Finite Element Analysis Of Stress Intensity Factor Of Steel Component

Fatigue in steel materials is the process of initiation and propagation of cracks under cyclic loading, the failure of the structure can occur when the crack is sufficiently propagated, resulting in fatigue failure. Therefore, the investigation of fatigue behavior is actually the research on cracks. The principal theory that is used to investigate the crack growth is LEFM (Liner elastic fracture mechanics) combined with experiments and finite element method.First, a central-hole model is analyzed in finite element modeling to understand the stress intensity factor on the crack tip, results show that the stress distribution of the numerical results are in good match with the theoretic results, also, the results show that the stress intensity factor along the thickness of the crack tip is distributed un-uniformly, the maximum value occurs in the middle and the minimum on the surface. This phenomenon implies that the crack growth rates along the thickness of the crack tip are different.Second, a series of analysis are conducted to investigate the relationship between the crack length and the stress intensity factor at the crack tip for one-side edge-notched specimen. The comparison between the FEM results and the regression formula shows good coincidence, which proves the effectiveness and accuracy of the FEM.Finally, on the brief analysis of the edge-notched specimen strengthened by pre-stressed CFRP, the relationship between the pre-stressing level and the stress intensity factor is obtained. The SIF decreases linearly with the increase of the pre-stressing level. Furthermore, this result reveals the with enough pre-stressing level, the crack propagation can be fully stopped when the threshold value of the stress intensity factor is reached.