Abstract

Microbending losses produced in optical fibers which are embedded between adjacent plys of graphite/epoxy composite materials during manufacturing are considered. Such losses occur due to the periodic corrugations in the individual layers which are caused by the constituent graphite fibers.¹ The geometrical arrangement of adjacent layers with respect to the embedded optical fiber sensor changes the spatial periodicity of the microbending and thus the resulting attenuation per unit length of embedded fiber. The measurements of this attenuation indicate the localized internal strain integrated along the length of the optical fiber. The simultaneous measurement of such attenuation in several fibers having different orientations with respect to the composite material structure allows the evaluation of different components of internal strain as well as interfacial boundary conditions. Potential applications in the nondestructive evaluation of composites are suggested by these results.

© 1985 Optical Society of America