Internal Strain Monitoring of Composite Materials with Microstructed Optical Fiber Bragg Grating Sensors

We present a sensing system based on a combination of 2 optical fibers sensors which are integrated in a composite laminate and that allows three dimensional internal strain measurement in the material. The fiber sensor consists in fiber Bragg gratings fabricated in a dedicated microstructured optical fiber which features enhanced response to transverse strain. We developed a numerical model of the sensor and benchmarked it with experiments performed on laminated composite coupons equipped with this sensor. With this technique, we can measure the strain along the three principal mechanical directions of the coupon with a theoretical strain resolution of 5 μe in the transverse directions which is a 6-fold improvement over results reported in literature. doi: 10.12783/SHM2015/14