High performance piezo electric nanocomposite sensor nodes for structural health monitoring

Fotouhi, Mohamad and Xiao, Bill and Pozegic, Thomas and Jalalvand, Meisam and Hamerton, Ian and Wisnom, Michael R. (2017) High performance piezo electric nanocomposite sensor nodes for structural health monitoring. In: 21st International Conference on Composite Materials, ICCM 2017, 2017-08-20 - 2017-08-25.

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Abstract

The increased usage of composite materials has raised the need for a more reliable damage detection strategy for structural health monitoring (SHM) systems. An important, and as yet unsolved, limitation of existing composite laminates is their susceptibility to impact damage. Low-velocity impact-induced damage is often hard to spot from the impacted side in a routine visual inspection, but it has a significant effect on the mechanical performance of laminates. This work investigates the possibility of embedding poly (vinylidene fluoride) (PVDF) as a sensor node for a passive SHM system in SE70 glass/epoxy laminates to monitor the damage while being subjected to an indentation test. The mechanical test results for the laminates both with and without embedded sensors indicate that the embedment of the PVDF sensors does not change the measured mechanical properties of the laminates. Acoustic emission (AE) signals obtained using the embedded PVDF sensor were compared with an identical PVDF sensor attached on the laminate’s surface. The results showed the possibility of successfully embedding PVDF sensors in composite laminates and the functionality of the PVDF sensors after the embedding procedure, i.e. their ability to withstand the composite curing temperature without experiencing degradation. However, the amplitude level of the AE signals obtained with the PVDF is lower than that of the commercial sensor, which is due to the low coupling factor and dielectric constant of the PVDF. Therefore, the development of two- and three-phase AE sensors (lead zirconate titanate (PZT)/epoxy and graphene nanoplatelets (GnPs)) were also explored to improve the sensitivity of the embedded sensor. The fabrication methods have been developed and the fabricated sensors showed better performance than PVDF sensors during the Hsu-Nielsen Source test. This is a continuing project, therefore further research will be conducted to implant the PZT nanocomposite sensors into composite laminate plates to examine the applicability of these novel sensors as flexible and light weight embedded sensor nodes for structural health monitoring systems.