Squeeze Flow of Continuous IM7/977-3 Prepreg to Characterize Transverse Viscosity

• Kamya Taneja, Mechanical Engineering, University of Delaware

• Suresh Advani, Mechanical Engineering, University of Delaware

In this study, continuous carbon fiber composite materials are paired with a thermosetting resin matrix. Continuous fiber composite is a high-performance, anisotropic material composed of carbon fibers aligned in a single, unbroken direction within a polymer matrix, offering exceptional strength, stiffness, and weight reduction for advanced engineering applications.  The anisotropic nature of the material leads to the primary source of strength residing along the fiber direction, though their mechanical properties are significantly reduced in the transverse direction posing real-world issues in forming applications. Although not significant in comparison to the fiber direction in terms of strength, it is necessary to test for the effective viscosity in the transverse direction to understand its impact on material formability. The viscosity characterizes the behavior with applied load and thus, deformation. An established squeeze flow methodology is used to determine the transverse viscosity for continuous fiber composites experimentally. This is conducted by applying force on the material causing a pressure gradient within the material leading to a flow in its transverse direction. Once the experiment is completed and the sample has cured in an oven, the sample is examined under a microscope to provide insight into aspects such as porosity and resin squeeze out. In addition, the testing setup tracks the force applied for two separate displacement measurements. These force versus displacement curves are then analyzed to derive the viscosities for each displacement.