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.

The fiber-resin interface is an important component that significantly affects mechanical properties of composites. Random vibration-assisted vacuum processing (RVAVP), a new method to improve the adhesion of the fiber-resin interface, was presented. The effects of different curing processes on mechanical properties were comprehensively assessed by combining the fiber push-out test, finite element model simulation, cure monitoring approach, and short-beam three-point bending test, and the correlation between fiber volume fraction and mechanical properties was quantified by a facile thermogravimetric analysis-based methodology. The results revealed that application of random vibration during the curing process can promote the impregnation of resin into fibers and impede the growth of interface defects while improving mechanical properties at the same time. For this reason, the laminates produced by RVAVP exhibited the average interfacial shear strength of 78.02 MPa and the average interface fracture toughness of 51.7 J/m², which is obtained a 48.26% and 90.77% improvement compared with the 0 MPa autoclave process. With the large observed increase in micro-mechanical properties, the average interlaminar shear strength of 93.91 MPa showed a slight reduction of 5.07% compared with the 0.6 MPa autoclave process. Meanwhile, the mechanical properties tended to be stable at the fiber volume fraction of 65.5%.

As an emerging composite curing process, the microwave curing process has been widely concerned by many research teams due to its several major advantages over conventional conductive heating when used to cure carbon fiber reinforced polymer composites, especially in speed of processing. However, many studies have shown that the quality and properties of microwave cured-composites have been reduced compared with the autoclave process, which limits the universal application of the technology in the field of composites manufacturing. In this study, in order to improve the quality of microwave cured-composites and reduce the influence of pressure on the forming process, a series of laminates have been prepared at different heating rates by introducing vibration treatment into the microwave curing process. The short-beam three-point bending test, optical digital microscopy, scanning electron microscope were used to analyze laminates from micro- and macro-scale point of view. The results showed that the introduction of vibration treatment could effectively reduce the internal defects and improve the mechanical properties of the microwave cured-laminates, which provided a new method for high-quality, low-defects microwave curing of composites.

Due to their mechanical load-bearing and functional wave transmission, adhesively bonded joints of carbon fiber–quartz fiber composites have been widely used in the new generation of stealth aviation equipment. However, the curing defects, caused by deviations between the process environment and the setting parameters, directly affect the service performance of the joint during the curing cycle. Therefore, the thermophysical parameter evolution of adhesive films was analyzed via dynamic DSC (differential scanning calorimeter), isothermal DSC and TGA (thermal gravimetric analyzer) tests. The various prefabricating defects within the adhesive layer were used to systematically simulate the impacts of void defects on the tensile properties, and orthogonal tests were designed to clarify the effects of the curing process parameters on the joints’ bonding performance. The results demonstrate that the J-116 B adhesive film starts to cure at a temperature of 160 °C and gradually forms a three-dimensional mesh-bearing structure. Furthermore, a bonding interface between the J-116 B adhesive film and the components to be connected is generated. When the curing temperature exceeds 200 °C, both the adhesive film and the resin matrix thermally degrade the molecular structure. The adhesive strength weakens with an increasing defect area ratio and number, remaining more sensitive to triangle, edge and penetration defects. By affecting the molecular structure of the adhesive film, the curing temperature has a significant impact on the bonding properties; when the curing degree is ensured, the curing pressure directly impacts the adhesive’s performance by influencing the morphology, number and distribution of voids. Conversely, the heating rate and heat preservation time have minimal effects on the bonding performance.