Properties Of Fiber Metal Laminates Research Articles

Effect of carbon fibres on the static and fatigue mechanical properties of fibre metal laminates

AbstractIt is crucial to understand the characteristic fatigue crack initiation and its growth mechanisms, as well as the relationship between the mechanical properties and the fatigue damage evolution in fibre metal laminates (FMLs). Two types of FML were studied in this work: a polyacrylonitrile‐based carbon fibre epoxy matrix composite sandwiched by Ti‐6Al‐4V (Ti‐alloy) sheets (IMS60‐Ti) and a pitch‐based carbon fibre epoxy matrix composite sandwiched by Ti‐alloy sheets (K13D‐Ti). The static and fatigue mechanical properties of IMS60‐Ti and K13D‐Ti were investigated. The increased failure strain of the FML was greater than that of carbon fibre‐reinforced polymer (CFRP) matrix composites. The fatigue life of IMS60‐Ti was much longer than that of K13D‐Ti. The fatigue damage process in IMS60‐Ti was related to the fatigue creep behaviour of the Ti‐alloy face sheet and mode II cracking at the CFRP/Ti‐alloy interface, and the damage in K13D‐Ti was related to the K13D CFRP laminate.

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.

Woven and Unidirectional Glass-Aluminium Fibre Metal Laminates (FML): Quasi-Static Indentation Properties

In this study, the effect of fibre arrangement and aluminium thin sheet on quasi-static indentation properties of fibre metal laminates (FML) based on glass fibre reinforced polymer composite (GFRP) and Aluminium (Al) was investigated. The woven and unidirectional types of glass fibre prepreg and 0.5mm, 1mm and 2 mm of Al sheet thickness were used in the fabrication of Glass fibre-Al FML systems. The GFRP and FML samples were fabricated using a combination of hand lay–up and hot press methods. Quasi-static indentation test was performed according to ASTM D6264. The results showed that the woven type of GFRP and FMLs exhibited the highest energy absorption as compared to those of unidirectional of GFRP and FMLs. It was observed that for the woven type specimens of GFRP and FMLs, the matrix cracking and fibre breakage/delamination triggered in weft and wrap direction, which showed diamond-shaped damage. While the damage surface of unidirectional GFRP and FMLs showed single axis orientation damage type that lateral with the direction of the fibre namely fibre splitting mechanism. The FML2 systems for both woven and unidirectional, that used 2mm thickness of Al, demonstrated the highest energy absorption when compared to the other FML systems. This shows that FMLs absorbed more energy when thicker Al sheet was used.

Influence of thermal aging on mechanical properties of fiber metal laminates hybridized with nanoclay

One of the main problems of polymer matrix composites in critical applications is their high sensitivity to thermal conditions. Therefore, an experimental study was performed to evaluate the thermal durability of traditional plain weave E-glass/epoxy as well as fiber metal laminates as a possible alternative in this case. In this way, both the laminate types were exposed to thermal aging at 130 ℃ for five weeks, and the plausible degradation is investigated through weight loss analyzes and mechanical testing. The possibility of improving the mechanical behavior of the studied laminates by nanoclay was also studied. The results demonstrated that the weight loss and mechanical degradation were more pronounced in thermally aged plain weave E-glass/epoxy composites. The results also indicated that nanoclay could enhance the mechanical properties of both laminates. On the basis of the results, the shielding role of aluminum layers and thermal resistance of nanoclay can synergistically offer a novel class of nano-fiber metal laminates with high thermal tolerance in thermo-oxidative conditions.

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.

Effect of prepreg gaps and overlaps on mechanical properties of fibre metal laminates

During the automated manufacturing of fibre reinforced laminates, defects can be produced. Gaps and overlaps between adjacent prepreg layers can be produced in composites during the tape-layup process. However, the topic is not yet studied for hybrid materials, in which metal sheets and thin prepreg layers lead to different effects due to the defects than in full composites. Here, the effect of gaps and overlaps on the mechanical properties of the Fibre metal laminates (FML) is evaluated. Specimens are manufactured with a specified width of gaps/overlaps and the mechanical performance of the panels is evaluated by some selected mechanical tests. Gaps show to have a considerable effect on the mechanical performance of FML. Compression strength of samples with overlaps was rather increased. Discussions are presented on the influence on each mechanical property according to the severity of the defect (gaps/overlap) and the failure mode(s) under consideration.

Effect of salt water conditioning on novel fiber metal laminates for marine applications

One of the issues with the widespread use of polymer matrix composites in marine applications is their high susceptibility to environmental degradation, particularly hygrothermal conditions. Therefore, the present research intends to contribute to the better protection of the marine polymer matrix composites through the introduction of a newly developed fiber metal laminate for marine applications. This type of fiber metal laminate consists of a marine aluminum alloy of 5083 alternating with glass fiber reinforced epoxy composite layers. In order to evaluate the characterization of the environmental durability of this novel material, the specimens made of fiber metal laminates as well as commercial woven glass–epoxy composites were exposed to hygrothermal aging and hygrothermal cycling in boiling salt water. Then, to study the structural degradation caused by exposure to salt water, the mechanical properties of fiber metal laminate and woven glass–epoxy specimens under three-point bending and impact loading were evaluated. Results show that exposure to the saline environment generally decreased the flexural strength of woven glass–epoxy and fiber metal laminate specimens, whereas a smaller deterioration in flexural stiffness of both laminate types was found. Moreover, it was observed that the hygrothermal conditioning in salt water did not affect significantly the impact properties of both the fiber metal laminate and woven glass–epoxy specimens as compared to the flexural properties.

Effects of various aluminum surface treatments on the basalt fiber metal laminates interlaminar adhesion

Fiber metal laminates (FMLs) are a new class of advanced materials consisting of metal and fiber reinforced polymer layers. Surface treatment of the metal layers can have significant effects on the interlaminar properties and thus the overall properties of FMLs. The aim of this study was to apply four different surface treatment methods on the aluminum layers and investigate their effects on the flexural behavior of a FML made up of Al2024, basalt fibers and epoxy Epon 828. To study the surface morphologies and fracture surface of samples, scanning electron microscopy (SEM), optical microscopy (OM) and profilometry were utilized. Results of the four methods applied, showed that the mechanical abrasion and alkaline etching treatments were not found suitable for enhancing the flexural properties due to weak interfacial adhesive bonding. OM images revealed that the adhesive failure was the failure type of mechanical abrasion and alkaline treated samples. On the other hand, Forest Products Laboratory etching (FPL-etching) and anodizing treatments caused significant improvements in the flexural properties. The improvements are attributed to the formation of surface oxide layers containing microscale pits. The microscale pits provided appropriate sites for the penetration of the polymer resin, which caused strong interfacial bonding by mechanical interlocking mechanism. Moreover, SEM and OM images indicated that the main failure type of FPL-etching and anodized samples was the cohesive failure.

The effects of stacking sequence and thermal cycling on the flexural properties of laminate composites of aluminium-epoxy/basalt-glass fibres

The current study aimed at investigating the effects of different stacking sequences and thermal cycling on the flexural properties of fibre metal laminates (FMLs). FMLs were composed of two aluminium alloy 2024-T3 sheets and epoxy polymer-matrix composites that have four layers of basalt and/or glass fibres with five different stacking sequences. For FML samples the thermal cycle time was about 6 min for temperature cycles from 25 °C to 115 °C. Flexural properties of samples evaluated after 55 thermal cycles and compared to non-exposed samples. Surface modification of aluminium performed by electrochemical treatment (anodizing) method and aluminium surfaces have been examined by scanning electron microscopy (SEM). Also, the flexural failure mechanisms investigated by the optical microscope study of fractured surfaces. SEM images indicated that the porosity of the aluminium surface increased after anodizing process. The findings of the present study showed that flexural modulus were maximum for basalt fibres based FML, minimum for glass fibres based FML while basalt/glass fibres based FML lies between them. Due to change in the failure mechanism of basalt/glass fibres based FMLs that have glass fibres at outer layer of the polymer composite, the flexural strength of this FML is lower than glass and basalt fibres based FML. After thermal cycling, due to the good thermal properties of basalt fibres, flexural properties of basalt fibres based FML structures decreased less than other composites.

The comparison of effects of hygrothermal conditioning on mechanical properties of fibre metal laminates and fibre reinforced polymers

Abstract The purpose of this article is to present the effects of elevated temperature and moisture conditioning of Fibre Metal Laminates and conventional Fibre Reinforced Plastics on some mechanical properties of these materials. The study was carried out by long-term conditioning of tested materials at elevated temperature (60 °C) and humidity (99% RH). The equilibrium of moisture absorption for both Fibre Metal Laminates and Fibre Reinforced Plastics was determined. The mechanical properties have been investigated by tensile strength and ILSS tests. The obtained results show that moisture absorption of Fibre Metal Laminates is significantly lower than that of a Fibre Reinforced Polymer composite. After conditioning, the loss of strength properties has been identified. The tensile strength of FMLs decreases by 1–15% and the ILSS decreases by 9–11%, depending on the configuration. The damage analysis revealed.

Effect of shape memory alloy wires on high-velocity impact response of basalt fiber metal laminates

Fiber metal laminates are commonly used materials in industrial applications due to low density and excellent mechanical properties such as impact resistance. In this study, the effect of shape memory alloy wires on the impact properties of fiber metal laminates is evaluated and discussed. The volume fraction of wires and the pre-strain of wires were selected as the variables of the experiments. The samples were fabricated using hand lay-up method and their behavior was evaluated under high-velocity impact test. Based on the results, a significant change in the amount of absorbed energy was obtained using embedded wires. However, with increasing the volume fraction of wires, the absorbed energy decreases due to the discontinuity in mechanical properties of the specimens. On the other hand, applying pre-strain leads to residual stresses in samples. The observed residual stress in specimens with four embedded wires and 2% pre-strain level shows the most absorbed energy.

An experimental review on the mechanical properties and hygrothermal behaviour of fibre metal laminates

Fibre metal laminates are high strength materials made up of alternating layers of metal alloy and composite materials. Commercially available fibre metal laminates include CARALL, ARALL and GLARE. Other than the commercially available fibre metal laminates, number of researches have been performed with the alternate metal alloys such as stainless steel, Ti, Mg alloys and polymer matrices based on polypropylene, polyimide, polyester, etc. In this study, various factors affecting the mechanical properties of fibre metal laminates have been addressed along with the different types of failure modes observed by various researchers in their experiments. Hygrothermal conditioning which involves the subjection of fibre metal laminates to moisture and temperature (80℃ and 90% humidity as per ASTM standard 5229), their behaviour and influence on mechanical properties has also been reported in this study based on the results from the various researchers.

Effect of adhesive quantity on failure behavior and mechanical properties of fiber metal laminates based on the aluminum–lithium alloy

The effect of adhesive quantity on the failure behavior and mechanical properties of fiber metal laminates based on the aluminum–lithium alloys (NFMLs) was investigated to optimize the manufacture process and further recognize the interface interaction. The NFMLs with different adhesive quantities (0g/m2, 20g/m2, 40g/m2, 60g/m2) were prepared primarily. Then, the influence of adhesive quantity on the interlaminar, tensile, flexural and fatigue properties of NFMLs was studied respectively. Also, the failure behaviors of NFMLs under different loading conditions were revealed. The results indicated that the adhesive layers significantly enhanced the interlaminar properties of the NFMLs within the investigated quantities. Moreover, the reasonable adhesive quantity also greatly improved the mechanical properties of the laminates, while an excessive amount deteriorated the performance. For the different properties, the peak values appeared under different adhesive quantities. Besides, the changing mechanical properties followed with the variation of failure mode. From the engineering perspective, the adhesive quantity of 40g/m2 is optimal to achieve the excellent performance of NFMLs.

잔류응력을 고려한 섬유 금속 적층판의 기계적 물성치 예측에 관한 이론적 연구

Uniaxial tensile tests were conducted to accurately evaluate the in-plane mechanical properties of fiber metal laminates (FMLs). The FMLs in the current study are comprised of a layer of self-reinforced polypropylene (SRPP) sandwiched between two layers of aluminum alloy 5052-H34. The nonlinear tensile behavior of the FMLs under in-plane loading conditions was investigated using both numerical simulations and a theoretical analysis. The numerical simulation was based on finite element modeling using the ABAQUS/Explicit code and the theoretical constitutive model was based on the volume fraction approach using the rule of mixture and a modification of the classical lamination theory, which incorporates the elastic-plastic behavior of the aluminum alloy and the SRPP. The simulations and the model are used to predict the inplane mechanical properties such as stress-strain response and deformation behavior of the FMLs. In addition, a post-stretching process is used to reduce the thermal residual stresses before uniaxial tensile testing of the FMLs. Through comparison of both the numerical simulations and the theoretical analysis with the experimental results, it is concluded that the numerical simulation model and the theoretical approach can describe with sufficient accuracy the actual tensile stress-strain behavior of the FMLs.

Analytical evaluation on uniaxial tensile deformation behavior of fiber metal laminate based on SRPP and its experimental confirmation

Uniaxial tensile tests have been carried out to accurately evaluate the in-plain mechanical properties of fiber metal laminates (FMLs). The FMLs in this paper comprised of a layer of self-reinforced polypropylene (SRPP) sandwiched between two layers of aluminum alloy 5052-H34. In this study, nonlinear tensile and fracture behavior of FMLs under in-plane loading conditions has been investigated with numerical simulations and theoretical analysis. The numerical simulation based on finite element modeling using the ABAQUS/Explicit and the theoretical constitutive model based on the volume fraction approach using the rule of mixture and the modified classical lamination theory, which incorporates the elastic–plastic behavior of the aluminum alloy and SRPP, are used to predict the in-plain mechanical properties such as stress–strain response and deformation behavior of the FMLs. In addition, the pre-stretching process is used to reduce the thermal residual stresses before the uniaxial tensile tests of the FMLs. Through comparing the numerical simulations and the theoretical analysis with the experimental results, it is concluded that the adopted numerical simulation model and the theoretical approach can describe with sufficient accuracy of the actual tensile stress–strain curve.

Improvement of interlaminar fracture toughness of Al/GFRP laminates

In this work, manufacturing techniques and mode-I interlaminar mechanical properties of fibre metal laminates (FML) based on aluminium alloy 2017 and glass fibre reinforced plastic (GFRP) were investigated. Various toughening techniques including patterned surface manufacturing and acid etching on Al, and addition of carbon nanofibres between Al and the GFRP were employed to improve the interlaminar fracture toughness of the Al/GFRP laminates. The double cantilever beam (DCB) tests indicated that the combination of these toughening techniques can significantly enhance the mode-I fracture toughness and resistance of the Al/GFRP laminates. Crack propagation path and fractured surface were observed by confocal laser scanning microscopy to interpret the improvement mechanism of interlaminar mechanical properties.

Fabrication of Structural Composite Accompanied with a Function of Thermoelectric Conversion

The composite accompanied with a function of thermoelectric conversion has been fabricated. It was a fiber metal laminate (FML) consisting of two aluminum alloy sheets of 0.5mm thickness and a central layer of glass fiber reinforced plastic (GFRP). The central layer with a thickness of 1mm included thermoelectric elements of Bi-Te based alloys between glass fibers. The mechanical properties of FML with and without the thermoelectric elements were evaluated by tensile and bending test. The thermomechanical properties were measured by a potentiometer for a module with heated and cooled sides, and plotted a potential as a function of difference in temperature between both sides.

Static Properties of Fibre Metal Laminates

In this article a brief overview of the static properties of Fibre Metal Laminates is given. Starting with the stress-strain relation, an effective calculation tool for uniaxial stress-strain curves is given. The method is valid for all Glare types. The Norris failure model is described in combination with a Metal Volume Fraction approach leading to a useful tool to predict allowable blunt notch strength. The Volume Fraction approach is also useful in the case of the shear yield strength of Fibre Metal Laminates. With the use of the Iosipescu test shear yield properties are measured.

Impact properties of Fibre Metal Laminates

Conventional composites are known for their sensitivity to impact damage. This has slowed their widespread application to thin, damage tolerance-critical primary structures such as fuselage pressure cabin skins. Therefore, impact tests were performed to determine the impact characteristics of Fibre Metal Laminates (GLARE and ARALL). Comparative low and high velocity impact tests were performed on monolithic aluminium, Fibre Metal Laminates, and carbon thermoplastic composites. Additional impact tests were performed on monolithic aluminium and ARALL specimens under tensile loading. The present article characterizes the impact properties of Fibre Metal laminates in comparison with other high-performance aerospace structural materials. The results demonstrate the superior behaviour of GLARE 3 compared with the other materials. The effect of the initial tensile loading on the damage size and the residual strength of ARALL is small for realistic operating stresses ( S < 200 MPa).