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Description
This study presents the development and implementation of a numerical model to analyze crack propagation in elasto-plastic materials using Griffith's criterion and cohesive zone models (CZM). The research focuses on bridging the gap between classical fracture mechanics and advanced micromechanical approaches to predict material failure under complex stress states. By integrating these methodologies within a computational framework, the study evaluates their applicability in describing crack initiation, propagation, and energy dissipation in materials with significant plastic deformation.
Griffith's criterion is applied as a benchmark for crack propagation in linear elastic fracture mechanics, where the energy release rate is directly correlated with crack extension. Its extension to elasto-plastic materials is evaluated by incorporating plasticity effects through energy correction factors. The cohesive zone model, in contrast, captures local material degradation ahead of the crack tip by defining traction-separation relationships, enabling precise simulation of nonlinear behaviors such as ductile tearing and fracture resistance curves (R-curves).
The numerical implementation employs finite element methods (FEM) with adaptive meshing to accurately resolve stress and strain fields near crack tips. The computational results are validated against theoretical predictions of fracture toughness and energy dissipation. The study also investigates the role of geometrical parameters, loading conditions, and material properties on crack trajectories and the effectiveness of each model in representing real-world fracture phenomena.
The findings highlight the limitations of Griffith's criterion in capturing nonlinear effects and demonstrate the superior accuracy of CZM in modeling complex fracture behaviors. This work contributes to the advancement of numerical tools for fracture analysis and provides insights into material optimization for engineering applications, particularly in structures subject to high stress and strain concentrations.
