| Offshore platform as a structure in a variety of harsh environments and withstand wind loads of the structure, waves, currents and earthquakes,Pressure vessel is an important part of offshore platform, and most of the pressure devices, the cylinder will produce a variety of injuries and defects,and in the defective parts will crack under complex loading conditions and the environment, and more prone to fatigue crack growth of the pressure vessel, the pressure vessel leading to fatigue failure and fracture failure, causing catastrophic damage.Therefore, the study of fatigue crack propagation behavior of fatigue crack propagation prediction methods and the law is very important,this study has important value in practical engineering applications.The article mainly use the finite element software simulation and numerical calculation of the combination of research methods,For internal crack in the fatigue life of Marine oil and gas gathering engineering pressure vessel is analyzed, and the inner crack in pressure vessel based on reliability analysis of fatigue life.In this paper, pressure vessel containing crack of Marine oil and gas gathering and transferring projects within the main research contents and research results were as follows:For the complex structure and stress state of the pressure vessel, having taken part in the cracks of the cylinder as the object of study, the finite element model with the inner surface of the cylinder oval shallow cracks using ANSYS / workbench finite element software to calculate the ellipse having an inner surface shaped pressure vessel inner pressure of shallow cracks, fatigue life under the combined effect of additional load and thermal load by calculation and analysis of axial cracks, circumferential cracks, crack length, crack depth, as well as the angle between the crack on fatigue life influence, and compare the results of axial cracks and crack depth are the main factors affecting the fatigue life.In addition, Compared to the results obtained with the Paris formula compares and analyze the reasons caused the error, there is a certain reference value in practical engineering applications.Considering the mechanical properties of material, the size of the crack defects,and working load there are uncertainty and randomness, for pressure vessels containing defects based on reliability analysis of fatigue life are calculated respectively in a certain reliability and residual life under certain reliability and confidence level,Compared the results of theoretical calculation with the analysis result.It is concluded that theoretical calculation results obtained much larger than the results of Monte Carlosimulation method to calculate, showing the results of theoretical calculations of large deviations, it should not be applied to engineering practice. |
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