Fracture predicting for semi-elliptic surface crack on 22NiMoCr3-7 steel plate
1.Faculty of Science, Jiangsu University, Zhenjiang, Jiangsu 212013, China; 2.Yangzhou Vocational College of Environment ＆ Resources, Yangzhou, Jiangsu 225127, China
Abstract：Based on three-dimensional elastic-plastic finite element analysis, the semi-elliptic surface cracks on 22NiMoCr3-7 pressure vessel steel plate were numerically calculated by ABAQUS software. The crack driving force of J and the crack tip constraint parameter of A2 were calculated from FEA results in the ductile-brittle transition range to describe the near crack tip stress fields. Based on J-A2 and RKR fracture theories, the ductile-brittle transition reference temperature of T0 and the crack propagation initiating spots were predicted. The results show that the maximum of J is at the deepest crack front of elliptic crack for the shallow semi-elliptic surface cracks, while that is near the crack edge for the semi-circle surface cracks. J and A2 are increased when temperature raises. The temperature effect on crack driving force of J is greater than that on crack tip constraint parameter of A2. Based on J-A2 approach and RKR fracture model, the predicting formula can well transfer the fracture toughness parameter from standard three-point bend samples to cracked structures for structural integrity assessment.
2012, Vol. 33 
