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Delamination is one of the life‐limiting failure modes for fiber reinforced polymer (FRP) composite composites resulting in poor damage tolerance, as this failure mode occurs at considerably lower loads. Owing to the enormous demand and mass production of FRP composites, a large amount of fiber waste is produced worldwide. This triggers concern about utilizing these fiber wastes for some valuable applications. The present study aims to improve the overall damage tolerance of laminated glass/epoxy composites via the introduction of waste short carbon fibers (SCFs) reinforcement in the epoxy matrix. The effect of various SCF contents (0.1, 0.3, and 0.5 wt%) in glass fiber/epoxy composites were evaluated experimentally for their interlaminar fracture toughness in terms of both crack development and propagation under mode I and II interlaminar fracture toughness tests, at elevated temperatures (30, 50, and 70°C). Based on the experimental results, glass/epoxy composite with 0.1 wt% of SCF revealed 13.49% and 20.45% increment in mode I and II interlaminar fracture toughness, respectively, at ambient temperature. A positive reinforcement effect could be noticed for GIC and GIIC values up to 50°C. However, due to residual interfacial stresses, interfacial debonding, and epoxy softening, a negative reinforcement effect could be noticed at 70°C. Delamination initiation and crack propagation mechanisms have been explored at elevated temperatures. Fractographic studies have been carried out using a scanning electron microscope to identify the failure mechanisms. [ABSTRACT FROM AUTHOR]

This research work investigates the influence of hybrid particulate fillers, Mg–Al layered double hydroxide (LDH), and nanoclay (NC), on the mechanical properties and formability of glass laminate AA5052 epoxy composites (GLARE). The composite laminates were prepared by varying the weight percentage (i.e., 3, 4, and 5 wt%) of the hybrid fillers in the epoxy resin. The conventional hand layup technique was utilized for the fabrication of the laminates. The tensile test samples were prepared in different orientations with respect to the rolling direction (i.e., 0°, 45°, and 90°) to address their anisotropic nature. The flexural, impact, lap shear, and formability tests were conducted as per ASTM and IS standards. The Erichsen cupping test was performed to study the formability of the composite laminates. For each test, the results were compared with that of the laminates containing individual LDH filler, NC filler, and no filler material. The results showed that the composite laminate with 5 wt% of LDH + NC hybrid filler exhibited enhanced tensile properties, impact energy, and lap shear strength while the laminate of 4 wt% LDH + NC filler possessed better flexural properties. The formability of the composite laminates with hybrid LDH + NC fillers was observed to be lower than that of the laminates with individual filler materials and laminate without any filler. The variation observed in the test results was justified by investigating the failure mechanism of the composite laminates using a scanning electron microscope. [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]

This research work is focused on development of epoxy based fiber metal laminate (FML) that comprised of multi‐walled carbon nano‐tube (MWCNT), glass fiber, and aluminum metal sheet. The hand layup technique was employed to fabricate the sandwich FML with different weight percentages (3, 4, and 5 wt%.) of MWCNT. The mechanical properties of the developed FMLs were determined through tensile, flexural, lap shear, and hardness tests following ASTM and IS standards. The scanning electron microscope (SEM) was used to characterize the failure mechanism of composites. The FML with MWCNT offered superior tensile and shear properties up to the addition of 4 wt%. The MWCNTs were found to be agglomerated in the epoxy when added more than 4 wt%. The FML's showed larger deformation before complete failure in shear mode with respect to the addition of MWCNTs. However, there was no considerable improvement recorded in the flexural and impact behavior of the FML composition. The addition of MWCNT fillers in the epoxy turned it more brittle and exhibited comparatively less deformation before failure in flexural mode. [ABSTRACT FROM AUTHOR]

The numerical simulation on the interlayer phase morphology evolution of "Ex‐Situ" toughened laminate was performed in this study. Specifically, the diffusion process of thermoset (TS) resin into thermoplastic (TP) resin was modeled incorporating the negative effect of resin curing reactions. The dynamic process of polymerization‐induced phase separation in TP/TS blends was predicted by the modified Cahn–Hilliard equation, in which the concentration‐dependent mobility was used to describe dynamic asymmetry between TP resin and TS resin, and the mixing free energy of the blends contained the contribution of resin curing reactions. The phase morphology evolution of polysulfone/epoxy blends in the interlaminar region was analyzed numerically, and the results indicated that the diffusion process resulted in the concentration‐gradient distribution of epoxy resin in interlayer, and when the concentration‐gradient decreased, the interlayer phase morphology developed from the coexistence of different microstructures to the presence of a single structural form. The post‐curing temperature played a more important role in the phase separation than that in resin curing reaction, and the separated structures were only observed in the local region of interlayer under low post‐curing temperature, due to small driving force of phase separation. Moreover, the movements of epoxy molecules dominated the microstructure formation process. POLYM. COMPOS., 40:3644–3656, 2019. © 2019 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]