Multiscale fail-safe topology optimization for lattice structures

In this paper, we address the critical issue of lattice structures losing functionality under local damage, which is a common safety deficiency in traditional lattice designs. A novel multiscale fail-safe topology optimization method is proposed to enhance the robustness of lattice structures. The method uses a simplified local damage model, aiming to minimize strain energy under the most critical failure scenarios, with design variables including macroscopic topology and geometric parameters of microscopic unit cells. By predefining an equivalent material model for the parameterized lattice structure, computational costs are significantly reduced. To overcome the non-differentiability of maximum strain energy, the Kreisselmeier-Steinhauser function is introduced as a substitute. Consequently, numerical simulation results demonstrate that this method effectively enhances lattice structure safety by providing more load-bearing paths to resist local damage. Compared to other fail-safe topology optimization methods, this approach expands the design space while maintaining the same computational cost, and it does not require adjustments to the predefined unit cell configuration for different working conditions.