What is an acoustic emission sensor? Principle and classification of AE sensors?

2023-03-24 14:32

Acoustic emission sensors are made of the principle that the physical properties of certain substances (such as semiconductors, ceramics, piezoelectric crystals, strong magnetic bodies and superconductors) change with the action of the outside world to be measured (piezoelectric effect). The piezoelectric element of the acoustic emission sensor can convert the tiny displacement of the material surface into a voltage signal through the piezoelectric effect. Acoustic emission sensor is mainly divided into two kinds, resonant acoustic emission sensor and broadband acoustic emission sensor.

 

• Resonant sensor: high sensitivity to specific frequency range signals.

   

• Broadband sensor: It has a stable response to signals in a wide frequency range.  
  
   

  

In the practical application of AE, a large number of metal structures with stable structure, such as pressure vessels, are encountered. In such applications, a frequency sensor with resonance frequency of 150kHz is often used to receive AE signals. For corrosion, leakage and other AE signals, resonant sensors with resonant frequency of 40kHz are used.  

 

Bandwidth and sensitivity are a pair of contradictory indicators, the larger the bandwidth, the lower the sensitivity, narrow band is easier to obtain higher sensitivity; The final purpose of application is high sensitivity. Broadband sensor should be used in principle for spectral analysis because its response sensitivity is relatively flat in a wide frequency band.