A Fail-Safe Topology Optimization Method for Fiber-Reinforced Composite Structures Under Dynamic Loads

A fail-safe topology optimization method for fiber-reinforced composite structures under dynamic loads is proposed to achieve the concurrent optimization of structural topology and fiber orientations, as well as enhance the structural redundancy subject to damage cracks of fiber-reinforced composite structures under external dynamic loads. To prevent fiber orientations from getting trapped in local optima, we employ a discrete–continuous parameterization method to convert the continuous orientation problem to a discrete subinterval selection problem and a continuous orientation optimization problem in a subinterval. To prevent structural catastrophic failure induced by damage cracks, we incorporate the fail-safe design concept by considering local damage via removing the stiffness of the composite in the predefined patch. Furthermore, to reduce the large computational burden involved in transient analysis under dynamic loads, we adopt the equivalent static loads method to transfer the dynamic loads into a set of static loads, thereby largely accelerating the optimization process while keeping the solution accuracy. The effectiveness of the method is verified by three numerical examples, showing that the equivalent static loads method-based fail-safe design of composite structures with concurrently optimized topology and fiber orientations can effectively resist the local damage induced by partial failure. Specifically, the method reduces the optimization time by around 40% while ensuring relative errors within 2% and convergence measures of fiber orientations larger than 95% in all examples, and can have up to six orders higher residual stiffness subjected to post-imposed damage patches compared to the traditional method, showing the efficiency of the proposed method.