Investigating Flexural Failure in Carbon Fiber Reinforced Polymer Composites Interleaved with Carbon Nanotube Sheets

Abstract

While carbon fiber reinforced polymer (CFRP) composites exhibit exceptional mechanical properties in tension, their relatively low compressive strength is often a limiting design factor. To mitigate this shortcoming, this study investigates effects of inserting aligned carbon nanotube (CNT) sheets at ply interfaces on flexural properties of CFRP composites. CNT sheets were placed between carbon fiber plain-weave fabrics prior to infusion with epoxy. Resin transfer molding (RTM) was subsequently used to fabricate the specimens. Composite specimens were examined after fabrication and similar quality for both CNT interleaved and reference samples were observed. Samples were tested for on-axis tensile and flexural properties where the aligned CNT sheets were parallel to the bending direction. As expected, on-axis tensile tests showed no change in stiffness due to CNT reinforcement. The addition of CNT sheets increased the flexural strength by 28.9% and improved the resistance to delamination compared with the reference samples. This study suggests an innovative, inexpensive and scalable solution for mitigating the low compressive and interlaminar properties of conventional composites while potentially improving their physical properties such as electromagnetic interference (EMI) shielding and electrical/thermal conductivities. Keywords: Carbon Fiber Polymer Composite, Carbon Nanotube Sheets, Compressive Strength, Flexural strength