ISO 12716 pdf download.Non-destructive testing — Acoustic emission inspection — Vocabulary
1 Scope
This International Standard defines the terminology that is used in acoustic emission inspection and forms a common basis for standards and general use.
2 Terms and definitions
2.1 acoustic emission AE class of phenomena whereby transient elastic waves are generated by the rapid release of energy from localized sources within a material, or the transient waves so generated NOTE Acoustic emission is the recommended term for general use. Other terms that have been used in AE literature include: a) stress wave emission; b) microseismic activity; c) emission or acoustic emission with other qualifying modifiers. 2.2 acousto-ultrasonics AU nondestructive examination method that uses induced stress waves to detect and assess diffuse defect states, damage conditions and variations of mechanical properties of a test structure combining aspects of acoustic emission (AE) signal analysis with ultrasonic materials characterization techniques 2.3 AE signal duration time interval between AE signal start and AE signal end 2.4 AE signal end recognized termination of an AE signal, usually defined as the last crossing of the threshold by that signal 2.5 AE signal generator device which can repeatedly induce a specified transient signal into an AE instrument 2.6 AE signal rise time time interval between AE signal start and the peak amplitude of that AE signal 2.7 AE signal start beginning of an AE signal as recognized by the system processor, usually defined by an amplitude excursion exceeding threshold 2.8 array group of two or more AE sensors positioned on a structure for the purposes of detecting and locating sources that would normally be within the array 2.9 attenuation decrease in AE amplitude per unit distance, normally expressed in dB per unit length 2.10 average signal level rectified, time-averaged AE logarithmic signal, measured on the AE amplitude logarithmic scale and reported in dB AE units (where 0 dB AE refers to 1 V at the preamplifier input) 2.11 channel, acoustic emission acoustic emission channel assembly of a sensor, preamplifier or impedance matching transformer, filters, secondary amplifier or other instrumentation as needed, connecting cables, and detector or processor NOTE A channel for examining fiberglass reinforced plastic (FRP) may utilize more than one sensor with associated electronics. Channels may be processed independently or in predetermined groups having similar sensitivity and frequency characteristics. 2.12 count, acoustic emission acoustic emission count count, ring-down ring-down count emission count N number of times the acoustic emission signal exceeds a preset threshold during any selected portion of a test 2.13 count, event event count N e number obtained by counting each discerned acoustic emission event once 2.14 count rate, acoustic emission acoustic emission count rate emission rate count rate N time rate at which emission counts occur 2.15 couplant material used at the structure-to-sensor interface to improve the transmission of acoustic energy across the interface during acoustic emission monitoring 2.17 dead time instrumentation dead time any interval during data acquisition when the instrument or system is unable to accept new data for any reason 2.18 distribution, amplitude, cumulative (acoustic emission) cumulative (acoustic emission) amplitude distribution F(V) number of acoustic emission events with signals that exceed an arbitrary amplitude as a function of amplitude V 2.19 distribution, threshold crossing, cumulative (acoustic emission) F t (V) cumulative (acoustic emission) threshold crossing distribution number of times the acoustic emission signal exceeds an arbitrary threshold as a function of the threshold voltage V 2.20 distribution, differential (acoustic emission) amplitude differential (acoustic emission) amplitude distribution f(V) number of acoustic emission events with signal amplitudes between amplitudes of Vand V+ ?Vas a function of the amplitude Vwhere f(V) is the absolute value of the derivative of the cumulative amplitude distribution F(V) 2.21 distribution, differential (acoustic emission) threshold crossing differential (acoustic emission) threshold crossing distribution f t (V) number of times the acoustic emission signal waveform has a peak between thresholds V and V+ ?V as a function of the threshold V where f t (V) is the absolute value of the derivative of the cumulative threshold crossing distribution F t (V)