Modeling of Fiber Reinforced Structures in hypermesh

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					    Modeling of Fiber Reinforced Structures in
                   HyperMesh
                               Dr.-Ing. U. Weerts, Dr.-Ing. R. Kickert

                                , Lilienthalplatz 5, 38126 Braunschweig, Germany


Fiber reinforced polymers are today increasingly used in all types of components. A time efficient
simulation process with a tight quality assurance is needed, especially with large numbers of parameters
being involved for describing material and failure characteristics. A modular concept for the design of
fiber reinforced structures is presented. As most of the “state of the art” ply failure criteria are not
supported by commercial finite element programs, pre- and post-processing tools must be modified in a
easy to use way by user-programmable features.

Libraries of material data including all essential strength properties and ply specific data are combined in
a spreadsheet program to laminate properties. These are transferred to HyperMesh via the HMASCII
interface using collectors including material data and ply specific data by card images. With the provided
geometry the structured meshing capabilities of HyperMesh are used, to build up the finite element
model. The analysis and post-processing is done with the commercial FE-program ANSYS. The
necessary ply failure criteria considering static and fatigue behavior are implemented by user-
programmable features, to support an efficient in time reporting.




                                                  Slide 1
                         Company Review


                          Inhouse-code development

Circular antenna (DLR)                               Blade root – hub connection
                                                             (REpower)




 Motorsailplane eta η                                 Train nose section (Voith)


                                     Slide 2
                       Introduction

• FE-Modeling of FRP-structures is time-consuming caused
  by numerous parameters
   – material and strength properties (fiber failure,
     intralaminar failure) for all used fabrics
   – many regions with different laminat lay-up
   – material, orientation and thickness of each layer
• Most “state of the art” failure criteria are not supported by
  commercial FE-programs
• Many not supported layer- or ply-based results-
  representations in commercial FE-programs



                             Slide 3
           Static Failure Criteria for FRP
                                                  UD-failure criteria
•   Fiber- and intralaminar-                                 (Puck)
    failure
    – UD-plies: Puck(1),
        Hoffman, Tsai-Wu, ...
    – Biaxial Fabrics:
        a) Devide into two UD-
            plies using Puck, ...
        b) fabric-failure-criteria,
            intralaminar shear load
            is separated

•   Core-failure: criteria based on transverse shear loads
•   Interlaminar failure: fracture mechanical criteria

                              Slide 4
           Fatigue Failure Criteria for FRP
• Fiber-, intralaminar- and core-failure:
   – principal of the critical section plane
     (non-proportional loading)
   – Calculation of range-mean-loading
     by the utilization degrees of the used
     failure criteria
   – damage accumulation with Wöhler-
     rule and mean-stress-effect             intralaminar section plane
     (e.g. Goodman-relationship     (2))

• Interlaminar-failure:
   – the crack plane is the interface plane
   – energy based crack-propagation-analysis (e.g. Paris-
     law)

                                  Slide 5
              Modular Design Concept
Spreadsheet                                 Material-library
               Data of fabrics
                                               Ply-data
               Laminat lay-up
                                           Region-Collectors
          Geometry, Loads, BC
                                            Preprocessing
                                                Solver
          Failure criteria of FRP
                                            Postprocessing



                                 Slide 6
                      Material Properties and Ply-data
• Spreadsheet based library of elasticity- and strength-
  properties for static and fatigue-loads
• Properties depend nonlinear on the fiber-volume-fraction
Material properties

Nr. Description                       θF        ρL          E1       E2      ν 12    G12       α1        α2       R1(+)    R1(−)    R2(+)
                                      /( )    /(kg/m³)    /(GPa)   /(GPa)    /( )   /(GPa)   /(10-6)   /(10-6)   /(MPa)   /(MPa)   /(MPa)

 1   2AX090-Fabrics-E-Glas           0.45      1780       20.000   20.000   0.100   3.000    4.000     4.000     280.00   280.00   280.00
 2   Foam-C70.55                      ---       60        0.045    0.045    0.250   0.018    80.000    80.000     1.30     1.30     1.30
 3
 4




• Ply-data with material-reference and fiber-grammage
Ply-data

Nr. Description                    Mat.-Nr.      qF        tL
                                     /( )     /(g/m²)    /(mm)

 1   2AX090-Fabrics CS-ITG 92110      1        163        0.14
 2   2AX090-Fabrics CS-ITG 92125      1        280        0.24
 3   Foam-C70.55                      2         ---       1.00
 4
 5




                                                         Slide 7
                                                   Laminat Lay-up
• The laminat lay-up is combined in Region-Collectors
• Each Region-Collector is assigned to an element-type
• Each layer is defined by the quantity of the plies, the sort-
  number and their orientations
Ply-data                                                       Elementtype

Nr. Description                       qF     tL                  Nr.   Name          K1   K2   K3   K4   K5   K6   K7   K8   K9 K10 K11 Remark
                                   /(g/m²) /(mm)

 1   2AX090-Fabrics CS-ITG 92110    163    0.14                   1    SHELL91       16                                 0            0    Nodes at middle surface
 2   2AX090-Fabrics CS-ITG 92125    280    0.24                   2    SHELL91       16                                 0            1    Nodes at bottom surface
 3   Foam-C70.55                     ---   1.00                   3    SHELL91       16                                 0            2    Nodes at top surface



Laminate lay-up

                                                                     Layernumber
                  ANSYS                        HMASCII
                                                                     BOTTOM
Nr. Region Collector                nL       tL  ITYPE LSYM ADMS L1                  L2             L3            L4            L5             L6
                                    /( )   /(mm)   /( ) /( ) /(kg/m²) Qty Ply Ori Qty Ply Ori Qty Ply Ori Qty Ply Ori Qty Ply             Ori Qty Ply     Ori
                                                                                  )             )             )
                                                                      /( ) /( ) /(° /( ) /( ) /(° /( ) /( ) /(° /( ) /( ) /(° /( ) /( )
                                                                                                                            )               )
                                                                                                                                          /(° /( ) /( )     )
                                                                                                                                                          /(°
                                                                       2    2    2    1    1    1    2    2    2   1    1    1   2  2      2    0    0     0
 1   Example Region 1                5      3.77    3                  1    1    0    1    2   45    3    3    0   1    2   45   1  1      0
 2   Example Region 2                5      3.28    3                  1    1    0                   3    3    0                 1  1      0
 3
 4




                                                                       Slide 8
               HyperMesh-Interface(3)
• The collected spreadsheet-data       HYPERMESH Input Deck Generated by leichtwerk : 2.0
                                       Generated using leichtwerk-HmAscii Template Version : 2.0
                                       *filetype(ASCII)
  are transferred via a HmAscii-File   *version(8.0)

                                       BEGIN DATA

• Material data including strength     BEGIN MATERIALS
                                       *material(1,"2AX090-Fabrics-E-Glas",7)

  properties are assigned to            *attributesforentity(MATERIALS,1,67)
                                        *attributeint(1,500,0,0,8)
                                        ...

  Material-Collectors                  END MATERIALS

                                       BEGIN PROPERTIES
                                       *property(1,"Example Region 1",0,7)
• The laminat lay-up is saved in        *attributesforentity(PROPERTIES,1,10)
                                        *attributeint(0,3032,0,0,8)
                                        ...
  Property-Collectors                  END PROPERTIES

                                       BEGIN COMPONENTS

• Component-Collectors are             *component(1,"Example Region 1",1,5)
                                        *attributesforentity(COMPS,1,3)
                                        *attributeint(0,3080,0,0,8)

  defined with property- and            ...
                                       END COMPONENTS


  element-type-reference               BEGIN SENSORS
                                       *sensor(1,"SHELL91_MID")
                                        *attributesforentity(SENSORS,1,14)
                                        *attributeint(0,1202,0,0,8)

• The element-type definitions are      *attributeint(91,141,0,0,8)
                                        ...
                                       END SENSORS

  saved in Sensor-Collectors           END DATA




                            Slide 9
          Preprocessing (HyperMesh)
• Geometry is imported by
  IGES-interface                     FE-Model of a train nose section (Voith)
• Geometry is organized by
  the predefined region-
  collectors
• FRP-parts are meshed with
  second-order-elements
• The structured meshing
  capabilities of HyperMesh
  are used
• Bondings are realized with
  second-order-solids


                          Slide 10
                           Solver and UPF
• The analyses are performed
  with ANSYS                   Pressure distribution of a train nose section (Voith)
• Therefore, the HyperMesh
  ADPL-Interface is used
• Aerodynamic surface loads
  are applied via an external
  Nastran BDF-interface
• The layer based static-
  and fatigue-failure-criteria
  are included by User-
  Programmable-Features
  (UPF)


                                       Slide 11
                          Postprocessing
• following items are currently supported for static analysis:
                                                            Fiber-Failure-Index
   – Intralaminar-failure-index
   – Intralaminar-failure-mode
   – Intralaminar-failure-angle
   – Fiber-failure-index
   – Layer stresses and
      strains               Intralaminar-Failure-Index Intralaminar-Failure-Mode

   – Layer orientations
   – Core-failure-index
   – Core shear stresses



                                     Slide 12
                      Postprocessing
• following items are currently              Range-mean-matrix of a
                                               blade root section
  supported for fatigue-analysis:
   – Intralaminar-failure-index
   – Fiber-failure-index
   – Core-failure-index
• damage accumulation can be
  performed for
   – Range-mean-matrices with
      serial consideration of multiple unit-loadcases
   – Load-time-series with superposition of unit-loadcases
      (principle of the critical section plane)


                               Slide 13
                               Summary
• modular design to combine the potentials of the programs
   – Spreadsheet based         Spreadsheet                     Material-library

      material libraries                  Data of fabrics

   – Spreadsheet based                                            Ply-data

                                          Laminat lay-up
      laminat-modeler
                                                              Region-Collectors
   – Preprocessing with               Geometry, Loads, BC
      HyperMesh                                                Preprocessing

   – Solver ANSYS                                                  Solver

   – Postprocessing with              Failure criteria of FRP

      customized ANSYS                                         Postprocessing


• currently analyses of static- and fatigue-behavior of UD-
  plies, several fabrics and cores are supported

                                    Slide 14
          Further Activities and Outlook
• Implementation of failure analysis
  of metals (FKM-guidlines(4))
• Solver independent failure
  analysis, therefore
  implementation of failure criteria
  and layer based output in                 ▬ B-Basis
                                            ▬ Regression


  HyperView
• Extension of the HyperMesh
  ADPL-Interface by customized
  Bonding-Interface-Elements(5)
  (J-Integral, Crack-Propagation)
                                      Crack-propagation-analysis of a bonded repair


                           Slide 15
                           References


(1) A. Puck, Festigkeitsanalyse von Faser-Matrix-Laminaten, München, 1996
(2) Germanischer Lloyd, Richtlinie für die Zertifizierung von
    Windenergieanlagen, Hamburg, 2003.
(3) HyperMesh User’s Manual, Version 8.0
(4) Forschungskuratorium Maschinenbau, Rechnerischer Festigkeitsnachweis
    für Maschinenbauteile, Frankfurt a.M., 2003
(5) Ulf Weerts, Bruchmeschabische Charakterisierung von Klebungen, Ph.D.
    thesis, Institut für Flugzeugbau und Leichtbau, TU-Braunschweig,
    Braunschweig, 2004




                                  Slide 16

				
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Description: hypermesh,fiber,reinforcement