考虑机翼柔性的磁流变减振起落架落振动力学分析

Analysis of Impacts of Magnetorheological Landing Gear on Aircraft Dynamics Considering Wing Flexibility

为研究飞机着陆过程中机翼柔性对磁流变起落架落振全过程动力学特性的影响,建立了集成单出杆磁流变减振器的飞机起落架落振动力学模型,并通过台架试验进行验证,进一步探究了柔性机翼飞机的磁流变起落架落振特性。考虑磁流变减振支柱内部尺寸、压力和流量变化、磁流变液特征,推导了磁流变减振起落架的磁流变阻尼力、压缩气体弹簧力、小孔阻尼力等集总参数动力学模型,并在Adams/View环境中建立磁流变起落架虛拟样机,模拟起落架落振台架试验工况进行仿真研究,仿真与试验对比结果表明,起落架总载荷峰值、垂直过载、动行程及轮胎压缩量相对误差均在10%左右。进一步地,将某型无人机的机翼简化为等截面悬臂梁,建立了考虑机翼柔性的磁流变减振起落架刚柔耦合动力学模型并进行落振动力学仿真分析,结果表明:机翼柔性会降低磁流变起落架减振系统载荷峰值和减振器最大行程;当磁流变减振器的输入电流分别为0、1.2 A时,减振前期机翼产生变形载荷的峰值分别为起落架系统总载荷峰值的0.40%、0.41%,减振后期分别为1.96%、4.16%,落振时柔性机翼弯曲变形所吸收的冲击动能大部分是在减振后期释放;通过改变输入电流实现磁流变减振器输出阻尼力的主动适应,可以在一定程度上缓解飞机着陆冲击,在延长飞机结构件的使用寿命上具有一定的工程价值。

This paper investigates the effects of wing flexibility on aircraft dynamics during the entire landing process.A drop-shock dynamic model of the nose landing gear equipped with a single-rod magnetorheological(MR)shock absorber is established and validated through a bench test.The drop-shock dynamic characteristics of the MR landing gear of the aircraft with flexible wings are investigated.Considering the internal structure dimensions of the MR shock absorber strut,pressure and flow variations,and properties of the MR fluid,a lumped parameter dynamic model for the MR landing gear considering the MR damping resistance,compressed pneumatic spring force and orifice damping force is derived.In addition,virtual prototype of the MR landing gear is built in Adams/View environment to carry out simulation research under the same drop-shock conditions as in the bench test.The comparison between the simulation and test results show that the relative errors in the peak load,vertical overload ratio,maximum stroke of the landing gear and tire compression are all about 10%.Further,the wing of a certain unmanned aerial vehicle is simplified as a cantilever beam of uniform cross-section and a rigid-flexible coupled dynamic model for the MR landing gear considering wing flexibility is established for the drop-shock dynamic analyses.According to the numerical results,the wing flexibility can reduce the peak load of the MR landing gear and the maximum stroke of the shock absorber:When the input currents of the MR shock absorber are 0 A and 1.2 A,the peak load of the landing gear due to flexible wing deformation is respectively 0.4%and 0.41%of the total in the earlier stage of the landing process,and 1.96%and 4.16%respectively in the later stage of the landing process.This indicates that a large part of the impact energy absorbed by flexible wing deformation is released in the later stage.In conclusion,the damping adaptation of the MR shock absorber can be realized by changing the input current,which can alleviate the impact of aircraft landing and prolong the service life of aircraft structural components to a certain extent.