柔性起落架间隙型摆振动力学分析

Dynamic Analysis of Clearance Shimmy of Flexible Landing Gear

针对某型飞机在服役过程中出现的起落架间隙型摆振问题,基于起落架柔性多体动力学模型,采用L-N(Lankarani-Nikravesh)接触理论建立了含间隙旋转副、球副动力学子模型,并采用起落架动力试验的结果对模型进行效验;定义了间隙位置对起落架间隙型摆振的影响分类;然后研究了运动副副元素刚度、运动副间隙大小以及飞机滑跑速度对起落架间隙型摆振的影响。结果表明:转环与上扭力臂处和支柱与下扭力臂处间隙对机轮低频摆振影响要比扭力臂间间隙影响大,但对起落架摆振影响都属于第一类。轮毂轮轴间间隙影响机轮高频摆振,对起落架摆振的影响属于第二类;在设计范围内,运动副副元素弹性模量越小,机轮摆角、运动副间碰撞接触力越小;运动副间隙越大,摆角越大。飞机滑跑速度越大,机轮摆角越小。研究结论可为间隙型摆振的发生机理和防摆设计提供研究途径。

Concerning the landing gear gap-type shimmy problem which appeared in a certain type of aircraft.Based on a flexible multi-body dynamics model of the landing gear,the L-N(Lankarani-Nikravesh)contact theory was adopted to establish the sub-model of the rotation and ball pair dynamics with clearance,The model was validated by the dynamic test results of landing gear.The effects of different clearance positions on the clearance-type shimmy of the landing gear are divided into two categories.Then the effects of the stiffness of the kinematic pair element,the size of the kinematic pair clearance and the aircraft's taxi speed on the landing gear clearance type shimmy were studied.The results show that the gap between the swivel and the upper torsion arm and the strut and the lower torsion arm have a greater impact on the low-frequency shimmy of the wheel than the gap between the torsion arms,but the impact on the landing gear tremor fall into the first category.The high-frequency vibration of the wheel is affected by the gap between the hub and axle,and the impact on the landing gear vibration is classified into the second category.Within the design range,the elastic modulus of the kinematic pair elements is reduced,and the swing angle of the wheel and the collision contact force between the kinematic pair are reduced too.The swing angle is increased when the movement pair clearance becomes larger.The higher the sliding speed,the smaller the wheel swing angle.As the sliding speed increases,the wheel swing angle becomes smaller.The research results can provide the mechanism of gap-type shimmy and anti-sway design with a research approach.