ISO 16836:2019 pdf free

ISO 16836:2019 pdf free.Non-destructive testing一Acoustic emission testing一Measurement method for acoustic emission signals in concrete
AE sensors shall be sensitive enough to detect AE signals generated in the target structure, taking acoustic coupling into consideration. They convert elastic waves (motions) on the surface of a material into electric signals, preferably, without any distortions. A resonance-type sensor is most sensitive around the resonant frequency, while a broad-band sensor has approximately flat response in the range but is less sensitive than the resonance-type. AE sensor shall be robust enough against temperature change, moisture condition and mechanical vibrations in the environments.Refer to Annex A for recommended types of sensors to be used in the concrete.
Sensitivity calibration of AE sensors shall be performed by employing the standard source, in addition to the calibration methods prescribed in ISO 12713 and ISO 12714. A simulated AE source due to pencil-lead break is defined in ASTM E976. This standard source is illustrated in Figure 3, where a guide ring is recommended to be employed.
The frequency range shall be determined prior to the measurement, taking into account the performance of AE sensors and the amplifiers. Selection of the frequency rage is closely related to elimination of noises. In concrete, the use of a band-pass filter between several kHz and several 100 kHz is recommended.
One waveform is to be counted as one AE event, while the cycles over the threshold level are named as AE ring- down counts (or simply “counts”). Here, the threshold is a preset voltage level, which has to be exceeded before one AE signal is detected and processed. Methods for AE counting are illustrated in Figure 4. In the case of multi-channel observation, AE occurrence is monitored at each sensor location.At some sensors, AE signals may not be observed due to attenuation or undetectable propagation path.The number of the events which are counted at one of the channels corresponds to the number of AE hits defined above.ISO 16836 pdf free download.