Experimental Investigation of In-Plane Shear Deformation of Out-of-Autoclave Prepreg

To ensure the production of high-quality continuous fiber-reinforced composites when forming complex shapes, the potential for in-plane deformation of the woven reinforcements must be taken into consideration. The study presented here used a bias extension test to determine experimentally the in-plane shear behavior of out-of-autoclave 8-harness and 5-harness satin woven carbon/epoxy prepregs. The test was performed at different displacement rates; changes in tow geometry with respect to shear angle were observed. The various stages of deformation and the onset of wrinkling during the shearing of woven fabrics were determined by a digital image correlation (DIC) technique. An infrared (IR) heater was used to investigate the effect of different elevated temperatures on in-plane shear properties. The results of the study show that a rise in temperature results in decreased viscosity of the resin and shear force. This decrease in viscosity, in turn, increases the allowable shear deformation, which results in a reduction of wrinkling. Fabric style and yarn size were also found to have a significant influence on in-plane deformation.