This document specifies a method for the determination of the receiving sensitivity spectra of a piezoelectric acoustic emission sensor, in absolute units of volts output per motion input, whereby the motion can be particle displacement (e.g. in nanometres) or particle velocity (e.g. in millimetres per second) over a frequency range used for acoustic emission testing, from 20 kHz to about 1,5 MHz, whereby the sensor is stimulated by a motion pulse in normal direction to the sensor’s face from a directly coupled piezoelectric transmitter.
This document also specifies a method for the determination of the transmitting sensitivity spectrum of a piezoelectric transmitter in absolute units, for example, in nanometres output per volt input, by measuring both the particle displacement pulse over the transmitter’s active face and the transmitter’s input voltage spectrum, using a scanning laser vibrometer.
This document does not include the known cancellation effects on a sensor’s response, when the angle of incidence differs from normal (90°) or when the length of the wave passing across the sensor’s sensitive face is shorter than about 10 times the dimension of the sensor’s sensitive face.
This document does not specify a method to measure the influence of different materials on a sensor’s sensitivity, but this effect is addressed in Annex F.
NOTE The methods described in this document can be considered for use with other than piezoelectric sensors, which detect motion at a flat face and work in the same frequency range.