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Opportunities for Structural Health Monitoring of Composite Material Structures with Novel Microstructured Optical Fiber Sensors

F. BERGHMANS, C. SONNENFELD, S. SULEJMANI, T. GEERNAERT, G. LUYCKX, N. LAMMENS, J. DEGRIECK, E. VOET, K. CHAH, F. COLLOMBET, W. URBANCZYK, P. MERGO, M. BECKER, H. BARTELT, H. THIENPONT

Abstract


The possibility of embedding optical fiber sensors inside carbon fiber reinforced polymer (CFRP) for structural health monitoring purposes has already been demonstrated previously. So far however, the sensitivity of these sensors to transverse load (i.e. out-of-plane load) remained considerably lower than that to axial strain. The design flexibility provided by novel microstructured optical fiber (MOF) technology now allows developing dedicated fibers with substantially enhanced sensitivity to transverse load. We exploited that flexibility and we developed a MOF that, when equipped with a fiber Bragg grating (FBG), leads to a sensor that allows measuring transverse strains in reinforced composite materials, with an order of magnitude increase of the sensitivity over the state-of-the-art. This is confirmed both with experiments on such fibers embedded in CFRP coupons and with finite element simulations. Our sensor brings the achievable transverse strain measurement resolution close to a target value of 1 microstrain (μ) and could therefore play an important role, not only in the domain of structural health monitoring, but also in the field of composite material production monitoring.

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