Numerical simulation of the crack shape for the thermo-mechanical loaded valve

In this paper, as a typical example, a valve in a coal-fired thermal power plant with a semi-elliptic crack in its body is presented to illustrate an effective method to predict the surface crack shape under thermo-mechanical loading. The 3D finite element analysis (FEA) is employed to estimate the stress intensity factor (SIF) based on the 3D constraint effect at a set of points along the crack front, and then the evolution of the crack shape is studied according to the SIF. Some numerical techniques were well applied to simulate the real charge condition during the valve operation. It has been assumed that each point in the front of the crack advances in direction perpendicular to such a front, according to the Paris–Erdogan Law. Numerical results of the present method agree fairly well with detective results.

► We model a thermo-mechanical loaded valve which has a semi-elliptic crack. ► Arbitrary surface crack shapes can be predicted based on the 3D constraint effect. ► The LEFM method can reproduce the real measured data without more EPFM analysis. ► Crack shapes can be effectively controlled by coupling with other detective methods.