Elastic-Plastic Finite Element Analysis For Circumferential Part-Throughwall Cracks On Mitered Elbow

Fracture mechanics has been used widely in practice with the development of the theories and computer science.It is very important for the pipes being used to make safety estimation in application of fracture mechanics.However,it is very scarce of the fracture parameters to make safe estimation in engineeringand,cause the safety evaluation not convenience.A model of the mitered elbow with circumferential part-throughwall cracks has been built in this works,and the results of elastic and elastic-plastic evaluation have been analyzed by the model,he stress intensity factors K₁ in elastic and J-integral in elastic-plastic in different dimension have been calculated.Based on the K₁ and J-integral results,the shape coefficients and full-plastic coefficients have been obtained.The study including:1.List domestic and abroad safety estimation of pipes with crack,study the method and devalopment of fracture mechanics for structure with crack,provide the evidence for further analysis.2.Study the method of establishing model with crack by using the FEA software of ANSYS.Prove the availability for the elements used,method of establish model and calculation results.Establish the model of mitered elboware by APDL language of ANSYS by its geometric,material and mmechanical parameter,and put forward new ideas on using submodel in crack-tip for complex space crack of a new way.3.After the use of ANSYS processor in the calculation of stress intensity factor module, in purely internal pressure,the moment load,calculate the stress intensity factors in elastic condition and conversion it into the shape factor F.4.Treat,in ANSYS,the definition of material non-linear,introduce the stiffen-exponent n,prepare J-solving process by APDL,and analysis the crack in elasticity-plasticity.According to EPRI in the J-integral,decide the method of evaluation in full-plastic.5.The full-plastic J-integral and coefficient h₁ has been given under internal pressure and under different load ratio of internal pressure and bending,and provide the tables of full-plastic coefficients h₁.