带环向切口金属杆的扭转剪切断裂

TORSION AND SHEAR FRACTURE OF METAL BAR WITH CIRCUMFERENTIAL NOTCH

扭转圆杆的环向切口根部存在高度集中的剪切应力,Ⅲ型应力强度因子是裂纹端部应力场奇异性的度量。为探求带环向切口的受扭金属圆杆最大承载力的计算方法,通过对不同切口尺寸杆件的扭转剪切断裂实验,由各试件的预制切口尺寸和实验中测到的最大转矩分别计算相应的应力强度因子;利用非线性断裂理论推导出计算带环向切口裂纹扭转杆承载转矩的计算公式,将理论计算数值与实验结果进行比较,表明铸铁比碳钢试验结果更接近理论计算值。

Along the circumferential notch root of round bar with torsion loading, there is highly concentrated shear stress value. The singular property of shear stress exists around the crack tip, and the type of Ⅲ stress intensity factor is an important parameter of the singular stress field. For seeking the method of calculating the maximum bearing torque of the twisted metal bars with circumferential notch, a series of test samples were loaded by torsion equipment on different incision size bars. The value of stress intensity factor was calculated through the practical prefabrication incision size and maximal test torsion moment. The computation formula of loading torque was deduced through the nonlinear fracture theory for the bar with circumferential notch. The calculated results were compared with the test results, and some discussion was given. The compare results indicate that the cast iron bars＇ test results are more closer to the theoretical values than that of the steel bars.