Air-coupled sensor based on gas-based 1-3 type piezoelectric composite material

Abstract

The invention discloses an air-coupled transducer based on an air-based 1-3 type piezoelectric composite material. The transducer comprises a 1-3 type piezoelectric composite material wafer, electrodes, a transmission layer, a damping layer, an impedance matching circuit, a transducer shell and a BNC (bayonet nut connector) interface, wherein the electrodes are plated on the surface of the 1-3 type piezoelectric composite material wafer and are concentrically adhered to a matching layer and the damping layer; meanwhile, lead wires led out of the upper and lower electrodes are connected with the BNC interface through the impedance matching circuit. By adopting an air filling mode, instead of a mode of combining a polymer and piezoelectric columns, the 1-3 type piezoelectric composite material taking air as a base body is formed; the sound impedance of the 1-3 type piezoelectric composite material is close to that of the air, so that the energy transmission rate between the transducer and the air can be increased; meanwhile, a fiber material with the sound impedance which is higher than that of the piezoelectric composite material and lower than that of the air is used as the matching layer, so that ultrasonic waves transmitted into the air during excitation are further increased.

Description

technical field [0001] The air-coupled sensor based on gas-based 1-3 piezoelectric composite materials belongs to the field of ultrasonic non-destructive testing, and can use air coupling to excite ultrasonic guided waves in structures such as plates and tubes. Background technique [0002] With the increasing demand for ultrasonic high-speed detection, non-contact detection technology has become a research hotspot at home and abroad. At present, non-contact ultrasonic detection methods mainly include air-coupled ultrasonic detection technology, laser ultrasonic detection technology and electromagnetic acoustic ultrasonic detection technology. . Among them, the air-coupled transducer (Air-Coupled Transducer) is the same as the other two methods, which can excite the ultrasonic guided wave in the DUT without using any couplant, but the former has lower requirements on the equipment and the DUT. In this way, the impact on the mechanical properties of the component due to the ...

AI Technical Summary

Problems solved by technology

[0003] Air-coupled ultrasonic testing can quickly detect various materials that are not suitable for direct contact, but there are three serious problems: (1) high attenuation of ultrasonic waves in the air; (2) high impedance difference between the detection medium and air; (3) ) The high impedance difference between the sensitive material of the sensor and the air

[0004] The acoustic impedance of conventional piezoelectric materials is about 30 to 40 MRayl, while the acoustic impedance of air is 420 Rayl, and the transmittance of sound waves is only 0.003% to 0.005%.

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