The Structure Design And Optimization Of Magnetorheological Buffer Of Lunar Landing System

The exploration and resource development of lunar have been one of the most important advanced technology. At present, many economically advanced countries have carried out their own lunar exploration program in succession. For now, China has completed the aims of two phases successfully which are circumlunar flight and lunar surface soft-landing. The aim of next phase is sampling and returnning back to the earth safely that will bring forward higher request of the lunar probe landing system.To target the requirement from lunar probe landing system to high-performance buffer, the optimal design theory and method of magnetrheological(MR) buffer structure are studied in this paper. Firstly, the structure design schematic of landing and buffering system is carried out through dynamic characteristic analysis. Secondly, the overall parameter design of landing and buffering system is proceeded according to the constraints of probe unfold envelope and ground clearance. The effectivemess of proposed scheme is verified through dynamic analytical software ADAMS. Thirdly, based on the requirement from landing system and rheological behavior of MR fluid, a mixed mode based MR buffer with single piston and gas compensation device is designed. Aim to the shear-thinning nature that the MR fluid will present when working in high flow rate and high shear conditions, the Herschel-Bulkley model is chosen to derivate the calculation formula of buffering force. Fourthly, target to the buffering demands of lunar probe landing system, according to buffering force fomula under impact load, Ampere circuital theorem and Gauss theorem, the structure and magnetic circuit of MR buffer are designed. Parameters concluding gas pressure, structure dimensions, turns and diameter of coil are determined. The rationality of magnetic design is proved through electromagnetic field finit element analysis. At last, the multi-objective optimal design to MR buffer structure is conducted by the method of NSGA-II with two objectives of minimum response time and minimum energy dissipation. The results show that the output buffering force of proposed MR buffer can match the design requirement. The buffering force fomula based on Herschel-Bulkley model can describe the shear-thinning phenomenon preferable. The optimization problems can be solved fast using the method of NSGA-II and the obectives of minimum response time and minimum energy dissipation are successfully realized.