SYSTEM AND METHOD FOR CRACK MONITORING

摘要

In accordance with an aspect of the present application, a system is provided for crack monitoring in a structure of interest, comprising means for extracting wave modes existing in a frequency interval of interest, means for finding a source of emission on the structure of interest, means for correcting for dispersion to reconstruct an original ratio of wave modes at the source of emission, and means for correlating the original ratio of wave modes to a crack depth.;One advantage of this solution in contrast to prior art techniques is that no a priori knowledge on propagation speed is necessary since actual wave modes can be detected from dispersion relations of wave modes, e.g. Lamb waves at a fixed frequency band in accordance with their calculated speeds. Decentralized acquisition and processing, i.e. monitoring a structure from a localized area, is an important feature of this solution, consequent to which, the data transfer and storage are reduced substantially.

主权项

1. A method for crack monitoring in a structure of interest using Acoustic Emission (AE) sensing, comprising:
placing a plurality of AE detectors on the structure of interest, having relative known positions; detecting during a preset time window acoustic power emitted by an AE source in the selected detectors as time traces; detecting relative time differences of arrival times of a wave mode with maximum acoustic amplitude as dominant wave mode in the time traces of said selected detectors; identifying, in a frequency interval of interest a next to maximum acoustic amplitude as a non-dominant wave mode in the time window; correlating a ratio of dominant and non-dominant wave mode amplitudes to a crack depth location using a characteristic curve; and populating in a history bank crack depths measured for corresponding locations, so that for a selected crack, identified by a calculated location of the AE source, its deepness be resolved by matching a calculated ratio of wave mode amplitudes with a progress in time of the specific ratio position in progress on the characteristic curve characterized in that the method further includes calculating a minimum error of an error function associated with an assumed combination of the source location, speed of a dominant wave mode, and identified arrival times of dominant and non-dominant wave modes, from time traces recorded by said selected detectors located on a single device having known relative detector positions, thereby finding a location of a source of acoustic emission on the structure of interest.