Composite materials, while strong and lightweight do not show visible signs of wear and tear like their metallic counterparts, which makes inspection of these material systems difficult. Therefore, with the use of composite materials becoming more prevalent, the importance of structural health monitoring (SHM) has increased. In recent years the use of fiber Bragg grating (FBG) technology in SHM has become more popular for its benefits over traditional methods. An example of FBG technology applied towards the monitoring of composite materials is demonstrated by researchers from the Department of Mechanical and Aerospace Engineering at North Carolina State University and the School of Aeronautics at Northwestern Polytechnical University. In this study the use of embedded FBG sensors and a Micron Optics sm130 Optical Sensing Interrogator is employed to monitor the curing process of a self-healing layer within a twelve-layer fiberglass laminate after impact.
For this experiment, five self-healing sandwich-like composite specimens were created and embedded with FBG sensors between the fiberglass and foam core. The fiberglass laminate was then impacted with the use of a drop tower and the curing process was monitored. The collected data was used to compare the cure of the resin and fiberglass alone to the cure of the resin from a self-healing specimen. The experiment proved that FBG sensors could potentially be used for cure monitoring in composites if the self-healing induces sufficient strain and temperature on the FBG sensor.
Specimen fabrication: (a) Steel wire scaffolding (b) resin curing (c) completed specimen
For more information about this study, you can purchase the full paper here.
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