Fracture toughness prediction of a valve body: Numerical analysis

The crack repair technique by “crack grinding”, due to its efficiency, has been widely used to extend the service life of the cracked structural components. The “crack grinding” technique is carried out by removing the materials which contains the crack. So it is of great importance to study the effects of this repair technique. In this paper, the finite element method is used to analyse the behavior of repaired cracks in mode I by computing the stress-intensity factors at the crack tip. 3D numerical simulation was carried out to model the steam governor valve in a coal-fired thermal power plant with a semi-elliptic crack. Since no extra auxiliary solutions are required for the computation, the proposed method appears to be visual and can be used for evaluation of the associated stress-intensity factors. The plot of the stress-intensity factors according to the crack length in mode I, shows that the stress-intensity factor exhibits an asymptotic behavior as the crack length increases. It’s to be noted that a transition zone allows connecting the refined specific crack tip mesh to the global structural discretization. So this technique can be used for complex industrial structures.