考虑增材制造悬垂约束的传力机架轻量化设计方法

Lightweight design method of transmission frame structureconsidering the overhang constraint of additive manufacturing

运载火箭发动机传力机架是将发动机的推力载荷传递至箭体的关键连接部件。对质量占比较大的发动机传力机架结构进行轻量化优化,可以有效地提升火箭发动机的推重比,实现结构的高效承载及使用增材制造技术稳定生产。基于移动可变形组件法(moving morphable component,MMC)框架,考虑增材制造过程中的悬垂约束,提出了一种运载火箭发动机传力机架结构的轻量化设计方法。此方法能够考虑刚度、质量、设计空间、制造约束等设计要求,在限制结构质量(体积)的约束条件下,实现结构刚度的最大化。推导了相关优化问题列式,给出了优化流程,并进行了若干典型算例。通过对优化结果的重分析可知:优化结果满足运载火箭发动机传力机架的刚度要求及传力机架材料的最大应力要求,在质量上相比传统的机架结构有显著优势,优化结果中不存在大悬挑结构且满足增材制造特有的悬垂约束,验证了此方法的有效性。

The transmission frame structure of lunch vehicles is the key connecting part which transmits the thrust load of the engine to the rocket body.The lightweight optimization of the transmission frame structures with a relatively large mass can effectively improve the thrust weight ratio of the lunch vehicles,realize the high-efficiency bearing of the structure and stable production by additive manufacturing technology.In this paper,based on the framework of moving morphable component(MMC)and considering the overhang constraint in additive manufacturing,a lightweight design method of lunch vehicle transmission frame structure was proposed.This method can consider the design requirements such as stiffness,mass,design space and manufacturing constraints,and maximize the structural stiffness under the constraint of limiting the weight(volume)of the structure.This paper deduces the formulation of related optimization problems,gives the optimization process,and shows some typical examples.Finally,through the analysis of the optimization results,the optimization results meet the stiffness requirements of the transmission frame structure of the launch vehicle engine and the maximum stress requirements of the transmission frame material,which have significant advantages over the traditional frame structure in terms of quality.There is no large cantilever structure in the optimization results,and the suspension constraints unique to additive manufacturing are satisfied,which proves the effectiveness of this method.