Crystal plasticity modeling of fretting fatigue crack initiation behavior in Ti6Al4V

Fretting Fatigue (FF) constitutes a significant concern in engineering applications, notably in components subjected to cyclic loading and relative motion, such as dovetail joints in aircraft engines. In this context, the mechanical behavior of Ti6Al4V, a widely employed titanium alloy distinguished by its exceptional mechanical properties, has critical importance. Despite Ti6Al4V's commendable strength-to-weight ratio, its susceptibility to FF presents significant challenges to the structural integrity and operational lifespan of crucial components. Consequently, a comprehensive understanding of the mechanical response of Ti6Al4V due fretting conditions and stands imperative for advancing the reliability and lifespan of aerospace structures. Microstructural characteristics, such as grain size and grain orientation, directly influence the material's macroscopic mechanical response and fatigue life. This study leverages a Crystal Plasticity Finite Element Method (CPFEM) coupled with a sub-modelling technique to systematically investigate FF crack initiation characteristics of Ti6Al4V under various loading conditions. The impacts of dual- phase grains, grain size, and crystal orientation on FF behavior are explored. The study employs the critical plane method to compute Damage Parameters (DPs), aiming to enhance the predictive accuracy of FF life. An isotropic model and three Crystal Plasticity Finite Element (CPFE) models with different grain sizes are compared, focusing on their stress-strain behavior and representation of DPs. The CPFE models, proposed herein, exhibit remarkable precision in forecasting FF crack initiation and is validated against experimental FF data.