Evaluating random vibration assisted vacuum processing of carbon/epoxy composites in terms of interlaminar shear strength and porosity

In the manufacturing process of carbon fiber-reinforced plastics composites, if the cure pressure that can form the hydrostatic pressure of resin is transferred inhomogeneously to the interior of composite structures, the critical imperfections such as voids and delamination which damage the mechanical properties and restrict subsequent use will be formed. Therefore, the present work reports the experimental research and analysis on the effect of random vibration applied to the curing system of carbon fiber-reinforced plastic laminates, mainly aiming at the reduction of the void content and improvement of mechanical performance under the vacuum pressure. The range of acceleration of vibrations was covered from 5 g to 15 g, for different periods of random vibration. Conducting a facile thermogravimetric analysis-based methodology, the influence of random vibration on the composite density, fiber volume fraction and void content of carbon fiber reinforced plastic laminates was analyzed. And the influence of voids on the interlaminar shear strength of materials was compared in terms of the initiation and propagation of interlaminar failure. In addition, the scanning electron microscopy was employed to observe the fracture surfaces of the composite specimens, which confirmed the different behaviors of fiber–matrix interface of various curing processes. The major benefits of the current research are that, the application of random vibration during the curing process can better wet through fibers by resin and increase the fiber volume fraction while reducing the bubbles and volatile gas of composite laminates at the same time.