Controllable Delamination of CNT-Reinforced Carbon Fiber Films by Harnessing Mechanical and Topological Characteristics of the Composites

Carbon nanotubes (CNTs) offer a remarkable reinforcement effect for the interlaminar toughness of laminated films, and optimizing the delamination of films through their toughening mechanism is of particular interest. Herein, we propose a theoretical model that combines the spatial evolution of aligned CNTs to describe the mode I fracture between opposing carbon fiber films. Our theoretical predictions quantitatively agree well with previous tests, and the influence of interfacial energy and modulus of films on toughness enhancement is considered. Our findings have demonstrated that aligned CNTs play a crucial role in enhancing delamination resistance, with the performance being highly sensitive to their volume fraction, mechanical properties, and geometric characteristics. We optimized interlaminar toughness by selecting appropriate strength and aspect ratio of CNTs based on two competitive failure modes. This work presents new concept for the topological design of composite laminates, bridging the properties of microfibers and macrostructures and ultimately achieving greater strength and toughness.