OUT-OF-PLANE DISPLACEMENTS OF COMPOSITE DCB SPECIMENS USING EMBEDDED OPTICAL FIBER STRAINS

Abstract

The use of polymer matrix composite materials in primary load-bearing structures has increased in the aerospace industry primarily due to their high strength-to-weight ratios and stiffnesses. However, composites are susceptible to delamination due to their low interlaminar fracture resistance, which can result in stiffness degradation, thereby decreasing the structural integrity of the part. Strains obtained from embedded optical fibers can be used to detect and monitor damages. Optical fiber strain sensors are lightweight, easy to embed, and offer higher resolution and data acquisition rates. In this study, double cantilever beam (DCB) specimens fabricated from Hexcel IM7/8552 carbon/epoxy prepreg are embedded with optical fibers. Outof- plane displacements of the DCB specimens were calculated using optical fiber strains and show excellent agreement with deflections measured using the DIC system.