Application of the Extended Isogeometric Analysis (X-IGA) to Evaluate a Pipeline Structure Containing an External Crack

Table 3

Comparison of the KI factors between the proposed method of X-IGA and the analytical, FEM, and X-FEM methods for the case of a crack with a = 5 mm.

KI [MPa.mm^0.5]
Analytical	FEM Method	X-FEM Method	X-IGA; 470 elements	X-IGA; 767 elements
12.88 [32]	13.79	13.69	13.18	13.015
Error ()	6.59	5.91	2.27	1.03