飞机起落架的拓扑与自由曲面形状优化

Topology and Free-form Surface Shape Optimization of Aircraft Landing Gear

为了深入研究飞机起落架在工作时其主要部件的受力情况,解决飞机起落架进行拓扑优化后出现的局部应力过大的问题。在经典的变密度法的基础上,选用SIMP模型作为材料的插值模型。以飞机起落架的外筒结构作为研究对象,将其单元密度作为设计变量,通过加入约束因子以控制达到相应的多元化设计要求,提出以降低飞机起落架应力值与轻量化为目标的拓扑优化数学模型。在此基础上,以选取标记处的形貌与厚度作为设计变量,将其应力最小作为优化目标,建立起自由曲面形状优化模型,获得了最优的解决方案。拓扑结果表明,其最大应力处的数值降低了11.5%,体积减少到了原来的83.6%。自由曲面形状优化结果表明,通过在标记处做3.6 mm的加厚处理,其最大应力处的数值降低了17%。由此可见,自由曲面优化可以很好的解决拓扑优化后出现的局部应力过大的问题,在强度保持不变的情况下,降低了应力,更好的改善了飞机起落架的力学性能,为后续的研究设计提供了参考。

In order to deeply study the stress of main parts of aircraft landing gear during operation,the problem of excessive local stress after topological optimization of aircraft landing gear is solved.Based on the classical variable density method,the SIMP model is chosen as the interpolation model.Taking the outer cylinder structure of the aircraft landing gear as the research object and the unit density as the design variable,a mathematical model of topology optimization aiming at reducing the stress value and lightweight of the aircraft landing gear was proposed by adding constraint factors to control the corresponding diversified design requirements.On this basis,the shape and thickness of the mark were selected as the design variables,and the minimum stress was taken as the optimization objective,and the shape optimization model of freeform surface was established to obtain the optimal solution.The topological results showed that the value at the maximum stress decreased by 11.5%and the volume decreased to 83.6%.The results of the shape optimization of the free-form surface show that the value at the maximum stress is reduced by 17%through the thickening treatment of 3.6 mm at the mark.Thus,it can be seen that free-form surface optimization can well solve the problem of excessive local stress after topology optimization.Under the condition that the strength remains unchanged,the stress is reduced,and the mechanical performance of aircraft landing gear is better improved,providing a reference for subsequent research and design.