Trans-Ply Crack Density Detection by Acousto-Ultrasonics
The use of advanced composite materials, particularly for aerospace use, requires dimensional stability and the absence of cracks. The presence of cracks reduces mechanical characteristics and exposes the fibers and interfaces to environmental (moisture) effects. Graphite/PMR polyimide composites are candidate materials to replace metals in moderate high temperature zones (up to 316°C) in jet engines. These types of applications will introduce thermal cycling which in turn will produce trans-ply cracking unless tougher matrix materials are developed. Because these trans-ply cracks are very undesirable, NDE techniques are needed to detect the presence of trans-ply cracks. This paper will demonstrate that acousto-ultrasonics can be used to detect trans-ply cracks in graphite/PMR polyimide cross-ply and woven fabric laminates.
KeywordsCrack Density Fabric Laminate NASA Lewis Research Pyromellitic Dianhydride Advanced Composite Material
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