(72c) Alternative Methodology for Characterizing Tool-Ply Friction of Unidirectional Carbon Fiber - Epoxy Prepregs at Various Processing Conditions

The quality of composite parts and structures depends strongly on the friction present during the composite forming process. The two major types of friction that cause deformations during this process are ply-ply friction and tool-ply friction. One of the challenges in the composite forming process is the occurrence of wrinkling and shape distortion of the fabric caused by the surface differences between the forming tool and surface of the laminate. Frictional measurements of composites can vary widely depending on processing parameters, measurement technique, and instruments used. The extent of interaction between the tool and surface of the laminate depends on the tooling height, and by extension, pressure, which cannot easily be monitored with traditional pull out test designs. In this study, a commercial rheometer was used to evaluate tool-ply friction of unidirectional carbon fiber epoxy prepreg at various contact pressures, temperatures and sliding velocities. Gap size and torque were monitored to provide information on the friction dependence on processing parameters. Preliminary results suggest this alternative methodology for measuring tool-ply friction produces similar trends as that seen in traditional pull-out tests.