Glass Reinforced Aluminum Laminates Research Articles

Vibration Characteristics of FML Cylindrical Shell Bonded by Thin Piezoelectric Actuator and Sensor Layer with and Without Fluid–Structure Interaction Resting on Pasternak Elastic Foundation

The present study investigates the vibration analysis of cylindrical shells composed of fiber metal laminate (FML) with embedded piezoelectric layers, undergoing fluid-structure interaction (FSI) and resting on a Pasternak elastic foundation based on the principles of three-dimensional elasticity theory. Using the state space approach, the equations of motion were derived under simply supported boundary conditions. The natural frequencies of the FML cylindrical shell, accounting for the presence of a moving fluid, were computed by solving the eigenfrequency equations. The study examined the influence of various parameters, including boundary conditions, length-to-radius ratio, fluid type, fluid velocity, circumferential wave number, and radius-to-thickness ratio, on glass-reinforced aluminum laminate (GLARE), aramid-reinforced aluminum laminate (ARALL), and carbon-reinforced aluminum laminate (CARALL). A constant composite/metal volume ratio was assumed. The results obtained were validated by comparing with natural frequency values from the existing literature, confirming the agreement and convergence with previous studies. The results confirm that the highest natural frequency values are assigned to the CARALL, ARALL and GRALE structures in descending order. Furthermore, an increase in fluid flow velocity through the cylindrical shell correlates with a reduction in natural frequency.

Analysis of the thermal expansion coefficient of glass- and carbon-fibre-reinforced composites

With the development of manufacturing processes, an increase in the importance of metal-fibre composites in materials engineering is observed. These are materials consisting of appropriately arranged layers of metal and various types of fibres. The very wide use of composite materials in the construction of machine and equipment components means they are often exposed to work in variable temperature conditions. The aim of this article was analysis of the thermal expansion of typical composites: carbon fibre-reinforced polymer, glass fibre-reinforced polymer, glass-reinforced aluminium laminate and carbon-fibre reinforced aluminium laminate. EN AW-6060 aluminium alloy was used as the reference material. The aim of the dilatometric tests was to determine the coefficient of thermal expansion and the dimensional stability of composite materials at elevated temperatures up to 100 °C. The EN AW-6060 aluminium alloy was characterized by the highest linear expansion coefficient (20.27×10−6 1/K). Composites containing glass fibres were characterized by the lowest positive linear thermal expansion coefficient. Among the composite materials tested, CARALLs exhibit the lowest thermal expansion coefficient.

Mechanical properties and formability behavior of glass-reinforced aluminum laminate, developed by semi-cured process

Mechanical properties and formability behavior of glass-reinforced aluminum laminate, developed by semi-cured process

Damage to inverse hybrid laminate structures: an analysis of shear strength test

Abstract Hybrid laminates with continuous fiber reinforcement, such as glass reinforced aluminium laminate (GLARE), aramid reinforced aluminum laminate (ARALL), or carbon reinforced aluminum laminate (CARALL), have been developed to increase the lightweight potential and fatigue resistance applied for aircraft structures. However, the use of thermosetting matrices imposes material limitations regarding recycling, malleability, and manufacturing-cycle times. The inverse hybrid laminate approach is based on a continuous fiber-reinforced thermoplastic matrix, in which a metal insert is integrated. For efficient manufacturing of the novel composites in high-volume production processes, conventional sheet metal–forming methods have been applied. It helped to reduce the cycle times and the costs of the forming equipment compared to currently used hybrid laminate-processing technologies. The present study analyzes the damage to the inverse hybrid laminate structures resulting from the interlaminar shear strength test. The tests were performed for eight laminate material configurations, which differed by the type and directions of the reinforced glass and carbon fibers in the polyamide matrix and the number of the fiber-reinforced polymer (FRP) layers in the laminates. Industrial computed tomography and scanning electron microscopy were used for analysis. Observed damages, including fiber–matrix debonding, fiber breakages, matrix fractures, interfacial debonding, and delamination in selected areas of the material, are strictly dependent on the laminate configurations. FRP layers reinforced by fibers perpendicular to the bending axis presented better resistance against fractures of the matrix, but their adhesion to the aluminum inserts was lower than in layers reinforced by fibers parallel to the bending axis.

Damping contribution of the glass reinforced aluminum laminates epoxy to the aluminum based-sandwich structures

Despite many potential use of aluminum sandwiches in advanced industries, their poor performance in damping and sound transmission demands new challenges for improvement. This study aims to improve dynamic performance of these sandwiches using hybrid face sheets in the form of Glass Laminate Aluminum Reinforced Epoxy (GLARE). While parameters related to the aluminum honeycomb core were kept constant, the effects of different fiber orientations of the GLARE on the fundamental natural frequency, equivalent flexural modulus, and especially damping values were investigated. The dynamic values of the structures have been measured using a specially designed non-contact vibrating beam test with free-free end conditions. A comparison of the sandwiches with the GLARE and with bare aluminum face sheets has also been made to find out their differences in the dynamic performance. The experimental results were compared to those from a numerical modal analysis via the Altair Hyperworks 2019 Software. The results have shown that the maximum equivalent modulus is obtained from the specimen with the unidirectional (0°) fibers, and the minimum value is from that with the 90° ones. But the opposite is the case if their Specific Damping Capacity values are compared. The values of the specimens with 0°/90° and 0°/45° fibers are on moderate levels. Considerable increments between 54% and 172% are found in the damping values of the specimens with GLAREs, compared to those with the bare aluminum face sheets. The results from the experimental and numerical works have been found in a good agreement.

Creep Age Forming of Fiber Metal Laminates: Effects of Process Time and Temperature and Stacking Sequence of Core Material.

Fiber metal laminates (FMLs) are a type of hybrid materials interlacing composites and metals. In the present work, FMLs with aluminum alloy 6061 as the skin and E-glass fiber-reinforced polypropylene (PP) as the core material are fabricated and formed by the creep age forming (CAF) process. The effects of time and temperature as the process parameters and thickness and stacking sequences of composites layers as the FML parameters are evaluated on the springback of glass-reinforced aluminum laminates (GLARE) FMLs. After the CAF process, the springback of creep age-formed FMLs is calculated. The results show that the FMLs can be successfully formed with the CAF process by considering appropriate time and temperature. In addition, the stacking sequence of composite layers can affect the springback behavior of FMLs significantly.

Interlaminar shear strength (ILSS) characterization of fiber metal laminates (FMLs) manufactured through VARTM process

The aircraft industry is always seeking materials with excellent mechanical properties and good strength to weight ratio. Fiber metal laminates (FMLs) are the emerging class of hybrid composite materials consisting of fiber-reinforced polymers (FRP) plies and metal sheets. Aircraft parts are subjected to different types of mechanical loading during operation. Combining the properties of FRPs and metals provides excellent resistance to impact as well as improves the fatigue performance of the aircraft. In this study, aluminum 7075-T6 sheets were used to fabricate FMLs with varying fiber reinforcements. These sheets were treated with different surface and chemical treatment processes. The short beam shear test is utilized in this work that gives practical information on interlaminar shear strength (ILSS) and it can also be employed in real design applications. The results indicated that the ILSS of carbon fiber reinforced aluminum laminates (CARALL) was higher than glass-reinforced aluminum laminates (GLARE) and aramid-reinforced aluminum laminates (ARALL) at all displacement rates. The reason for the higher ILSS of CARALL is due to the stifness of carbon fiber and the strong adhesion of carbon with aluminum metal. However, ILSS for all three types of FMLs did not change significantly which shows that it is independent of displacement rates.

Synthesis Effect of Nano-fillers on the Damage Resistance of GLARE

GLARE (glass reinforced aluminum laminate) is applied in the aerospace and in vehicle structures. Degradation and failure in these applications commonly initiate at the location of cracks and joints. To improve the damage resistance of GLARE against stress concentration presented in the vicinity of the hole and around the crack tip, GLARE has been filled with different types of nano-fillers. Aluminum (Al) skin layers were treated to achieve good bonding between Al-sheets and nanocomposite laminate. Results showed that a maximum enhancement of 26.3 %, 35 %, and 22.6 % in bearing strength, inplane shear strength, and fracture toughness, respectively, was attained by the inclusion of silica nano-filler to GLARE. Adding alumina to GLARE also causes an enhancement in these properties in a good manner. An improvement of 21.6 %, 28.7 %, and 20.7 % was obtained in bearing strength, in-plane shear strength, and fracture toughness, respectively, as compared to pristine GLARE. Other nano-modified GLARE laminates showed an improvement in bearing strength, in-plane shear strength, and fracture toughness as compared to pristine GLARE. However, adding nanoclay has an adverse effect. The elemental map showed a uniform distribution of alumina nano-filler into the epoxy matrix, which reveals the enhancement in the mechanical properties.

Comparison between the frequencies of FML and composite cylindrical shells using beam modal function model

A comparison between the vibration of fiber-metal laminate (FML) and composite cylindrical shells has been studied in this manuscript. Love’s first approximation shell theory has been applied to obtain Strain-displacement relations. In addition, beam modal function model has been used to analyze the cylindrical shell with different boundary conditions. In this manuscript, the frequencies of FML and composite cylindrical shells have been compared to each other for different materials, lay-ups, boundary conditions, axial and circumferential wave numbers. The most commercially available FMLs are CARALL (carbon reinforced aluminium laminate), and GLARE (glass reinforced aluminium laminate), which are studied in this research. The results showed although the frequencies of carbon/epoxy are greater than glass/epoxy for all of the n, this process is not constant for FML. Also, with increasing the n, the frequencies of FML cylindrical shells are converged more faster than the composite one. Moreover, the frequencies of both boundary conditions are converged with increasing n for both FML and composite cylindrical shells.

Improvement and Properties of Fiber Metal Laminates Used in Aircraft Wing by Using Graphite-Polyester

The main objective of this study is to reduce weight and to improve the mechanical properties of aircraft wing by using Hybrid materials known as fiber metal laminates (FMLs). They are new age of engineering materials, which consist of metal layers reinforced with fibers emerged by matrix phase. In this study, seven layers were used to produce the FMLs, which are consist of aluminum alloy2024-T3 reinforced by carbon and glass fibers bonded with using blend of graphite-polyester as adhesion. The Carbon Glass Reinforced Aluminum Laminates (CAGRALLs) is used as FMLs. The results show that the CAGRALLs give better in mechanical properties because of increasing in tensile strength, yield strength, , elastic modulus, elongation at fracture, flexural modulus and impact toughness except flexural strength by comparing with FMLs by using commercial epoxy as adhesion for other researchers. The increasing in layers is led to weaken adhesion force between layers of FMLs that led to decrease almost mechanical properties. The FMLs has good mechanial properties by using carbon and glass fiber by comparing with carbon and jute fibers. The CAGRALLs have the higher numbers of cycles at failure under cyclic loadings than Aramid Reinforced Aluminum Laminates (ARALLs). The CAGRALLs have the lower density by comparing with aluminum alloy 2024-T3 and steel that used in manufacturing of aircraft wing.

Development and Properties of Fiber Metal Laminate Used in Aircraft Wing by Using Epoxy-Novolac

The purpose of this study is to reduce weight and to improve the mechanical properties of aircraft wing by using fiber metal laminates (FMLs). They are layered materials based on stacked arrangements of aluminum alloy layers and fiber reinforced plastic (FRP) layers. They have benefits over both aluminum and fiber reinforced composites. In this study, seven layers consist of 2024-T3 aluminum alloy reinforced by carbon and glass fibers bonded using blend of epoxy-novolac as adhesion, were used to produce the Carbon Glass Reinforced Aluminum Laminates (CAGRALLs) as FMLs. The mechanical properties (tensile, flexural, impact and fatigue) of CAGRALLs are experimentally investigated. The results revealed that CAGRALLs give good mechanical properties because of increasing in tensile strength, yield strength, elastic modulus, elongation at fracture, flexural modulus and impact toughness except flexural strength comparing than Carbon with Glass Reinforced Aluminum (CACAGRALLs) and Carbon with Jute Reinforced Aluminum (CAJURALLs) using epoxy. The increasing in layers led to weaken adhesion between layers of FMLs that led to decrease almost mechanical properties. The fabricated CAGRALLs showed higher fatigue strength than Aramid Reinforced Aluminum Laminates (ARALL) and lower density than aluminum alloy 2024-T3 and steel that used in manufacturing of aircraft wing.

Improving the Mechanical Properties of Fiber Metal Laminate Composite Used in Aircraft Wing

The purpose of this study is to reduce weight and improve the mechanical properties of aircraft wing using Hybrid materials known as fiber metal laminates (FMLs). In this study, seven layers were used to produce the FMLs that consist of aluminum alloy2024-T3 reinforced by carbon and glass fibers bonded with blend of epoxy-resole. The Carbon Glass Reinforced Aluminum Laminates (CAGRALLs) was used as FMLs. The results showed that The CAGRALLs gave good mechanical properties because of increasing in tensile strength, elongation at fracture and impact toughness except flexural strength by comparing with other FMLs using commercial epoxy. The increasing in layers led to weaken adhesion force between layers of FMLs caused decreasing almost mechanical properties. The FMLs has good mechanical properties by using carbon and glass fibers by comparing with carbon and jute fibers. The CAGRALLs have higher numbers of cycles at failure under cyclic loadings than Aramid Reinforced Aluminum Laminates (ARALLs). The CAGRALLs have lower density by comparing with aluminum alloy 2024-T3 that used in manufacturing of aircraft wing.

Interlaminar fracture toughness of GLARE laminates based on asymmetric double cantilever beam (ADCB)

Interlaminar fracture toughness of GLARE laminates (Glass reinforced aluminum laminates) with different fiber orientation, such as cross-plies/0° and unidirectional-plies/0°, were investigated by the combination of experiments and finite element analyses. The Beam Theory and Fracture mechanics theory were used to calculate the proportion of Mode I and Mode II and further to predict the interlaminar fracture toughness of GLARE laminates. Also, the effect of loading rates (1 mm/min, 5 mm/min and 10 mm/min) on the interlaminar fracture properties was studied. Finite element analyses were carried out based on cohesive zone model (CZM) to numerically simulate delamination propagation by using the above experimental GIC. The results showed that the interlaminar fracture toughness in cross-plies/0° laminates(0.248 kJ/m2) was higher than that in unidirectional-plies/0° laminates(0.093 kJ/m2), and the interlaminar fracture toughness was increased with the growth of the loading rates. The numerical results agreed well with the experiments at crack initiation and furthermore supported the absence of mode mixity. The deviation between theoretical calculations and experimental results gradually increased with the crack propagation. Meanwhile, they were conformed to the linear function for unidirectional-plies/0° and cross-plies/0° laminates, respectively. Besides, the experimental data are highly consistent with both theoretical calculation and numerical simulation results.

Investigation into Composites Property Effect on the Forming Limits of Multi-Layer Hybrid Sheets Using Hydroforming Technology

Fiber-metal laminates (FMLs) such as Kevlar reinforced aluminum laminate (ARALL), Carbon reinforced aluminum laminate (CARALL), and Glass reinforced aluminum laminate (GLARE) offer great potential for weight reduction applications in automobile and aerospace construction. In order to investigate the feasibility for utilizing such materials in the form of laminates, sheet hydroforming technology are studied under the condition of uniform blank holder force for three-layered aluminum and aluminum-composite laminates using orthogonal carbon and Kevlar as well as glass fiber in the middle. The experimental results validate the finite element results and they exhibited that the forming limit of glass fiber in the middle is the highest among the studied materials, while carbon fiber material performs the worst. Furthermore, the crack modes are different for the three kinds of fiber materials investigated in the research. This study provides fundamental guidance for the selection of multi-layer sheet materials in the future manufacturing field.

Investigation into the Fiber Orientation Effect on the Formability of GLARE Materials in the Stamp Forming Process

Glass-reinforced aluminum laminate (GLARE) is a new class of fiber metal laminates (FMLs) which has the advantages such as high tensile strength, outstanding fatigue, impact resistance, and excellent corrosion properties. GLARE has been extensively applied in advanced aerospace and automobile industries. However, the deformation behavior of the glass fiber during forming must be studied to the benefits of the good-quality part we form. In this research, we focus on the effect of fiber layer orientation on the GLARE laminate formability in stamp forming process. Experimental and numerical analysis of stamping a hemisphere part in different fiber orientation is investigated. The results indicate that unidirectional and multi-directional fiber in the middle layer make a significant effect on the thinning and also surface forming quality of the three layer sheet. Furthermore, the stress-strain distribution of the aluminum alloy and the unique anisotropic property of the fiber layer exhibit that fiber layer orientation can also affect the forming depths as well as the fracture modes of the laminate. According to the obtained results, it is revealed that multi-directional fiber layers are a good alternative compared to the unidirectional fibers especially when a better formability is the purpose.

A Review: Fiber Metal Laminates (FML’s) - Manufacturing, Test methods and Numerical modeling

Weight reduction of components is the main aim of different industrial sectors. This leads to increasing application areas of fiber composites for primary structural components. Aiming this objective, a new lightweight Fiber/Metal Laminate (FML) has been developed. Fiber metal laminate is one such material which is being widely investigated for its performance compared to existing material.. The most commercially available fiber metal laminates (FML’s) are ARALL (Aramid Reinforced Aluminium Laminate), based on aramid fibers, GLARE (Glass Reinforced Aluminium Laminate), based on high strength glass fibers and CARALL (Carbon Reinforced Aluminium Laminate), based on carbon fibers. The mechanical properties of FML show advantages over the properties of both aluminium alloys and composite materials individual. This paper reviews relevant literature which deals with different manufacturing techniques for FML’s with excellent properties under tensile, flexure and impact conditions. It also reviewed recent modeling techniques on FML’s. Modeling of tensile, flexure and impacts behavior on fiber metal laminates requires understanding the bonding between the metal and composite layer. Further research is necessary in the assessment of mechanical performance of complex structures in real world conditions.

Experimental investigation on impact performances of GLARE laminates

An experimental investigation was carried out on the damage resistance to a concentrated quasi-static indentation force and low-velocity impact of four kinds of glass-reinforced aluminum laminates (GLARE for short). Compared with the experimental results of the CFRP (Carbon Fiber Reinforced Plastics) laminates, the performance of GLARE was determined. By means of concentrated quasi-static indentation force test, typical force–displacement response, the maximum contact force and dent depth were received. Through drop-weight low-velocity impact tests, impact force histories, indentation depths (through a new method) and dissipated energy were obtained. The test results show that the force–displacement response of GLARE 4 laminates under the concentrated quasi-static indentation force has an obvious flat roof and the failure is instantaneous, which are different from CFRP laminates. The indention will be visible once the impact happens. C-scan results find that there is no delamination besides the impact area after both the concentrated quasi-static indentation and low-velocity impact. The dissipated energy approximately equals the impact energy.

Impact Behaviour of GLAREs with MWCNT Modified Epoxy Resins

In this study, GLAREs (Glass Reinforced Aluminum Laminates) with 3/2 configuration were fabricated in-house with multi-walled carbon nanotubes (MWCNTs) modified epoxy resins. Uniform dispersion of MWCNTs in epoxy resin was achieved via a two-step dispersion method with concentration up to 2.0 wt%. The influence of MWCNTs on the flexural property and the impact performance of GLAREs was investigated through the three-point bending and drop weight Dynatup impact testings, respectively. The incorporation of MWCNTs into epoxy evidently improved the flexural strength and modulus. In comparison with pure epoxy bonded GLARE, the modified GLAREs generally showed improvement of impact resistance. The improvement was more obvious at low concentration of MWCNT due to better dispersion of nanotubes in the resin and reasonable wettability of glass fibres and aluminium to the modified resin. Diversified failure mechanisms including plastic deformation and rupture of metal layers, breakage of fibres and matrix, delamination between composite and metal layers, and delamination between composite plies were observed. In addition, debonding, pull-out, and bridging effects of carbon nanotubes were observed, which proved the contribution of MWCNTs to the improved impact resistance of the modified GLAREs.

Bearing strength of commingled boron/glass fiber reinforced aluminum laminates

The bearing properties of recently developed hybrid fiber/metal laminates, or COmmingled Boron/glass fiber Reinforced Aluminum laminates (COBRA), are investigated in this study. The bolt-type bearing tests on GLass REinforced aluminum laminates (GLARE), non-commingled hybrid boron/glass/aluminum fiber/metal laminates (HFML) and COBRA were carried out as a function of e/D ratio, metal volume fraction, fiber volume fraction, and fiber orientation. Experimental results show that with the same joint geometry and metal volume fraction, the commingling of boron fibers improves the bearing strength of fiber/metal laminates. Observations show the boron/glass fiber prepreg, transverse to the loading direction, results in a bearing mechanism that effectively increases the bearing strength. The bearing strength of COBRA with longitudinal fibers is lower than that with transverse fibers due to the fact that shearout failure takes place before maximum bearing strength is reached. The experimental results show that, with only either transverse fiber orientation or longitudinal fiber orientation, COBRA with 18% boron fiber volume fraction possesses a higher bearing strength when compared to HFML with 6% boron fiber volume fraction. In addition to the properties in COBRA with parallel-plies commingled prepreg, the bearing properties of various COBRA with [0°/90°] and [0°/90°/90°/0°] cross-ply commingled prepregs are also discussed.

An experimental study of the fibre orientation and laminate sequencing effects on mechanical properties of Glare

Glare (glass-reinforced aluminium laminate) is a new class of fibre metal laminates and has been selected as a suitable substitute for metal structures, especially in aerospace structural applications. It is a hybrid composite consisting of alternating thin layers of aluminium sheets and glass-reinforced epoxy prepreg. In this study, the mechanical properties of this attractive material including impact, tensile, and bending strength and the effect of fibre orientation on them are investigated. Test results show that glass fibre sheet with zero orientation in laminate considerably improves the mechanical properties. Comparing similar specimens with different layer arrangement shows the importance of fibre orientation and its arrangement on the mechanical properties. Aluminium layers have higher role on these properties. Moreover, the difference of orientations for two glass layers in the laminate helps better resistance against various loads, and these types of specimens present more suitable performance. Finally, statistical analysis of data shows the effect of the independent variables and interactions with their relative significance on the mechanical behaviour.