Fatigue life analysis on spot welds in automotive hood based on modal stress recovery
LIANG Ting;WU Zexun;MENG Fanliang;ZHANG Linbo;Chery Automobile Co.Ltd.;
The finite element model of spot welds on automotive hood is built and analyzed. The comparison of the analysis results with the test mode results indicates that the finite element model is valid. The quasi-static and modal stress recovery methods are used to obtain the time history of stress.The fatigue life estimation of spot welds is implemented based on Palmgren-Miner linear damage accumulation rule and S-N curve,and the effect of cut-off frequency and structural damping on the fatigue life of spot welds is considered in modal stress recovery method. The comparison with the virtual rig test results indicate that the fatigue life obtained by quasi-static method is larger than that of test,and the modal stress recovery result is consistent with the test result while the structural damping is 0. 06 and the cut-off frequency is 200 Hz. The optimized hood passed the durability road test.