A strategy for avoiding spurious localized buckling modes in topology optimization

We introduce a strategy preventing the occurrence of spurious modes in the spectrum computed by linearized buckling analysis in the context of topology optimization. Spurious buckling modes may appear in low density regions, a well-known and largely discussed phenomenon. However, localized modes may also appear in solid areas, where stress concentrations occur. This second phenomenon, which is due to the inherent limitations of the linearized buckling analysis when used for complex stress states, is hardly addressed in the topology optimization literature. The remedy we propose makes use of elementary operations in the topology optimization framework: filtering and erosion, but now applied to the stress field. We show how this simple strategy helps mitigating the occurrence of spurious modes, in turn regularizing the optimization process towards high performance designs, which are then verified by nonlinear analysis.