SERVICE TOUGH COMPOSITE PANEL

1Advanced composite materials such as carbon/epoxy are prone to delamination or splitting between the piles caused by handling or service impacts. Delamination is often internal and is difficult to detect even with sophisticated instrumentation. Critical components must be designed for conservative stress levels because of the possibility of an undetected delamination. Preventing delamination or limiting propagation under load would save weight through higher design allowables, and would reduce inspection, repair and replacement costs. Foster-Miller has recently developed a process to transversely reinforce composites on-tool in the autoclave. Our initial tests results indicate that the method has the potential to significantly reduce delamination in carbon-epoxy, and also to eliminate or reduce some of the problems related to mechanical fasteners. We have recently shown that through thickness (T2) reinforcement with carbon fibers improves mode I fracture toughness ten times in AS4/3501-6. Unlike stitching, the method does not adversely affect the in-plane properties. In the proposed program we plan to conclusively demonstrate these advantages through a logical sequence of activities leading to fabrication and service testing of a T2 reinforced component for a Navy aircraft in Phase II. This effort will involve the support and participation of McDonnell Aircraft Co.