Research on Fatigue Damage of Independent Suspension Support Structure for a Commercial Vehicle Based on Load Spectrum of Basic Vehicle

In this paper, an equivalent conversion method is proposed to apply the six-dimensional force road spectrum of the four-axle vehicle on the same platform to the three-axle through the axle load comparison. Further, the feasibility of the devolved equivalent conversion method is verified, and the fatigue performance improvement of the wishbone support structure of a commercial vehicle is finally achieved. Specifically, firstly, the load spectrum at each attachment point of the suspension for the three-axle vehicle is obtained through the iteration of the multi-body dynamic model. Furthermore, the finite element model of the suspension for the three-axle vehicle is established; the analysis of fatigue life for the suspension structure is performed by extracting stress amplitude through the multi-axis cyclic counting method and calculating equivalent force amplitude through McDiarmid’s criterion, combined with the SN curve of the material. Finally, the prediction and optimization design of the fatigue weak position for the wishbone support are realized. The results of the three-axle vehicle after trial production show that the fatigue damage position of the control arm bracket is consistent with the simulation prediction, and the fatigue performance of the optimized suspension is significantly improved. Therefore, the developed method can be applied to the fatigue analysis of replacement vehicle components, which can shorten the design cycle and improve the efficiency under the premise of ensuring the accuracy and reliability of fatigue life prediction.