Shape optimization for elasto-plastic deformation under shakedown conditions

An integrated approach for all necessary variations within direct analysis, variational design sensitivity analysis and shakedown analysis based on Melan's static shakedown theorem for linear unlimited kinematic hardening material behavior is formulated. Using an adequate formulation of the optimization problem of shakedown analysis the necessary variations of residuals, objectives and constraints can be derived easily. Subsequent discretizations w.r.t. displacements and geometry using e.g. isoparametric finite elements yield the well known 'tangent stiffness matrix' and 'tangent sensitivity matrix', as well as the corresponding matrices for the variation of the Lagrangian-functional which are discussed in detail. Remarks on the computer implementation and numerical examples show the efficiency of the proposed formulation. Important effects of shakedown conditions in shape optimization with elasto-plastic deformations are highlighted in a comparison with elastic and elasto-plastic material behavior and the necessity of applying shakedown conditions when optimizing structures with elasto-plastic deformations is concluded. (c) 2006 Elsevier Ltd. All rights reserved.