Simplified fatigue durability assessment for rear suspension structure

The eight-channel test rig is widely used in durability assessment of vehicle components while for some cases of rear suspension, this costly instrument is unnecessary. Based on the analysis of structure and forces, a simpler one-channel testing approach is presented for the durability calculation of a dependent rear suspension. Taking a punched rear shock tower as the study object, a FEA strain-stress analysis was first performed to determine the risk area. Then, the entire vehicle test system was created, and the proving ground tests were carried out so that the real strain on the part could be measured. Based on the road test data and the P-S-N curve of the component, the cumulative fatigue damage of a 15,000-kilometer proving ground test road was calculated, and the computational result indicates that the modified structure was safe for durability analysis. Moreover, a standard 50% S-N survival fraction curve was plotted using Corten and Dolan’s method, which can be utilized in the durability analysis for other similar components. Finally, the road test for this modified suspension structure was carried out, and the test result certified that the punched shock tower can be subjected to a 15,000-kilometer proving ground test road without the appearance of fatigue failure.