Corrosion Sensing Mechanism Based On Piezoelectric Impedance Technology And Its Application In Anchorage Structure

As one of the main supporting forms in geotechnical engineering,anchoring structure is widely used in major projects.But the harsh working condition is a major test for the durability and safety of the anchoring structure.It is important to prevent the engineering structure accident caused by rust and fracture of the anchoring structure.At present,the traditional corrosion monitoring methods have limitations in insufficient precision and low sensitivity,and an effective monitoring method for anchor structure corrosion is urgently needed.In this paper,a rust sensor consisting of piezoelectric patches and metal pieces was designed.A new type of anchor structure corrosion monitoring based on piezoelectric impedance theory was proposed.The method provides a possibility to quantitatively evaluate the corrosion degree of the anchoring structure,and has important research significance and application value for the real-time monitoring of the corrosion of the anchoring structure.The sensor can be regarded as the coupling system of the PZT-metal sheet.The metal sheet is reduced in thickness due to the rust damage,and the mechanical impedance changes.Based on the electromechanical coupling effect,the electrical impedance change of the PZT patch reflects the coupling system.Based on the electromechanical coupled impedance theory of bending vibration,the electromechanical impedance expression of the sensor was derived.By establishing the sensor finite element model,the impedance response and mode shape of the sensor thickness change process were analyzed,and the bending mode and impedance of the sensor were explored.Corresponding the relationship between peak frequencies shows that the higher the degree of corrosion of the sensor,the more obvious offsets of the corresponding peak frequency in the impedance analysis admittance spectrum.According to the theoretical model of rust sensing mechanism,the sensor was fabricated and the waterproof material selection,sensor packaging and temperature response analysis were carried out.The results confirmed that the silicone rubber material is better than the epoxy resin material in water-repellent treatment,which verifies the correctness of the sensor corrosion mechanism and numerical simulation analysis results.It shows that the sensor has good stability under different temperature conditions.Considering the actual corrosion environment of the bolt,and the relevant specifications of the bolt construction,the rust anchor monitoring platform was built,and the feasibility of the sensor working under actual conditions was studied.The results show that the sensor can estimate the degree of corrosion by the deviation of the peak frequency in the monitoring data,which is consistent with the theoretical mass loss result of the bolt,and achieves the purpose of sensor corrosion monitoring.