A Critical Distance Parameter for Random Vibration Fatigue Life Estimation of Notched Metallic Structures in the Frequency Domain

Abstract

A critical distance parameter is introduced to describe the stress gradient effect of notched metallic structures under random vibration loadings, which is the frequency domain expression of the theory of critical distance (TCD) based line method stress. Fatigue life estimation on notched metallic structures could be carried out by combining this parameter with the spectral method for random vibration fatigue life analysis. The fatigue experiment under random vibration loadings is conducted on two types of notched plate specimens of 7075-T6 aviation-grade aluminum alloy, where both circumstances of large and small stress gradients in the notch region are investigated. Good correlation between the calculated results given by the proposed model and the experimental fatigue life results shows the satisfactory prediction capability on random vibration fatigue life for notch conditions of both steep and mild stress distribution variations.