【摘要】 本文应用超声瑞利波在含有裂纹的试件内传播性质的变化特征,采用脉冲回波重合法,精确测定裂纹开口处和裂纹尖端处瑞利波两个脉冲反射信号的时延,从而测定出在疲劳载荷作用下,裂纹的扩展尺寸.测量疲劳裂纹扩展速率da/dN的精度可达到10^-3mm/周次,适应于在弹塑性区域内疲劳裂纹扩展速率的测定.更多还原

【Abstract】 The changing characteristics of propagation properties by using Rayleigh waves in the test specimen with crack are put forward. The delay time of the two pulse reflection signal of Rayleigh waves in crack open point and crack tips has been accurately measured by adopting pulse-echo-overlap-method. So the crack extension range under fatigue load has been measured as well. The accuracy of fatigue crack extension rate measurement can approach 10~3 mm/cycle. Therefore, the measurement can be used in elastoplastic areas.更多还原