Damage Analysis in Reinforced LCP Composites by Acoustic Emission Location Techniques

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Abstract
Damage processes during cyclic deformation of short glass fiber reinforced liquid crystalline polyesters (LCP) have been investigated by acoustic emission (AE) source location techniques. The approach consisted of placing two sensors equidistant from a notch and monitoring the AE signals emitted from damage accumulation as cycling progressed. This was done in conjunction with a video-camera recording system and an infra-red thermal measuring device. The visual and thermal data indicated that no measur able stable crack propagation occurred. Acoustic emission measurements suggested that failure resulted in the last 20% of the cycling time by a damage-related microcracking mechanism. Three-dimensional linear location plots showed that damage was very local ized in the notch region in the reinforced materials and somewhat broader in the neat LCP resin. Correlations between the location of damage, the time and stress level at which it occurred as well as its AE amplitude characteristics have been made.