Microstructure-informed, predictive crystal plasticity finite element model of fatigue-dwells

Crystal plasticity finite element (CPFE) modelling is an effective tool from which detailed information on the meso-scale behaviour of crystalline metallic systems can be extracted and used, not only to enhance the understanding of material behaviour under different loading conditions, but also to improve the structural integrity assessment of engineering components. To be of full benefit however it must be demonstrated to not only predict the average global response of the material, but also the local behaviour, to provide insight into localised regions of stress and plastic strain. In this study, a slip system based constitutive model is developed to improve the simulation capability of time independent and time dependent plasticity. Comparison has been made between the macro-mechanical behaviour predicted by the model and previous experiments carried out at engineering length scale. Critically, the macro-mechanical behaviour predicted by the model has been examined against the behaviour of the materials at the meso-scale crystalline level measured by previous diffraction experiments. The robustness of the model is demonstrated on both the macro- and meso-scale through the successful prediction of macro-scale behaviour and lattice strain evolution under a variety of loading conditions. The model not only effectively recognised the influence of prior deformation on subsequent loading, but also complemented neutron diffraction data to enrich the understanding of the influence of an important loading condition on the deformation of grains within the material.