核电安全端结构中材料拘束的作用范围研究

Constraint is the resistance of a specimen or structure against plastic deformation. It contains geometry constraint and material constraint. Both of them can affect the fracture behavior of the material significantly. For the material constraint, most of the previous studies focused their attention on the strength mismatch of both sides of the crack, such as over-match and under-match. There is another interesting issue, the effect range of material constraint, which also needs to be clarified. In the previous studies, the effect range of the material constraint has already been proved in different specimens by the authors. In this study, the actual and the simplified nuclear safe end structures were selected, the J-M curves, the areas surround by PEEQ isoline and the failure assessment curves of the two structures under different material constraints were calculated to investigate the effect range of material constraint in structure. The results show that the effect range of material constraint exists in both the two structures. The J-M curves, the areas surround by PEEQ isoline and the failure assessment curves are not affected by the material which located out of the effect range. Compared with the actual nuclear safe end structure, the simplified structure has a lower geometry constraint, a larger material constraint effect range and a higher failure assessment curve, and may produce a non-conservative assessment result.