Numerical simulation of fatigue crack propagation: A case study of defected steam pipeline

Abstract

In order to prevent the premature failure of steam pipeline produced of molybdenum-vanadium steel, the experimental tests were performed to measure fracture toughness and to determine the mechanical behaviour of cracked pipes. A finite element method was used to calculate the fracture behaviour of the pressurized pipeline made of 14MoV6-3 steel based on the J-integral computation. The J-R curves were experimentally obtained by the elastic unloading compliance method for the single edge notched bend specimens and compared with those obtained using finite element method. A two dimensional finite element analysis was performed in Ansys Workbench software to determine the stress distribution and calculate J-integral values for the selected specimen geometry. Special attention was paid to the influence of applied boundary conditions on the accuracy of J-integral values, as well as to the influence of mesh density. It is shown that numerically obtained J-values significantly depend on the number of nodes used to apply displacements. However, if recommendations proposed in this paper are implemented, the accuracy of calculated values is satisfactory and successful failure analysis can be carried out. This approach can be useful in engineering applications where time saving and costs reducing are required.