Keywords: automotive component design, topology optimisation, optimality criteria.

A topology optimisation method based on optimality criteria for total potential energy maximisation with a volume constraint has been implemented. The volume constraint is controlled by using a Lagrange multiplier depending on static (stress) and dynamic (natural frequency) constraints. As a consequence, the volume of the final solution of the optimisation process has not to be specified a priori and represents the minimum necessary to satisfy the imposed constraints. Single and multiple loading conditions can be analysed.

The topology optimisation of a McPherson rear suspension subframe of a mid size commercial vehicle is presented. Stiffness maximisation for three different independent loading conditions and first natural frequency maximisation have been faced together with constraints on the maximum allowable stresses. The results of the optimisation process are shown.

The optimisation process converges in a few iterations toward a quite well defined structure with a very little percentage of elements characterised by intermediate material properties. Bulk zones are characterised by elements whose material properties are those of the base material. Void zones are characterised by elements that simulate the presence of void by assuming material properties, the Young modulus and the mass density, close to zero. The stress constrain is verified everywhere. The only exception is a small area near the fastening system of the original component (no design domain) where a stress concentration effect leads to a stress peak value larger than imposed.

1

G. Chiandussi, I. Gaviglio, A. Ibba, "Evolutionary method for topology optimisation with maximum stress control", Proc. European Conference on Computational Mechanics, 2001.

2

G. Chiandussi, I. Gaviglio, A. Ibba, "Topology optimisation with optimality criteria and a given volume Lagrange multiplier", Proc. XXX Nat. Conf. Italian Association Stress Analysis, 1103-1112, 2001.

3

M.P. Bendsoe , "Optimization of structural topology, shape, and material", Springer-Verlag, Heidelberg, 1995.

4

Y.M. Xie, G.P. Steven, "Evolutionary structural optimization", Springer, Berlin, 1997.

5

E. Hinton, J. Sienz, "Fully stressed topological design of structures using an evolutionary procedure", Engineering Computations, 12, 229-244, 1995. doi:10.1108/02644409510799578

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