对螺栓连接部位的螺母进行测试，将精密阻抗仪黏附在螺母外侧的压电材料上来测试电导纳信号，对得到的压电材料的电导纳谱峰值频率和螺栓预紧力之间的变化规律进行分析。根据测试得到的压电材料阻抗峰值频率来监测螺栓的连接状态。试验时，所有预紧力条件下导纳峰值频率都发生了右移的现象，根据峰值频率可以得到螺栓预紧力，从而推断出螺栓的连接情况。当预紧力载荷上升后，压电材料的刚度将提高，压电材料与螺母耦合后将形成更大的谐振频率。

The test was carried out on the nut at the connecting part of the butterfly bolt. The precision impedance meter was adhered to the piezoelectric material on the outside of the nut to realize the function of testing the electrical admittance signal. The variation law between the peak rate of piezoelectric admittance spectrum and the bolt pre-tightening force was analyzed, and then the connection state of the bolt was monitored according to the peak impedance frequency of the piezoelectric material. The peak frequency of admittance shifted to the right under all preload conditions. According to the peak frequency, the bolt neck tightening force can be obtained, so as to infer the bolt connection situation. When the preload increases, the stiffness of the piezoelectric material will increase, and the piezoelectric material will form a larger resonance frequency after coupling with the butterfly mother.