Defect detecting for fireproof sealing system of cable shaft based on piezoelectric ultrasonic

Once a fire occurs in a cable shaft, it is easy to produce the “chimney effect”, thereby accelerating the spread of fire. In order to evaluate the performance of the fireproof sealing system for the cable shaft, a defect detecting method for the fireproof sealing system based on piezoelectric ultrasonic is proposed in this paper. Firstly, the propagation characteristics of Lamb waves in composite fireproof board are analyzed, and the frequency of excitation signal is determined by frequency sweep experiments. Secondly, through the defect detection experiment based on ultrasonic guided wave on the composite fireproof board, the defect detection and location of the composite fireproof board are studied. The research results show that the Lamb waves can be excited by a piezoelectric sensor with a resonant frequency of 130 kHz in the composite fireproof board, and it can be received by a piezoelectric sensor array. By comparing the attenuation rates of the received signal amplitudes of different sensors, the defects of the composite fireproof board can be detected and located.