柔性起落架间隙型摆振动力学分析

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.

Dynamic analysis of clearance shimmy of flexible landing gear

: The clearance shimmy of landing gear will cause long-term loss of motion pairs, reduce the service life, and cause resonance of the rest of the aircraft structure. In order to solve this problem, based on the flexible multi-body dynamic model of landing gear, the dynamic model of the landing gear with clearance rotating pair and ball pair is established by using L-N contact theory. The influence of clearance position, element stiffness, coefficient of restitution, clearance size and aircraft sliding speed on the clearance shimmy of landing gear is studied. The results show that the influence of the clearance between the ring and the upper torsion arm and between the strut and the lower torsion arm on the low frequency shimmy of the wheel is greater than that between the torsion arms, but the influence on the landing gear shimmy belongs to the first category. The results show that the wheel shimmy is affected by the clearance between wheel hub and axle, which belongs to the second category; the clearance between the moving pair and the aircraft"s running speed have influence on the wheel shimmy. The larger the clearance, the greater the swing angle. The higher the sliding speed is, the smaller the wheel swing angle is; within the design range, the elastic modulus of motion pair elements has influence on the wheel swing angle, while the recovery coefficient has no effect on the wheel swing angle. The smaller the element elastic modulus of the moving pair is, the smaller the wheel swing angle and the collision contact force are.