Stochastic fatigue damage accumulation under broadband loadings

Abstract Fatigue tests were conducted on 72 high-strength welded steel cruciform-shaped specimens subjected to stochastic loadings. Results of these tests are used to investigate experimentally the effects of loading non-normality and frequency bandwidth and truncation on the rate of fatigue damage accumulation. Test results are compared with predictions made using Rayleigh approximation and rainflow analysis in terms of cycles and time to failure. Results indicate that non-normality can significantly increase the rate of fatigue damage accumulation, and can result in non-conservative fatigue life estimates if its effect is not accounted for, regardless of frequency content. Likewise, frequency content was also found to influence the rate of fatigue damage accumulation, but to a lesser extent than non-normality. When higher-frequency components were included, shorter fatigue lives were observed. Fatigue life predictions using rainflow analysis produced good agreement with experimental results; predictions made using Rayleigh approximation produced non-conservative fatigue life estimates.