中文摘要：

Q345钢材已被广泛使用在许多领域中,但目前仍缺乏实时在线损伤监测的可靠方法,为此提出声发射检测技术对Q345钢材裂纹生长过程进行动态监测。首先根据试验设备配套模具设计出钢材试件;然后用电子万能试验机对试件完成拉伸和三点弯曲实验,并用声发射仪器采集试件预置裂纹变化过程中发出的声发射信号;最后提取声发射检测信号特征参数,并采用经历图分析法研究计数和能量特征参数随时间变化的规律,结合这种变化规律找到评价试件裂纹的变化状况。实验结果表明：试件在萌生、扩展和断裂不同变化阶段,声发射特征参数都有不同特征表现,可以通过这2个特征参数表征和评价Q345钢材的损伤状况。

英文摘要：

Q345 steel has been widely used in many fields, but there is still a lack of reliable method for real-time and online monitoring damage, and therefore Acoustic Emission （AE） technology is presented for dynamic monitoring of crack growth process in Q345 steel. Firstly, specimens of the steel are designed according to the test equipment. And then tensile and three point bending experiments to the specimen are completed by electronic testing machine, and AE signals are collected by AE instrument during the course of crack changing process. And finally, characteristics parameters are extracted from acoustic emission signals and the changinglaw of counting and energy to time is researched by using the experience of the graph, and changing state of specimen crack can be evaluated from the change law. The experimental results show that the AE characteristic parameters have different performance characteristics in different initiation, propagation and fracture stages of the specimen, and the damage status of Q345 steel can be evaluated through the two characteristic parameters.