考虑破损安全的民机复合材料典型连接区结构优化设计方法研究

Design Optimization of Typical Hybrid-Junction of Commercial Aircraft Based on Fail-Safe Analysis

针对民用飞机复合材料典型连接区结构,根据适航条款的有关要求,对于失效后能够引起灾难性事故的结构必须依据适航要求开展损伤容限分析评估,其中破损安全性能分析是损伤容限分析评估的重要组成部分。典型复材重要连接区,需定义为破损安全-多传力路径结构,对于破损安全设计要求,考虑一个结构单元由于任何原因失效,其剩余结构必须能够在一定时间段内承受限制载荷直到损伤/破坏在规定的维修计划(间隔)中被发现。对于多传力路径要求,在一条传力路径失效后,载荷能够通过剩余传力路径进行重新分配。本文首先在优化初始构型的基础上,详细定义了民用飞机复材典型连接区域的破损安全失效模式和分析场景。围绕初始优化构型,基于破损安全分析范畴定义,建立了破损安全强度分析方法,并开展了相关破损安全强度计算,识别出初始优化构型安全裕度薄弱的位置并进行补强。所提方法有助于暴露初始强度设计的薄弱位置,并有效提高复材典型连接区结构的破损安全性能。

With respect to typical hybrid-junction(composites-metallic)of commercial aircraft,according to the relevant airworthiness requirements,for each part of the structure that could contribute to a catastrophic failure,the damage tolerance and fatigue evaluation must be assessed to ensure that the anticipated service life can reasonably be achieved.Moreover,the Fail-Safe analysis is one of the most dispensable part among the damage tolerance evaluation.As for the typical&critical hybrid-junction(e.g.wing box root-joint,vertical tail plane(VTP)root-joint,etc.),it needs to be defined as Fail-Safe&Multiple Load Path(FS-MLP)simultaneously.Given the Fail-Safe design requirement,once one of the structural elements fails under any circumstances,the remaining structure must be able to take the Design Limited Load(DLL)until the damage/failure is discovered in specified maintenance interval.With regard to the Multiple Load Path design requirement,once one of the multiple load paths fails under any circumstances,the load can be re-distributed by the remaining load paths.The typical composites VTP root-joint structure of commercial aircraft is taken as an research object.Firstly,the initial optimized configuration is determined on the basis of DFEM level simulation analysis and trade-off,then the definition of Fail-Safe analysis is clarified precisely for the VTP root-joint area.Based on the initial optimized configuration,Fail-Safe calculations with respect to multiple-level and various locations are accomplished following the specified definition,the structural elements whose Margin of Safety are inadequate have been strengthened,while those whose Margin of Safety are excessively adequate have been modified.Through the iteration which is mentioned above,a composites VTP root-joint structure which meets the Fail-Safe design requirement is attained.The final optimized configuration not only obtains the weight reduction,but also enhances the Fail-Safe performance.