几种金属材料断裂条件的试验研究

考察了几种金属材料在常规破坏试验与拉-扭双轴破坏试验中，随受力条件不同，材料不同形式断裂破坏变化规律和相应的断裂条件；利用几种韧性材料复合型断裂试验结果，分析了随应力三维度变化，材料中孔洞成核形状与聚合方式的变化规律，分析了不同断裂形式时启裂点、启裂方向变化规律及主要影响因素。研究表明，从材料断裂物理机制来看，裂纹体与无裂纹体断裂破坏实质是相同的，随材料塑性因素与应力三维度变化的影响。材料内孔洞成核形状由椭球形逐渐变化为细长形，材料断裂由正拉断转向剪断，裂纹体与无裂体材料的断裂形式、断裂危险点、危险点上断裂方向等宏观量也有着相同的变化规律；区分不同物理机制建立断裂条件，可能适合解决金属材料不同形式的断裂力学问题。

Test Study of Fracture Conditions for Some Metal Materials

The varying laws and corresponding fracture condition of some metal materials for different fracture modes along with different loading, under normal and traction-twisting destructive test in two directions, were investigated. Based on the test results for mixed mode fracture of some ductile materials, the varying laws for shape of hole nucleation and polymeric mode along with the varying of the stress tri-axicity were analyzed. The varying laws for initiation break point and initiation crack growth direction and the main affect element were analyzed. Study shows that as viewed from the fracture physical mechanism of the materials, the bodies with crack or not are sameness in essentiality. Along with the affect of plastic factors and the stress tri-axicity, the shape of hole nucleation changed from ellipse to slightness.and the fracture modes changed from traction fracture to shear break. The fracture mode and dangerous point and growth direction on the dangerous point have the same varying laws in the bodies with crack or not. Distinguish the different physical mechanism to built different fracture condition can suitable to solve different problems in fracture mechanics.