GB/T 45578-2025 Non-destructive testing—Acoustic emission testing—Verification of the receiving sensitivity spectra of piezoelectric acoustic emission sensors

Scope

This document describes a method for determining the reception sensitivity spectrum of piezoelectric acoustic emission sensors. The method directly couples the acoustic emission sensor to the surface of the piezoelectric emission transducer. By exciting the sensor with a pulse perpendicular to its surface, the corresponding voltage output under the input of a unit particle motion is obtained as its absolute sensitivity. The particle motion can be a particle displacement (e.g., in nanometers) or a particle velocity (e.g., in millimeters per second), covering the acoustic emission detection frequency range (20 kHz to 1.5 MHz). This document also describes a method for determining the absolute value of the emission sensitivity spectrum of piezoelectric transducers (displacement output under a unit voltage input, such as nanometers per volt). This value can be obtained by measuring the particle displacement pulses on the active surface of the emission transducer and the input voltage spectrum of the emission transducer. The particle displacement can be measured using a scanning laser vibrometer. This document does not include the "cancellation effect" on the sensor response when the incident angle is different from the normal (90°) or when the wavelength of the elastic wave passing through the sensor's sensing surface is less than 10 times the size of the sensing surface. This document does not describe methods for measuring the impact of different materials on the sensor sensitivity, but an explanation of this impact is provided in Appendix F. Note: The methods described in this document can be considered for use in sensors other than piezoelectric sensors for detecting motion on planar components and operating within the same frequency range.

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