| Elbow is used for changing pipeline direction. It's an important part of piping system. Elbow is easily to produce crack because of kinds of reasons, so it's necessary to give the elbow crack a safe assessment. But elbow's fracture parameters are insufficient at present. In this paper, based on fracture mechanics, the elbow was studied by adopting the finite element analysis software ANSYS. Including:(1) To provide theoretical basis for In-depth study, related theory about fracture mechanics and safe assessment standard were discussed.(2) Finite element model of elbow without crack was built; the stress of it was analyzed and found that elbow's inside surface is a dangerous part which inclines to give birth to cracks.(3) Straight pipe model with crack was built to study the method of simulated crack tip's stress singularity, According to the results provided by EPRI, the paper can proof the method is correct, which is the base and foundations of farther research.(4) Elastic finite element analysis was given for elbow with circumferential part-throughwall cracks. Stress intensity factor of different size of crack was got and transformed to shape factor F to give convenient to engineering staff using.(5) Plastic limit load reduction coefficient of elbow with crack was got by nonlinear analysis.(6) The J-integral of elbow with circumferential part-throughwall cracks was calculated under internal pressure and bending moment and the database of full-plastic coefficients was done.(7) The failure assessment diagram was got and compared with the universal curve in state criterion to investigate.
|
PDF Full Text Request