Abstract
Acoustic emission is a promising technique for damage detection and location in composite structures. It refers to the process of using a sensor array to detect the elastic waves generated by a damage source within a structure. However, it is challenging to propose suitable and reliable damage location strategies when applying this technique on composite-honeycomb sandwich panels due to their complex nature which affects the acoustic wave propagation. Further, composite-honeycomb sandwich panels are susceptible to damage on either one of their surfaces, yet acoustic emission sensors are likely to be bonded to just one of these surface and the ability of acoustic emission to locate events occurring on the opposite surface from which they are bonded has yet to be explored. This paper seeks to shed light on this phenomenon with an investigation into the ability of acoustic emission to locate sources in a glass fibre aluminium honeycomb sandwich panel, for sources originating from both the front and back surfaces. An array of four sensors was bonded to the front surface of a 820 x 820 mm sandwich panel. Artificial emission sources were generated on both front and back surfaces of sandwich panel. Two location techniques were used to locate the sources; difference in time of arrival, and Delta-T Mapping. For sources generated on the front surface, difference in time of arrival technique located all sources with an average error of 20.2 mm, while Delta-T Mapping located all sources with average error 11.1 mm. For the sources generated on the back surface, opposite to the sensors, difference in time of arrival technique located all sources with average error 42.8 mm, while Delta-T Mapping located them with an average error of 20.78 mm. Overall, Delta-T Mapping technique consistently demonstrates its potential and credibility for source location in complex structures when inspecting the sandwich panel in 2D and 3D, as well.
Published Version
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