Simultaneous Measurement of Two Strain Components in Composite Structures Using Embedded Fiber Sensor

This paper uses an in-line fiber etalon (ILFE) cascaded with an in-fiber Bragg grating to simultaneously measure axial and transverse strain components inside a cantilever beam fabricated from a graphite/epoxy composite material. The ILFE and Bragg grating sensor signals are demultiplexed using a variation of coherence division multiplexing, and then demodulated using a Pseudo-Heterodyne scheme. Composite cylinders models are developed that allow the optical measurements to be related to the strains in the host composite material. Experimental results show that both of the measurement errors of the two strain components are approximately 5 uE.