Miter Bends Along The Pipe To Penetrate The Crack Elastic-plastic Finite Element Analysis

It is important to give the safety estimation of piping being used. The theories and applicationes of fracture mechanical have developed more since 1970s But,to many structures with cracks being used in engineering, the fracture parameters can be used for safety-estimation are scarce. On the basis of fracture mechanical theory, adopting the technique of finite element analysis(FEA), the study calculated the fracture parameters of stress intensity factor KI and J-integral for the throughwall cracks along the axis of piping elbow with four sections, gived the shape factors F and full-plastic coefficients h1 to supply the datebase of full-plastic solution. Concluding:1. The finite element models of piping elbow with four sections were built, on the basis of the models, the study analyzed the distributions of stress under internal pressure .combined internal pressure and moment to give references for the analysis of fracture.2. Studying the method of building the finite element model for ANSYS program, the study testifid the model on the basis of some known examples. Also, the study compiled the program of creating model in use of a parameter design language(APDL) by the parameters of geometry materials load etc..3. On the basis of the theory of displacement method, the study calculated the linear elastic fracture parameters KI under internal pressure and moment loads through the postprocessor, then, getted the fomulation of shape factor F.4. The study treated with the definition of nonlinear material properties, using the stiffering exponent-n. The program of the solution of J-integral were compiled and the elastic-plastic FEA were done, on the basis of EPRI plastic J-intigral estimation, the full-plastic J-integral and full plastic solution h1 were done.5. The study gived the full plastic solution coefficients h1 under internal pressure and combined internal pressure and moment in different properties.