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First CentrAl concept for fuselage (a) and lower wing skin panels (b) [21] and modified CentrAl concept (c) [22].
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![Fig. (3). Tapered lower wing skin concept [14].](profile/Rene-Alderliesten/publication/228684079/figure/fig3/AS:669964604301312@1536743417420/Fig-3-Tapered-lower-wing-skin-concept-14_Q320.jpg)
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The hybrid technology of combining metallic constituents with fibre reinforced polymers in a laminated configuration has been developed over the past two decades. This paper provides an overview of the patents that have been filed worldwide on these hybrid material concepts and related manufacturing aspects.
Contexts in source publication
Context 1
... FMLs at both sides of a thick aluminium panel, Roebroeks and Gunnink [21] introduced another wing skin concept based on the combination of thick aluminium layers connected to FMLs. In addition, they claim that a similar concept can also be applied to fuselage skin panels by reducing the aluminium layer thicknesses. The concepts are illustrated in Fig. (5a,b), where the outer aluminium layers are bonded by the glass fibre epoxy systems to FML straps that are oriented perpendicular to the glass fibre orientation. The straps are made of FML using a Zylon fibre (PBO type) with a higher stiffness as compared to glass fibre based FMLs. The post stretching technique that will be discussed later ...
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... however, illustrated that in case the thick aluminium layers are bonded to the FML straps with only epoxy adhesive, the fatigue cracks that may occur in the outer aluminium layers are propagating directly into the outer layers of the straps. This can be avoided by adding reinforcement to the adhesive using high strength fibres, as illustrated in Fig. (5a), but that causes large dela- minations induced by the fatigue cracks in the outer aluminium layers. These delaminations significantly reduce the effectiveness of the concept. As a solution to this pro- blem, Roebroeks and Gunnink [22] propose to bond the thick [19], a discontinuity in fibre/epoxy plies only (b) and additionally in one ...
Context 3
... concept is illustrated in Fig. (5c), where in grey scale is illustrated that if required additional thick aluminium layers can be added to both sides of the laminate, bonded with the same fibre reinforced epoxy systems with reduced ...
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... difference between the original concept [21] and the modified concept [22] is mainly related to the connection between thick aluminium layers and the reinforcing FMLs in the centre. The original patent describes that the thick aluminium layers are bonded with an epoxy adhesive to the FML, see Fig. (5a,b), while the modified patent proposes to bond the thick layers with a fibre reinforced polymer ...
Citations
... The polymer matrices utilized in FMLs can be classified as either thermosetting or thermoplastic. Thermosetting polymers, such as epoxy resin, have found extensive applications in the field: the so-called GLARE (glass-reinforced aluminum) is an example of FMLs currently used in the aerospace sector [5]. However, one of the drawbacks of using thermosetting polymers is given by the long duration of the forming cycle that must include the curing process of the polymer [6]. ...
This paper illustrates the thermoforming process carried out on thermoplastic polymer and magnesium-based fiber metal laminates (FMLs). Flat laminates were formed at elevated temperatures into a hat-shape part. The forming force was acquired and, after forming, the thickness of each constituent of the FMLs in different zones was measured. A non-uniform thickness distribution was found in the formed parts, with a significant reduction of the prepreg thickness at the part bottom radii. Moreover, it was observed that the higher the blank-holder force the higher the forming force and the more significant the prepreg thickness variation.
... For this reason, they are the largest subset of composites. [1][2][3] Among natural fibers, basalt fibers due to their good strength properties, good adhesion between resin and fibers, sound insulation properties, high operating temperature range, lower price than carbon and Kevlar fibers, and also higher strength than optional glass fibers which are appropriate for utilization in various industries as reinforcement in the polymers. [4][5][6] Silica is used in various forms in various products, including silica powder, silicone gel, silica fume (SF), silica aerogel, and so forth. ...
In this study, the effect of the addition of silica particles modified with silane agent on the mechanical properties of basalt fibers‐epoxy composites were studied with the interlayer shear strength (ILSS) test. In the first stage, silica fume particles were synthesized using the sol‐gel method and surface modified using tri mercaptopropyl trimethoxy silane agent. The results of the characterization showed that the synthesized powder is nanometric scale, amorphous and high purity. The surface‐modified silica fume particles (0, 2, 4, 6 wt.%) were distributed inside the epoxy matrix using a mechanical stirrer and ultrasonic waves. The hand lay‐up method was used to fabricate composite samples, then the effect of adding these particles on the mechanical properties of basalt fibers‐epoxy composites under interlayer shear loads was studied. The results of the research indicated that the addition of silica fume particles has a significant effect on improving the mechanical properties of basalt fibers‐epoxy composites, and the greatest improvement in mechanical properties was achieved by adding 4 wt.% of modified silica fume particles. In the case of composites without SF particles, the shear strength was 34 MPa, which was increased to 40 MPa by adding 4 wt.% of SF particles (about 20% improvement). On the other hand, results demonstrated that the optimal distribution of silica fume particles within the polymer matrix performs an impressive role in improving the mechanical response of composite samples.
Highlights
The use of silica fume in the polymer composite is one of the research innovations.
Silica fume is a super‐fine spherical powder that is collected as a by‐product.
The silane is used to better distribute and optimal interaction of the silica fume in epoxy.
Sol‐gel is one of the methods to synthesis of silica fume.
ILSS test was done to investigate the strength of the interface of basalt fibers and epoxy.
... Although, certain post-treatments can enhance it. During ARALL fabrication, the residual stress was eliminated by stretching the cured laminate till the yielding of Al sheets [7]. The fabricated FMLs are inspected using various mechanical tests like X-ray, ultrasound, and visual techniques [1,34]. ...
This article reported a comprehensive review of computational modelling and analysis of fibre metal laminates (FMLs),
including the experimental techniques. The research is relevant to the metal (aluminium) stacked in the advanced fibres
(Glass/Carbon/Kevlar) reinforced with epoxy matrix, and composite behaviour is discussed in detail. The discussion also
includes damages like delamination on the bonds’ responses (frequency and static/dynamic deflections). The metal-bonded
composite has shown tremendous potential in the transportation industries without increasing the weight penalties in the
overall structure. This review focuses on recently devised technologies for making FML components, with brief overviews
of other working parameters. A complete outline of the historical background and contemporary advances of FMLs includes
the categories, sheet production procedures, benefits and drawbacks. Moreover, the forming technologies are discussed, indicating
their promising options for the large-volume manufacturing of intricate shape components of FML. The fracture and
flaws in the fabrications of FML, including the complexities available in the earlier studies, are surveyed comprehensively.
Finally, state-of-the-art research on the numerical methodologies of the FML structural modelling using different theoretical
approaches and experimental verifications is provided in detail.
... In particular, there is a desire to introduce FML structures in the military, automotive, and maritime industries, where they set a clear benefit to fulfil industry requirements compared to conventional structural materials. Currently, FMLs are used as fuselage skin, cargo floor, doors in the aerospace sector [4][5][6][7], propeller blades, submerged hull ships, or deepwater risers [8][9][10] in the maritime sector. In the automotive industry, FML structures are sought after to make car bonnets, whereas those materials are used as armour plates in military applications. ...
... The polymer matrix of the prepregs used in existing FMLs is either thermosetting or thermoplastic. Thermosetting polymers, such as the epoxy resin, have been widely used, such as the FMLs named GLARE [10]. However, their forming cycle is quite long due to the time needed for the thermosetting polymer curing process [11]. ...
This research presents a methodology for the compaction characterization of thermoplastic prepregs with a twill weaving style under a range of parameters typical of the thermoforming process applied to magnesium alloy-based fibre metal laminates (FMLs). The compaction tests were conducted making use of a plate-to-plate mode testing setup. The through-thickness and transverse width of the prepregs were evaluated on the FML specimen cross-section at varying compaction force and temperature. Significant deformations were observed at the lowest compaction force above the prepreg polymer melting point, whereas a further increase in the compaction force led to gradually smaller through-thickness and in-plane deformations. Additionally, a higher decrease in thickness and increase in width of the prepregs were detected at higher temperatures.
... This procedure involves alternating dry fiber layers, thermoplastic resin, and metal cover, as illustrated in Fig. 4b. Afterward, the FML is bonded using a hot press or an autoclave [130,131]. ...
Fiber metal laminates (FMLs) are a super hybrid material that provides the combined advantages of metals and composites and offers significant potential as an ultralight structural material in the aerospace industry. Consequently, there has been increased research attention on FML mass production processes. The recent developments in FML component production and FML sheet preparation are the main topics of this review. First, a general overview of the development history, fabrication process, and properties of FMLs and their production process is presented in this paper. With a focus on combined die forming, such as stamping and hydroforming, which is the most promising method for the mass manufacture of complex curve-shaped FML components, several other forming technologies are also discussed in depth. Afterward, the FMLs’ forming limitations and challenges, which have been observed in previous research, are also mentioned thoroughly. The defect and deformation modes that can develop during the forming processes of FMLs are addressed. Furthermore, considering all the relevant factors, the future scope of study and development has also been evaluated.
... Hybrid components provide a combination of the advantages of the constituent materials, with higher mechanical properties than monolithic metals or common fibre-reinforced laminates [7]. Based on previous studies, some advantages of fibre metal composites include higher fatigue resistance, impact resistance, fracture toughness, and energy-absorbing capacity, and a lower density, and weight [2,5,19]. A hybrid composite can be manufactured by bonding the composite plies to metal plies. ...
Carbon fibre–reinforced polymers (CFRP) are increasingly utilised as materials within hybrid components in combination with plastics and metals. Although hybrid components provide a combination of advantages from the constituent materials, there are some challenges for the manufacture of high-quality hybrid components, including weak interface bonding between the constituent materials. This research focuses on utilising additive manufacturing (AM) technology to control an aluminium substrate's surface features to enhance interfacial bonding with a CFRP laminate. For this purpose, different surface structures were designed and manufactured using laser powder bed fusion (LPBF) technology to understand the influence of surface geometry and roughness on the interface. A lattice structure with a unit cell size of 3 × 3 × 1.5 mm was manufactured to create a substrate surface with porosity. A second substrate surface was designed with the same lattice structure; however, the voids were filled to present an equivalent surface topology (EST), excluding porosity. This comparison provides an understanding of the influence of the porosity of the substrate surface on interfacial bonding strength. Interfacial bonding between the aluminium substrates and a CFRP laminate was assessed using short beam strength (SBS) and flatwise tensile tests. The results from the SBS testing indicated a 3D-printed substrate with random surface roughness increased the interlaminar shear strength of the hybrid component by almost 200% compared to a hybrid laminate with non-printed substrate. The results from flatwise tensile tests illustrated that the out-of-plane bonding strength can also be improved significantly (almost 100%).
... The typical straightforward design approach in aerospace industry of the last 30 years is to select, combine and join different materials with the aim of optimizing mass, manufacturing performance and operation phase [1]. Especially, carbon fiber-reinforced polymers have succeeded to become the pioneer structural material in the aviation industry, as they combine remarkably lightweight and strength properties [2]. ...
We consider recycling as a complex, non-mechanical function during the design phase. We investigate the impact of substituting pristine with recycled fibers on the main structural function of a component by applying the function-oriented spiral development approach. The integration of the function is defined and included at the requirements and the design phase. Here, the recycling-as-a-function approach aims to design by meeting the recycling criteria, while considering its impact on the global stiffness and on the efforts for typical loading conditions of a hat-stiffener with skin.
... In 1978, a new composite material was fabricated by bonding unidirectional aramid fibers to aluminum alloy in Delft University of Technology [6], which was known as ARALL. By comparing with aluminum alloy, ARALL exhibits higher strength, better anti-fatigue, and anti-impact performance and was applied to lower wing skin panels of the former Fokker 27 aircraft and cargo doors of the Boeing C-17 [7]. ...
Fascinating advantages (e.g., lightweight and superior performances combined with ductility and strength) of metal-FRP (fiber reinforced polymer) hybrid components attract increasing attentions of engineers and scientists from aviation and automotive industries. Forming and joining are currently two main technical approaches to fabricate metal-FRP hybrid components. However, it is challenging to fabricate metal-FRP hybrid components due to the fact that the physicochemical properties of metal and FRP are quite different. This work aims to comprehensively review existing fabrication processes of metal-FRP hybrid components and involved surface treatment methods in literature, where potential applications and key issues of each process are also pointed out. Joining processes, including adhesive bonding, riveting, and welding, are widely used to join pre-formed metal and FRP parts, and are of high precision and consistency. Nevertheless, due to the fact that joining processes are accompanied by high cost, long cycle time and potential damages to FRP in riveting and welding etc., forming processes (classified into forming of metal-FRP hybrid laminates, co-curing forming of metal and FRP prepreg sheets, forming prepreg to metal part followed by co-curing) have been increasingly developed to fabricate metal-FRP hybrid components with high efficiency and flexibility. Metal-FRP interfacial bonding plays a critical role in the mechanical performance of metal-FRP hybrid components fabricated by nearly all processes (except riveting), since interfacial debonding between metal and FRP breaks their stress transferring path and dissolves the reinforcement of FRP to metal. Therefore, surface treatments are generally applied to enhancing interfacial bonding between metal and FRP. In comparison with mechanical and chemical surface treatment methods, energy methods (e.g., laser) are of wider application, higher effectiveness, and more friendly to environment. This review provides a reference for the fabrication of metal-FRP hybrid components.
Graphical abstract
... GLARE based on S-2 glass fibre/epoxy prepreg and aluminium alloys is currently being used for the primary aircraft structures such as the fuselage and wing skin materials. Similar to GLARE, ARALL finds its application in aerospace industries for the wing skin panels and the cargo door (Alderliesten, 2009). In contrast, CARALL is generally used as the impact absorber for helicopter struts and aircraft seats (Vlot & Gunnink, 2001). ...
Composite materials have been subjected to permanent interest among engineers, scientists and research communities due to their various promising characteristics compared to metallic alloys. The technological evolution in the composite field has led to the development of advanced composite materials, namely, fibre-metal laminates (FMLs). FMLs are those sandwich materials that are formed by the coalescence of composites and metallic alloys. Through the years, FMLs such as glass laminate aluminium-reinforced epoxy (GLARE) have been employed as the fuselage structural materials in aerospace industries due to their excellent fatigue crack resistance. However, it has been identified that FMLs also encompass superior impact properties. This chapter intends to give a comprehensive overview of the FMLs in aerospace sectors, including the classification of standardised FMLs and manufacturing techniques. The various surface pre-treatment methods of FMLs are discussed and explained. Finally, the potential applications of natural/synthetic fibre-based FMLs in aerospace sectors are presented.
