Detection of foreign materials in uncured hand layup composites

Fiber-reinforced polymer prepreg materials are supplied in the form of tape, tow and fabric. During the cutting and lay-up processes, some of the backing material (release film) remains on the prepreg. Composite parts manufactured using such prepreg materials can fail since the backing material prevents a good bond between individual plies. Menon and Associates proposes to demonstrate a RF-based profiler system to detect the backing material. The principle is based on exciting specific nuclei inside composite materials. These nuclei are found within the contaminants and are very different from those found in the fiber and matrix. The profiling process allows individual layers within a structure to be inspected rapidly while the various plies are being laid down in the mold. Contaminants such as aluminum, copper, steel, paper, plastic, glove fragments, Teflon, oil, insects, food and moisture can be detected and identified. In Phase I we demonstrated feasibility of detecting the contaminants in uncured prepregs. In addition we demonstrated the system can detect incipient heat damage in composites. In Phase II we will build and demonstrate a prototype hand held system for detecting contaminants in uncured composites. The system will also be demonstrated to detect heat damage in composites.