| Abstract Scope |
Composite structures are commonly selected in aerospace applications due to their excellent in-plane mechanical properties. However, with most of their strength relying on in-plane fiber reinforcement, severe limitations are observed in their interlaminar region. Prior research on interlaminar reinforcements has investigated techniques to improve the through-thickness mechanical properties of fiber-reinforced polymer composites, including z-pinning, 3D weaving, and stitching. However, these methods have drawbacks, such as decreased in-plane properties and increased manufacturing complexity. Traditional carbon nanotube reinforcement techniques have proven successful in enhancing the mechanical properties of the interlaminar region. However, the synthesis, manufacturing process, and agglomeration challenges significantly increase complexity and financial costs. Roll-to-roll manufacture of vertically aligned carbon nanotubes (VACNTs) has become an attractive solution for these challenges. In this project, the morphological parameters of VACNTs, including diameter, length, aspect ratio, and density, were optimized through the Design of Experiments (DOE) approach and finite element simulations. Then, VACNTs with optimized morphological parameters were manufactured and transferred to prepreg layers using roll-to-roll manufacturing. After that, pristine and VACNTs-reinforced Cycom 5320-1/IM7 12K carbon/epoxy unidirectional laminates were manufactured. Then, samples were cut and tested under quasi-static loading (Mode I and Mode II fracture tests and tension tests). Fractographic analysis was performed before and after testing to understand the effect of VACNTs on crack mitigation of the laminates. The findings demonstrated that by carefully selecting the VACNTs parameters, the quasi-static properties and crack mitigation can be enhanced without decreasing the laminates' in-plane mechanical properties. |