The Finite Element Analysis And Optimization Design Of A Stair-climbing Wheelchair Frame

With the raising living standards and technological level,the needs to the multi-functional stair-climbing wheelchair of the elderly and the disability are more urgent.In response to this social demand,the project researched a multifunctional wheel-legged stair-climbing wheelchair.It is not only capable of walking on level ground,but also can complete movements like stair-climbing,obstacle-crossing and ditch-over.The security of the wheelchair is the most basic and important requirement.The chassis studyed in the paper connects several parts of the wheelchair as a whole and supports them,so the strength of the chassis is the basic requirement to ensure the continuous movement of the wheelchair.At the same time,a good stiffness of the chassis is key to ensure a highly accuracy of the transmission system.Therefore,in order to assess the mechanical behavior of the chassis,this paper made static analysis and calculations to the chassis via FEM analysis software.Firstly,we described the overall centroid coordinate of the wheelchair in mathematical equation,and established a gravity allocation model of the wheelchair.Based on the distribution of the gravity of the wheelchair,we got the maximum counterforce of each wheel that contacted with the ground directly.Meanwhile,according to strength theory of materials,we calculated the suitable preload of screws that fix the chassis of the wheelchair.Secondly,we made the finite element analysis to the chassis,and made some improvements of the structure of the chassis against its existence defects and deficiencies.Then we made the finite element analysis of the improved structure and verified that its performance can meet the requirements of the wheelchair under extremely working conditions.Finally,we established optimization model of the chassis and made optimum calculations to the assembly position of the big wheel that fixed on both sides of the chassis.According to the optimization results and actual structural conditions,we got the optimum assembly position of the big wheel.