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为满足镜筒结构高强度、轻量化及良好的热环境适应性的要求,研究了多工况下同时考虑结构刚度和一阶固有频率的多目标优化问题。首先,基于变密度连续体结构拓扑优化方法,采用加权和法和靶向量法定义了多工况下多目标优化函数;然后进行了镜筒的优化设计。整个优化设计包括拓扑优化和厚度优化两部分。在拓扑优化中,以刚度和频率最大为目标函数,得到了满足要求的镜筒结构材料的最佳分布,并以此为依据,完成了镜筒结构的三维建模;以拓扑优化所得结构的柔度值和一阶频率为约束,质量最小为目标函数,对镜筒结构各厚度进行了优化。优化设计结果表明,镜筒质量由18.63 kg减少至12.46 kg;重力作用下最大变形由0.013 mm减少至0.001 9 mm;热载荷作用下最大变形由0.098 mm减少至0.062 mm;一阶固有频率从65.6 Hz提高至189.83 Hz。该优化设计方法有效缩短了设计周期,提高了镜筒结构的性能,满足了系统设计要求。
In order to meet the requirement of high strength, light weight and good thermal environment adaptability of the tube structure, the multi-objective optimization problem considering both the structural rigidity and the first-order natural frequency under multiple working conditions is studied. Firstly, based on the method of topology optimization of variable density continuum structure, the multi-objective optimization function under multi-conditions was defined by the weighted sum method and the target-based method. Then the optimal design of the lens barrel was carried out. The entire optimization design includes topology optimization and thickness optimization in two parts. In the topology optimization, the optimal distribution of the material of the lens tube structure satisfying the requirements is obtained with the maximum stiffness and the frequency as the objective function. Based on the above, the three-dimensional modeling of the lens tube structure is completed. Flexibility value and first-order frequency as the constraint, the minimum mass is the objective function, and the thickness of the lens barrel structure is optimized. The optimized design results show that the mass of the lens barrel is reduced from 18.63 kg to 12.46 kg, the maximum deformation under gravity is reduced from 0.013 mm to 0.001 9 mm, the maximum deformation under thermal load is reduced from 0.098 mm to 0.062 mm, and the first natural frequency is reduced from 65.6 Hz to 189.83 Hz. The optimized design method effectively shortens the design cycle, improves the performance of the lens barrel structure and meets the system design requirements.