Numerical study of microstructural fatigue crack growth using damage mechanics

Abstract Generally the external load applied to engineering components is significantly below the yield strength. Yet, the materials fail without showing any visible indication. Furthermore, the fatigue crack growth behavior should be observed microscopically. Thus, the microstructural study of fatigue crack growth becomes important. The microstructural study of fatigue crack growth in metals does not only demonstrate the effect of microstructural properties (grain size, grain boundary thickness, etc.) on the mechanical response of the system but also informs about a microstructural modification to resist fatigue crack growth so that fatigue life of the component can be enhanced. In the present work, fatigue crack growth simulations are performed on compact tension (CT) specimen. The microstructure region is generated near the crack tip using the Voronoi tessellation approach. Further, an in-house MATLAB code based on the finite element method and continuum damage mechanics (CDM) is implemented to perform the numerical analysis. Damage based analysis is done on the microstructure meshing system to visualize the effect of microstructural quantities (average grain size, grain boundary thickness) and material constant on the fatigue crack growth in this work. Here, the obtained result shows good agreement with the experimental result and the effect of microstructural quantities on the crack initiation life is observed.