PSI - Issue 42

Ayse Cagla Balaban et al. / Procedia Structural Integrity 42 (2022) 292–298 Ayse Cagla Balaban et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction It is clear that metallic materials are replaced by composite materials for different engineering applications in the aerospace, marine and automotive industries. Carbon and Glass Fibre composite materials are widely used in various industries due to their high strength/density and high stiffness/density ratios (Rajak et al., 2021). Thanks to nanotechnology, these types of fibres can be reinforced at the nanometre level or/and they can be improved by nanostructure additives. Carbon nanotubes (CNTs) are the best example of nanostructures with excellent physical and mechanical properties, as well as low density. CNTs which are increasingly the focus of attention, are very difficult to test due to their small structures (Bonduel et al.,2016). Fibre-reinforced composites often exhibit complex damage mechanisms such as fibre failure and matrix fracture. Failure modes such as interface cracking, and delamination between layers can be caused by impact loading and load bearing capacity (Balaban et al., 2019). Although there are studies in the literature on the mechanical behaviour of composites, studies obtained from nanocomposites and sandwich composites that are reinforced with nanoparticles are still very new and these materials are quite promising for different industrial applications. Due to their stronger mechanical properties and lower densities, nanoparticles have great potential to be used as fibres in composite materials. The introduction of such CNT-modified resins into already matured carbon fibre-reinforced plastics (CFRP) opens the possibility for the creation of new multifunctional multiscale materials with optimised mechanical, thermal, as well as electrical properties (Inam et al., 2010). Therefore, the examination of the mechanical properties of such materials, the analysis of their behaviour under different loading conditions and the pre-analysis of the fracture scenarios should be well examined to prevent catastrophic consequences that may occur in the application areas of these materials in the future. It has been shown that CNTs can significantly strengthen polymer matrices if the nanotubes are well dispersed, bonded, and aligned. In this study, a toughening agent was added to the matrix of the Carbon Fibre composites depending on the literature on using nano-scale particles as CNTs in order to improve the mechanical properties of the material. CNTs can provide better interlaminar and intralaminar reinforcement as well as improve the delamination resistance in composites (Ciselli et al., 2007(a); 2007(b)). This paper is a part of a larger project aimed at developing Carbon Fibre/Epoxy composites containing CNTs for special applications. The main goals of this paper are to investigate the material properties of Carbon Fibre/Epoxy composites with and without CNTs under tension and compression loadings and to determine the strengthening effect of the nanotubes by investigating the effect of CNTs on the tensile and flexural properties of Carbon Fibre/Epoxy composites. 2. Materials and Manufacturing In this study, several types of Carbon Fibre/Epoxy composites with and without nanomaterials were manufactured. All materials were manufactured by using a vacuum-assisted resin infusion moulding process (VARIM) at Dokuz Eylul University. A vacuum was applied between the mould and bag to squeeze the resin/reinforcement together and remove any air. Carbon Fibre clothes having the density of 200 g/m 2 and 450 g/m 2 were chosen for this study and they can be seen in Figure 1. The carbon cloths were cut into 40cm x 50 cm for the manufacturing process and the epoxy mixtures were slowly infused into a vacuum bag containing four plies of woven carbon fibre cloths with a (0/90 0 ) lay-