Abstract：Fail-safe designed structures with redundant load paths exhibit high tolerance to damage (residual load-bearing capacity), which is of essential significance to the safety of flight vehicles. Meanwhile, the redundant structural configuration resulted from safety consideration inevitably increases the weight and reduces consequently the efficiency of flight vehicle structures. This paper proposes to design lightweight and fail-safe structures using Bi-directional Evolutionary Structural Optimization (BESO) method. Specifically, the design method with "0/1" discrete topology variables minimizes structural weight (material volume), meanwhile constrains the residual load-bearing deformation of locally damaged structures below a safety threshold. To address the bottleneck of the BESO method in dealing with multiple constraints, the deformation constraints are aggregated by the p norm global measure. The aggregated p norm constraint is augmented to the design objective with the introduction of a Lagrange multiplier, achieving simultaneous design for lightweight and fail-safe. Furthermore, the significance of local region to the damage tolerance is calibrated according to the maximum residual load-bearing deformation. The design efficiency can be largely improved by saving the residual load-bearing deformation analyses and constraints of the low-significant local regions. The effectiveness and efficiency of the proposed method is demonstrated through a series of benchmark design examples.
2023, Vol. 44 
