The increasingly performance of piezoelectric ceramic materials has made it the most widely used class of functional piezo ceramics. Not only used in industrial and civil products, such as ceramic filters, ceramic discriminators, ceramic attenuators in the communication equipment; underwater acoustic transducers and torpedo detectors for underwater communication and detection; radar, television,ceramic transformers and ceramic surface wave devices, but also a large number of applications in the military, such as the piezoelectric ceramics made of underwater acoustic transducers, can smoothly carry out underwater navigation, communication, reconnaissance enemy ships, cleaning enemy water mines for work; piezoelectric fuze made of piezoelectric ceramics can accurately ignite and kill weapons such as blasting bullets. In addition, it is also widely used in precision measurement, navigation, ultrasonic flaw detection, ultrasonic cleaning, and ultrasonic diagnosis. With the development of surface mount technology (SMT), multi-layer chip-forming of functional energy harvesting piezoelectric plate components, chip component integration, integrated component simulation and multi-function are gradually required. At present, the hottest issue of the latest research is how to realize the multi-functional integration of piezoelectric ceramics, and obtain a new type of piezoelectric device that is integrated, intelligent and miniaturized.
As a link of electromechanical coupling, piezoelectric materials can be roughly divided into two aspects: piezoelectric ceramic frequency control devices represented by piezoelectric resonators and quasi-static applications that convert mechanical energy and electrical energy. Including piezoelectric vibrators and piezoelectric ceramic frequency control devices, piezoelectric transformers, piezoelectric transducers and piezoelectric ultrasonic motors. In the application of precision instruments, piezoelectric transducers and piezoelectric vibrators are the most common. The following is an introduction to various examples of precision instruments, focusing on the performance of various piezoelectric ceramic applications.
Piezoelectric plate piezoceramic transducers have many characteristics in precision detection equipment because of their subtle characteristics in the mutual conversion of mechanical energy and electrical energy, that is, there is obvious electrical signal feedback given a slight mechanical deformation. The common features of such applications are better measurement accuracy, strong anti-interference ability, and wide application range. It has a good application prospect in the detection of small changes.
Concrete crack damage detection equipment
Concrete materials are one of the main components of civil engineering structures. Cracks are the main damage factor to the safety of concrete structures. Therefore, the monitoring of concrete materials is very important. The methods of health monitoring of structures using piezo ceramic transducer is mainly divided into passive methods and active methods, while the latter can be divided into mechanical impedance methods and wave propagation methods. Among them, the wave propagation analysis method was originally proposed by the injury when the composite material was monitored. The method can effectively monitor the delamination and fatigue damage in the composite material, and has high sensitivity to crack in the metal. Drawing on the application of this method in composite monitoring, researchers have tried to use piezoelectric ceramics for health monitoring of concrete structures. The piezoelectric ceramic is buried in the concrete, and the crack damage signal is used to monitor the crack damage in the concrete. A smart concrete technology based on buried piezoelectric disc piezoelectric crystal was established.
The piezoelectric transducer ultrasound is buried in the concrete and is excited to generate stress waves in the concrete. According to the principle of the wave method, the piezoelectric ceramic sensor developed by itself is used to monitor the process of crack damage in concrete. The damage index defined by wavelet packet analysis method is used to calculate the damage under different working conditions. The results show that the change trend of the damage index is in good agreement with the development trend of the corresponding strain gauge monitoring signal and load-displacement curve. Monitoring and identification of crack damage. The crack detection equipment using piezoelectric ceramics is highly accurate enough to meet the resolution requirements of most projects. Moreover, the calculation amount is relatively small when calculating the crack parameters, which greatly saves engineering time. In practical applications, the abstract cracks are transformed into specific data and images, which greatly promotes the simplification of engineering design. The same principle can also be used for earthquake prediction and crack detection of large objects. The shortcoming of this method lies in the fact that the piezoelectric ceramic sensor is buried in the concrete to obtain a corresponding waveform, and the detection of small objects such as metal cracks is incapable. And there is a great limit to further improvement in accuracy.
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