Tubing analysis and selection process for the frame of the IXA walker

Abstract

A thorough analysis and test of the frame for a walker was conducted in order to select the optimal size tubing for the walker. Initially a rough first order bending analysis was completed to make an initial decision on tubing size. Finite element analysis was done on the tubing selected to confirm the theory of the first order analytical model, and to determine the expected deflection. A test rig was then built with a 1:1 scale frame in order to test the actual deflection of the frame. Weights were used to measure the deflection for masses varying from 0 lbs to 150 lbs. The results of the complete analysis and testing show that a 1.5" outer diameter by 1.26" inner diameter tube will optimally meet the deflection and weight requirements of the walker. The experimental results are within 5% error of the expected deflection from the finite element analysis, while the quick first order analysis was within 7% of the results from the finite element analysis.