Multicriteria design of ceramic piston crown

Abstract

Multicriteria shape optimization of a ceramic piston crown used in a medium speed diesel engine is considered in this article. The special features of ceramic materials, which suggest a different structural design approach for ceramics than for other materials, are explained. The basic ideas and equations of the finite element method (FEM) in the linearly elastic case are presented because the optimization and decision-making processes are closely connected with the numerical analysis of structures. A two parametric Weibull distribution is applied to the strength test results in order to assess the reliability of a ceramic component. Its complement, the probability of failure, is chosen as one criterion to be minimized. Another competing criterion is the material volume which usually is the only optimized quantity in structural optimization. Finally, a bicriteria problem for the piston crown is formulated in detail by using the locations of the control nodes, which by B-splines determine the shape of the crown, as the design variables. The technical background of the piston design problem is briefly discussed and some Pareto optimal shapes have been generated for the decision-maker.