Analysis Of Fatigue Life And Crack Growth Behavior In Pressure Vessel

With the rapid development of economy and industry, pressure vessels have been widely used in petroleum, chemical and other industrial sectors as well as daily life. A large number of pressure vessels and various types of and pressure equipment are working in a complex load, it is easy to cause fatigue crack propagation for engineering structures, which can lead to catastrophic damage. Therefore, there are important theoretical and practical significances for system-depth study of the fatigue crack growth rule and prediction method of crack propagation behavior. In this paper, the method of combining numerical calculation and simulation has been adopted to analyze the forces and the life of the pressure vessel; The simulation is used for the surface crack morphology in different initial morphology. The main content and achievements are listed as following.A reasonable model and load constraints are established based on the force condition and the structure the pressure vessel, and the force and deformation of various parts of the pressure vessel are analyzed, working conditions of the pressure vessel are simulated to get its overall service life, and weak links of the pressure vessel are determined.Stress intensity factor K around the cracks existing in pressure vessel surface and semi-elliptical surface varies with θ. Stress intensity factor at the crack tip Along the short and long axle determine the crack growth rate, which affects the crack morphology. The relationship between the crack length and depth is determined by using comparison of numerical results with experimental results, which can provide the basis for fatigue life assessment of the pressure vessel containing surface crack.Material parameters and crack propagation rules are analyzed under the degree at25,200,400,550based on service conditions of the pressure vessels, and the previous experimental data and using steel316L of pressure vessel for the study, which can obtain a relationship describing the crack propagation rate da/dN and material properties constant. The relationship can be used to predict the fatigue crack growth rate at different temperatures.