Measurement of Stress-strain Relation by Means of Instrumented Charpy Impact Bending

对夏比冲击弯曲法测量应力应变关系进行了实验研究，并对其实际应用进行了探讨。所得到的应力-应变关系是基于梁试件在示波冲击弯曲下的简单塑性弯曲理论，其中假定静力学是根据由卷积积分的冲击响应函数估计的冲击载荷来确定冲击弯矩，而弯曲应变是通过粘贴在冲击点背面的应变片来测量的。将不同试件的结果与霍普金森杆式冲击压缩的结果进行了比较。结果表明，除了小应变或低强度材料外，本方法是可行的，尽管所得到的应力-应变关系有或多或少的波动。此外，利用该方法还获得了高硬度钢合金热处理后的动态应力应变关系。因此，研究了它们的应变速率和屈服或断裂强度对硬度的依赖关系。结果表明，在维氏硬度为HV600-700时，强度达到最大值，且不受应变率的影响。

Some experimental studies on the measurement of stress-strain relations by means of Charpy impact bending were carried out and the practical application of them were discussed. Stress-strain relations obtained are based on the simple plastic bending theory of a beam specimen under instrumented Charpy impact bending, where the statics is supposed in determining the impact bending moment from the impact load estimated by impact response function of convolutional integral and the bending strain is measured by a strain gage cemented to the back side of impact point. The present results using various specimens were compared with those by impact compression of Hopkinson bar type. As a result, it was found that the present method was available except for the case of small strain or low strength materials, though more or less fluctuations were seen in stress-strain relation obtained. Furthermore dynamic stress-strain relations of heat treated steel alloys with high hardness were obtained by the present method. So the strain rate and the hardness dependency of yield or fracture strengths of them was studied. According to the result the strength becomes maximum at Vickers hardness HV600-700 and it is not so affected by strain rate.