An updated Lagrangian +nite element sensitivity analysis of large deformations using quadrilateral elements

A continuum parameter and shape sensitivity analysis is presented for metal forming processes using the +nite element method. The sensitivity problem is posed in a novel updated Lagrangian framework as suitable for very large deformations when remeshing operations are performed during the analysis. In addition to exploring the issue of transfer of variables between meshes for +nite deformation analysis, the complex problem of transfer of design sensitivities (derivatives) between meshes for large deformation inelastic analyses is also discussed. A method is proposed that is shown to give accurate estimates of design sensitivities when remeshing operations are performed during the analysis. Sensitivity analysis for the consistent +nite element treatment of near incompressibility within the context of the assumed strain methods is also proposed. In particular, the performance of four-noded quadrilateral elements for the sensitivity analysis of large deformations is studied. The results of the continuum sensitivity analysis are validated by a comparison with those obtained by a +nite di=erence approximation (i.e. using the solution of a perturbed deformation problem). The e=ectiveness of the method is demonstrated by applications in the design optimization of metal forming processes. Copyright ? 2001 John Wiley & Sons, Ltd.