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讨论。应力-应变关系的建立基于简单塑性弯曲理论的梁试件在仪器Charpy冲击弯曲下的应力-应变关系，其中静力学假设是由冲击响应函数的卷积积分估计的冲击载荷来确定冲击弯矩，弯曲应变通过粘接在冲击点背面的应变片来测量。并与Hopkinson杆式冲击压缩试验结果进行了比较。结果表明，所得的应力-应变关系存在或多或少的波动，但除小应变或低强度材料外，该方法是有效的。此外，还得到了热处理后的高硬度钢合金的动态应力-应变关系。因此，研究了它们的应变速率以及屈服强度和断裂强度与硬度的关系。结果表明，合金强度在维氏硬度hv600 ~ 700时达到最大值，且受应变速率的影响较小。

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.