タケダ　マサカズ   Masakazu Takeda   武田　真和    所属   追手門学院大学  理工学部 機械工学科    職種   講師
発表年月日	2020
発表テーマ	Impact force calculation using non-smooth dem and consideration of landing contact surface shape of landing leg for small mars lander
会議名	Proceedings of the International Astronautical Congress, IAC
発表形式	その他
開催期間	2020～2020
発表者・共同発表者	Shiori Matsumoto,Shun Yamaguchi,Takumi Takise,Yoshiki Sugawara,Takeda Masakazu,Shinichi Nakasuka,Yasuko Kasai
概要	THz observations by the Herschel Space Observatory suggested that the surface of Mars may be rich in oxygen. Atmospheric observations have not been made on the Mars surface or around the orbit, including the Herschel Space Observatory, and continuous observations on and around the surface of Mars are required. Therefore, a low-cost, short-term development of a small THz Mars spacecraft is underway for the purpose of continuous Mars landing exploration with short-term development. This plan requires a proposal for a new landing system. Conventional landing systems are complex and heavy. In this project, the landing legs made of aluminum foam with shock-absorbing capacity are studied. The deformed aluminum foam absorbs the shock of landing and at the same time reduces the load on the spacecraft during landing. Therefore, we proposed a multi-stage landing model that uses aluminum foam as a shock absorber. Drop experiments were conducted with the proposed landing legs, and the landing legs pierced the ground and the shock absorber did not deform sufficiently. This indicates that the impact absorption was affected by the ground. In order to calculate the impact force with the effect of the ground taken into account, Non-smooth DEM is used to analyze the impact force. However, Non-smooth DEM may cause undesirable penetration due to the effect of the time step. To reduce the penetration rate, this paper proposes an analysis method in which a part of DEM (Distinct Element Method) is used to calculate a repulsive force depending on the amount of penetration. The impact force calculation for the ground consisting of rocks was performed using only Nom-smooth DEM analysis, and undesirably the impact force was yielded during two steps. On the other hand, the penetration of particles was reduced with the proposed method compared to the results of Non-smooth DEM alone. Thus, the impact force was calculated in one step with reduced penetration. The results show that the proposed method, which is designed to reduce penetration, is likely to be more accurate than Non-smooth DEM alone.