Computational Method for Crack-Opening-Area of Nuclear Pressure Pipe With Circumferential Through-Wall Crack

The determination of crack-opening-area (COA) is very important in the application of LBB technique. A numerical method based on coupled finite element-meshless Galerkin method (FEM/EFG) is proposed to calculate the crack-opening-area of cracked pipes in nuclear power station. By means of the method by which the meshless nodes are used in the vicinity of crack front and the finite elements are applied in remained zone, the resolved domain is numerically discreted. This technique can speed up the set up of the numerical model and improve the computational precise. Based on the displacement field determined by the coupled FEM/EFG, a kind of surface integral method is used to accurately calculate the crack-opening-area. The correctness and validity of the presented method are demonstrated by comparing the COA results of centre-cracked panel under uniform load determined by the presented method with those from theoretic formula. Subsequently the numerical method for cracked panel is employed to calculate the crack-opening-area of nuclear pressure pipe. The numerical COA results are compared with those determined by engineering methods. It is shown that for thick-wall or middle-thick-wall pipes, the COA results obtained by the presented method are more conservative than those by the engineering methods, whereas for thin-wall pipes, the results by the later one are more conservative than those by the former.