【作者】 朱书华；

【导师】 童明波；

【作者基本信息】 南京航空航天大学 ， 飞行器设计， 2009， 博士

【摘要】 鸟撞经常给飞机安全带来灾难性的后果。据美国空军1987年关于鸟撞事故中撞击部位的统计,鸟撞风挡/座舱盖的次数占总数的21.4%,位居首位,而且,研究表明撞击这个部位比撞击其它部位更为危险。目前,国内鸟撞风挡的研究主要依赖于鸟撞试验,并结合数值方法进行仿真分析,但现有模型仿真分析结果与鸟撞试验结果存有较大差距,很难满足工程上对虚拟数值试验的要求。因此,进一步对鸟撞试验和数值仿真建模关键技术开展深入研究,并在此基础上建立一个鸟撞风挡仿真虚拟试验平台,具有现实的工程意义和重要的学术价值。首先通过某型飞机全尺寸风挡鸟撞试验,采用高速摄像系统和数据测量采集系统详细研究了鸟撞风挡的动响应全过程,分析了风挡遭鸟撞击后的破坏模式,得到了风挡抗鸟撞击的临界速度及结构关键点的位移、应变时间曲线等重要数据。所获结果为建立合理的鸟撞风挡有限元模型提供了重要的试验依据及验证算例。选取鸟撞铝板模型为研究对象,详细研究了三种鸟体几何形状及多种鸟体本构关系对靶体撞击力和变形响应的影响,经与文献试验结果分析、对比,获得了与试验结果最为吻合的鸟体几何形状和鸟体本构关系,并基于优化方法反演求解出该鸟体本构关系的最优材料参数。采用非线性有限元方法,基于ABAQUS/Explicit软件平台及内嵌的材料用户定义子程序(VUMAT),建立了鸟撞飞机风挡的力学分析模型,详细模拟了鸟撞风挡时损伤产生及演化的全过程。通过与全尺寸风挡鸟撞试验结果的对比,验证了该有限元模型的有效性。分析比较了考虑与不考虑弧框和骨架作用的两种不同边界条件对风挡动响应分析结果的影响。分别探讨了玻璃骨架、橡胶垫片的厚度和弹性模量对风挡抗鸟撞能力的影响规律。经详细研究无机玻璃/PVB/有机玻璃层合结构整体式圆弧风挡的抗鸟撞性能,分析了胶层(PVB)厚度、无机玻璃层厚度、有机玻璃层厚度、不同层合结构对整体式圆弧层合风挡的抗鸟撞性能的影响规律。最后,详细研究了建立鸟撞风挡仿真试验平台的总体方案、关键技术、详细设计及其实现,并通过实例验证了该鸟撞风挡仿真试验平台的有效性和实用性。该鸟撞仿真平台可以为风挡设计和改型的工程应用提供便捷和帮助。更多还原

【Abstract】 The bird impact against aircraft structures can cause catastrophic damages. The statistical data from U.S.Air Force in 1987 showed that the probability of windshield and cockpit impacted by birds was about 21.4%, the biggest probability comparing with the other components of the aircraft. The records also presented that the impacted windshield and cockpit was much more dangerous than the other components. At present, the common way to determine the windshield’s capabity against bird-stike is to carry out a full-scale bird-strike experiment. In the meantime, finite element (FE) analysis is taken as an important method to simulate the whole process of bird strike windshield. But numerical results of current models are not in good agreement with the experimental data. It is difficult for the numerical simulation of bird strike against windshield to meet the engineering requirement. Therefore, it is necessary to continue studying on the bird strike behavior of aircraft windshield by the means of both experiments and numerical analysis, and to build a virtual bird-strike test platform as well. The investigation has much more important academic value and practical engineering significance.Firstly, an experimental study was performed on bird impact against a full-scale aircraft windshield. The whole dynamic response process of bird impact on windshield was recorded with the high speed video cameras and the data acquisition system. A comprehensive discussion was presented on the deformation of bird and windshield, and the damage modes of the windshield. Experimental results, the history curves of the displacement and the strain of all the measure points on the windshield, were obtained. The experimental study provides an important physical basis and verification cases for establishing a reasonable finite element model of bird strike on the aircraft windshield.Secondly, the bird FE model was studied through the combination analysis of three kinds of geometry shapes and several constitutive equations. The impact force and displacement histories were calculated and compared with the experimental data of bird impact on a flat aluminum plates. A reasonable bird geometry shape and a constitutive model were obtained, of which the analysis results was the most agreeable with the experimental data. The parameters of the bird constitutive model were optimized by the optimization methods.Thirdly, based on the experiment investigation, a finite element model of bird impact on the windshield was established to predict the damage initiation and propagation of the windshield after bird impact via the nonlinear finite element method, combined with the user-defined materials subroutine (VUMAT) of the ABAQUS/Explicit software. By comparing the instantaneous deformation of bird and windshield, the damage modes of the windshield, displacement curves and strain curves of the measured points on the windshield, it was shown that the simulation results and the full-scale bird impact test results had a good agreement. The boundary conditions of the windshield FE model were discussed via two modeling strategies. One way was to simplify the supporting structures around the windshield glass as the fixed constraint boundary condition acting on the windshield glass directly. The other way was to take into account the surrounding structure of the windshield glass in the FE model. The sensitivities of the design parameters of aircraft windshield, including skin thickness, skin elastic modulus, rubber thickness, and rubber elastic modulus, were discussed to the windshield’s capability against bird-strike comprehensively. In addition, the capability of the layered windshield against bird-stike, composed of inorganic glass, PVB and organic glass, was discussed with the different adhesive film (PVB) thickness, inorganic glass thickness, organic glass thickness, as well as the different numbers of layer.Finally, based on the previous study, a virtual test platform of bird impact on aircraft windshield was studied and established for the engineering application. Presented in the paper were the general schematic of the platform, the key technology, the detail design of each function modules. An expample of the bird strike test of aircraft windshield showed the efficiency and practicability of the virtual test platform. It was shown that the virtual test platform could be helpful for designing and modifying an aircraft windshield.更多还原