Fiber Optics for a Damage Assessment System for Fiber Reinforced Plastic Composite Structures

There are a limited number of nondestructive evaluation techniques available for field inspection of large composite structures and practically no viable techniques for in-service inspection. With this in mind, an innovative Damage Assessment System is proposed which is based on a concept of using an optical fiber mesh, implanted into the body of a fiber reinforced composite structure. Such a mesh would become an integral part of the structure during the course of its fabrication. The selection of the mesh fibers would be predicated on their strain to failure characteristics and strain compatibility with the base, composite reinforcing fibers. This optical system will be capable of locating damage, assessing severity and monitoring damage growth. A successful implementation of the total Damage Assessment System would involve the interaction of the optical fiber mesh with an adequately designed interrogative electronic package. This paper focuses on the former aspect of the total system. It will address some recent experimental work showing the practicality of the concept in assessing various modes of failure due to impact of composite plates, optical fiber selection, location and spacing of fibers, as well as the utility of the system for damage assessment in large, complex composite structures.