阻力伞锁滚柱梁冲击失效分析

Impact failure analysis of parachute lock roller beams

滚柱梁是阻力伞锁传力路径上的主承力件之一。某型阻力伞锁滑车试验过程中,滚柱梁失效导致开伞失败,故障分析认为滚柱梁失效模式为冲击剪切失效。对滚柱梁冲击剪切失效机理进行了分析,认为阻力伞锁运动机构在牵引伞初始冲量作用下获得初始冲击速度,并与滚柱梁发生碰撞-接触-挤压,该过程导致滚柱梁剪切失效。通过建立阻力伞锁运动机构的动力学模型,获得了初始冲击速度和运动机构等效质量,并将滚柱梁模型化为在均匀冲击载荷作用下的两端固支圆截面梁。应用刚塑性材料模型,考虑剪切失效厚度系数和弯曲-剪切共同作用,进行剪切失效分析,推导得到临界失效冲击速度,解释了滚柱梁失效机理。进一步讨论了套筒与滚柱梁质量比对滚柱梁失效的影响,为结构改进设计提出了建议。

The roller beam is one of the main load-bearing members of parachute locks.In the rocket-sled tests of a parachute lock,the roller beam failure led to fail in opening the drag chute.According to the failure analysis,the mode of roller beam failure under impact is shear failure.In the paper,the roller beam impact shear failure mechanism was analyzed and it is shown that the parachute lock obtains an initial impact velocity under the action of the initial impulse of extraction parachute,and then collides with the roller beam,which causes the roller beam shear failure.The initial impact velocity and the equivalent mass of the motion mechanism were obtained by modelling the dynamics of the parachute lock,and the roller beam was modelled as a circular cross-section beam clamped at both ends under uniform impact load.The rigid-plastic material model was used,and the thickness coefficient of the shear failure and the bending-shear interaction were taken into account.The threshold impact velocity of roller beam failure was derived based on the bending-shear theory.The effect of the mass ratio of the sleeve to the roller beam on the roller beam failure was discussed.Some improvements for structure design were proposed.