New methodology for determination of load spectra for the vehicle accelerated durability testing associated with the time correlated fatigue damage analysis method

The generation of valid and effective test spectra from proving ground recorded load spectra is critical for automotive durability testing. Traditional methods mostly based on spectrum damage were used to select load spectra. Statistical characteristics of load spectra were taken into account, and a new load spectra determination method based on a concatenation of a multi-section minimum standard deviation spectrum (CMSD) was proposed. The CMSD spectra were created and based on proving ground recorded load spectra. Fatigue damage analyses showed that the CMSD spectra approximated the mean damage spectra and were representative of proving ground load spectra. Subsequently, the CMSD spectra were edited by applying the time correlated fatigue damage (TCFD) analysis method to generate accelerated loading spectra. The spectra editing process of the TCFD was discussed in detail. Validation of the accelerated spectra was conducted from amplitude and frequency domains. The same fatigue damage and identical spectrum properties were retained in the accelerated spectra. A vehicle 4-post testing was finally conducted where the accelerated loading spectra were applied as the target spectra. Several fatigue fracture phenomena occurred during our test, which showed good agreement with the field test. Therefore, the load spectra determination method CMSD associated with the load spectra editing method TCFD were demonstrated reasonable and practical.