Multi-stiffness topology optimization of zero Poisson's ratio cellular structures

This work features a multi-stiffness topology optimization of a zero Poisson's ratio cellular structure for morphing skin applications. The optimization is performed with stiffness constraints to minimize the weight by using a state-of-the-art solid isotropic microstructure with penalty (SIMP) method. The topology optimization has been performed to minimize flatwise compressive and transverse shear moduli for aerodynamic pressures and shear forces. The multi-stiffness topology optimization is performed using a norm method with weighting coefficients. Both the single-stiffness and the multi-stiffness topology optimization have generated new honeycomb design by imposing symmetry conditions and geometric post-processing to avoid the presence of stress concentrations. The mechanical performances of the new honeycomb designs are validated using two approaches: one based on force boundary conditions (HyperWorks) and another with displacement BCs (ANSYS). The work shows some alternate potential topologies and configurations of cellular structures for lightweight zero Poisson's ratio honeycomb designs.