用声发射预测静疲劳下陶瓷材料的断裂

PREDICTION OF FAILURE IN CERAMIC MATERIALS BY MEANS OF ACOUSTIC EMISSION

运用声发射检测技术，检测出受静载荷作用的陶瓷材料内部形成做裂纹和亚临界裂纹扩展的声发射信号，研究了裂纹形成、扩展时所激发的声发射计数率ｄＮ／ｄｔ与静载荷作用时间ｔ的关系。实验发现试样在顷裂前２２～３０ｓ所检测到的亚临界裂纹扩展的声发射信号具有明显不同的变化规律，试样所受的静载荷趋小，初次检测到亚临界裂纹扩展的声发射信号离发生断裂的时间越长。

Acoustic emission signals induced by microcrack initiation and subcritical crack propagation understatic load are obtained by means of the acoustic emission transducer.The relation between the time of applicationof the static load and the acoustic emission rate dN/dt induced by microcrack initiation and subcritical crackpropagation is studied.It is observed that the variation of the acoustic emission signals which occur about 20～30s before fracture caused by subcritical crack propagation is different obviously,The smaller the static load is,the longer the period from the time of the first signal induced by subcritical crack propagation to the occurrenceof fracture.