- Email: [email protected]
Amplitude sorting system for mechanical stress monitoring
train to the pulse counters associated with the remaining channels. When the AE pulse reaches the remaining transducers the associated counters are stopped leaving the 4429 displaying the relative times of arrival ( in microseconds) of the AE burst at three transducers with reference to the fourth. The relationship between the three times displayed define the position on the surface of the specimen under which the burst apparently originated. For linear systems (ie pipelines), only two transducers are required. An interlock device in the analyser prevents the system being triggered by ringing from a previously measured AE burst. This is useful in computer controlled location systems where the 4429 may perform a location task and be reset at millisecond intervals. After resetting, the system can only be triggered after the signal level in all channels is simultaneously below the trigger level. Any number of 4429s
AE Transducers I
Digital output ~ --~ to calculator or computer |
w
Wideband conditioning amplifiers Fig. 2
AE Pulse analyzer 4429
Four transducer set-up used for location of AE events
may be coupled in paralM to form two or three dimensional location
systems with the delay times being fed to a computer.
Amplitude sorting system for mechanical stress monitoring The Industrial Electronics Group at the University of Surrey, England have designed and manufactured an amplitude sorting system to superceed their previous equipment (NDT International 7 No 5 pp 257-258). The system is designed to provide high gain and low noise over a bandwidth of 70 kHz-1 MHz so that a broad spectrum of emissions can be processed. The complete system, including five preamplifiers and transducers is shown in Fig. 3. In normal operation one channel would be used to detect AE while a second channel operates as a guard. Up to four summed guard inputs can also be used to detect emissions from outside the region of interest. The guard transducers are so placed that emissions arising from the region of the specimen near the signal transducer will be detected by the sig-
nal transducer before being received by the guard transducers. Double screening provides high resistance to RV interference. The modular construction of the system was chosen so that systems can be assembled consisting of more
Fig. 3
than two amplitude sorting channels. The system is capable of supplying power to four modules which can either be amplitude sorters suitable for descriminating six levels of amplitude or guard/interlock summing modules.
The Industrial Electronics Group's AE amplitude sorting system
On-line source location and analysis EMI Electronics Limited's 6300-DM acoustic emission, detection, location and analysis system has been designed as an engineering tool to provide data acquisition and an analytic capability. The system can perform on-line source locati6n and analysis with a minimum number of sensors placed at arbitrary positions on the structure to be examined. The 6300 then presents the AE data on-line, simultaneoulsy
236
mapping source locations onto an engineering drawing of the structure. The standard 6300 system offers a 63 channel capacity which may be increased with additional input hardware. Since AE suffers from attenuation and dispersion with distance, each channel is designed to measure the various event characteristics such as arrival time, leading edge or peak
amplitude and rise time. Totally independant modular detection and measurement channels, featuring logarithmic compression and leading edge or peak timing generate the values to be encoded in the C-space describing the AE event. As new parameters evolve, these may be added as a new vector to be encoded in hardware and passed to the analytic Cspace decomposition routines.
NDT INTERNATIONAL. OCTOBER 1980
AE Transducers I
Digital output ~ --~ to calculator or computer |
w
Wideband conditioning amplifiers Fig. 2
AE Pulse analyzer 4429
Four transducer set-up used for location of AE events
may be coupled in paralM to form two or three dimensional location
systems with the delay times being fed to a computer.
Amplitude sorting system for mechanical stress monitoring The Industrial Electronics Group at the University of Surrey, England have designed and manufactured an amplitude sorting system to superceed their previous equipment (NDT International 7 No 5 pp 257-258). The system is designed to provide high gain and low noise over a bandwidth of 70 kHz-1 MHz so that a broad spectrum of emissions can be processed. The complete system, including five preamplifiers and transducers is shown in Fig. 3. In normal operation one channel would be used to detect AE while a second channel operates as a guard. Up to four summed guard inputs can also be used to detect emissions from outside the region of interest. The guard transducers are so placed that emissions arising from the region of the specimen near the signal transducer will be detected by the sig-
nal transducer before being received by the guard transducers. Double screening provides high resistance to RV interference. The modular construction of the system was chosen so that systems can be assembled consisting of more
Fig. 3
than two amplitude sorting channels. The system is capable of supplying power to four modules which can either be amplitude sorters suitable for descriminating six levels of amplitude or guard/interlock summing modules.
The Industrial Electronics Group's AE amplitude sorting system
On-line source location and analysis EMI Electronics Limited's 6300-DM acoustic emission, detection, location and analysis system has been designed as an engineering tool to provide data acquisition and an analytic capability. The system can perform on-line source locati6n and analysis with a minimum number of sensors placed at arbitrary positions on the structure to be examined. The 6300 then presents the AE data on-line, simultaneoulsy
236
mapping source locations onto an engineering drawing of the structure. The standard 6300 system offers a 63 channel capacity which may be increased with additional input hardware. Since AE suffers from attenuation and dispersion with distance, each channel is designed to measure the various event characteristics such as arrival time, leading edge or peak
amplitude and rise time. Totally independant modular detection and measurement channels, featuring logarithmic compression and leading edge or peak timing generate the values to be encoded in the C-space describing the AE event. As new parameters evolve, these may be added as a new vector to be encoded in hardware and passed to the analytic Cspace decomposition routines.
NDT INTERNATIONAL. OCTOBER 1980