中文摘要：

利用声发射（AE）技术在实验室环境下对叶片疲劳裂纹扩展速率进行研究。通过对三点弯曲疲劳实验中的叶片材料裂纹产生过程的监测，得出裂纹扩展速率从中速率区向高速率区转变时应力强度因子范围约为50MPa·m^1/2；叶片裂纹声发射信号的幅值主要集中在68～73dB，且其能量和持续时间的关系能定性描述叶片的疲劳状态。同时，得到了表征材料疲劳裂纹扩展的AE计数率、能量变化率、裂纹扩展率以及应力强度因子之间的相互关系。研究结果为利用声发射技术对水轮机转轮的安全性评估和寿命预测提供了参考。

英文摘要：

The fatigue crack growth rate of hydraulic turbine blades was studied using acoustic emission （AE） technique in the laboratory. Through monitoring the crack growth process of the blade material in three point bending fatigue tests, the following results are obtained： the stress intensity factor （SIF） range of crack transited from the region with middle crack grown rate to the region with high crack grown rate is about 50MPa· m^1/2 ; the amplitude of crack AE signals is mainly concentrated on 68～73dB; and the correlation of the energy and duration of events can qualitatively describe the fatigue state of blades. At the same time, the correlations among the AE count rate, energy rate, crack growth rate and SIF are obtained as well. The results provide reference for security evaluation and lifetime prediction of hydraulic runner using AE technique.