Experimental and numerical studies on compaction of carbon fiber composite joint with variable cross‐section using thermal expansion process

For hollow composite with complex shape, thermal expansion process is usually used to ensure uniform compaction pressure and excellent processing quality. This study focused on compaction of carbon fiber/epoxy matrix composite joint with variable cross‐section using thermal expansion process. Three kinds of silicone rubber core molds were adopted and experiments were performed to study the effect of elastomer core mold on resin pressure distribution inside prepreg stack during process and processing quality of composite joint. Moreover, based on numerical analysis, thermal expansion behaviors of different core molds and compaction pressure on prepreg stack were studied. The results indicate that material properties and geometric structure of core mold significantly influence thermal expansion behavior of core mold and compaction pressure distribution on prepreg stack. Due to irregular shape of core mold, thermal expansion of core mold at the regions with different cross‐sections is obviously uneven. And core mold with large coefficient of thermal expansion and small compressive modulus is more likely to fill process gap and achieve uniform compaction pressure distribution on prepreg stack. Therefore, controlling thermal expansion behavior of core mold to improve processing quality of composite involves reasonable material properties of core mold and adjusting process gap at different cross‐sections of composite. POLYM. COMPOS., 40:E1057–E1074, 2019. © 2018 Society of Plastics Engineers