中文摘要：

针对工程结构中的螺栓连接件易松动的问题,进行了基于压电阻抗技术（EMI）的螺栓松动监测实验。实验将锆钛酸铅压电陶瓷材料（PZT）直接粘贴在螺栓和螺母上,通过万能试验机对螺栓施加不同的拉力来模拟螺栓预紧力的变化,采用精密阻抗分析仪提取不同螺栓和螺母上压电材料的导纳信号,引入基于电导纳的均方根偏差（RMSD）损伤指标,建立螺栓松动程度和预紧力之间的对应关系。试验结果表明,不同型号的螺栓和螺母上安装的压电材料都可以感知预紧力的变化;得到了损伤指标（RMSD）和预紧力之间的定量对应关系;通过分析损伤指标和预紧力之间的关系可得到螺栓的松动情况,并且可直接定位松动的螺栓。研究表明基于压电阻抗技术的智能螺栓（智能螺母）可以实现松动自检测。

英文摘要：

For the bolt joint loosing problem, an experimental study on detecting bolt looseness based on the electro-mechanical impedance （EMI） had been implemented. Lead zirconate titanate piezoelectric ceramic （PZT） was bonded on bolts and nuts directly. The universal testing machine was used to simulate the pre -tightening force of bolt. Impedance analyzer was used to measure the admittance of PZT , and the damage index based on root means square deviation （RMSD） of admittance had been introduced to identify bolt looseness quantitatively. The relationship between RMSD damage index and pre-tightening force had been achieved through the experiments. The experiment results show that, PZTs bonded on different models of bolts and nuts can identify the variation of bolt pre-tightening force, and it can also position the loosened bolt directly. EMI based smart bolt （smart nut） can realize looseness self-detection.