On the benefit of thin plies on flexural response of CFRP composites aged at elevated temperature

This paper demonstrated the benefits of thin plies for enhancing the flexural response of conventional composites at elevated temperatures. Two types of carbon fabrics i.e., traditional ply (320 um thick) and thin ply (80 um thick), and general purpose epoxy was used to fabricate composites using autoclave manufacturing process. Three configurations of laminates were made, with the first one having all traditional plies, second one with the core made of all thin plies surrounded by traditional plies and the third one with each traditional ply sandwiched by a set of thin plies. Three-point bending test was conducted after thermal aging for 24 h at of 140 degrees C, 160 degrees C, 180 degrees C, 200 degrees C and 220 degrees C. The results demonstrated that the laminates containing thin plies have higher flexural strength and modulus at all the considered ageing temperatures, due to the existence of thin plies that delayed the compressive fiber damage at the plies in contact with the indenter. Moreover, the existence of these plies interrupted the heat flow to the laminate core, which reduced the propagation of delamination and matrix cracks inside the laminate core. The laminate with conventional plies surrounded by thin plies, showed the highest flexural strength improvement of 20 % at 220 degrees C.