【作者】 李思政；

【导师】 杨智春；

【作者基本信息】 西北工业大学 ， 固体力学， 2006， 硕士

【摘要】 在一些必要合理的假设下,利用达朗贝尔原理,建立了多轮多支柱式及小车式起落架飞机地面滑跑动态响应分析的全机模型,考虑全机沉浮、机体弹性(前n阶弹性模态)和定常气动力的影响,起落架支柱的弹性变形,小车式起落架的车架的俯仰运动以及弹性变形,对等速滑跑飞机建立了全机运动的微分方程,并以旧金山28-R跑道为地面输入,利用时域积分的方法得到飞机滑跑的各种响应。 对于随机的地面的滑跑响应,在飞机滑行方向跑道路面不平度为平稳随机函数假设下,通过对起落架缓冲系统刚度和阻尼的线化处理,将非线性随机振动问题简化为线性平稳随机振动问题,运用功率谱密度方法,计算滑行时由地面不平度引起的飞机结构动态响应。 通过对多轮单支柱和多轮多支柱式飞机的时域计算分析,得到如下结论:考虑机体弹性运动是很必要的,特别是对于大型飞机,应该考虑其机体弹性运动。起落架空气腔初始压强和初始容积对起落架的刚度影响较大,而多轮多支柱式起落架飞机,不仅是多个输入问题,还存在起落架载荷分配问题,所以起落架的敏感参数对于全机的动载荷有明显的影响,合理的起落架布局和参数选取有利于降低机体动载荷水平。同时本文还针对多轮多支柱式起落架飞机地面滑跑响应开发了相应的软件,该软件具有友好的用户界面,且软件设计立足于起落架布局、属性的可设计性,因此可以将其应用于实际工程当中,而且还可以根据实际情况,进行扩展、丰富分析模型。 通过对多轮单支柱和多轮多支柱式飞机的频域计算的算例分析,得到如下结论:考虑弹性运动对系统的响应有一定影响。 本文建立的全机模型接近飞机匀速滑跑的实际情况,能真实地反映机体的动力学特性,能够同时考虑机体结构弹性、飞机的定常气动力,具有工程应用价值。更多还原

【Abstract】 To study the taxiing-induced dynamic response of the aircraft with multiple wheels and multiple landing gears due to runway unevenness, base on several reasonable and necessary assumptions, the mathematical model of aircraft in taxiing is established using the d’alembert’s principle. It can simulate taxiing inpact properties accurately, it considers in detail the vertical and horizontal motion and pitching about its center of gravity and the significant symmetric elastic modes. Also considered are the nonlinear hydropneumatic landing gear characteristics, the structural flexibility of landing gear, the nonlinear load-deflection characteristics of the tires, the rolling and sliding friction of the tires versus slip ratio, the rolling moments of inertia of the tire and wheel, the pitching motion and the structural flexibility of carriage and the aerodynamic force. The motion equations of the aircraft taxiing in constant velocity are derived. Using the San Francisco Airport 28R runway unevenness as the input, the taxiing-induced response time history can be integrated.The dynamic responses are also obtained by the statistical analysis with PSD method. The significant problem is that the input of runway unevenness is stationary stochastic process and how the oleo-pneumatic shock absorbers could be linearized. These are all presented in details in this paper.With determinate method, the analysis of taxiing-induced response of aircraft with the multiple wheels and multiple landing gears is conducted. The results show that the flexibility of body should be taken into account, especially to the large aircraft. Additionally, the initial parameter of the oleo-pneumatic shock absorbers affects the loads distribution. The reasonable selection of parameters can help to alleviate dynamic response. Based on the above analysis ,a user-oriented computing program is developed, and it’s easy to expand the function of the program with landing gear model.Correspondingly, we analyse the taxiing-induced response of the aircraft with PSD method. And get the same conclusion that the flexibility of airframe could affect thetaxiing-induced response of the aircraft.更多还原