FATIGUE LIFE PREDICTION FOR A SUSPENSION ARM MADE OF CAST ALUMINIUM ALLOY

摘要

Fatigue life prediction for a rear suspension arm for a passenger vehicle made of AlSi7Mg cast aluminium alloy was carried out using a fracture mechanics approach based on laboratory specimen test results. Crack growth behaviour was measured by using Four Point Bend (FPB) and Corner Crack (CC) specimens on single cast bars. Defect distribution, such as porosity, was quantified using image analysis techniques. The predicted fatigue lives were consistent with real rig test results on the component. In the lower life regime the fatigue life is dominated by the crack propagation from a defect. However, at longer lives crack initiation at the defect must also be considered in order to predict the observed fatigue response.