Three Dimensional Tip-over Analysis and Optimization of Lunar Lander - Flexible Multi-body Dynamic Approach

초록

To accomplish the lunar mission, lunar lander should touches down safely on lunar surface. When it makes a landing, there may be several threats. The first one is hard landing which causes severe deceleration of lunar lander. In this case, excessive deceleration of lunar lander may lead to failures of payload although structural failure does not occur. The second one is disastrous tip-over of lunar lander. Once tip-over of lunar lander occurs, it is nearly impossible to return to the earth as well as to accomplish the lunar mission, even though it may not cause any damage in lunar lander. Therefore, lunar lander should be designed to prevent tip-over when it touches down on lunar regolith. In the line of thought, tip-over analysis of lunar lander is carried out in this work. Conventionally, tip-over analysis in previous works has been carried out by modeling the shock absorption system as spring and dashpot elements. However, this work adopts a rather different approach. In this work, honeycomb shock absorption system is modeled by elasto-plastic materials in order to take into account the realistic behaviors of permanent deformation of honeycomb shock absorption system. And the elasto-plastic model for the shock absorption system is plugged into 3-dimensional flexible multi-body lunar lander system to simulate the dynamic behavior of lunar lander during touch-down and to observe whether tip-over occurs or not during landing on lunar regolith. Additionally, to investigate the effect of inclination of lunar surface on tip-over, 3-dimensional simulations are carried under various landing scenarios. Furthermore, metamodel based design optimization of lunar lander is carried out in order to prevent tip-over as well as to minimize the landing deceleration of lunar lander.