铸铁承压设备声发射特征研究

为开展声发射技术应用于铸铁承压设备检测的应用研究,首先应研究铸铁材料拉伸过程的声发射特征,然后获取铸铁构件上典型裂纹扩展的声发射信号,找到铸铁构件开裂所特有的声发射信号特征,为活性缺陷的正确检测和识别奠定基础。因此,本文首先研究了灰口铸铁HT200材料拉伸试件的声发射特性,然后在报废的造纸烘缸上预制了表面裂纹,采用水压循环加载的方式,用声发射监测其加载试验过程的声发射现象,获取缸体表面裂纹扩展的声学信号样本,确定了随载荷变化,裂纹缺陷扩展的声发射参数特征和定位特征,其结果为后续波形信号的特征提取和模式识别研究提供了典型声发射源信号数据,也为铸铁类构件的声发射检测提供了参考。

The Activity Characteristics of Acoustic Emission Produced by Cast Iron Pressure Equipments

In order to research the feasibility of acoustic emission （AE） technique applied in cast iron pressure equipment, the characteristics of AE of cast iron tensile specimen should be investigated firstly. Then, the typical acoustic emission signals produced by crack propagation in cast iron structure should be obtained secondly because it is the foundation for AE detection and crack defect recognition. Therefore, the AE testing of some tensile specimen for HT200 grey cast iron were performed. Two cracks were prefabricated on the surface of an older paper dryer. Along with hydraulic testing, the whole dryer was monitored by AE system. Finally, the acoustic signal samples of surface crack propagation were determined, and the AE features of crack extension and location changing with load were analyzed. The results provide typical data of acoustic emission source signals for subsequent waveform signal feature extraction and pattern recognition, and also give reference for AE test and evaluation of cast iron pressure equipment.