Rim Section Fatigue Results of Aluminum and Steel Wheels

A rim section fatigue test technique was introduced in order to determine the actual fatigue behavior of the material at the most critical area of the rim, the inner radius of inboard bead seat area, where the ordinary crack initiation began as observed from the wheel radial fatigue test. The rim section fatigue S-N curves at the stress ratios of R = 0.1 and 0.5 for the 1008 steel and aluminum 5454 rims were presented. FEM was employed to determine the stress levels corresponding to the test loads used during the rim section fatigue test. A fairly good agreement has been shown in all comparisons of FEM results and strain gage measurement. Tensile and bending fatigue data from the flat specimens of the sheet metals with 30% cold rolling were used to compare with the rim section fatigue results. It was concluded that the equivalent amount of simple cold rolling to the material at the inner radius of inboard bead seat area of the rims appeared to be near 30%.