Spectral methods for multiaxial random fatigue analysis of metallic structures

This paper presents computationally efficient frequency domain methods for estimating the high-cycle fatigue life of metallic structures subjected to a random multiaxial loading. The equivalent von Mises stress method proposed earlier by the senior author is first reviewed. It is then shown that the multiaxial rainflow method, initially formulated in the time domain, can be implemented in the frequency domain in a formally similar way. The consistency of the results are checked by comparison with a time domain method based on the critical plane. It is observed that frequency domain methods produce enormous computer savings and correlate fairly well with the time domain method in terms of localizing the critical areas in the structure. A frequency domain implementation of Crossland's failure criterion is also proposed; it is found in very good agreement and much faster than its time domain counterpart.