A COMPUTATIONAL METHOD FOR DESIGN SENSITIVITY ANALYSIS OF ELASTOPLASTIC STRUCTURES

Design sensitivity analysis of structural systems having elastoplastic material behavior is developed using the continuum formulation and it s implementation into a finite element program is described. The main idea is to develop a computational procedure for design sensitivity an alysis based on the response obtained by an incremental load approach for non-linear response analysis, where the elastoplatic (time-indepen dent) constitutive model is employed to account for the plastic materi al behavior; i.e. kinematic hardening and isotropic hardening. Discont inuities in the design sensitivity coefficients are investigated and a procedure is proposed to alleviate them. The control/reference domain approach is used to treat shape and non-shape design variables simult aneously. The direct variation method is adopted for this path-depende nt problem to obtain the design sensitivity expression for the respons e variables. Analytical examples are used to demonstrate the developed sensitivity procedure and gain insights for numerical implementation. The design sensitivity expression is discretized to implement it into a computer program using the isoparametric formulation of finite elem ent analysis. Numerical examples are presented to calculate the design sensitivity coefficients and compare them with those using the centra l finite difference method.