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A Parametric FEA System for Fixturing of Thin walled Cylindrical

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A Parametric FEA System for Fixturing of Thin walled Cylindrical Powered By Docstoc
					   A Parametric FEA System for
Fixturing of Thin-walled Cylindrical
            Components
                  Presented By: Michael Cope
                        October 29, 2008




   Authors: Yan Wang; Jianfan Xie, Zhijian Wang; Nabil Gindy
   Accepted: 20 November 2007 by the Journal of Materials
             Processing Technology
                      Function
• “Propose a parametric FEA system that can
automatically mesh components, assign material
properties and boundary conditions, and create
FEA files ready for calculation with limited human
interference (Page 338)”
          Why Does this Matter?
• Current cylinders can be modeled parametrically, but the
FEA still needs to be inputted by hand (Pg. 340)


• Reducing Manufacturing costs while increasing component
quality. (Pg. 338)


•Reduce the # of Spoiled Parts
                                                References
ABAQUS, 2004. Analysis user’s manual, version 6.5, Hibbit,         Ratchev, S., Liu, S., Huang, W., Becker, A.A., 2004a. A flexible force
Karlsson & Sorensen, Inc., USA.                                    model for end milling of low-rigidity parts. Journal of
Brave, U., Altuzarra, O., Lopez de Lacalle, L.N., Sanchez, J.A.,   Materials Processing Technology 153–154, 134–138.
Campa, J.J., 2005. Stability limites of milling considering the    Ratchev, S., Nikov, S., Moualek, I., 2004b. Material removal
flexibility of the workpiece and the machine. International        simulation of peripheral milling of thin-wall low-rigidity
Journal of Machine Tool and Manufacture 45,                        structure using FEA. Advanced in Engineering Software 35,
1669–1680.                                                         481–491.
Commercial product of Forkardt, Expanding mandrels for very        Ratchev, S., Huang, W., Liu, S., Becker, A.A., 2004c. Modelling and
large components, http://www.forkardt.com/products/                simulation environment for machining of low-rigidity
specialchucks/page8.html.                                          components. Journal of Material Processing Technology
Commercial product of Forkardt, Clamping solution for              153–154, 67–73.
thin-walled rings, http://www.forkardt.com/products/               Ratchev, S., Liu, S., Huang, W., Becker, A.A., 2004d. Milling error
specialchucks/page7.html.                                          prediction and compensation in machining of low-rigidity
Mehdi, K., Rigal, J.F., Play, D., 2002a. Dynamic behaviour of a    parts. International Journal of Machine tools & Manufacture
thin-walled cylindrical workpiece during the turning process.      44, 1329–1641.
Part 1. Cutting process simulation, Transaction of ASME.           Thevenot, V., Arnaud, L., Dessein, G., Cazenave-Larroche, G., 2006.
Journal of Manufacturing Science and Engineering 124,              Integration of dynamic behaviour variations in the stability
562–568.                                                           lobes method: 3D lobes construction and application to
Mehdi, K., Rigal, J.F., Play, D., 2002b. Dynamic behaviour of a    thin-walled structure milling. International Journal of
thin-walled cylindrical workpiece during the turning process.      Advanced Manufacturing Technology 27, 638–644.
Part 2. Experimental approach and validation, Transaction of       Tsai, J., Liao, C., 1999. Finite-element modelling of static surface
ASME. Journal of Manufacturing Science and Engineering 124,        error in the peripheral milling of thin walled workpieces.
569–580.                                                           Journal of Materials Processing Technology 94,
Ratchev, S., Govender, E., Nikov, S., 2002. Towards deflection     235–246.
prediction and compensation in machining of low-rigidity           Koelling, R., 1998. Apparatus and method for precision machining
parts. Proceedings of the Institution of Mechanical Engineers,     of metal rings. US Patent, No. 5,711,195, issued 27th January.
Part 2 216, 129–134.
   How Does this Relate to ME 482?
For Turning

Total cost per part:
   Cc = Co Th + Co Tm + Co Tt /np + Ct /np
Substituting for Tm and np:
   Cc = Co Th + Co p DL/fv + (CoTt + Ct )pDLv(1/n -1)/( f C(1/n) )

Minimizing cost per part (dCc/dv = 0) gives cutting speed and tool life to
minimize machining costs per part:
        vmin = C{n Co/[(1 – n)(Ct + CoTt)]}n
        Tmin = (1 – n) (Ct + CoTt)/(n Co)


What is Co?
Operator Cost!

              Don’t forget Spoiled Products!
                                      Parameters
Nomenclature                                               FIX2 constraint on the top end surface of the component
a the oblique angle of conic thin-walled cyinder           ID(i, j, k) the identity number of a node and is a function
ap the oblique angle of the pth section of anglevarying    of i, j and k
thin-walled cylinder                                       IDe the identity number of element
b The angle around the z axis of the reference             IDnm the identity number of the mth node of a element
between two nodes N(i, j, k) and N(i, j, k+1)              L the total length of the straight or conic thinwalled
BC(i, j, k) Boundary condition, which is the function of   cylinder
variables i, j and k                                       Lp the length of the pth section of the anglevarying
CS the coordinate system on the centre of the top          thin-walled cylinder
surface of the thin-walled cylinder                        LET the number of finite element across the cylinder
DL element size in the length direction of the component   thickness
DR element size in the radius direction of the component   NL the number of nodes in the length direction of
DT element size in the thickness direction of component    the component
E Young’s modulus                                          NR the number of nodes in the radius direction of
E1(i, j, k) element vector of element C3D8 and is a        the component
function                                                   NT the number of nodes in the thickness direction
of i, j and k                                              of the component
E2(i, j, k) element vector of element C3D20 and is a       N(i, j, k) node vector and is a function of variables i, j and
function                                                   k
of i, j and k                                              R/R0 Internal radius of the top surface of the thinwalled
F machining force specified by user                        cylinder
FCi the force boundary condition on component              R(i, j, k) The distance from the node N(i, j, k) to the z
during the ith step                                        axis
FIX1 constraint on the bottom end surface of the           of the reference coordinate system cylinder
component
Parameters Continued
 S The number of section of the angle-varying
 thin-walled cylinder
 T Thickness of the thin-walled cylinder
 TLi The tolerance constrains on the component
 during the ith step
 Tol Tolerance in the thickness direction on the
 thin-walled cylinder
 X(i, j, k) The X value regarding the CS of node N(i, j, k)
 XS boundary condition on X direction for XY symmetry
 Y(i, j, k) The Y value regarding the CS of node N(i, j, k)
 YS1 boundary condition on Y direction for X symmetry
 YS2 Boundary condition on Y direction for of XY
 symmetry
 Z(i, j, k) The Z value regarding the CS of node N(i, j, k)
 ˇ The angle of the component in the radius
 direction representing the symmetry boundary
 condition
  Poisson ratio
                   Design Principles
   3 Cylinder Types
                                                           1. Standard Thin
                                                              Walled Cylinder
                                                           2. Conical Thin
                                                              Walled Cylinder
                                                           3. Varying Angle
                                                              Thin Walled
                                                              Cylinder



Assumptions: Elastic Deformation, Point Force, Rigid Fixture/Support (Pg. 340
Design Principles cont…
       Experimental Equipment
• ABAQUS FEA software
used to analyze systems
• Use of custom user
interface to facilitate
FEA
Design Principle Application
               • After the user inputs
               all the parameters,
               the system crunches
               the math.
               • A fully usable file is
               then imported into
               ABAQUS
        Correlation of Results and the
                    Model
                           NONE!!!!

• No testing to validate model!
• “Much of the work to build a simulation is repeatable.”
(Pg 346)
• Even a comparison with “Hand” calculations would have been
better
                   Practical Use
• Eliminate hours of work spent in FEA software
• Greater communication between design and manufacture
• Autonomy for the manufacturing engineer
• Reduce the cost of developing thin-walled cylinders
          Technical Advancement

•   Accuracy          Improved Manufacturing of parts


• Reduced vibration and deformation
• Opens the door for fully parametric FEA analysis software
          Industries Impacted
• Aerospace
• Automotive
• Power
Questions?