Vibration Fatigue Test Acceleration Factor Under Broadband Random Excitation: Analytical Modeling and Experimental Validation

The vibration fatigue tests of engineering structures performed under real loading conditions are time-consuming and expensive. In order to reduce the vibration fatigue test time, a novel analytical random vibration fatigue acceleration model under broadband excitation is proposed in this paper. The multi-peak response stress spectrum is divided into several single-peak spectra with only one peak in each segment. The Rayleigh model is used to fit the stress amplitude probability distribution. The concept of scale factor is introduced and the scale factor of each divided single-peak stress spectrum is calculated according to the probability density function. The acceleration factor is obtained based on the scale factor. The random vibration fatigue tests of 2024-T3 and 7075-T6 aluminum-alloy specimens with elliptical and slot holes were performed and the vibration fatigue lives were obtained under different load spectra. It is demonstrated that the results calculated by the presented model are in sound agreement with the test results.