Failure Prediction of Superheater Tubes in Rotary Tube Bending Process Using GTN Damage Model

Superheater tubes are one of the main parts of boilers which are subjected to high temperature and stress. Fracture is one of the main defects which happen during the forming process of these tubes. In the present study, tube rotary draw bending (RDB) process is used for forming of superheater tube. Gurson–Tvergaard–Needleman (GTN) damage model is used for fracture prediction in the numerical simulation of tube RDB. Response surface methodology is coupled with the finite element to identify the GTN parameters. For this purpose, different sets of GTN parameters are used to simulate the uniaxial tensile test in the Abaqus software. Effect of GTN parameters is investigated on the predicted stress–strain curve of the uniaxial tensile test in the numerical simulation. The best-identified GTN parameters are used in the finite element simulation of tube RDB of superheater tube. Results indicate that there is an appropriate agreement between the predicted fracture location of the numerical and experimental sample after RDB.