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Fiber-reinforced polymer (FRP) is a composite material made of a polymer matrix reinforced with fibers. Hybrid composites are referred to as high-performance FRP materials used in safety-critical structural applications. Generally, FRP composite laminates are very weak in their out-of-plane properties, to address this issue unidirectional (UD) Glass laminates are prepared by modifying the matrix using plasma-treated multi-walled carbon nanotubes (MWCNTs) in epoxy matrix and compared fracture toughness characteristics with low-cost micro fillers like Aluminum oxide (Al2O3) and Sodium Carbonate (Na2CO3). These Nano and Micro fillers are loaded with 0.5wt%, 1wt% and 2wt% in the epoxy matrix while making FRP laminates. Adding these fillers into the epoxy matrix was caused a significant increase in the out-of-plane load-bearing capacity of the composites as compared to plain Glass epoxy laminates. Thus, the fracture toughness was enhanced by 20-26% and 14-17% under mode I and mode II loading respectively. Further, a Scanning electron microscopic analysis was also done on delaminated glass laminates to understand the failure mechanisms. [ABSTRACT FROM AUTHOR]

Cracks can occur in the composite structures during production, assembly, or usage. Environment temperature, deformation rate, and crack geometry have a direct influence on the fracture behavior of laminated composites. In this study, the fracture behavior of S‐2 glass/epoxy composites having different crack geometry at different temperatures and deformation rates was investigated experimentally and numerically. Within the scope of the study, the fracture toughness (K) and strain energy release rate (G) values of samples with 5 mm crack geometry were calculated for the crack tip opening conditions in Mode I and Mode I/II. Fracture tests at different environmental temperatures were performed to investigate the effects of temperature on fracture behavior. Fracture tests were achieved at three different deformation rates, to exhibit the relationship between crack initiation and deformation rate. Also, the fracture behavior of S‐2 glass/epoxy laminated composites was analyzed by using the finite element method (FEM). S‐2 glass fabric reinforced composite is used as a new alternative to traditional building materials, especially in the aviation, space and military industries. The results obtained from the experimental and FEM studies of this composite structure showed that different environmental and loading conditions were effective on the fracture behavior of the composite structure. [ABSTRACT FROM AUTHOR]

The compatibility between the majority of thermoplastic veils (TPVs) and epoxies is typically poor, owing to the inherently low surface energies of thermoplastics. This tends to largely affect the toughening performance of TPVs as interlayer materials of carbon fibre/epoxy composites. The traditional methods for surface activation of thermoplastics, such as corona discharge, plasma treatment and acid etches, are not applicable to TPVs as they could cause significant damage to the thermoplastic fibres with nano-/micro-scale diameters. Herein, a UV-irradiation technique was proposed to active the surfaces of polyphenylene-sulfide (PPS) veils, that effectively improved their adhesion with epoxies. Consequently, the effects of an improved veil/epoxy adhesion on the mode-I and mode-II fracture behaviour and corresponding fracture mechanisms of the interleaved laminates were investigated. It was found that an improved veil/epoxy adhesion significantly enhanced the toughening performance of the PPS veils for the laminates manufactured by resin transfer moulding of non-crimp fabrics, by introducing additional carbon fibre delamination and significant PPS fibre damage during the fracture process. In contrast, the increased level of veil/epoxy adhesion inhibited PPS fibre bridging during the fracture process of the laminates produced from unidirectional prepregs, and caused considerable adverse effects on the fracture performance. Unlabelled Image • A UV-irradiation method was proposed for the surface functionalisation of PPS veils. • The veil/epoxy adhesion had been significantly improved upon the UV-treatment. • The effects of the veil/epoxy adhesion on the fracture behaviour of interleaved laminates were studied. • The toughening performance and mechanisms of the PPS veils were significantly affected by the UV-treatment. [ABSTRACT FROM AUTHOR]