Acoustic emission testing of fiber composite materials

Abstract

Acoustic emissions (AE) can be used to nonintrusively monitor and, in some instances, characterize the progression of damage in composite materials during deformations. In the present investigation, AE from graphite epoxy tape laminates and acrylonitrile butadiene styrene (ABS) specimens with and without short glass fibers were monitored and analyzed during cyclic loadings and monotonic proof tests. Usual AE parameters such as hits, counts, and amplitude were correlated with spectral analyses of acoustic emissions recorded during various portions of the loading waveform. Due to bandpass limitations of the acoustic emissions device, few correlations of the spectral content of the acoustic emissions could be made with the loadings or mechanisms of damage. However, some useful information for users of the AE technique was obtained from a wideband spectral analysis measurement made with the acousto-ultrasonic (AU) technique. With the simulated acoustic emission events generated with the AU technique, it was shown that physical parameters such as transducer resonance, source-to-receiver distance, specimen geometry, and material properties such as fiber orientation and composition have distinct and reproducible effects on the measured spectral response.