【作者】 何欢；

【导师】 陈国平；

【作者基本信息】 南京航空航天大学 ， 固体力学， 2007， 博士

【摘要】 通用飞机耐撞性仿真分析与抗坠毁设计技术是飞机设计的重要内容。本文以实际工程研究为背景,以瞬态非线性有限元分析技术为手段,研究了飞机结构耐撞性仿真和设计中的若干关键问题。具体可归纳为如下几点:1)文章首先讨论了飞机结构坠撞分析建模所涉及到的基本理论和关键技术,总结了飞机结构坠撞试验和仿真分析数据处理方法。2)引入全局近似模型构造了结构耐撞性优化目标函数、约束函数与设计变量之间的响应面方程,利用遗传算法对响应面进行了优化分析。提出了全局近似模型迭代和优化分析的混合算法,提高了分析效率。3)引入子结构综合技术对分析模型进行自由度减缩。构造了一种与保留模态加权正交的向量集,通过这组向量集容易实现自由-自由结构的剩余柔度矩阵的计算。在此基础上,结合飞机结构坠撞问题的特点,提出了相应的有阻尼结构的自由界面子结构综合法。文章随后还给出了一种具有普遍意义的实系数解耦变换方法,构造了与这种变换方法相适应的左、右加权正交向量集,并且在此基础上提出了实数域内的有阻尼结构自由界面子结构综合法。给出了与瞬态非线性有限元分析中广泛采用的中心差分计算格式相容的子结构综合方程。算例分析表明,利用本文方法进行结构碰撞分析,能够大幅提高计算效率,也具有很好的计算精度。4)建立了带油箱的机身框段坠撞分析模型。模型中考虑了燃油与油箱结构的液/固耦合作用。通过仿真分析,揭示了坠撞环境下燃油量对机身各部分结构的坠撞响应和损伤的影响,研究了机身框段各部分结构的能量吸收情况。给出了在应急着陆或可生存坠撞条件下飞行员所应采取的应急措施。5)开展了50%的Hybrid III型标准假人模型与我国普通乘员体格差异性研究,通过仿真分析算例比较了相同输入条件下不同百分位的Hybrid III型假人模型头部响应数据,评价了50百分位的Hybrid III型标准假人模型的适用性,并给出了相应的建议。6)为了评价飞机结构抗坠毁性能对乘员的保护作用,建立了带标准假人模型的全机坠撞有限元模型。比较了材料应变率敏感性对分析结果的影响,给出了建立材料模型时所需遵循的准则。利用仿真分析评价了某轻型飞机的抗坠毁性能,找到了不利于乘员生命安全的因素,提出了相应的设计修改方案。利用仿真分析手段,通过比较研究验证了设计修改的可靠性。为仿真分析技术辅助飞机结构抗坠毁设计提供了指导依据。更多还原

【Abstract】 Aircraft crashworthiness design and crash simulation is an important parts of aircraft design. This paper focuses on several key techniques about aircraft crash simulation and crashworthiness design. The content is listed below:1) General methods in developing an aircraft finite element model under crash environment have been discussed firstly. Test data and simulation result evaluation and filtering methods have been summarized.2) Global approximation model is employed for optimization of the energy absorption structure under crashworthiness requirement. The response surface of both object and constraint obtained through global approximation model is coupled with Genetic Algorithms to perform the objective optimization. A mixture method for response surface iteration and objective optimization has been developed to reduce total optimization work.3) Components synthesis methods have been integrated into crash simulation. In order to accurately model the dynamics of the structure, the flexibility matrix is calculated through a weighted-orthogonal matrix formulated in this paper. Based on the weighted-orthogonal matrix, a new free interface components synthesis method for damping structure is developed. In order to obtain the real coefficients synthesis equation, a general transformation decoupled method is developed, through which the complex coefficients decoupled equations can be converted into the real coefficiets ones. Left and right weighted-orthogonal matrix compatible with the transformation decoupled method has been obtained. Based on these works, a free interface component synthesis method for damping structure is formulated. The synthesis equation is a real coefficient function, and the form of the equation is compatible with the central differential integration methods. The validation of this method is demonstrated through analytical simulation subsequently.4) Finite element model of a fuselage section with fuel tank has been developed. In order to accurately model the dynamics and failure of the fuel tank, the complicated fluid/structure interaction model has been considered in. Simulation result reveals the relationship of the the fuel weight and the responses and failure of fuselage section. The energy absorption capabilities of each part of the fuselage section have been discussed. Recommends have been proposed for the pilots to deal with emergency landing and survival crash.5) The differences of the body characteristics between 50% Hybrid III dummy and ordinary Chinese people are discussed. 5%, 50% and 95% Hybrid III dummies head responses have been calculated out to illustrate the effection of the differences of the body characteristic upon the simulation results. The adaptability of 50% Hybrid III dummy for full scale crash test has been evaluated. Corresponding suggestions have been proposed.6) A full scale finite element model of a light fixed wing aircraft integrated with a dummy model has been developed. Influence of strain rate dependent of the material effects on the total simulation results has been discussed. Criterion for material modeling has been suggested. The crashworthiness of the light aircraft has been evaluated through analytical methods, and the unfavourable factors of the aircraft have been found out. Modifications have been carried out to improve the protection of the seat system for the occupants. The validation of the modifications has been demonstrated by simulation method.更多还原