A probabilistic framework for the modeling of fatigue in a lamellar XDTM gamma titanium aluminide alloy

This paper presents a probabilistic framework for the modeling of fatigue damage in a gamma titanium aluminide alloy (Ti–45Al–2Mn–2Nb +0.8 vol% TiB2). This includes: empirical stress-life and fracture mechanics approaches to the estimation of material reliability or the risk of failure. Empirical reliability functions are obtained initially from multiple stress-life experiments designed to identify the statistical distributions that best describe the measured variabilities in fatigue life. Fracture mechanics-based reliability functions are also derived using statistical distributions that characterize the measured variabilities in fatigue crack growth data obtained from fatigue crack growth experiments in the long crack regime. The anomalous behavior of short cracks is then discussed before assessing the implications of the current work for the design of engineering structures and components from gamma-based titanium aluminides.