Low velocity impact damage to composite laminates can result in a complicated network of matrix cracks and delaminations beneath the laminates surface, which are extremely difficult to detect by visual inspection. Current non-destructive evaluation (NDE) techniques such as ultrasonic C-scan and x-ray imaging create significant downtime, which leads to costly inspection programmes. Embedded sensors offer the potential to increase the automation of inspection, and decrease the downtime when compared with current NDE practices. However, for such systems to be practical, sensors must be integrated within composite structures without producing unacceptable loss of structural performance. This paper identifies techniques for embedding slim sensors with comparatively large in-plane dimensions inside composite materials. Interlaminar shear strength tests were used to identify an encapsulating layer for the sensors. Flexural strength testing was carried out on laminates containing sensors embedded towards the compressive surface of flexural specimens. The experimental study was complemented with finite element analysis, which identified the load paths within different embedment configurations and aided with the interpretation of the experimental results. The results show that with careful selection of sensor materials, geometry, embedding location and embedment technique, sensors can be integrated within composite structures without producing any significant reduction of mechanical performance.
Bibliographical noteDate of Acceptance: 14/08/2015
- embedded sensors
- composite materials
- structural integrity