大约在过去的一年中有一种采用修正的紧凑拉伸试件(图1)的趋势。降低H/W比的优越性当然在于能获得较长的裂纹长度,从而为一个单独的实验增加了数据点。可是,在那种情况下,由于通常难于保持直线裂纹,故H/W比不能无限的减少。当弯曲应力增大到超出某个值时,裂纹将是曲线而非直线。 Around the past year there was a tendency to use modified compact tensile specimens (Figure 1). The advantage of reducing the H/W ratio is of course that a longer crack length can be obtained, thereby adding data points for a single experiment. However, in that case, the H/W ratio cannot be infinitely reduced because it is usually difficult to maintain straight cracks. When the bending stress increases beyond a certain value, the crack will be a curve rather than a straight line.