【作者】 陈磊；

【导师】 金海波；

【作者基本信息】 南京航空航天大学 ， 飞行器设计， 2010， 硕士

【摘要】 在飞机结构设计中,对于飞机主承力构件的轻量化设计十分关键。布局优化技术是目前开展结构轻量化设计研究十分有效的手段之一。拓扑优化作为布局优化技术的一种重要方法,正被更多的结构设计者所关注。实际上,无论是拓扑优化还是其它布局优化技术,其本质都是在寻求最直接的传力路径,即传力路径最短。本文基于研究传力路径的重要意义,首先从研究Michell桁架准则入手,引入结构承载因子概念,以结构的传力路径作为设计变量,通过在传力路径上对结构内力进行积分,得到相应的结构承载因子。由于该承载因子是结构传力路径的泛函,以此本文用变分法导出对应结构最短传力路径的微分方程,并用里兹法求解该微分方程,得到结构的最短传力路径。并和用Michell桁架理论得到的最小质量桁架进行比较,证明了本文提出量化模型的有效性。接着,通过对飞机机身加强框的传力分析,分别采用基于传力路径的解析方法和数值优化方法,优化得到了最优的刚框缘条轮廓和最佳的刚框内力分配比值。通过对比优化结果,其最大误差在5%以内,证明了量化模型的正确性。最后,通过对相同外形和载荷作用下的半框有限元模型进行尺寸优化,得到了与解析模型相同的结构承载因子,证明了本文提出解析模型的有效性。同时,优化后的结构最小质量略高于解析解,表明本文提出的解析模型能够估算传力结构的最小质量,也为设计者在结构减重设计时提供了一个参照目标。更多还原

【Abstract】 In the design of aircraft structures, the lightweight design of aircraft with the main component of force bearing is very critical. Currently, the layout optimization technique is one of very effective mean to carry out the design of structural lightweight. In layout optimization technique, topology optimization is a kind of important method, are being more structural designers attention. In fact, whether topological optimization or other layout optimization technology, its essence is seeking the most direct load-carrying path, namely the shortest load-carrying path.This paper, based on the research significance of load-carrying path, we first studied Michell truss criterion, introduced concept of structural load-carrying factor, took the structural load-carrying path as the design variables, by the integral to internal force of structure in the load-carrying path, corresponding load-carrying factor is obtained. As the load-carrying factor is the functional of structural load-carrying path, then we derived differential equation of the shortest load path of the corresponding structure with variational method, and solving the differential equation with the Ritz method, obtained the shortest load-carrying path structure. Compared with the result by Michell truss theory, proved that we put forward the quantification model is effective.Then, the paper analyzed the force transfer of fuselage bulkhead, respectively by analytical method and numerical optimization method based on the load-carrying path, optimized and got the best outline of edge strip and optimum the internal force distribution ratio of bulkhead. Through comparing the optimization results, the maximum error is less than 5%, proved the validity of the model theory.Finally ,adopt size optimization method optimized the half frame finite element model under the same shape and loads, we obtained the same load-carrying factor with the analytical model, Proved the validity of analytical model is put forward in this paper. Meanwhile through comparing the optimization results and analytical calculations of the structure minimum quality, show that the proposed analytical model can estimate the minimum quality of the force transmission structure also provided a reference goal for designers when they reduced weight in structure design.更多还原