Recent advances in aircraft materials and their manufacturing technologies have enabled progressive growth in innovative materials such as composites. Al-based, Mg-based, Ti-based alloys, ceramic-based, and polymer-based composites have been developed for the aerospace industry with outstanding properties. However, these materials still have some limitations such as insufficient mechanical properties, stress corrosion cracking, fretting wear, and corrosion. Subsequently, extensive studies have been conducted to develop aerospace materials that possess superior mechanical performance and are corrosion-resistant. Such materials can improve the performance as well as the life cycle cost. This review introduces the recent advancements in the development of composites for aircraft applications. Then it focuses on the studies conducted on composite materials developed for aircraft structures, followed by various fabrication techniques and then their applications in the aircraft industry. Finally, it summarizes the efforts made by the researchers so far and the challenges faced by them, followed by the future trends in aircraft materials.

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The primary purpose of this study is to realize quantitative fiber loading effects on free vibration, damping behavior, fracture toughness, thermal conductivity, inter-laminar shear strength, and flammability of jute-banana fiber phenolformaldehyde (PF) hybrid composites. These composites were manufactured with fiber weight percentages ranging from 30% to 60% using hot press technique. Hybrid composite with equal amount of fiber and resin (PJB-2) had a higher natural frequency in the range of 4.8%-59%, a higher inter-laminar shear strength varying from 30% to 54%, a higher fracture toughness with minimum of 19 to maximum of 44%, and a low damping factor in the range of 25%-59% to that of other composite having unequal amount of fiber and resin loading. In contrast to other composites, the composite containing 30 wt% fiber (PJB-4) has a high heat conductivity of about 10%-20%. However, the thermal conductivity of jute-banana fiber PF composites declined as the fiber content increased beyond 30 wt%, while the flame resistance was improved as the resin concentration increased. Additionally, Scanning electron microscopy (SEM) studies clearly indicates the failure patterns of fiber matrix interface under Inter laminar shear strength and fracture toughness tests were supports to justify the experimental results.

Laminates of L-bends are inherently weak in the through thickness direction at the region of curvature. To address this behavior, experimental investigations have been made to find the influence of graphene oxide (GO) and Kenaf short fibres on interlaminar radial stress of a unidirectional glass epoxy L-bend composite laminate. Kenaf in the range of 5-10 wt% and GO in the range of 1-2 wt% were loaded at each ply at the curvature of a L-bend and their influence on curved beam strength (CBS) was investigated experimentally as per ASTM D6415. L-bend composite specimens with and without fillers were fabricated with the aid of hand lamination technique. Four point bending fixtures were designed and fabricated to hold the specimen firmly in the uniaxial tension machine. Tests were carried out as per ASTM D6415 and load displacement plots were carefully recorded. Experimental data revealed that the laminate loaded with Kenaf fibres at the curvature radius of L-bend had greater influence on CBS and interlaminar stresses than GO. Further, the delaminated surfaces of L-bend at the curvature region was carefully examined using scanning electron microscope to know the interfacial adhesion mechanism of Kenaf and GO with epoxy and glass fibre.

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Epoxy resins, due to their high stiffness, ease of processing, good heat, and chemical resistance obtained from cross-linked structures, have found applications in electronics, adhesives coatings, industrial tooling, and aeronautic and automotive industries. These resins are inherently brittle, which has limited their further application. The emphasis of this study is to improve the properties of the epoxy resin with a low-concentration (up to 0.4% by weight) addition of Multi-Walled Carbon Nanotubes (MWCNTs). Mechanical characterization of the modified composites was conducted to study the effect of MWCNTs infusion in the epoxy resin. Nanocomposites samples showed significantly higher tensile strength and fracture toughness compared to pure epoxy samples. The morphological studies of the modified composites were studied using Scanning Electron Microscopy (SEM).

In this paper, the effect of integration of natural fibers in UD carbon fiber is studied. The integration of natural fibers in carbon fiber is made via intra fiber hybridization. Natural fiber hybrid composite samples were prepared for Mode I and Mode II fracture tests. XRD analysis was done for the chosen natural fibres to know the crystallinity index and then compared with Carbon and Glass fibres. The fracture test experimental results, revealed that the effect of Jute fiber integration in UD Carbon epoxy composite was found significant in getting relatively good Mode I and II fracture toughness at the crack initiation without losing its stiffness. In addition to this Kenaf Carbon epoxy composite indicated better crack suppression with 30% higher propagation toughness values as compared other hybrid combinations and pristine composites. It is observed that integration of jute fibers in UD carbon epoxy composites was significant in achieving good mode I and mode II fracture toughness at the crack initiation without losing its stiffness and also kenaf carbon epoxy composites indicated better crack suppression with 30% higher propagation toughness as compared to other hybrid combinations used.

The resistance to delamination in polymer composite depends on their constituents, manufacturing process, environmental factors, specimen geometry, and loading conditions. The manufacturing of laminated composites is usually carried out at an elevated temperature, which induces thermal stresses in composites mainly due to a mismatch in the coefficient of thermal expansion (CTE) of fiber and matrix. This work aims to investigate the effect of these process-induced stresses on mode-I interlaminar fracture toughness (GI) of Glass-Carbon-Epoxy (GCE) and Glass-Epoxy (GE) composites. These composites are prepared using a manual layup technique and cured under room temperature, followed by post-curing using different curing conditions. Double cantilever beam (DCB) specimens were used to determine GI experimentally. The slitting technique was used to estimate residual stresses (longitudinal and transverse direction of crack growth) inherited in cured composites and the impact of these stresses on GI was investigated. Delaminated surfaces of composites were examined using a scanning electron microscopy (SEM) to investigate the effect of post-curing on the mode-I failure mechanism. It was found that GI of both GE and GEC composites are sensitive to the state of residual stress in the laminas. The increase in the GI of laminates can also be attributed to an increase in matrix deformation and fiber–matrix interfacial bond with the increase in post-curing temperature.