SUMMARY

The mechanical behavior of additively manufactured components is a critical topic interest for the many industries wanting to leverage the weight reduction and ease of complex part fabrication that such components can provide. While mechanical behavior of these materials has been quantified in many post mortem investigations, a rigorous understanding of how this behavior is mediated by the presence of various intrinsic AM defects (e.g. porosity, lack of fusion and surface roughness) has yet to be established. In this regard, prior studies have yet to quantify evolution of failure due to these defects. As such, without developing a better understanding and knowledge base of how these defect fields affect the mechanical behavior of AM components, model-based efforts to predict failure cannot be fully validated and such parts cannot be adequately qualified. The proposed thesis investigation will examine the role that internal defects play in the deformation behavior of thin-walled AM-produced structures using laser powder bed fusion of 316L stainless steel powder as a model system. The proposed study will center on: (1) tomographic characterization of the defect field in AM components, (2) in situ characterization of the evolving defect field in terms of morphological parameters and deformation variables (e.g., displacement, strains and strain rates), (3) development of an analytical modeling framework for predicting failure as a function of the defect field characteristics, and (4) determination of the role of simulated AM defect configurations on deformation and failure. This research will provide robust tools for the analysis and qualification of defect criticality in AM components and uncover what characteristics of defects drive their failure. Taking advantage of the knowledge and tools developed by this study, the AM design and manufacturing community will have the framework for widespread adoption of 316L stainless steel AM components.