AN ELASTIC-VISCO-PLASTIC DEFORMATION MODEL OF AL–LI WITH APPLICATION TO FORGING

Abstract

Recent alloy developments have produced a new generation of Al–Li alloys that provide not only weight savings, but also many property benefits such as excellent corrosion resistance, good spectrum fatigue crack growth performance, a good strength and toughness combination and compatibility with standard manufacturing techniques. The forging of such alloys would lead to mechanical properties that closely match the aircraft engine requirements including lower weight, improved performance and a longer life. As a result, detailed analyses need to be performed to determine which material properties are best suited for a specific structure and how to achieve the required mechanical and damage tolerant properties during material processing. We developed an integrated physics-based model for prediction of microstructure evolution and material property prediction of third-generation Al–Li alloys. In order to develop such a model, an elastic-plastic crystal plasticity model is developed and incorporated in finite element software (ANSYS). The model accounts for microstructural evolution during non-isothermal, non-homogeneous deformation and is coupled with the damage kinetics. Our model bridges the gap between dislocation dynamics and continuum mechanics scales. Model parameters have been calibrated against lab tests including micropillar in-situ simple compression tests of Al–Li alloy 2070. Numerical predictions are verified against the lab results including stress–strain curves and crystallographic texture evolution.