Effects of Self-heating Process on the Mechanical Properties and Energy Consumption in Molding of Carbon Fiber/Epoxy Composites

Abstract

In order to increase the molding efficiency of carbon fiber composites and reduce their energy consumption in molding and manufacturing costs, this study explores the self-heating molding process of carbon fiber composites and investigates the uniformity of temperature distribution of carbon fiber/epoxy (CF/EP) composites. Besides, the mechanical properties, molding efficiency and energy consumption of CF/EP composite laminates are studied, and the comparison with the conventional hot compression molding process is conducted. The results show that the fixing mode of the electrodes greatly affects the heating rate and temperature uniformity-specifically, the use of bolted pressure plates leads to a faster heating rate and a more uniform temperature distribution than the use of conductive adhesive tape. During the self-heating process, the temperature difference inside the prepreg stack of CF/EP composite laminates was found less than 5°C. Compared with the CF/EP composite laminates molded by hot compression, those molded by self-heating exhibited an increase in tensile strength by 14.9%, compressive strength by 14.2%, interlaminar shear strength by 2.5%, tensile modulus by 11.6%, and flexural modulus by 11.1%, except for bending strength that showed no significant improvement. The self-heating molding process showed a heating rate of 5-10 times higher than the hot compression molding process, consumed only about 6.8% of the energy that the latter required, and increased the molding efficiency by 32%.