Accurately modeling ductile fracture behavior of metals is a necessary but difficult task. Recently, a new theoretical framework, the Exclusion Region, ER, theory, for modeling ductile fracture, along with a numerical method, the Arbitrary Local Mesh Replacement method, to accommodate crack advance in a finite element mesh, have been developed and show significant promise in advancing the accurate prediction of elastic-plastic fracture. This model was previously implemented in the two-dimensional finite element code FEFRAC in a linear version and a fully nonlinear version. The ER theory has already shown accurate results in the linear FEFRAC version. However, for the ER theory to be a useful modeling tool for inelastic materials, material constants for ductile materials to support the ER theory must be determined.; The present research attempts to determine material constants for a ductile material to validate the ER theory. To this end, a model-driven full matrix experimental program of fracture tests was completed using 2024 Al specimens in both symmetric and unsymmetric three-point bend configurations. Using the load, CMOD, and crack length experimental data, comparisons to these same values as determined by the finite element implementation of the ER theory were made for the purpose of calibrating the proposed material constants of the Exclusion Region theory. During this process, it was determined that the 2024 Al's behavior in the near-tip region is not indicative of typical ductile fracture behavior. This resulted in the lack of applicability of conventional local constitutive models for ductile behavior. As this research's goal was to show the applicability of the ER theory and not to develop a new constitutive model, model calibration continued with experimental data collected from other researchers for three-point bend specimens of Inconel 718.; The ER theory successfully modeled the load vs. CMOD behavior of the Inconel 718 fracture specimens. Initial ranges of appropriate magnitudes for fracture-related material constants are suggested for the Inconel 718. This modeling work provides a richer understanding of the applicability of the various stress- and deformation-based separation criteria used in conjunction with the ER theoretical framework to accurately model ductile fracture.
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