Abstract:

The component fatigue life can be precisely predicted by service-simulation fatigue test. A set of reasonable and practical accelerated testing method is eagerly required to save test time. The emphasis of this research is on the accelerated testing method for the condition that only outer excitations such as force, displacement and acceleration are possessed while local strain responses are not possessed. A set of engineering-application-conveniently accelerated testing method is created for the service-simulation fatigue test. This approach is achieved by applying the modified Miner rule, the fatigue data editing(FDE) technique and treating the pseudo damage retention rate as the small load omission threshold. Taking automotive front sub-frame fatigue tests as an example, three accelerated loading spectra with pseudo damage retention rate of 99%, 95% and 90% are generated. The 95% and 90% retention accelerated spectra and the original spectrum are selected to conduct the fatigue tests by fully considering the load characteristics and acceleration effects of every accelerated loading spectrum. Test results show that both the two accelerated spectra have reduced test time efficiently while guaranteed the same test results as those of original spectrum tests. Additionally, the 90% retention accelerated spectrum is proved to have better acceleration effect. This set of method is engineering-application-conveniently and is an alternative way for other automotive components service-simulation fatigue tests.

Key words: accelerated test, fatigue data editing (FDE) technique, pseudo damage, small load omission criterion, service-simulation fatigue test