含缺陷韧性金属材料的失效评估研究

Failure Assessment Research of Flawed Ductile Metals

以韧性较好的核电站用结构钢S355为研究对象,进行了紧凑拉伸试样的断裂韧性试验,试验中发现随着拉力的增大,裂尖塑性垮塌代替了裂纹扩展,且失效载荷对应有限的塑性屈服范围。随后采用Gurson模型模拟了该试样受拉伸载荷时的失效过程,计算结果表明,该模型能较好地模拟裂纹尖端的塑性垮塌现象。最后结合试验结果和有限元模拟结果,建立了1条适用于S355钢的通用失效评估曲线,并确定了塑性失效载荷与裂纹长度之间的对应关系。

Standard fracture toughness measurement was explored on contact tension specimen made of ductile metal S355 used for nuclear plant structure. During the test, plastic collapse instead of crack extension occurred ahead of crack tip with increasing tension load and only local area around crack tip yielded when the whole specimen failed. After that, Gurson model was used to simulate the failure process of contact tension specimen made of S355. The calculation results show that Gurson model can reproduce crack tip collapse well. At last, a universal failure assessment curve was built for S355 by combining finite element simulation with test measurement, and relationship between plastic failure load and crack length was determined.