Simulation And Optimization Research Of Superelastic NiTi-based Memory Alloy Buffer Device

The development of China’s aerospace（especially deep space exploration）field,such as the need for energy-absorbing devices for extraterrestrial planet landings,superelastic shape memory alloys have repeatable high energy-absorbing properties,which are expected to meet the needs.At present,the research on the application of shape memory alloys to buffer devices is still in its infancy.Finite element analysis is an important method for design and analysis of buffer devices.In this thesis,based on the mechanical properties of Ni₅₀Ti₄₉V₁memory alloy,the finite element simulation and fitting of the buffer device made of shape memory alloy is carried out.Based on the different widths,thicknesses and inclination angles of memory alloy sheets,three buffer devices of type A,B and C were designed,and the stress-strain distribution and energy absorption characteristics of the buffer devices were analyzed by finite element method to determine the location of stress concentration.The parameter optimization platform of the buffer structure is built through Isight,and the parametric modeling commands and finite element analysis modules are imported.The energy absorption is used as the optimization objective,and the parameters that control the structure of the buffer device are used as the optimization variables.The automatic annealing algorithm is used to optimize the structure.The main findings are as follows:The research shows that under the compressive load of 800 N and the same loading rate（time step）,the energy absorption of the A-type,B-type and C-type buffer devices is 0.81 J,0.8J,and 0.52 J in turn,and their maximum recoverable displacements are19.88 mm,16.46 mm,6.13 mm,and the maximum recoverable strains are 8.5%,3.9%,and 1.1%,respectively,indicating that the A-type buffer device has the best performance in energy absorption and recoverable displacement.During the process,the more regions where the device undergoes martensitic transformation,the better the energy absorption effect.On the basis of the above research,the A-type buffer device is further optimized.The parameters of the structure of the A-type buffer device are selected as the optimization variables.The energy absorption of the optimized A-type device（1.29 J）is higher than that before optimization（0.81 J）,the volume of the device is reduced by5%（reduced weight）,and the volume energy absorption ratio is increased by 67.6%.The parameters that determine the structure and the width and height of the memory alloy sheet are selected as variables,and the A-type device is further optimized to increase the energy absorption to 1.79 J,the structure volume to 17.5%,and the volume energy absorption ratio to 168%.The recovery displacement is increased by 22%,the maximum Von Mises stress is decreased by 27%,and the stress concentration is effectively improved.The effectiveness of the optimization method in improving the comprehensive performance of the buffer device is verified.