Fail-safe topology optimization for multiscale structures.

• A fail-safe topology optimization is presented for multiscale structures. • The damage in both the macroscale and microscale is considered. • Simplified damage models for truss-like microstructures are utilized. • The use of Heaviside projection speeds up convergence and obtains better results. • Multiscale fail-safe structures are more damage-resistant and self-supporting. This paper presents a novel fail-safe topology optimization method for multiscale structures. The partial damage of both macroscopic and microscopic scales is considered for structural design. To ensure precision, the effective elasticity tensor obtained by the homogenization method is fitted as a high-order polynomial function. Meanwhile, the simplified models of partially damaged truss-like microstructure are employed to reduce the computational cost and the difficulty of fitting. Moreover, Heaviside projection is applied to speed up the convergence and yield a relatively clear configuration. Three numerical examples are tested to demonstrate that the optimized multiscale structures successfully obtain comprehensive performances than optimized solid structures when appropriate microstructure configurations are chosen. Besides, multiscale structures are more self-supporting than solid structures and thus more suitable for additive manufacturing due to the large number of gray elements diffused. [ABSTRACT FROM AUTHOR]