Fatigue Damage Accumulation Under Stochastic Stress Histories

by Shahram Sarkani, George Washington Univ, Washington, United States,
Naser K. Buresli, George Washington Univ, Washington, United States,
George Michaelov, George Washington Univ, Washington, United States,



Document Type: Proceeding Paper

Part of: Structures Congress XII

Abstract:

An extensive simulation study was performed to generate random Gaussian stress time histories from power spectral densities (psd's). The psd's of time histories were selected to represent a wide range of actual stress power spectra of dynamic systems encountered in practice. A total of ninety six single block, bi-modal and smooth unimodal psd curves were used to simulate time histories by the popular Gaussian simulation technique. Rainflow cycle counting method is used to determine the moments of stress range resulting from all the generated stress time histories. Based on analysis of simulation results a new spectral fatigue damage calculation model is introduced. It is based on the spectral bandwidth parameter ?_1.5. The fatigue damage calculations based on the proposed model have been found to be significantly more accurate than the Rayleigh approximation for most psd cases. The damage prediction from the new model compares well with predictions from rainflow analysis, but is simpler to use than the rainflow.

Subject Headings: Power spectral density | Stress analysis | Stochastic processes | Fatigue (material) | Stress history | Rain loads | Gaussian process

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