Spectral methods to estimate local multiaxial fatigue failure for structures undergoing random vibrations

This paper proposes computationally efficient frequency domain formulations for two well-known multiaxial fatigue failure criteria, namely Matake's cr itical plane criterion and Crossland's criterion. For that purpose, it is s hown how fatigue-related variables involved in both criteria can be estimat ed front the power spectral density matrix of the local stress vector. The finite element model of an example structure is then used to illustrate the application of the proposed frequency domain approaches. It is observed th at both frequency domain formulations produce consistent results when compa red with those obtained in the tune domain from Monte-Carlo simulations of local stress vectors while offering tremendous computer savings. A frequenc y domain tool indicating whether the principal stress directions do rotate with time or not during the loading at a given location in the structure is also presented.