
If the location of a GRID is defined using this system, the
 locations (X1, X2, and X3) will be in the local R, q, and F
 directions of this system (measured from its origin).
If this system is used as CD for a GRID, then the local U1,
 U2, and U3 are defined as follows:
    U1 is parallel to the radius vector
    U2 is Uq
    U3 is Uf
This means that if a spherical system is used, the
 Displacement system may be different at each point



NAS101, Page 4 - 53
      Sample of Coordinate Systems
Suppose you want to conduct an analysis of a cylindrical
 grain silo with a spherical dome roof. The use of local
 coordinate systems can greatly simplify your job




NAS101, Page 4 - 54
      Sample of Coordinate Systems
                 (cont.)




NAS101, Page 4 - 55
      Sample of Coordinate Systems
                 (cont.)
For this problem we will use a cylindrical system for the
 wall and a spherical system for the dome
The origin of the wall system will be at a location X=100. in
 the Basic system
The following CORD2C will define system 1, which we will
 use for the wall
    The Reference system is Basic


  CORD2C,1,0,100.,0.,0.,100.,0.,1.,+C1

                      Point A = Origin
  +C1,101.,0.,1.                         Point B = on positive Z axis

  Point C = in plus X-Z plane


NAS101, Page 4 - 56
      Sample of Coordinate Systems
                 (cont.)
The origin of the dome system will be at a location X=100.,
 Z=50. in the Basic system (at R=0., Z=50. In system 1)
The following CORD2S will define system 2, which we will
 use for the dome


    The Reference system is Basic


 CORD2S,2,0,100.,0.,50.,100.,0.,51.,+C1
                      Point A = Origin
                                         Point B = on positive Z axis
 +C1,101.,0.,51.
 Point C = in plus X-Z plane


NAS101, Page 4 - 57
      Sample of Coordinate Systems
                 (cont.)
If we wish to define the dome coordinate system relative
 to system 2, that will allow us to move the entire structure
 by simply re-positioning system 2
The following CORD2S will define system 2


 The Reference system is System 1


  CORD2S,2,1,0.,0.,50.,0.,0.,51.,+C1
                      Point A = Origin
                                         Point B = on positive Z axis
  +C1,1.,0.,51.
  Point C = in plus X-Z plane


NAS101, Page 4 - 58
       Using Coordinate Systems on
              GRID Entries
Now that systems 1 and 2 are defined, they can be used
 on GRID entries to locate and measure the motion of the
 GRID points
Let us define 2 GRID points on a circle using the Basic
 system to measure their motion
 GRID,10,1,10.,45.,0.      No CD is specified, therefore
 GRID,20,1,10.,135.,0.       the BASIC system is used
These points lie on the plane at Z=0 at a radius of 10 units
 and at angles or 45 (GRID 10) and 135 (GRID 20) degrees
The next page shows these GRID points and their
 Displacement (GLOBAL) systems


NAS101, Page 4 - 59
       Using Coordinate Systems on
           GRID Entries (cont.)




NAS101, Page 4 - 60
       Using Coordinate Systems on
           GRID Entries (cont.)
Let us change the 2 GRID points to use system 1 to
 measure their motion
 GRID,10,1,10.,45.,0.,1
 GRID,20,1,10.,135.,0.,1
These points will be located at the same locations as
 before, but their motion will now be measured using
 system 1 (cylindrical), rather than the default (system 0)
Their GLOBAL system is the projection of system 1 at
 each point
This is shown on the next page

NAS101, Page 4 - 61
       Using Coordinate Systems on
           GRID Entries (cont.)




NAS101, Page 4 - 62
                      The SPOINT Entry
The SPOINT entry defines scalar points
Scalar points have only one dof associated with them
 (remember GRID points have 6)
This dof has no location or orientation in space
These are normally used for advanced applications




NAS101, Page 4 - 63
                      The GRDSET Entry
This optional entry is used to set default values for the
 GRID entries
Used for fields 3 (CP), 7 (CD), 8 (PS), and 9 (SEID)
Only one GRDSET may be used per run
Values on the GRDSET are overridden by any values in the
 associated fields on a GRID entry




NAS101, Page 4 - 64
                         Constraints
A single-point constraint (SPC) is a constraint applied to
 one or more components of motion at selected grid or
 scalar points.
 Uses of SPCs include
    Support a structure (apply constraints)
    Apply symmetric or antisymmetric boundary conditions by restraining
     the DOFs that must have zero values in order to satisfy symmetry or
     antisymmetry
    Remove degrees of freedom unconnected or weakly coupled to the
     structure
    Remove degrees of freedom not used in the structural analysis (e.g.,
     out-of-plane DOFs for a 2-D analysis)
    Apply zero or nonzero enforced displacements to grid points

NAS101, Page 4 - 65
                      Constraints (cont.)

Constraints can be defined as:
    Permanent - defined on GRID entry
    User-selected - done in Case Control with SPC=SID. Defined in the
     Bulk Data on SPC, SPC1, or SPCD entries
    Automatic - PARAM,AUTOSPC,YES


Reaction forces at SPC’d grids (termed forces of single-
 point constraint), may be obtained by including the Case
 Control request SPCFORCES=ALL



NAS101, Page 4 - 66
                      Constraints (cont.)
Permanent constraints
The method of permanently removing degrees of freedom
 associated with a specific grid point is by defining these
 DOFs in field 8 of the GRID entry




     Any dof listed in field 8 (PS) are permanently constrained
These constraints are always applied. Constraint requests
 in Case Control have no effect on them

NAS101, Page 4 - 67
         Constraints - SPC and SPC1
User-selectable constraints can defined on SPC and SPC1
 Bulk Data entries
These constraints are selected by the SPC Case Control
 request
These constraints are only applied if requested
The set of constraints applied may be different for each
 SUBCASE
BE CAREFUL - if SPC and SPC1 entries are used, they are
 not applied unless specifically requested in Case Control



NAS101, Page 4 - 68
         Constraints - The SPC Entry
SPC - Used to define either zero or nonzero enforced
 displacements. Useful when applying a small number of
 enforced displacements




NAS101, Page 4 - 69
        Constraints - The SPC1 Entry
SPC1 - Used to define only zero enforced displacements.
Useful when applying a large number of zero-enforced
 displacements. SPC set ID selected in Case Control.




NAS101, Page 4 - 70
         Constraints - SPC and SPC1

Note also that DOFs specified on SPC-type entries can be
 redundantly specified in the PS field on GRID entry

SPCs are specified in the output coordinate
 (displacement) system of the grid point at which they are
 defined. Remember that the grid point output coordinate
 system is defined in field 7 of the GRID entry




NAS101, Page 4 - 71
                      Constraints - SPCD
SPCD - Used to define nonzero-enforced displacements.
 Selected in Case Control with LOAD=SID. Useful when
 applying a large number of nonzero enforced
 displacements.
A coordinate referenced on this entry must be referenced
 by a SPC or SPC1 entry (which is selected in Case
 Control)
The SPCD entry computes the equivalent load required for
 the requested enforced displacement
Use of the SPCD entry allows different enforced
 displacements in different subcases, without causing the
 stiffness matrix to be decomposed for each subcase

NAS101, Page 4 - 72
           Constraints – SPCD (cont.)




NAS101, Page 4 - 73
                       Workshop 4

              Roof Truss--Enforced displacement at an
                              Incline




NAS101, Page 4 - 74
                      Workshop # 4 (cont.)




NAS101, Page 4 - 75
 Workshop 4 - Coordinate Systems
        and Constraints
Using the truss model from Workshop 3, change the
 constraints and add a fourth loading condition.
The new constraints will be a ―roller‖ constraint along a 45
 degree surface at the right edge (GRID point 7)
In the additional loading condition:
    Apply a displacement of .05 units normal to the sloped surface
    Apply no other loads for this loading condition
In order to do this, we will need to define a ―displacement‖
 coordinate system (CORD2R 100) for GRID 7
 CORD2R,100,,576.,0.,0.,576.,0.,1.
 ,577.,1.,0.

NAS101, Page 4 - 76
                 Model for Workshop 4




NAS101, Page 4 - 77
     New and Modified Case Control
     and Bulk Data for Workshop 4
TITLE = GARAGE ROOF FRAME           SUBCASE 30
SUBTITLE = WOOD AND STEEL MEMBERS     SUBTITLE = GRAVITY LOAD
  DISPLACEMENT = ALL                  LOAD = 30
  SPCFORCES = ALL                   SUBCASE 40
  STRESS = ALL                        SUBTITLE = SUPPORT SETTLING
  SPC = 10                            LOAD = 40
TEMP(INIT) = 20                     BEGIN BULK
SUBCASE 1                           CORD2R,100,,576.,0.,0.,576.,0.,1.
  SUBTITLE=TRUSS_LBCS               ,577.,1.,0.
  LOAD = 1                          SPCD,40,7,2,-.05
SUBCASE 20                          $ modified GRID 7 - displacement coordinate
  SUBTITLE = THERMAL LOAD              system
TEMP(LOAD) = 26                     GRID   7        576.0 0.0    0.0    100 345




NAS101, Page 4 - 78
 Partial Input File for Workshop # 4




NAS101, Page 4 - 79
 Partial Input File for Workshop # 4




NAS101, Page 4 - 80
        Workshop 4 -- F06 Output for
               Subcase 40





NAS101, Page 4 - 81
    Workshop # 4 -- Deformed plot for
             Subcase 40





NAS101, Page 4 - 82
            Solution for Workshop # 4




NAS101, Page 4 - 83
            Solution for Workshop # 4




NAS101, Page 4 - 84
                      Material Properties




NAS101, Page 4 - 85
            Material Properties (cont.)
Some possible material types

        • Isotropic (MAT1)

        • Two-dimensional anisotropic (MAT2)

        • Axisymmetric solid orthotropic (MAT3)

        • Two-dimensional orthotropic (MAT8)

        • Three-dimensional anisotropic (MAT9)


Temperature-dependent material properties are defined on
 MATTi entries
NAS101, Page 4 - 86
           Material Properties - MAT1
For purposes of this seminar, we will only deal with the
 MAT1 entry
This material definition is for Isotropic materials
Minimum properties:
    E - Young’s Modulus - Modulus for extension and bending
    G - Modulus for torsion and transverse shear
    u - Poisson’s ratio
    If only 2 of the above 3 are provided, the following equation is used
     to calculate the value for the third:


For thermal stress analysis
    A - Thermal expansion coefficient

NAS101, Page 4 - 87
  Material Properties - MAT1 (cont.)




NAS101, Page 4 - 88
  Material Properties - MAT1 (cont.)




NAS101, Page 4 - 89
                      Element Library
         Includes over 50 finite elements
               One-dimensional
               Two-dimensional
               Three-dimensional
               Scalar
               Axisymmetric
               Rigid
               Mass and damping
               Heat transfer
               “Genel” user-supplied element
               Fluid-structure
               p-version
               Contact

NAS101, Page 4 - 90
           Commonly Used Elements

           Line Elements Surface    Solid      Other
                         Elements   ELements   Elements
           CBAR          CQUAD4     CTETRA     CBUSH
           CBEAM         CTRIA3     CHEXA      CELASi
                                               (I = 1, 2, 3, 4)
           CROD         CQUAD8      CPENTA
           CONROD       CTRIA6
           CBEND        CSHEAR
           CTUBE




NAS101, Page 4 - 91
             Elements in MSC.Nastran
Degrees of freedom are components of translation and
 rotation (no higher order derivatives).
Stiffness matrix is independent of grid point sequence




Elements of different types are compatible



NAS101, Page 4 - 92
    Elements in MSC.Nastran (cont.)
Full range of capabilities

    Stiffness
    Mass
    Damping
    Differential Stiffness
    Anisotropy
    Temperature
    Internal Loads
    Stress Output




NAS101, Page 4 - 93
         Element Coordinate Systems
All Elements use an Element Coordinate System
Element Coordinate Systems are used to:
    Orient components of force and stress output
    Orient section properties (line elements)
    Orient pressure loads (surface elements)
Each element has its own coordinate system that is
 defined by element connectivity order or by other data on
 the element’s connectivity. Positive z-direction of
 element coordinate system always follows the right-hand
 rule
Surface and solid elements also have optional material
 coordinate systems that may be used to orient
 orthotropic or anisotropic material properties. Material
 coordinate systems are defined on the element’s
 connection or property entries

 NAS101, Page 4 - 94
        Element Coordinate Systems
                  (cont.)
In addition to the element and material coordinate
 systems, stress output can be obtained in any user-
 defined coordinate system by using the Case Control
 GPSTRESS capability
Remember in almost all cases:
 Grid point information is output in the global system. Element
 information is output in the element coordinate system




NAS101, Page 4 - 95
           One Dimensional Elements

ROD, CONROD, TUBE: Pin-ended rod - 4 DOFs

BAR:                 Prismatic beam - 12 DOFs

BEAM:                Straight beam with warping - 14
 DOFs

BEND:                Curved beam or pipe - 12 DOFs



NAS101, Page 4 - 96
 One Dimensional Elements (cont.)
General features of CROD, CONROD, and CTUBE
 elements are:
    Connected by 2 GRID points
    Force components = Axial force and Torsional moment
    Displacement components in matrix = axial and torsional
    Straight, Prismatic members
The element stiffness matrix contains terms only for axial
 displacement and torsional rotation




NAS101, Page 4 - 97
 One Dimensional Elements (cont.)
CROD versus CONROD versus CTUBE
CROD       - Element connectivity is defined using the
             CROD entry. Properties are defined using the
             PROD entry. Useful when several elements
             have identical properties
CONROD - Element connectivity and properties are
             defined on the CONROD entry. Useful when
             each element has different properties
CTUBE - Connectivity on CTUBE, properties on PTUBE -
             models a hollow tube. You can specify the inner
             and outer diameters.
Of the 3, the CROD is the most commonly used


NAS101, Page 4 - 98
 One Dimensional Elements (cont.)
ROD-type elements - Geometry




NAS101, Page 4 - 99
                       The BAR Element
Connects to two grid points
Formulation derived from classical beam theory (plane
 sections remain plane under deformations)
Includes optional transverse shear flexibility
Force components
    Axial force P
    Torque T
    Bending moments about two perpendicular directions Mi
    Shears in two perpendicular directions Vi
Displacement components in element stiffness matrix
    3 translations and 3 rotations at each end


NAS101, Page 4 - 100
              The BAR Element (cont.)
Neutral axis may be offset from the grid points (internally a
 rigid link is created).
Principal axis of inertia need not coincide with element
 axis
Pin flag capability used to represent linkages, etc
Principal limitations
    Straight, prismatic member (i.e., properties do not vary along the length)
    Shear center and neutral axis must coincide (therefore, not
     recommended for modeling sections which are not doubly-symmetric).
    Torsional stiffening effect of out-of-plane cross-sectional warping is
     neglected
The CBEAM element has these additional capabilities.
        • See Section 4.1 of the MSC/NASTRAN Linear Static Analysis User’s
          Guide and Section 5.2.2 of the MSC/NASTRAN Reference Manual for
          detailed information about CBAR.


NAS101, Page 4 - 101
                       The BEAM Element
Connects to 2 GRID points
Force components
    Axial force P
    Torque T
    Warping torque Tw
    Bending moments in planes 1 and 2 Mi
    Shears in planes 1 and 2 Vi
Displacement components in element stiffness matrix
    3 translations and 3 rotations plus dq/dx (represented by SPOINTs)
     at each end




NAS101, Page 4 - 102
            The BEAM Element (cont.)
The beam includes all capabilities of the CBAR element
 plus several additional capabilities, including:
    Variable cross-section -the cross-sectional properties may be specified
     at as many as nine interior points and at both ends
    The neutral axis and shear center axis need not be coincident (correctly
     accounts for sections which are not doubly-symmetric)
    The effect of cross-sectional warping on the torsional stiffness
    The effect of taper on the transverse shear stiffness (shear relief).




NAS101, Page 4 - 103
            The BEAM Element (cont.)
Input format:




NAS101, Page 4 - 104
            The BEAM Element (cont.)
Field      Contents
EID        Element identification number (integer > 0)
PID        Identification number of PBEAM or PBEAML
 property entry
GA,GB      Grid point identification numbers of connection
 points
X1,X2,X3 Components of vector v at End A, measured at
 the offset point for End A, parallel to the components of
 the displacement coordinate system for GA
G0         Grid point identification number to optionally
 supply X1, X2, and X3


NAS101, Page 4 - 105
            The BEAM Element (cont.)
 Field                 Contents

 PA,PB                Pin flags for beam Ends A and B, respectively
                       (in the element coordinate system)
 W1A,W2A,W3A
  W1B,W2B,W3B          Components of offset vectors, measured in the
                       displacement coordinate systems at Grid Points A
                       and B, from the grid points to the end points of
                       the axis of shear center (real or blank)

 SA,SB                Scalar or grid point identification numbers for the
                       Ends A and B, respectively. The degrees of
                       freedom at these points are the warping variables
                       dq/dx


NAS101, Page 4 - 106
            The BEAM Element (cont.)




NAS101, Page 4 - 107
                       BEAM Properties




NAS101, Page 4 - 108
              BEAM Properties (cont.)
FIELD       CONTENTS                                DEFAULT
PID         Property identification number          Required
MID         Material identification number          Required
A(A)        Area of beam cross section at point A   Required
I1(A)       Area Moment of inertia of Beam cross    Required
            section in plane 1 (about element Z
            axis) at point A
I2(A)       Area Moment of inertia of Beam cross    Required
            section in plane 2 (about element Y
            axis) at point A
I12(A)      Area product of inertia at end A        0.0
            (I1*I2-I12>0)
NAS101, Page 4 - 109
              BEAM Properties (cont.)
FIELD         CONTENTS                                   DEFAULT
J(A)          Torsional stiffness constant at end A      0.0
              (if warping is present, J>0) (real)
NSM(A) Nonstructural mass per unit length at             0.0
              end A (real)
Ci(A), Di(A), The locations (element Y and Z) at end     0.0
Ei(A), Fi(A)
              A for stress data recovery (real)
SO            Stress output option (BCD)                 Required
              YES = Stresses recovered at points
              C,D,E,F on next continuation entry
              YESA = Stresses recovered at points with
              same y,z locations as end A
              NO = no stress output
NAS101, Page 4 - 110
               BEAM Properties (cont.)
FIELD        CONTENTS                                  DEFAULT
X/XB         Distance from end A in the element        Required
             coordinate system (X) divided by the
             length (XB)
A, I1, I2,   Properties at current cross-section       See following
J, NSM                                                 pages
Ci, Di, Ei, Y,Z (element coordinate system)
Fi          locations for stress calculation on the
             current cross-section
K1, K2       Shear stiffness factor K for Plane 1 and 1., 1.
             2
S1, S2       Shear relief coefficient due to taper for 0., 0.
             plane 1 and 2


NAS101, Page 4 - 111
                BEAM Properties (cont.)
FIELD           CONTENTS                                  DEFAULT
NSI(1),         Nonstructural mass moment of inertia      0., same
NSI(2)          per unit length about nonstructural       as end A
                mass center of gravity at ends A and B
                (real)
CW(A),          Warping coefficient for ends A and B      0., same
CW(B)           (real)                                    as end A
N1(A), N2(A),
N1(B), N2(B)    Y and Z coordinates (offsets) of the      0., same
                neutral axis for ends A and B             as end A
M1(A), M2(A),
M1(B), M2(B)    Y and Z coordinates (offsets) of the      0.0, same
                center of gravity of nonstructural mass   as end A
                at ends A and B


NAS101, Page 4 - 112
              BEAM Properties (cont.)
A(I), J(I), I1(I), I2(I), I12(I)

These properties must be specified for end A (except I12,
 which defaults to 0.0)
By default end B will have the same properties as end A
Unless properties are specified for Intermediate sections,
 these properties will be found by linearly interpolating
 between those of end A and end B




NAS101, Page 4 - 113
              BEAM Properties (cont.)
Shear Relief coefficient due to Taper (S1, S2)
    The shear relief factor accounts for the fact that in a tapered flanged
     beam, the flanges sustain a portion of the transverse shear load. This
     situation is illustrated below




NAS101, Page 4 - 114
              BEAM Properties (cont.)
The value of the shear coefficient for a tapered beam with
 heavy    flanges that sustain the entire moment load may
 then be written as




For additional information, see      the   MSC/NASTRAN
 Reference Manual, Section 5.2.1.



NAS101, Page 4 - 115
              BEAM Properties (cont.)
Cross-Sectional Warping - Coefficients CW(A), CW(B)

Open section members, such as, channels, undergo
 torsion as well as bending when transverse loads act
 anywhere except at the shear center of a cross section.

This torsion produces warping of the cross section so that
 plane sections do not remain plane, and as a result, axial
 stresses are produced. This situation can be represented
 in the differential equation for the torsion of a beam about
 the axis of shear centers (on the following page)


NAS101, Page 4 - 116
              BEAM Properties (cont.)
Cross-Sectional Warping - Coefficients CW(A), CW(B)




NAS101, Page 4 - 117
              BEAM Properties (cont.)
Cross-Sectional Warping - Coefficients CW(A), CW(B)

Note: The warping constant Cw has units of (length)6. The
 development of the differential equation and methods for the
 numerical evaluations of the warping constant are available in
 the literature. (See, for example, Timoshenko and Gere,
 Theory of Elastic Stability, McGraw Hill Book Company, 1961.
 Also see Roark & Young, Formulas for Stress and Strain, for
 values for different sections.)




NAS101, Page 4 - 118
              BEAM Properties (cont.)
Neutral Axis Offset from Shear Center (N1, N2)




NAS101, Page 4 - 119
              BEAM Properties (cont.)
Neutral Axis Offset from Shear Center (N1, N2)




N1 and N2 allow you to specify the offset between the
 shear center and the neutral axis

NAS101, Page 4 - 120
    BEAM Properties - The PBEAML
The PBEAML defines the properties of a BEAM element by
 using the dimensions of the cross section




NAS101, Page 4 - 121
      BEAM Properties - The PBEAML
Field              Contents

PID                Property identification number

MID                Material identification number

Group              Cross-section group (default = "MSCBML0"

TYPE               Cross-section shape. See Remark 4.. (Character:
                   "ROD", "TUBE", "L", "I", "CHAN", "T", "BOX",
                   "BAR", "CROSS", "H", "T1", "I1", "CHAN1", "Z",
                   CHAN2", "T2", "BOX1", "HEX", "HAT" for
                   GROUP="MSCBMLO")
DIMi(A)…           Cross-section dimensions at end A and B. (Real >
DIMi(B)            0.0 for GROUP="MSCBMLO"
NSM(A)…            Nonstructural mass per unit length
NSM(B)
NAS101, Page 4 - 122
    BEAM Properties - The PBEAML
              (cont.)
Field              Contents

SO(j)              Stress output request option for section (j)
                   YES = Stress recovered at this section
                   NO = no stress output for this section
X(j)/XB)           Distance from end A to intermediate section (j)
                   divided by the length of the element
NSM(j)             Nonstructural mass per unit length at section (j)

DIMi(j)            Cross-section dimensions at section (j)



For more information, including section information, see the QRG,
section 5 (or the V69 Release Notes)
NAS101, Page 4 - 123
                 BEAM Element Output
BEAM element forces and moments




NAS101, Page 4 - 124
        BEAM Element Output (cont.)
The forces and moments in plane 1 can also be viewed as:




NAS101, Page 4 - 125
        BEAM Element Output (cont.)
The forces and moments in plane 2 can also be viewed as:




NAS101, Page 4 - 126
                       CBEAM Example
Let us create a model of a cantilever beam




NAS101, Page 4 - 127
               CBEAM Example (cont.)




NAS101, Page 4 - 128
               CBEAM Example (cont.)
Material properties:
    E = 30.+6
    u = 0.3
    Yield stress = 36000.
    G = calculated by program




NAS101, Page 4 - 129
               CBEAM Example (cont.)
Input data for BEAM element




NAS101, Page 4 - 130
               CBEAM Example (cont.)
Alternate Input data for BEAM Properties




NAS101, Page 4 - 131
            CBEAM Example - Output




NAS101, Page 4 - 132
   CBEAM Example – Output (cont.)




NAS101, Page 4 - 133
   CBEAM Example – Output (cont.)




NAS101, Page 4 - 134
   BEAM Element with Intermediate
             Output
 For the following problem, let us create a BEAM element with output
  requested at 0., .25, .5, .75, and 1.0 times the length. (Using the same
  cross-section as before)




 Note: GRID 202 is constrained in Y-translation, but not in X-translation

NAS101, Page 4 - 135
   BEAM Element with Intermediate
           Output (cont.)
PBEAM entry for intermediate output




NAS101, Page 4 - 136
     BEAM Element with Intermediate
             Output (cont.)
  PBEAML entry with intermediate output

 1             2        3    4      5     6    7      8   9   10
PBEAML    1        1              BAR
          4.       6.             YES   .25

          YES      .5                         YES   .75

                            YES   1.0




NAS101, Page 4 - 137
   BEAM Element with Intermediate
         Output - Results




NAS101, Page 4 - 138
   BEAM Element with Intermediate
      Output – Results (cont.)




NAS101, Page 4 - 139
   BEAM Element with Intermediate
           Output (cont.)




NAS101, Page 4 - 140
         Two-Dimensional Elements --
              Plates and Shells
Plates and Shells - Background




Definition: A plate (or shell) is a structural element which
 represents a component with one small dimension and
 two large dimensions.
Plate and shell elements are used to model thin plates. A
 thin plate is one in which the thickness is much less than
 the next larger dimension (roughly 1/15).
 NAS101, Page 4 - 141
        Two-Dimensional Elements --
          Plates and Shells (cont.)
Plates and Shells - Background

For linear analysis, MSC.Nastran plate elements assume
 classical engineering assumptions of thin plate behavior
    The deflection of the midsurface is small compared with the thickness
    The midsurface remains unstrained (neutral) during bending (this
     applies to lateral loads, not in-plane loads).
    The normal to the midsurface remains normal to the midsurface during
     bending




NAS101, Page 4 - 142
        Two-Dimensional Elements --
          Plates and Shells (cont.)
Plates and Shells - Background

An important fact about plate and shell elements is that
 they have no stiffness term for in-plane rotational dof. As
 such, if BAR or BEAM elements are connected to a plate
 of shell, special modeling effort is required
Some references on basic plate theory:

    1. Theory of Plates and Shells, by S. Timoshenko and S. Woinowsky-
     Krieger, 2nd ed., McGraw Hill, 1959

    2. Stresses in Plates and Shells, by A. C. Ugural, McGraw Hill, 1981


NAS101, Page 4 - 143
       Two-dimensional Elements in
              MSC.Nastran
TRIA3       Three-noded isoparametric flat plate element.
 Commonly used for mesh transitions. May have
 excessive stiffness particularly for membrane strain
QUAD4       Four-noded isoparametric flat plate element.
 Behaves well when irregularly shaped, good results can
 be obtained with skew angles up to 45 degrees
TRIA6       Isoparametric triangle element with three corner
 and three midside grid points. Used in regions with
 curvature
QUAD8       Isoparametric element with four corner and four
 edge grid points. Useful for modeling singly-curved shells
 (e.g., cylinder). QUAD4 performs better for doubly curved
 shells (e.g., sphere).
NAS101, Page 4 - 144
       Two-dimensional Elements in
           MSC.Nastran (cont.)
SHEAR       Four-noded, shear and extensional force only
 element. Used for analyzing thin reinforced plates and
 shells. Commonly used with rod elements to analyze thin-
 skinned aircraft structures (best if rectangular)
TRIAR       Three-noded isoparametic flat element.
 Companion to the QUADR element
QUADR Four-noded isoparametric flat plate element
 with without membrane-bending coupling. Less sensitive
 to distortion and extreme values of Poisson ratio than the
 QUAD4
NOTE: It is not recommended to use TRIAR or QUADR
 elements for curved surfaces unless PARAM,SNORM is
 used
NAS101, Page 4 - 145
                   The QUAD4 Element
The QUAD4 element is the most commonly used plate
 element
It is a 4-noded flat plate element
It is capable of resisting both in-plane and out-of-plane
 loads
It is capable of modeling either plane strain or plane stress
It has terms in its stiffness matrix to account for
 transverse shear flexibility and also for membrane-
 bending coupling
Once again, it has no term in the stiffness matrix for the
 in-plane bending stiffness (a false term can be added by
 using PARAM,K6ROT,x.xx)
NAS101, Page 4 - 146
          The QUAD4 Element (cont.)




NAS101, Page 4 - 147
          The QUAD4 Element (cont.)
Element force output includes:
    Fx,Fy        Membrane force per unit length
    Fxy          Membrane shear force per unit length
    Mx,My        Bending moments per unit length
    Mxy          Twisting moment per unit length
    Vx,Vy        Transverse shear forces per unit length
Element Stress output includes:
    Stress components: sx, sy, txy, (at center - optionally at corners)


The sign convention for these terms is shown on the next
 pages


NAS101, Page 4 - 148
   Sign Convention of Force Output
        for the QUAD4 Element




NAS101, Page 4 - 149
  Sign Convention of Stress Output
    for the QUAD4 Element (cont.)




NAS101, Page 4 - 150
  QUAD4 Element Definition (cont.)




NAS101, Page 4 - 151
  QUAD4 Element Definition (cont.)
Field            Contents
EID              Element identification number (integer > 0)
PID              Identification number of a PSHELL or PCOMP
                  property entry
G1,G2,
 G3,G4            Grid point identification numbers of connection
                  points. (All interior angles of this element must
                  be less than 180.)
q                Material property orientation specification. If
                  real or blank, specifies material property
                  orientation angle in degrees. If integer, material
                  x-axis orientation is along projection onto the
                  plane of the x-axis of the specified coordinate
                  system.
NAS101, Page 4 - 152
  QUAD4 Element Definition (cont.)
Field            Contents
T1,T2,
 T3,T4            The continuation entry is optional. If supplied,
                  it describes the membrane thickness of the
                  element at grid points G1 through G4 (real  0.,
                  not all zero). If not supplied, then T1 through T4
                  is set equal to the value of T on the PSHELL
                  data entry.
ZOFFS            Offset from the surface defined by the grid
                  points to the element reference plane in the
                  element coordinate system



NAS101, Page 4 - 153
          QUAD4 Element Coordinate
                  System
The element coordinate system
    Is defined based on the order and location of the connecting points
    Defines positive sense of normal pressures applied to the element
    Used to define layers of a composite material
    Used to interpret the element output forces and stresses (element
     output is in the element coordinate system by default for these
     elements)


See illustration on following page



NAS101, Page 4 - 154
          QUAD4 Element Coordinate
              System (cont.)




NAS101, Page 4 - 155
          QUAD4 Element Coordinate
              System (cont.)
Element x-axis bisects the angle 2a. Positive direction is
 from G1 towards G2

Element y-axis is perpendicular to the element x-axis and
 lies in the plane defined by G1, G2, G3, and G4. Positive
 direction is from G1 toward G4.

Element z-axis is normal to the x-y plane of the element.
 Positive sense is defined by the right-hand rule and the
 ordering of the connected grids


NAS101, Page 4 - 156
           QUAD4 Element Properties
Are defined using either a PSHELL or PCOMP (composite)
 entry




NAS101, Page 4 - 157
  QUAD4 Element Properties (cont.)
 Field           Contents
 PID             Property identification number
 MID1            Material identification number for membrane behavior
                  (integer > 0 or blank)
T                Plate or membrane thickness
 MID2            Material identification number for bending behavior
                  (integer > 0 or blank, MID2 = -1 represents plane strain)
             NOTE: THE DEFAULT FOR MID2 IS NOT TO INCLUDE THE
             BENDING STIFNESS.
   FOR MOST MODELS, MID2 SHOULD NOT BE BLANK
 12I/T3          Normalized bending inertia per unit length (real or blank,
                  default = 1.0). The default value is correct for solid,
                  homogeneous plates.


NAS101, Page 4 - 158
  QUAD4 Element Properties (cont.)
Field            Contents
MID3             Material identification number for transverse
                  shear behavior (integer > 0 or blank)
TS/T             Transverse shear thickness divided by
                  membrane thickness (default = .833333). The
                  default value is correct for solid, homogeneous
                  plates.
NSM              Nonstructural mass per unit area (real)
Z1,Z2            Stress recovery distances for bending (real,
                  default Z1 = -1/2 thickness, Z2 = +1/2 thickness)
MID4             Material identification number to define
                  coupling between membrane and bending
                  deformation

 NAS101, Page 4 - 159
 QUAD4 Element Properties (cont.)
The QUAD4 element can have in-plane, bending, and
 transverse shear behavior.    The element mechanical
 behavior is specified by the presence or absence of a
 material ID number in the appropriate field(s) on the
 PSHELL entry.

To model a membrane plate, use MID1 only




NAS101, Page 4 - 160
 QUAD4 Element Properties (cont.)
To model a plate with bending stiffness only, use only
 MID2



For bending with transverse shear flexibility, use MID2 and
 MID3




Note: Mass is not calculated if MID1 is blank
NAS101, Page 4 - 161
 QUAD4 Element Properties (cont.)
Use MID3 to include an extra shear term in the element
 stiffness calculations (i.e., includes transverse shear
 flexibility).




NAS101, Page 4 - 162
 QUAD4 Element Properties (cont.)

For a solid homogeneous plate, MID1, MID2, and MID3
 should reference the same material ID

MID4:            The MID4 field (bending and membrane
                  deformation coupling) should be defined only if
                  the element’s cross section is unsymmetric.
                  Default is blank = symmetric cross section.

For more information on MID4, see the MSC/NASTRAN
 Common Questions and Answers


NAS101, Page 4 - 163
 QUAD4 Element Properties (cont.)
In summary, the results of leaving an MID field blank are:

MID1             No membrane or coupling stiffness
MID2             No bending, coupling, or transverse shear
                  stiffness
MID3             No transverse shear flexibility
MID4             No bending-membrane coupling




NAS101, Page 4 - 164
                       QUAD4 Example




NAS101, Page 4 - 165
               QUAD4 Example (cont.)




      Notice that the in-plane rotation is constrained
NAS101, Page 4 - 166
               QUAD4 Example (cont.)




NAS101, Page 4 - 167
               QUAD4 Example (cont.)




NAS101, Page 4 - 168
               QUAD4 Example (cont.)




                sHVM = [(3.024E6)2 – (3.024E6)(2.268E5) + (2.268E5)2] ½ = 2.917E6



NAS101, Page 4 - 169
               QUAD4 Example (cont.)




NAS101, Page 4 - 170
            QUAD4 Alternate Property
                  Definition
The PCOMP property entry may be used when the element
 is a composite consisting of layers of unidirectional fibers.
 The information on the PCOMP entry includes the
 thickness, orientation, and material identification of each
 layer. This information is used within MSC.Nastran to
 compute the entries of a PSHELL entry, which should not
 be simultaneously entered by the user for the same
 element(s). Special layer-by-layer output is provided when
 the PCOMP option is used.

See Section 6.5 of the MSC/NASTRAN Reference Manual
 for detailed information about simulating composite materials
 with MSC.Nastran


NAS101, Page 4 - 171
                         Workshop 5

                 Stiffened Plate Subjected to Pressure
                                  Load




NAS101, Page 4 - 172
                       Workshop 5
Stiffened Plate Model




GOAL: model a stiffened panel using plate elements for
 the panel and BEAM elements for the stiffener



NAS101, Page 4 - 173
                       Workshop 5 (cont.)
Stiffened Plate Model
We will model a plate which is .1 inches thick, 20.0 inches
 long, and 10.0 inches wide. The stiffener is shown below,
 along with the plate dimensions and loading




The model has pinned supports at the corners
NAS101, Page 4 - 174
                       Workshop 5 (cont.)
Stiffened Plate Model
Material properties:
    E = 10.3E+6 psi
    Poissons Ratio = .3
    Density = .101 lb/in3 (weight density)
The stiffener will be modeled using a BEAM with a
 PBEAML to define the cross-section
The GRID points will lie at the mid-plane of the plate, so
 the BEAM must be offset from the GRID points by 1.05
 (half the BEAM height pus half the plate thickness)



NAS101, Page 4 - 175
                       Workshop 5 (cont.)
Stiffened Plate Model
The Model




NAS101, Page 4 - 176
                       Workshop 5 (cont.)
Stiffened Plate Model
PBEAML Entry

  PBEAML,2,1,,I
  ,2.,1.,1.,.1,.1,.1

Sample CBEAM

CBEAM      21          2   31   32   0.     0.   1.
                           0.   0.   1.05   0.   0.   1.05




NAS101, Page 4 - 177
                       Workshop 5 (cont.)
 Stiffened Plate Model - Pressure Load Definition
 Pressure loads on plate and shell elements are defined using PLOAD2 or
  PLOAD4 entries




 SID = Static Loading Set ID
 EIDi = Element ID
 P = Pressure (applied in element coordinate system)
  PLOAD2,1,-.5,1,THRU,20



NAS101, Page 4 - 178
                       Workshop 5 (cont.)




NAS101, Page 4 - 179
    Partial Input File for Workshop # 5





NAS101, Page 4 - 180
    Partial Input File for Workshop # 5
                   (cont.)





NAS101, Page 4 - 181
        F06 Output for Workshop # 5





NAS101, Page 4 - 182
        F06 Output for Workshop # 5
                  (cont.)





NAS101, Page 4 - 183
        F06 Output for Workshop # 5
                  (cont.)





NAS101, Page 4 - 184
    Deformed Plot for Workshop # 5





NAS101, Page 4 - 185
           Workshop # 5 -- Von Mises
           Stresses for Plate Element





NAS101, Page 4 - 186
            Solution for Workshop # 5





NAS101, Page 4 - 187
    Solution for Workshop # 5 (cont.)





NAS101, Page 4 - 188
                       Solid Elements
Commonly used solid elements:
    PENTA (6-15 nodes)
                            Note - any or all mid-side
    HEXA (8-20 nodes)       nodes may be deleted
    TETRA (4-10 nodes)




NAS101, Page 4 - 189
                 Solid Elements (cont.)
HEXA -
   Recommended for general use. Accuracy degrades when element is
    skewed and used in a situation where bending behavior is dominant. In
    most modeling situations, it has superior performance to the other 3-D
    elements.
PENTA -
   Commonly used to model transition. This element is designed to behave
    well as a reasonable thin shell element. If the triangular faces are not on
    the exposed surfaces of the shell, excessive stiffness results
TETRA -
   Frequently used by automatic mesh generators and to fill in odd-shaped
    holes that occasionally appear in models made with HEXA and PENTA
    elements. Unless "perfectly-shaped", the 4-noded TETRA is not
    recommended for modeling large portions of solid continua, the 10-noded
    TETRA elements will provide much better accuracy




NAS101, Page 4 - 190
                 Solid Elements (cont.)
Solid elements connect to only translational dof.
Therefore, any connection to a solid element which is
 intended to transfer moment requires special modeling
For example, connecting a plate element to a solid
 element results in a ―piano-hinge‖ condition unless
 special modeling is done (the RSSCON handles the
 moment transfer between plate and solid elements)
If a BAR or BEAM is connected to a solid element, the
 resulting connection is a ―pinned‖ connection, no matter
 what pin flags are set on the BAR or BEAM (an RBE3 can
 be used to transfer the moments from the BAR or BEAM to
 the solid)

NAS101, Page 4 - 191
                 Solid Elements (cont.)
CHEXA -

Connects to 8 to 20 GRID points (either 8 or 20 are
 recommended for best results)

Stress components include : sx, sy, sz, txy, tyz, tzx (at center
 and corner points)

Stiffness matrix contains terms for translations only

Can use isotropic or anisotropic material


NAS101, Page 4 - 192
                 Solid Elements (cont.)
CHEXA -




NAS101, Page 4 - 193
                 Solid Elements (cont.)
CHEXA -




EID = element id
PID = PSOLID id
G1…G20 = attachment GRID points (in order shown on
  previous page)


NAS101, Page 4 - 194
                 Solid Elements (cont.)
CHEXA - Element Coordinate System
Determining the element coordinate system for solid
 elements is very complicated.
The method to do this is described in the QRG
By default, the stress output for solid elements is in the
 material coordinate system (default = BASIC) for the
 element.
The PSOLID entry contains the field which determines the
 coordinate system used for the element output (CORDM)




NAS101, Page 4 - 195
                 Solid Elements (cont.)
CHEXA - Properties - The PSOLID Entry
Properties for SOLID elements are defined on the PSOLID




PID = Property identification number
MID = Material identification number (points to a MATi
 entry)
CORDM = material coordinate system for elements using
 this PSOLID (default=0). If you want the element system,
 set this field to -1
The other fields are more advanced features
NAS101, Page 4 - 196
                 Solid Elements (cont.)
CHEXA - Output
Stress output consists of the six components of stress
 measured in the material coordinate system defined in the
 CORDM field of the PSOLID entry (default=BASIC system).
Additional output includes the magnitude and direction of
 the three principal stresses, the mean pressure, and the
 octahedral stresses.
These stresses are provided at the corner grid points and
 at the center of each element.
 See Section 5.4 of the MSC/NASTRAN Reference Manual and
 section 4.3 of the MSC/NASTRAN Linear Static Analysis
 User’s Guide for more detailed information about solid
 elements
NAS101, Page 4 - 197
             Solid Elements - Example




NAS101, Page 4 - 198
   Solid Elements – Example (cont.)
Pressure loads on solids are defined using the PLOAD4
 entry




SID = loading set
EID = element id
P1-P4 = pressure at corners of the surface (P1 = default for
 P2-P4)
G1 = GRID on one corner of the loaded surface
G3 = GRID on a corner diagonally opposite G1 on the
 loaded surface
NAS101, Page 4 - 199
   Solid Elements – Example (cont.)
The PLOAD4 entry (cont)




CID = coordinate system for orientation vector
N1, N2, N3 = Coordinates of the vector (in CID)
 determining the direction of the load
By default, the load is positive inwards



NAS101, Page 4 - 200
   Solid Elements – Example (cont.)
SOL 101
CEND
TITLE = SOLID EXAMPLE
DISP = ALL
STRESS = ALL
LOAD = 1
BEGIN BULK
CHEXA 6700      1       6701   6702   6703   6704   6711     6712   +CH1
+CH1    6713    6714
GRID    6701            0.     0.     0.            123456
GRID    6702            10.    0.     0.            23456
GRID    6703            10.    10.    0.            3456
GRID    6704            0.     10.    0.            3456
GRID    6711            0.     0.     10.           456
GRID    6712            10.    0.     10.           456
GRID    6713            10.    10.    10.           456
GRID    6714            0.     10.    10.           456
MAT1    1       30.E6          .3
PLOAD4 1        6700    8.     8.     8.     8.     6711     6713
PSOLID 1        1
ENDDATA
NAS101, Page 4 - 201
NAS101, Page 4 - 202
   Solid Elements – Example (cont.)
Output verification:
p = pressure = 8.0 psi

sz     =         principal stress = P= -8.0 psi
po     =         mean pressure = = = 2.667 psi
sn     =         von Mises stress




von Mises stress is related to octahedral shear stress by

NAS101, Page 4 - 203
                        Loading Entries
Type of Load                               Bulk Data Entries
Forces applied directly to GRID points     FORCE, FORCE1, FORCE2
Moments applied directly to GRID ponts     MOMENT, MOMENT1, MOMENT2
Loads on scalar points (SPOINTs)           SLOAD

Loads on line elements                     PLOAD1
Pressures and Tractions on surfaces        PLOAD, PLOAD2, PLOAD4, PLOADX
Gravity                                    GRAV
Centrifugal or centripetal force           RFORCE
Thermal expansion                          TEMP, TEMPD, TEMPP1, TEMPP3, TEMPRB
                                           (plus coefficient of thermal expansion)
Enforced extensional deformation of line   DEFORM
elements
Enforced displacements at GRID points      SPC, SPCD

Linear combination of loadings             LOAD




NAS101, Page 4 - 204
                Loading Entries (cont.)
See Chapter 6 of the MSC/NASTRAN Linear Static Analysis
 User’s Guide for detailed information on static loads available
 in MSC.Nastran.

See Chapter 7 of the MSC/NASTRAN Reference Manual for
 detailed information on all load types available in MSC.Nastran




NAS101, Page 4 - 205
            Force and Moment Entries
There are three different entries available for defining
 force input and three entries available for defining moment
 input
The three FORCE entries differ only in the way the
 direction of the force is specified
    FORCE uses the components of a vector
    FORCE1 uses two grid points, not necessarily the same as the loaded
     grid points
    FORCE2 defines the direction of the force as the direction of a vector
     that is the vector product of two other vectors
The distinctions between the three MOMENT entries are
 similar to the ones for the FORCE entries


NAS101, Page 4 - 206
        FORCE and MOMENT Entries
                 (cont.)




    SID = Load set
    G = GIRD id
    CID = coordinate system used to define load
    F or M = scale factor
    N1, N2, N3 = components of vector in CID (applied load = scale
     factor * vector)
NAS101, Page 4 - 207
        FORCE and MOMENT Entries
                 (cont.)
The applied load =




NAS101, Page 4 - 208
         Distributed Loads -- PLOADi
PLOAD       Defines uniform pressure loads on triangular and
 quadrilateral surfaces defined by grid points rather than
 elements
PLOAD1 Defines concentrated loads and linearly distributed
 loads on line elements
PLOAD2 Defines uniform pressure loads on surface
 elements
PLOAD4 Defines linearly varying pressure loads and
 tractions on surfaces
PLOADX Defines linearly varying pressure loads on TRIAX6
 elements
See next page for applicability
NAS101, Page 4 - 209
         Distributed Loads -- PLOADi
                    (cont.)




NAS101, Page 4 - 210
                       The PLOAD1 Entry


SID = static load id
EID = element id
TYPE = Input load description
    FX,FY,FZ,MX,MY,MZ = load in BASIC coordinate system
    FXE, FYE, FZE, MXE, MYE, MZE = load in element system
SCALE = Determines how X1 and X2 are defined
    LE = Actual length from start
    FR = Fractional length from start
    LEPR = Projected length from start
    FRPR = Fractional projection from start
NAS101, Page 4 - 211
            The PLOAD1 Entry (cont.)




X1, X2 = distance along the element from end A to the
 location of the load (X2 may be blank, or real)

P1, P2 = Load factor at locations X1 and X2



NAS101, Page 4 - 212
        The PLOAD1 Entry - Samples



Defines the following Load:




NAS101, Page 4 - 213
       The PLOAD1 Entry – Samples
                (cont.)


Defines the following Load:




NAS101, Page 4 - 214
       The PLOAD1 Entry – Samples
                (cont.)


Defines the following Point Load (since X2 and P2 are
 blank):




NAS101, Page 4 - 215
       The PLOAD1 Entry – Samples
                (cont.)


Defines a projected Load:

Total Load = 100*50=5000lb




NAS101, Page 4 - 216
                         Workshop 6

                Roof Truss Subjected to a fifth loading
                       condition--snow loading




NAS101, Page 4 - 217
                       Workshop 6
Using the roof truss model from workshop 3, add a snow
 load of 5 lb/in (projected) on the sloping members
For this, we will add an additional SUBCASE (number 50),
 which applies the snow load on the roof

(NOTE: this requires using BEAM or BAR elements for the
  sloping elements, which has already been done)




NAS101, Page 4 - 218
                       Workshop 6
We will apply the load on elements 1-4 using PLOAD1
 Entries




PLOAD1 Entries-
 PLOAD1,55,1,FY,LEPR,0.,-5.,161.,-5.
 PLOAD1,55,2,FY,LEPR,0.,-5.,161.,-5.
 PLOAD1,55,3,FY,LEPR,0.,-5.,161.,-5.
 PLOAD1,55,4,FY,LEPR,0.,-5.,161.,-5.

NAS101, Page 4 - 219
 Partial Input File for Workshop # 6
  $
  $ wkshp6.dat
  $
  SOL 101
  CEND
  TITLE = GARAGE ROOF FRAME
  SUBTITLE = WOOD AND STEEL MEMBERS
      DISPLACEMENT = ALL
      SPCFORCES = ALL
      STRESS = ALL
      SPC = 10
      TEMP(INIT) = 20
  SUBCASE 1
      SUBTITLE=TRUSS_LBCS
      LOAD = 1
  SUBCASE 20
      SUBTITLE = THERMAL LOAD
      TEMP(LOAD) = 26
  SUBCASE 30
      SUBTITLE = GRAVITY LOAD
      LOAD = 30
  $
  $ add snow loading callout
  $




  BEGIN BULK
  $
  $ add the snow loading entries
  $
NAS101, Page 4 - 220
  Partial Input File for Workshop # 6
                 (cont.)




NAS101, Page 4 - 221
        F06 Output for Workshop # 6





NAS101, Page 4 - 222
    Workshop # 6 - Deformed plot for
           Snow Loading





NAS101, Page 4 - 223
      Solution File for Workshop # 6





NAS101, Page 4 - 224
      Solution File for Workshop # 6
                  (cont.)





NAS101, Page 4 - 225
    Combined Loadings - The LOAD
               Entry
The LOAD entry allows you to combine multiple loading
 sets into a single loading
If you wish to combine GRAV or RFORCE entries with
 other loadings (without using SUBCOMs), this is the only
 way to do it
    GRAV entries each must have their own unique loading id
The LOAD Bulk Data entry is selected by the LOAD Case
 Control Command




NAS101, Page 4 - 226
    Combined Loadings - The LOAD
            Entry (cont.)




NAS101, Page 4 - 227
NAS101, Page 4 - 228
                       Workshop 7

               Roof Truss Structure--Combined Loads




NAS101, Page 4 - 229
      Workshop 7 - Combined Loads
Using the model from workshop 6, replace the individual
 SUBCASEs with a single SUBCASE which applies all of
 the loads simultaneously

Note: The individual loads could be combined using a
 SUBCOM, but then we would have a separate SUBCASE
 for each component of the loading




NAS101, Page 4 - 230
                       Workshop 7 (cont.)
This run requires only a LOAD entry in the Bulk Data to
 combine the individual load sets plus a single SUBCASE
 in the Case Control pointing to the LOAD entry
Use workshop 6 as a starting point

The following LOAD entry combines the loads

 LOAD,100,1.,1.,1,1.,30,1.,50




NAS101, Page 4 - 231
                       Workshop 7 (cont.)
The following Case Control applies the combined static
 loads plus the thermal load (note that the thermal load is
 retained as separate requests - the LOAD entry only
 combines the mechanical loadings)
TITLE = GARAGE ROOF FRAME
SUBTITLE = WOOD AND STEEL MEMBERS
   DISPLACEMENT = ALL
   SPCFORCES = ALL
   STRESS = ALL
   SPC = 10
TEMP(INIT) = 20
SUBCASE 100
   SUBTITLE=COMBINED LOADING
   LOAD = 100
TEMP(LOAD) = 26


NAS101, Page 4 - 232
           F06 Output for Workshop 7





NAS101, Page 4 - 233
      Deformed Plot for Workshop 7





NAS101, Page 4 - 234
              Solution for Workshop 7





NAS101, Page 4 - 235
     Solution for Workshop 7 (cont.)





NAS101, Page 4 - 236
                       Workshop 7A

               Roof Truss Structure--Combined Loads
                          using SUBCOM




NAS101, Page 4 - 237
                       Workshop 7A
For comparison, we will use a SUBCOM to combine the
 loadings

To do this, we will add the following SUBCOM to a copy of
 workshop6.dat

SUBCOM 110
SUBTITLE = COMBINED LOADINGS
SUBSEQ = 1.,1.,1.,1.
TEMP(LOAD)=26




NAS101, Page 4 - 238
            Solution for Workshop 7A





NAS101, Page 4 - 239
    Solution for Workshop 7A (cont.)





NAS101, Page 4 - 240
    The Zero-Dimensional Elements
CELAS1, CELAS2, CELAS3, CELAS4, CBUSH
The CELASi elements are connected by two degrees of
 freedom - one at each grid/ground connection point
The CBUSH elements connects from 1 to 6 dof between
 two GRID points.
Force components:            axial force P
                        or    moment M
Displacement components: axial translation u
                        or    rotation q




NAS101, Page 4 - 241
    The Zero-Dimensional Elements
                (cont.)
CELAS1          Connects two points, which may be grid points,
                 scalar points, or both, with references to a
                 property entry
CELAS2          Connects two points, which may be grid points,
                 scalar points or both, without reference to a
                 property entry
CELAS3          Connects only scalar points with reference to a
                 property entry
CELAS4          Connects only scalar points without reference
                 to property entry
CBUSH           Connects two GRID points. Avoids the
                 grounding problem inherent in CELASi
                 elements (when mis-used). May connect 1 to 6
                 dof.

NAS101, Page 4 - 242
     The Zero-Dimensional Elements
                 (cont.)
The CBUSH is the recommended form for scalar springs.

     It avoids the potential grounding which may occur when two non-
      coincident points are connected.
     The CELASi elements simply insert terms directly into the stiffness
      matrix without considering geometry or displacement coordinate
      systems.
     The CBUSH correctly accounts for the effects of geometry and
      displacement coordinate systems


See page 61 and pp. 121 through 125 of the MSC/NASTRAN Linear Static Analysis User’s
  Guide and Section 5.6 of the MSC/NASTRAN Reference Manual for detailed information
  about scalar elements. The CBUSH element is documented in the V69 Release Guide




 NAS101, Page 4 - 243
    The Zero-Dimensional Elements
                (cont.)
The CBUSH - Defines a generalized spring-and-damper
 structural element that may be nonlinear or frequency
 dependent




NAS101, Page 4 - 244
    The Zero-Dimensional Elements
                (cont.)
The CBUSH -



Field            Contents

EID              Element identification number. (Integer > 0)
PID              Property identification number of a PBUSH
                  entry. (Integer > 0; Default =EID)
GA, GB           Grid points identification number of
                  connections points. (Integer > 0)


NAS101, Page 4 - 245
    The Zero-Dimensional Elements
                (cont.)
The CBUSH -
Xi      Component of orientation vector, from GA, in
         the displacement coordinate system at GA.
GO      Alternate method to supply orientation vector
         using grid point GO. Direction is from GA to
          GO.
CID     Element coordinate system identification.
         A 0 means the basic coordinate system.
         If CID is blank, then the element coordinate
         system is determined from GO or Xi.

NAS101, Page 4 - 246
 The Zero-Dimensional Elements
        (cont.)
The CBUSH -




S                Location of spring-damper(Real; Default =0.5)

OCID       Coordinate system identification of spring-
            damper offset. (Integer; Default=-1 which
            means element coordinate system)
S1, S2, S3 Components of spring-damper offset in the
            OCID coordinate system if OCID <> 0.
NAS101, Page 4 - 247
    The Zero-Dimensional Elements
                (cont.)
The PBUSH - Defines the nominal property values for a
 generalized spring-and-damper structural element




Field            Contents
PID              Property identification number. (Integer > 0)
"K"              Flag indicating that next 1 to 6 fields are
                  stiffness values. (Character)
Ki               Nominal stiffness values in directions 1
                  through 6. (Real; Default=0.0)
NAS101, Page 4 - 248
    The Zero-Dimensional Elements
                (cont.)
The PBUSH - Defines the nominal property values for a
 generalized spring-and-damper structural element




Field            Contents
"B"              Flag indicating that the next 1 to 6 fields are
                  force-per-velocity damping. (Character)
Bi               Nominal damping cofficient in units of force per
                  unit velocity. (Real; Default=0.0)


NAS101, Page 4 - 249
    The Zero-Dimensional Elements
                (cont.)
The PBUSH - Defines the nominal property values for a
 generalized spring-and-damper structural element




Field            Contents
"GE"             Flag indicating that the next fields is structural
                  damping. (Character)
GE1              Nominal Structural damping constant.
                  (Real;Default=0.0)


NAS101, Page 4 - 250
    The Zero-Dimensional Elements
                (cont.)
Field           Contents
"RCV"           Flag indicating that the next 1 to 4 fields are stress
                 or strain coefficients. (Character)
SA              Stress recovery coefficient in the translational
                  component numbers 1 through 3. (Real,
                 Default=1.0)
ST              Stress recovery coefficient in the rotational
                  component numbers 4 through 6. (Real;
                 Default=1.0)
EA              Strain recovery coefficient in the translational
                 components. (Real; Default=1.0)
ET              Strain recovery coefficient in the rotational
                 components. (Real; Default=1.0)
NAS101, Page 4 - 251
                           Workshop 7B

                       Roof Truss Structure--Right end
                           supported with Spring




NAS101, Page 4 - 252
                   Workshop 7B (cont.)
For this workshop, let us represent the right support on
 the truss as a spring
We will start with the model from Workshop 3 (3 loading
 conditions)
Remove the constraint on GRID 7
Add an additional GRID point (GRID 700) coincident to
 GRID 7
Constrain this new GRID to have 0.0 displacements
Connect GRID 7 to GRID 700 with a y-direction spring with
 a stiffness of 10,000 lb/in



NAS101, Page 4 - 253
            Solution for Workshop 7B




NAS101, Page 4 - 254
   Solution for Workshop 7B (cont.)




NAS101, Page 4 - 255
         F06 Output for Workshop 7B




NAS101, Page 4 - 256
    Deformed Plot for Workshop 7B

                       Point Loads




NAS101, Page 4 - 257
    Deformed Plot for Workshop 7B
               (cont.)

                       Thermal Load




NAS101, Page 4 - 258
    Deformed Plot for Workshop 7B
               (cont.)

                       Gravity Load




NAS101, Page 4 - 259
                       CWELD ELEMENT
Although originally intended to be a ―spot weld‖ element,
 the CWELD is actually a ―connector‖ element, not simply a
 ―spot weld‖ element
It allows you to make connections from ―point to point‖,
 ―point to patch‖, and ―patch to patch‖
Possible uses include
    Spot Welds
    Bolts
    Screws
    Rivets




NAS101, Page 4 - 260
          CWELD Connectivity Types
    Point to point
     for nearly congruent meshes,   n
     point wise connection


    Point to patch
     for non congruent meshes,
     point to area connection


    Patch to patch (recommended
     method)
     for non congruent meshes,
     area connection



NAS101, Page 4 - 261
                       CWELD Entry




NAS101, Page 4 - 262
                       CWELD Entry




NAS101, Page 4 - 263
                       CWELD Entry




NAS101, Page 4 - 264
                       CWELD Entry




NAS101, Page 4 - 265
                       PWELD Entry




NAS101, Page 4 - 266
   CWELD Point to Point Definition

    Point to Point
    connecting shell vertex grids GA and GB




     Shell normals at GA and GB are automatically generated


NAS101, Page 4 - 267
            CWELD ―ALIGN‖ Example
   CWELD      EID      PID         ―ALIGN‖   GA   GB
   CWELD      311      4           ALIGN     4    205


   PWELD      PID      MID   D                    MSET
   PWELD      4        1     0.5                  OFF




NAS101, Page 4 - 268
                 CWELD Point to Patch
  Point to patch
  connecting shell vertex grid GS and solid grids GAi
                                        n



                                   GS



                        GA4                       GA3

                              GA



                  GA1

                                            GA2




     Shell normal at GS is automatically generated
NAS101, Page 4 - 269
                 CWELD Point to Patch
For Point to Patch, ―GRIDID‖ must be selected on the
 CWELD entry
A single GRID (GS) is then connected to a ―patch‖ of
 GRIDS (GA1-GA8) depending upon how you define the
 ―patch‖
The ―patch‖ is defined using SPTYP on the CWELD
For ―GRIDID‖, SPTYP may be ―Q‖ (quadrilateral) or ―T‖
 (triangular)
The list of GRID points on the ―patch‖ must then follow the
 order shown on the following page
The connection will be created between GS and GAi


NAS101, Page 4 - 270
                 CWELD Point to Patch




NAS101, Page 4 - 271
           CWELD ―GRIDID‖ Example
  CWELD      EID       PID         GS    ―GRIDID‖                  ―Q‖
             GA1       GA2         GA3   GA4




  PWELD      PID       MID         D


                                                   n



                                              GS



                             GA4                             GA3

                                         GA



                   GA1

NAS101, Page 4 - 272                                   GA2
                 CWELD Patch to Patch
  Patch to patch
  projecting spot weld grid GS on upper and lower shell id
  or
  projecting spot weld grid GS on grid ids of upper and lower patch
   independent of element topology.
                                        GS



                             GA4                   SHIDA
                       GB3
                                                     GA3

                                   GA
           GA1
                                             GA2           GB2


                                        GB         SHIDB


                             GB1
NAS101, Page 4 - 273
          CWELD ―ELEMID‖ Example
   CWELD      EID      PID     GS   ―ELEMID‖
              SHIDA    SHIDB


   PWELD      PID      MID     D

                                          GS


                                               SHIDA




                                               SHIDB



NAS101, Page 4 - 274
           CWELD ―GRIDID‖ Example
  CWELD      EID       PID    GS    ―GRIDID‖                    ―QT‖
             GA1       GA2    GA3   GA4
             GB1       GB2    GB3


  PWELD      PID       MID    D

                                               GS


                                    GA4
                        GB3
                                                          GA3



              GA1
                                                    GA2                GB2




NAS101, Page 4 - 275                GB1
                   CWELD GEOMETRY
  Normal projection of spot weld grid GS on surface
   patch A and B, respectively, determines the spot weld
   element axis GA,GB.
                                        GS
                             GA4



                                                   GA3
                                        GA
                         GA1

                                                   GA2
                       GB1                   GB3
                                   GB

                                             GB2

NAS101, Page 4 - 276
                   CWELD GEOMETRY
       For the general connector, the effective length for stiffness
        calculation is adjusted in case of extremely short (if L<0.2*D,
        then Le = .2D) and long ( if L>5.0*D, then Le = 5.0D)
        connections
       For ―ELEMID‖ with weld type ―SPOT‖ the effective length is
        always:
                     L= 0.5*(TA+TB)
        where TA and TB are the shell thicknesses.
       For coincident grids GS,GA,GB, the local normal of the first
        surface is the spot weld element axis
                         GS                           n




                       GA,GB                       GS,GA,GB




NAS101, Page 4 - 277
           PWELD Property Definition
          Material
          Diameter D
          Flag to write or condense m-set (MSET) dof
          Options for weld type
                General connector (BLANK) or SPOT
                More types in future releases




NAS101, Page 4 - 278
      INTERNAL REPRESENTATION
        OF THE WELD ELEMENT
       WELD
        Bar type element with normal, shear, bending
         and torsional stiffness based on weld diameter D
         and length L (2 points x 6 dof)
       CONNECTION OF WELD
        Point to point connection with vertex shell
         normals (no torsional stiffness calculated)
        Point to patch or patch to patch connection with
         Kirchhoff constraints (6 or 2x6 constraints)



NAS101, Page 4 - 279
    WELD TO PATCH CONNECTION
        Interpolation constraints for translations
                                                                                 z
        u                          u 
                                    
         v    N I  A ,  A    v 
        w                          w                                  GA4        y
         A                          I
                                                                                          GA3
                                                                                GA
                                                                                     x
        Kirchhoff constraints for rotations                         GA1                  GA2



                 w
        q xA         N I , y  wI
                 y

                   w
        q yA  -       -  N I , x  wI
                   x

                 1  v u  1
        q zA       -        N I , x  v I -  N I , y u I 
                 2  x y  2
NAS101, Page 4 - 280
                               RESULTS OUTPUT
                                                      mx


                                                     fx

                                                                          m zB
                                                      xe
                                                                    fz
                                                GB


                                                                    fy              fx   axial force
                                                                                    fy   shear forceplane 1
                        m yA                                             m yB
                                                          plane 2                   fz   shear forceplane 2
                                      fy                                            m x torque
                                           GA                   ze                  m yA bending moment end A, plane 2
                                                           plane1                   m yB bending moment end B, plane 2
                                 fz
                                                                ye                  m zA bending moment end A, plane 1
                      m zA
                                            fx                                      m zB bending moment end B, plane 1
    zb
         yb

              xb                           mx



         Figure: CWELD Element Coordinate System and Sign Convention of Element Forces and Moments


NAS101, Page 4 - 281
                       Results of Testing

       Good agreement with results from beam and
        shell theory
       6 rigid body modes for all cases:
        curved geometry, midside nodes, etc.
       More accurate than traditional modeling tools
        like RBAR, RBE2, RBE3 etc.




NAS101, Page 4 - 282
            BENCHMARK PROBLEMS
       Models from several car manufacturers have
        been tested by MSC
       V2001 beta has been tested by VW
          see AUC 2000 paper by A.Jonscher, M.Lewerenz, C.Hoff,
          MSC.Nastran’s New Spot Weld Element in the CAE Process
       Good agreement with experimental results of a
        Body in White




NAS101, Page 4 - 283
                       CWELD SUMMARY
            Constraints are always of proper rank,
             results are free of spurious modes
            No K6ROT or SNORM necessary
            Option without constraints (no m-set dof)
            Takes diameter (area) into account
            Diameter can cover up to a whole element or
             a surface patch of up to 8 grids
            Minimum number of dof and constraints
            Handles non congruent meshes



NAS101, Page 4 - 284
                       Sample Problem
   The sample is a simple plate-to-plate connection
   The connection is between 2 parallel plates
   One plate is constrained at one end
   The loads are applied on the end of the other plate
   The connection will be done 2 ways:
    1) Point-to-point
    2) patch-to-patch




NAS101, Page 4 - 285
                       Sample Problem   Loads applied on
                                           this edge
 1) Point-to-point CWELD
          elements




2) Patch-to-patch
CWELD element




NAS101, Page 4 - 286
      Sample Problem – Point-to-Point                    PARAM    POST    0
$ file weldtest_point_to_point.dat
SOL 101                                                  PSHELL   100     10      .1      10     1.             .833333
                                                         CQUAD4   4002    100     4002    4003   5003    5002   0.      0.
CEND
                                                         CQUAD4   4012    100     5014    5015   5021    5020   0.      0.
TITLE = point-to-point cweld element example
                                                         MAT1     10      3.+7    1.153+7 .3     .0074
   SPC = 1                                               GRID     4001            .5      1.5    0.
   DISPLACEMENT(plot)=ALL                                GRID     4002            1.      1.5    0.
   SPCFORCES(plot)=ALL                                   GRID     4003            1.5     1.5    0.
   STRESS(PLOT)=ALL                                      GRID     4004            2.      1.5    0.
   set 998 = 1,2                                         GRID     5002            1.      2.     0.
   FORCE=998                                             GRID     5003            1.5     2.     0.
   set 999 = 4001,4004,5013,5016                         GRID     5013            .5      1.5    .25
                                                         GRID     5014            1.      1.5    .25
   gpforce = 999
                                                         GRID     5015            1.5     1.5    .25
SUBCASE 1
                                                         GRID     5016            2.      1.5    .25
   SUBTITLE=force x                                      GRID     5020            1.      2.     .25
   LOAD = 1                                              GRID     5021            1.5     2.     .25
SUBCASE 2                                                SPC1     1       123456 1000     THRU   1005
   SUBTITLE=force y                                      $ Nodal Forces of Load Set : force x
   LOAD = 3                                              FORCE    1       5030    0       1.     1.      0.     0.
SUBCASE 3                                                FORCE    1       5031    0       1.     1.      0.     0.
   SUBTITLE=force z                                      FORCE    1       5032    0       1.     1.      0.     0.
                                                         FORCE    1       5033    0       1.     1.      0.     0.
   LOAD = 5
                                                         FORCE    1       5034    0       1.     1.      0.     0.
SUBCASE 4
                                                         FORCE    1       5035    0       1.     1.      0.     0.
   SUBTITLE=moment z                                     $ Nodal Forces of Load Set : moment z
   LOAD = 7                                              FORCE    7       5006    0       1.     0.      1.     0.
BEGIN BULK                                               FORCE    7       5011    0       1.     0.      -1.    0.
$ use 2 elements for stability (no torsional stiffness   ENDDATA
$ in point-to-point)
cweld,1,11,,align,4004,5016
cweld,2,11,,align,4001,5013
pweld,11,10,.3
$
  NAS101, Page 4 - 287
1
       Sample Problem – Point-to-Point
     POINT-TO-POINT CWELD ELEMENT EXAMPLE                                   FEBRUARY     26, 2001   MSC.NASTRAN   2/23/01   PAGE   13
     FORCE X                                                                                                      SUBCASE 1
                                   F O R C E S   I N   W E L D   E L E M E N T S       ( C W E L D )

    ELEMENT           BEND-MOMENT END-A             BEND-MOMENT END-B                 - SHEAR -               AXIAL
      ID          PLANE 1 (MZ) PLANE 2 (MY)    PLANE 1 (MZ) PLANE 2 (MY)      PLANE 1 (FY) PLANE 2 (FZ)      FORCE FX     TORQUE MX
          1       4.138080E-01 9.247767E-01 -3.361920E-01 -5.752233E-01       3.000000E+00 -6.000000E+00 -4.482560E-01     .0
          2       4.138080E-01 -9.247767E-01 -3.361920E-01 5.752233E-01       3.000000E+00 6.000000E+00    4.482560E-01    .0
1    POINT-TO-POINT CWELD ELEMENT EXAMPLE                                    FEBRUARY 26, 2001 MSC.NASTRAN 2/23/01      PAGE    19
     FORCE X                                                                                                  SUBCASE 1
                                           G R I D    P O I N T   F O R C E    B A L A N C E
    POINT-ID    ELEMENT-ID     SOURCE              T1             T2              T3             R1             R2             R3
       4001          3000    QUAD4         -1.198263E+00 -3.102399E+00 -2.281184E-01       2.720501E-01 -8.206545E-02     .0
       4001          3001    QUAD4         -9.204701E-01 -1.672550E+00 -3.498562E-01       3.953950E-01 -1.742824E-01     .0
       4001          4000    QUAD4          5.588197E-03 -5.286519E-01      1.519746E-02   8.891658E-02 -4.265509E-02     .0
       4001          4001    QUAD4         -8.868553E-01 -6.963984E-01      1.145210E-01   1.684151E-01 -1.148050E-01     .0
       4001             2    WELD           3.000000E+00    6.000000E+00    4.482560E-01 -9.247767E-01    4.138080E-01    .0
       4001                  *TOTALS*       1.998401E-14 -2.664535E-15 -1.487699E-14         .0          -1.332268E-15    .0
0      4004          3003    QUAD4         -9.204701E-01    1.672550E+00    3.498562E-01 -3.953950E-01 -1.742824E-01      .0
       4004          3004    QUAD4         -1.198263E+00    3.102399E+00   2.281184E-01 -2.720501E-01 -8.206545E-02       .0
       4004          4003    QUAD4         -8.868553E-01    6.963984E-01 -1.145210E-01 -1.684151E-01 -1.148050E-01        .0
       4004          4004    QUAD4          5.588197E-03    5.286519E-01 -1.519746E-02 -8.891658E-02 -4.265509E-02        .0
       4004             1    WELD           3.000000E+00 -6.000000E+00 -4.482560E-01       9.247767E-01   4.138080E-01    .0
       4004                  *TOTALS*       1.021405E-14    3.552714E-15    2.875478E-14   1.554312E-15 -3.885781E-15     .0
0      5013          4005    QUAD4          6.686928E-01    8.557717E-01 -1.013758E-01     6.517072E-02 -3.272174E-02     .0
       5013          4006    QUAD4          2.538449E-01    9.084527E-01    1.370176E-01   1.395422E-01 -9.810203E-02     .0
       5013          4010    QUAD4          2.827896E-01    1.588919E+00    1.068439E-01   1.542671E-01 -8.540848E-02     .0
       5013          4011    QUAD4          1.794673E+00    2.646857E+00    3.057704E-01   2.162432E-01 -1.199598E-01     .0
       5013             2    WELD          -3.000000E+00 -6.000000E+00 -4.482560E-01 -5.752233E-01        3.361920E-01    .0
       5013                  *TOTALS*      -3.552714E-15 -1.154632E-14      1.337819E-14 -1.032507E-14    3.164136E-15    .0
0      5016          4008    QUAD4          2.538449E-01 -9.084527E-01 -1.370176E-01 -1.395422E-01 -9.810203E-02          .0
       5016          4009    QUAD4          6.686928E-01 -8.557717E-01      1.013758E-01 -6.517072E-02 -3.272174E-02      .0
       5016          4013    QUAD4          1.794673E+00 -2.646857E+00 -3.057704E-01 -2.162432E-01 -1.199598E-01          .0
       5016          4014    QUAD4          2.827896E-01 -1.588919E+00 -1.068439E-01 -1.542671E-01 -8.540848E-02          .0
       5016             1    WELD          -3.000000E+00    6.000000E+00   4.482560E-01    5.752233E-01   3.361920E-01    .0
       5016                  *TOTALS*      -1.332268E-15    5.417888E-14 -1.987299E-14     1.443290E-15 -1.609823E-15     .0

    NAS101, Page 4 - 288
     Sample Problem – Patch-to-Patch
$ file weldtest_patch_to_patch.dat
                                                       PARAM    POST    0
SOL 101                                                PSHELL   100     10      .1      10     1.             .833333
CEND                                                   CQUAD4   4002    100     4002    4003   5003    5002   0.      0.
TITLE = patch-to-patch cweld element example           CQUAD4   4012    100     5014    5015   5021    5020   0.      0.
   SPC = 1                                             MAT1     10      3.+7    1.153+7 .3     .0074
   DISPLACEMENT(plot)=ALL                              GRID     100             1.25    1.25   1.
   SPCFORCES(plot)=ALL                                 GRID     4001            .5      1.5    0.
   STRESS(PLOT)=ALL                                    GRID     4002            1.      1.5    0.
                                                       GRID     4003            1.5     1.5    0.
   set 998 = 1,2
                                                       GRID     4004            2.      1.5    0.
   FORCE=998
                                                       GRID     5002            1.      2.     0.
   set 999 = 3002,3003,4002,4003,5008,5009,5014,5015   GRID     5003            1.5     2.     0.
   gpforce = 999                                       GRID     5013            .5      1.5    .25
SUBCASE 1                                              GRID     5014            1.      1.5    .25
   SUBTITLE=force x                                    GRID     5015            1.5     1.5    .25
   LOAD = 1                                            GRID     5016            2.      1.5    .25
SUBCASE 2                                              GRID     5020            1.      2.     .25
   SUBTITLE=force y                                    GRID     5021            1.5     2.     .25
                                                       SPC1     1       123456 1000     THRU   1005
   LOAD = 3
                                                       $ Nodal Forces of Load Set : force x
SUBCASE 3
                                                       FORCE    1       5030    0       1.     1.      0.     0.
   SUBTITLE=force z                                    FORCE    1       5031    0       1.     1.      0.     0.
   LOAD = 5                                            FORCE    1       5032    0       1.     1.      0.     0.
SUBCASE 4                                              FORCE    1       5033    0       1.     1.      0.     0.
   SUBTITLE=moment z                                   FORCE    1       5034    0       1.     1.      0.     0.
   LOAD = 7                                            FORCE    1       5035    0       1.     1.      0.     0.
BEGIN BULK                                             $ Nodal Forces of Load Set : moment z
$ use 1 patch-to-patch element                         FORCE    7       5006    0       1.     0.      1.     0.
                                                       FORCE    7       5011    0       1.     0.      -1.    0.
cweld,1,11,100,gridid,,,qq
                                                       ENDDATA
,5008,5014,5015,5009
,3002,4002,4003,3003
grid,100,,1.25,1.25,1.
pweld,11,10,.3
$
  NAS101, Page 4 - 289
      Sample Problem – Patch-to-Patch
1    PATCH-TO-PATCH CWELD ELEMENT EXAMPLE                                        FEBRUARY    26, 2001   MSC.NASTRAN   2/23/01   PAGE   13
     FORCE X                                                                                                          SUBCASE 1
                                    F O R C E S        I N   W E L D   E L E M E N T S      ( C W E L D )

  ELEMENT           BEND-MOMENT END-A             BEND-MOMENT END-B                     - SHEAR -                AXIAL
    ID          PLANE 1 (MZ) PLANE 2 (MY)     PLANE 1 (MZ) PLANE 2 (MY)         PLANE 1 (FY) PLANE 2 (FZ)       FORCE FX      TORQUE MX
         1     -1.243632E-13 -1.911339E-13    1.500000E+00 2.574135E-13        -6.000000E+00 1.794190E-12     2.155437E-13 -1.050000E+01
1     PATCH-TO-PATCH CWELD ELEMENT EXAMPLE                                        FEBRUARY 26, 2001 MSC.NASTRAN 2/23/01       PAGE    19
       FORCE X                                                                                                      SUBCASE 1
                                             G R I D  P O I    N T   F O R C   E   B A L A N C E
    POINT-ID    ELEMENT-ID     SOURCE               T1                T2               T3              R1             R2             R3
       3002                  F-OF-MPC        -3.750000E+00      5.250000E+00     1.500000E+00     .0             .0             .0
       3002          2001    QUAD4           -1.935388E-01     -3.261676E+00    -3.721753E-02 -1.342836E-02 -1.418169E-01       .0
       3002          2002    QUAD4            3.882505E-01     -1.248684E+00    -1.561370E+00    7.583191E-02   2.052062E-01    .0
       3002          3001    QUAD4            2.675819E+00     -1.719266E+00    -1.684336E-01 -4.071281E-02 -6.010709E-02       .0
       3002          3002    QUAD4            8.794696E-01      9.796265E-01     2.670216E-01 -2.169073E-02 -3.282173E-03       .0
       3002                  *TOTALS*         1.543210E-14      2.220446E-15     1.287859E-14    2.307182E-15   6.054185E-16    .0
0      3003                  F-OF-MPC        -3.750000E+00     -5.250000E+00    -1.500000E+00     .0             .0             .0
       3003          2002    QUAD4            3.882505E-01      1.248684E+00     1.561370E+00 -7.583191E-02     2.052062E-01    .0
       3003          2003    QUAD4           -1.935388E-01      3.261676E+00     3.721753E-02    1.342836E-02 -1.418169E-01     .0
       3003          3002    QUAD4            8.794696E-01     -9.796265E-01    -2.670216E-01    2.169073E-02 -3.282173E-03     .0
       3003          3003    QUAD4            2.675819E+00      1.719266E+00     1.684336E-01    4.071281E-02 -6.010709E-02     .0
       3003                  *TOTALS*         7.549517E-15      3.330669E-15    -4.632406E-14 -2.595146E-15 -4.232725E-16       .0
0      4002                  F-OF-MPC         6.750000E+00      5.250000E+00     1.500000E+00     .0             .0             .0
       4002          3001    QUAD4           -3.463663E+00     -2.966465E+00     2.102813E-02    5.537652E-02 -1.316848E-01     .0
       4002          3002    QUAD4           -8.794696E-01      7.793126E-01    -8.032993E-01 -5.241801E-03     1.373516E-01    .0
       4002          4001    QUAD4           -1.204910E+00     -1.213300E+00    -2.031264E-01    1.764892E-02 -1.025030E-01     .0
       4002          4002    QUAD4           -1.201958E+00     -1.849547E+00    -5.146024E-01 -6.778364E-02     9.683615E-02    .0
       4002                  *TOTALS*         3.419487E-14      2.664535E-15     1.654232E-14 -2.123302E-15 -2.400857E-15       .0
0      4003                  F-OF-MPC         6.750000E+00     -5.250000E+00    -1.500000E+00     .0             .0             .0
       4003          3002    QUAD4           -8.794696E-01     -7.793126E-01     8.032993E-01    5.241801E-03   1.373516E-01    .0
       4003          3003    QUAD4           -3.463663E+00      2.966465E+00    -2.102813E-02 -5.537652E-02 -1.316848E-01       .0
       4003          4002    QUAD4           -1.201958E+00      1.849547E+00     5.146024E-01    6.778364E-02   9.683615E-02    .0
       4003          4003    QUAD4           -1.204910E+00      1.213300E+00     2.031264E-01 -1.764892E-02 -1.025030E-01       .0
       4003                  *TOTALS*         1.332268E-15     -2.442491E-15    -2.134404E-14 -1.394718E-15 -3.053113E-16       .0
    NAS101, Page 4 - 290
  Sample Problem – Patch-to-Patch
Why does the CWELD show up as MPC forces?
Because the default value for MSET on the PWELD entry is
 ―ON‖, which generates MPC-equations to connect the
 element to the RGID points
Let us try again with MSET = ―OFF‖




NAS101, Page 4 - 291
     Sample Problem – Patch-to-Patch
$ file weldtest_patch_to_patch.dat
                                                       PARAM    POST    0
SOL 101                                                PSHELL   100     10      .1      10     1.             .833333
CEND                                                   CQUAD4   4002    100     4002    4003   5003    5002   0.      0.
TITLE = patch-to-patch cweld element example           CQUAD4   4012    100     5014    5015   5021    5020   0.      0.
   SPC = 1                                             MAT1     10      3.+7    1.153+7 .3     .0074
   DISPLACEMENT(plot)=ALL                              GRID     100             1.25    1.25   1.
   SPCFORCES(plot)=ALL                                 GRID     4001            .5      1.5    0.
   STRESS(PLOT)=ALL                                    GRID     4002            1.      1.5    0.
                                                       GRID     4003            1.5     1.5    0.
   set 998 = 1,2
                                                       GRID     4004            2.      1.5    0.
   FORCE=998
                                                       GRID     5002            1.      2.     0.
   set 999 = 3002,3003,4002,4003,5008,5009,5014,5015   GRID     5003            1.5     2.     0.
   gpforce = 999                                       GRID     5013            .5      1.5    .25
SUBCASE 1                                              GRID     5014            1.      1.5    .25
   SUBTITLE=force x                                    GRID     5015            1.5     1.5    .25
   LOAD = 1                                            GRID     5016            2.      1.5    .25
SUBCASE 2                                              GRID     5020            1.      2.     .25
   SUBTITLE=force y                                    GRID     5021            1.5     2.     .25
                                                       SPC1     1       123456 1000     THRU   1005
   LOAD = 3
                                                       $ Nodal Forces of Load Set : force x
SUBCASE 3
                                                       FORCE    1       5030    0       1.     1.      0.     0.
   SUBTITLE=force z                                    FORCE    1       5031    0       1.     1.      0.     0.
   LOAD = 5                                            FORCE    1       5032    0       1.     1.      0.     0.
SUBCASE 4                                              FORCE    1       5033    0       1.     1.      0.     0.
   SUBTITLE=moment z                                   FORCE    1       5034    0       1.     1.      0.     0.
   LOAD = 7                                            FORCE    1       5035    0       1.     1.      0.     0.
BEGIN BULK                                             $ Nodal Forces of Load Set : moment z
$ use 1 patch-to-patch element                         FORCE    7       5006    0       1.     0.      1.     0.
                                                       FORCE    7       5011    0       1.     0.      -1.    0.
cweld,1,11,100,gridid,,,qq
                                                       ENDDATA
,5008,5014,5015,5009
,3002,4002,4003,3003
grid,100,,1.25,1.25,1.
pweld,11,10,.3,,,OFF
$
  NAS101, Page 4 - 292
                                                            Set MSET to OFF
      Sample Problem – Patch-to-Patch
1    PATCH-TO-PATCH CWELD ELEMENT EXAMPLE                                     FEBRUARY     26, 2001   MSC.NASTRAN   2/23/01   PAGE   13
     FORCE X                                                                                                        SUBCASE 1
                                   F O R C E S     I N   W E L D    E L E M E N T S      ( C W E L D C )

  ELEMENT           BEND-MOMENT END-A            BEND-MOMENT END-B                    - SHEAR -               AXIAL
    ID          PLANE 1 (MZ) PLANE 2 (MY)    PLANE 1 (MZ) PLANE 2 (MY)       PLANE 1 (FY) PLANE 2 (FZ)       FORCE FX      TORQUE MX
         1     -1.277931E-13 -1.986996E-13   1.500000E+00 2.501067E-13      -6.000000E+00 1.795225E-12     1.939893E-13 -1.050000E+01
1     PATCH-TO-PATCH CWELD ELEMENT EXAMPLE                                      FEBRUARY 26, 2001 MSC.NASTRAN 2/23/01      PAGE    14
       FORCE X                                                                                                   SUBCASE 1
                                             G R I D   P O   I N T   F O R C E    B A L A N C E
    POINT-ID    ELEMENT-ID     SOURCE               T1               T2              T3             R1             R2             R3
       3002          2001    QUAD4           -1.935388E-01    -3.261676E+00 -3.721753E-02 -1.342836E-02 -1.418169E-01        .0
       3002          2002    QUAD4            3.882505E-01    -1.248684E+00 -1.561370E+00     7.583191E-02   2.052062E-01    .0
       3002          3001    QUAD4            2.675819E+00    -1.719266E+00 -1.684336E-01 -4.071281E-02 -6.010709E-02        .0
       3002          3002    QUAD4            8.794696E-01     9.796265E-01    2.670216E-01 -2.169073E-02 -3.282173E-03      .0
       3002             1    WELDC           -3.750000E+00     5.250000E+00   1.500000E+00     .0             .0             .0
       3002                  *TOTALS*         1.021405E-14    -1.065814E-14 -1.865175E-14     8.569534E-16   2.460272E-15    .0
0      3003          2002    QUAD4            3.882505E-01     1.248684E+00    1.561370E+00 -7.583191E-02    2.052062E-01    .0
       3003          2003    QUAD4           -1.935388E-01     3.261676E+00    3.721753E-02   1.342836E-02 -1.418169E-01     .0
       3003          3002    QUAD4            8.794696E-01    -9.796265E-01 -2.670216E-01     2.169073E-02 -3.282173E-03     .0
       3003          3003    QUAD4            2.675819E+00     1.719266E+00    1.684336E-01   4.071281E-02 -6.010709E-02     .0
       3003             1    WELDC           -3.750000E+00    -5.250000E+00 -1.500000E+00       .0            .0             .0
       3003                  *TOTALS*         5.773160E-15     1.243450E-14 -2.597922E-14     4.232725E-16   2.539635E-15    .0
0      4002          3001    QUAD4           -3.463663E+00    -2.966465E+00    2.102813E-02   5.537652E-02 -1.316848E-01     .0
       4002          3002    QUAD4           -8.794696E-01     7.793126E-01 -8.032993E-01 -5.241801E-03      1.373516E-01    .0
       4002          4001    QUAD4           -1.204910E+00    -1.213300E+00 -2.031264E-01     1.764892E-02 -1.025030E-01     .0
       4002          4002    QUAD4           -1.201958E+00    -1.849547E+00 -5.146024E-01 -6.778364E-02      9.683615E-02    .0
       4002             1    WELDC            6.750000E+00     5.250000E+00    1.500000E+00     .0            .0             .0
       4002                  *TOTALS*         1.776357E-14    -4.440892E-15    8.215650E-15 -2.692291E-15 -3.858025E-15      .0
0      4003          3002    QUAD4           -8.794696E-01    -7.793126E-01    8.032993E-01   5.241801E-03   1.373516E-01    .0
       4003          3003    QUAD4           -3.463663E+00     2.966465E+00 -2.102813E-02 -5.537652E-02 -1.316848E-01        .0
       4003          4002    QUAD4           -1.201958E+00     1.849547E+00   5.146024E-01    6.778364E-02   9.683615E-02    .0
       4003          4003    QUAD4           -1.204910E+00     1.213300E+00   2.031264E-01 -1.764892E-02 -1.025030E-01       .0
       4003             1    WELDC            6.750000E+00    -5.250000E+00 -1.500000E+00       .0            .0             .0
       4003                  *TOTALS*         9.769963E-15     3.552714E-15 -3.241851E-14     8.396062E-16 -3.802514E-15     .0
    NAS101, Page 4 - 293
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NAS101, Page 4 - 294

				
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