Title: Design optimisation of a thermo-elastic-plastic process for plate forming

Authors: Seonho Cho, Jong Gye Shin

Addresses: Altair Engineering Inc., 2070 Business Center Drive, Suite 220, Irvine, CA 92612, USA. Department of Naval Architecture and Ocean Engineering, Seoul National University, San 56-1, Shillim-Dong, Kwanak-Gu, Seoul, Korea.

Abstract: A design optimisation problem for the thermo-elastic-plastic process or the line heating (LH) process for plate forming is formulated. The deviations of position vectors from the objective shape are used as constraints. The objective function is to minimise the weight sum of these constraints. Design variables are torch velocity, torch strength, cooler distance, and plate thickness. An automated design optimisation procedure is developed using the method of feasible direction and the finite element solvers for heat convection and thermal stress analyses. The necessary gradient information is obtained using the forward finite difference method. During the LH process, the temperature field is assumed to be uncoupled with the displacement field. A numerical experiment shows that inelastic behaviour of the material is crucial to the residual stress during the LH process. Application of the design optimisation to a flat plate model shows applicability and effectiveness for the LH process.

Keywords: design optimisation; finite difference sensitivity; heat convection; line heating (LH) process; method of feasible direction; residual stress; thermal stress analysis; thermo-elastic-plastic process.

DOI: 10.1504/IJMPT.2001.001281

International Journal of Materials and Product Technology, 2001 Vol.16 No.6/7, pp.564-578

Published online: 01 Jul 2003 *

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