结构钢开裂准则及断裂试验分析

为探寻结构钢开裂机理及抗断设防,给出了结构钢在应力三轴空间的广义屈服轨迹方程。结合古典强度理论和现代损伤力学对金属屈服和断裂解释的力学原理,基于三向等拉伸应力状态下结构钢屈服和宏观脆断重合性假设,导出了结构钢在应力三轴空间的开裂准则。在结构钢开孔板的单向等速拉伸断裂试验中,较为精确地测量了初始开裂时的加载位移及全程载荷-位移曲线。试验结果显示,初始裂纹位于孔边且扩展迅速。通过对结构钢开孔板断裂试验的数值模拟分析,对比验证了该开裂准则的普适性及精度。最后,给出了结构钢广义屈服和开裂模型的物理解释及抗断设防。

CRACK CRITERION AND FRACTURE TESTS OF STRUCTURAL STEEL

In order to study the crack mechanism and fracture design theory of structural steel, generalized yield locus in the three-dimensional stress space is brought forward. Combining the theories of metal yielding and fracture in classical strength theory with those in damage mechanics, crack criterion of structural steel in the three-dimensional stress space is deduced based on the assumption of simultaneous yielding and fracture in the isotropic tensile stress field. In the fracture tests of rectangular steel plates with circular hole subjected to uniaxial tension with mean velocity, the load-displacement curves at initial cracking were accurately measured. Test results reveal that the first crack lies at the edge of the circular hole and spreads rapidly. By numerically simulating the stress field at initial cracking in the fracture tests, the applicability and accuracy of the crack criterion are comparatively verified.