Optimization of Sandwich Structures with Respect to Local Instabilities with MBB-Lagrange

Abstract

MBB-LAGRANGE is a powerful optimization code which allows the optimization of structures. To achieve the optimal design of a structure all special requirements must be fulfilled, that means that constraints e.g. stress, strains or displacements have to be in a feasible range while the objective function e.g. the structural weight reaches a minimum value. The results are strongly dependent on the optimization constraints which must be fulfilled. In this context local and global stability constraints may be essential for the design process. In the continuing development of MBB-LAGRANGE stability constraints are one of the major topics the MBB-LAGRANGE team is busy developing. One topic is the realization of local stability constraints of sandwich structures which will be discussed in this paper. The theoretical background and the integration into the optimization code MBB-LAGRANGE will be shown. An example of a helicopter sandwich structure will demonstrate the influence of this constraint type in the design process while optimal results are found. These results satisfy all requirements: local stability, stress and dynamic constraints.