火星着陆缓冲气囊冲击过程的仿真分析

Simulation of Attenuating Airbag Impact Dynamics for Mars Landing

气囊缓冲着陆技术适用于小型着陆器着陆火星。针对总体指标30m/s冲击速度下峰值加速度小于200G的要求,设计了一种适用于火星环境的小型封闭式气囊结构用于着陆缓冲。为了探索气囊特性和节省环境仿真试验成本,运用非线性有限元工具LS-DYNA分析了气囊充气压力、冲击速度、冲击姿态角等参数对缓冲性能的影响。仿真结果表明,相同冲击速度下,着陆器峰值加速度随充气压力增大而增大,但受冲击姿态角影响甚微。冲击时间与冲击速度、冲击姿态角无关,而充气压力与系统结构的函数。系统弹性刚度要随充气压力增大而增大,随冲击姿态角增大而减小。结论是设计满足设计指标。

Airbag attenuation technology is suitable for light-weight probes for Mars landing. An attenuating air- bag system was designed to fit the critical requirement that peak acceleration should limit to less than 200G during a 30m/s-velocity impact. To study attenuation character economically, the airbag impact dynamics was analyzed with LS-DYNA nonlinear FEA tool. Simulations were made separately by various inflated gas pressures, impact velocities, and impact attitude angles. Simulations depict that with the identical impact velocity, peak acceleration increases with inflated gas pressure, nevertheless, it has little relationship to the Lander＇ s attitude angle. Impact time is only a function of gas pressure and system configuration. System elastic stiffness varies little with impact velocity, which in- creases with inflated gas pressure but decreases with increasing attitude angle. Conclusion is that a 1.75 m-diameter airbag system is feasible for the design requirement. Ground tests were undertaken as expected.