计算韧性断裂传播阻力的颈缩区模型

报告了对用销钉加载、双面开槽的双悬臂梁试件拉伸撕裂试验测定韧性断裂传播阻力的试验方法的改进,提出了描述韧性断裂传播问题的颈缩区模型:在平面应力条件下韧性裂纹传播路径的两侧,存在着总宽度为dn的颈缩区,实验表明该区内的平均应变εn仅仅取决于材料性能和试件厚度。根据这一模型导出了计算韧性断裂传播阻力的工程方法。进行了一系列对低碳钢的试验以改进试件的设计并考察颈缩区模型的合理性。

A Necking Zone Model for Calculating Ductile Crack Propagation Resistance

The improvement of the testing technique for the measurement of the Mode I ductile crack propagation resistanceis reported. The test consists of a side-grooved Double Cantilever Beam (DCB) specimen being loaded via pins.A necking zone model, with the necking zone (total width = dn ) present along both sides of the path of thecrack propagating under plane stress conditions, is used to model ductile crack propagating problems. The testshows that the average strain in the necking zone is related only to the property of the material and the thicknessof the specimen. An engineering approach based on this model to calculating the crack propagation resistance isderived. A series of experiments on mild steel was conducted to improve the design of the DCB specimens and toexamine the reliability of the necking zone model.