Structural Optimization Considering Flexibility (2nd Report, Multicriteria Optimization Considering Multi-flexibility and Eigen-frequency)

In automotive body design it is possible that better performance can be obtained with a flexible structure rather than the stiffest structure. However, if only the flexibility is considered, the total performance of the structure may decline since flexibility may lower the stiffness and the eigen-frequency. To overcome this problem, a multi-criteria design method must be developed. In this paper, a methodology to obtain an optimum design considering flexibility, stiffness, and eigen-frequency is presented. First, the flexibility, the stiffness, and the eigen-frequency and their sensitivities are formulated using variational calculus, and a new multi-objective function is constructed. This multi-objective function considers the maximum of the three criteria and is also extended to the multi-flexibility case. Next, the optimization problem is solved using the homogenization method and sequential linear programming (SLP). Finally, several design examples are provided to confirm that the proposed design method satisfies the problem specifications.