Corrosion-sensitive Multiscale Fatigue Modelling PhD

The application of repetitive loads results in fatigue damage that can propagate and cause catastrophic failures. The ambient conditions around a fatigue crack tip has a dramatic effect on the fate of a component—a part may survive millions of cycles in vacuum and last only a few hundreds of thousands in air and much lower in actively corrosive environments. Although there is a clear synergy between fatigue damage and corrosion, most fatigue prognosis models do not explicitly consider the role of the environment, which is usually reduced to obscured fitting coefficients. This strategy carries large uncertainty and requires vast amount of expensive and time-consuming experimental data. Worse, sometimes the experimental data is simply inaccessible.

The need for cost-efficient research that prevents fatigue failures has pushed towards integrated computational materials engineering approaches that improve competitiveness. These approaches rely on physics-based models that can be validated with experiments and bottom-up models at multiple scales in order to predict the macroscopic response. Hence, this research will investigate the degradation of metallic materials under corrosion-fatigue conditions by integrating multiscale physics-based models combined with mesoscale experimental tests.

This research will study the effects of corrosion-induced changes in composition on fatigue damage in metallic materials. We will employ 3-D crystal plasticity models in order to understand the role of compositional changes in fatigue damage. We will correlate these changes with a realistic degradation from corrosion processes. The simulations will be integrated with mesoscale experimental to evaluate the constitutive response of smooth specimens degraded by corrosion. Given the innovative nature of this research, it will represent a milestone in corrosion-fatigue research and will likely mark a path towards future degradation assessments.