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Optimization of sensor selection for acoustic emission source location
Chlada, Milan ; Převorovský, Zdeněk
Similarly to Global Positioning System (GPS), location of material defects by acoustic emission method meets the geometrical dilution of precision (GDOP) phenomena. Besides the several attitudes how to mathematically express its measure and compare particular sensor configurations in accordance with desired location precision, recently proposed method brings extended possibilities for detection of critical regions characterized by strong sensitivity of location results to signal arrival time changes or errors. Analogically to GDOP parameter it yields the sensitivity map available even for non-continuous or anisotropic materials. During the computation it uses the algorithm for finding the shortest ways in discretely defined bodies, which furthermore enables to view the problem through the so-called similarity and ambiguity maps.
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Mapping of problematic regions in AE source location
Chlada, Milan ; Převorovský, Zdeněk
Similarly to Global Positioning System, location of material defects by acoustic emission method meets the geometrical dilution of precision (GDOP) phenomena. Besides the several attitudes how to mathematically express its measure and compare particular sensor configurations in accordance with desired location precision, recently proposed method brings extended possibilities for detection of critical regions characterized by strong sensitivity of location results to signal arrival time changes or errors. Analogically to GDOP parameter it yields the sensitivity map available even for non-continuous or anisotropic materials. During the computation it uses the algorithm for finding the shortest ways in discretely defined bodies, which furthermore enables to view the problem through the so-called similarity and ambiguity maps.
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Monitoring of fatigue crack growth in riveted aircraft structures by acoustic emission
Chlada, Milan ; Převorovský, Zdeněk
In principle, the acoustic emission (AE) represents one of NDT and structure health monitoring (SHM) methods for the detection and identification of growing material defects. Different types of signals detected by the AE method are supposed to correspond to different types of defects or operational noises. Monitoring of structures by acoustic emission needs new robust and fast methods for emission source location and classification. Recently proposed AE source location method using so called signal arrival time profiles and artificial neural networks (ANN) was applied for monitoring of growing defects during long term fatigue testing of riveted aircraft wing flange. The potentialities of the method regarding the on-line monitoring of dangerous crack growth in selected critical parts of aircraft structures are discussed.
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Vliv nejistoty v určení časových diferencí na přesnost lokalizace zdroje akustické emise
Blaháček, Michal
Acoustic emission (AE) is a non-destructive testing method using acoustic, mostly ultrasonic, waves emitted by AE sources and propagating in structure to find out desired information about the tested construction or sample state. The AE source location is its basic (and very important) parameter. Most of location algorithms use time differences of AE signal arrival times from the source to different transducers and acoustic wave propagation velocity as input data.However, the parameters are often difficult to obtain in real conditions, especially out of laboratory and in the working conditions where acoustic noise is presented. Main goal of this paper is to analyze influence of time differences uncertainty (i.e. errors in the detected times)and the elastic wave velocity uncertainty on AE source 2-D location accuracy. The analysis will be done for a classic triangulation location algorithm.
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