火箭发动机七机并联机架预应力模态分析及优化

针对新一代载人运载火箭七台火箭发动机并联机架在大推力作用下的非线性振动问题，开展了七机并联传力机架的预应力模态分析及优化设计方法研究。以该研究为基础，发展了一种预应力条件下机架材料等效替换方法。在不改变结构传力路径的情况下，通过结构预应力频率优化设计，能够有效降低机架材料物性参数改变所带来的低阶预应力频率误差，以此降低传力机架在动静联合试验时的试验成本。针对七机并联机架结构开展了钛合金和不锈钢材料等效替换，结果表明优化后的不锈钢机架相比原始的钛合金机架，刚度和动力学特性变化维持在合理变化范围之内，验证了该方法的有效性。

Pre stress Modal Analysis and Optimization of Parallel Frame of Seven Rocket Engines

In order to solve the nonlinear vibration problem of the paralleling frame of seven rocket engines of the next generation manned launch vehicle under high thrust, a pre stressed modal analysis and optimization design method is studied. Based on this research, an equivalent substitution method of frame materials under pre stressed conditions is developed.Without changing the load transfer path, this method can effectively reduce the low order pre stress frequency error caused by the change of the physical parameters of the frame material. Therefore, this method can also reduce the experimental cost of the frame in the combined dynamic and static experiments. Finally, the equivalent substitution of titanium and steel materials is carried out for the parallel frame of seven rocket engines. The results indicate that compared with the original titanium frame, the optimized steel frame could maintain the changes in stiffness and dynamic characteristics within a reasonable variation range, which verifies the effectiveness of the method.