Acoustic emission (AE) technology suitability for testing composite materials

Abstract

In this work the suitability of using Acoustic Emissions (AE) technology for evaluating the damage and location in composite materials during coupon tests has been analysed. The selected material for the evaluation tests is a carbon fibre reinforced epoxy composite material. Using coupon level tests, two permanent damage detection methods has been evaluated. The felicity ratio, in which applying load up to a known level and then discharging it, if in a subsequent load the sensors detects acoustic emissions before the 95% of the previous load is reached, it is indicative that damage has appeared in the sample. And the Palier effect, in which a structure is kept at a certain loading level, during the first 2 minutes some counts or hits can be emitted, but in the next 2 minutes period the material should not show acoustic activity, unless the structure is permanently damaged. During the same coupon tests, the damage location technique by acoustic emissions has been also evaluated on 1D and 2D samples. Results show that it is possible to detect damage with Acoustic Emissions technology, and to establish procedures able to predict the final failure before it happens. Moreover, the use of several sensors allows the damage to be located.

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