Fiber Reinforced Metal Laminates Research Articles

Ballistic Performance of Thermoplastic Fiber-Reinforced Metal Laminates Subjected to Impact Loadings

Ballistic Performance of Thermoplastic Fiber-Reinforced Metal Laminates Subjected to Impact Loadings

Effect of synergistic action of anodising and graphene on the mechanical properties of fibre-reinforced metal laminates

Fibre reinforced metal laminates (FMLs) are widely used in various fields due to their excellent properties. However, the weak interlayer properties of FMLs limit their applications. In this paper, the interlayer properties of FMLs are enhanced by anodising the 2024-T3 aluminium alloy layer in FMLs or by epoxy matrix modification of graphene nanoplatelets (GNPs). The effect of both synergistic impacts on the interlayer properties of most FMLs is investigated. The FMLs were manufactured using the wet lay-up technique using 2024-T3 aluminium alloy, E51 epoxy and EW100 glass fibre. The results showed that the type I fracture toughness, tensile strength, flexural strength, interlayer shear strength and single layer shear strength of FMLs after anodic oxidation treatment were increased by 406.4%, 10.3%, 18.3%, 42.6% and 28.3%, respectively, compared with those of pure FMLs. The type I fracture toughness, tensile strength, flexural strength, interlayer shear strength and single layer shear strength of the GNPs-modified FMLs matrix were increased by 280.4%, 3.7%, 6.8%, 34.5% and 19.1%, respectively, compared with those of pure FMLs. Moreover, the synergistic effect of FMLs indicates that the simultaneous anodic oxidation and GNPs modification of FMLs can lead to the best mechanical properties of FMLs. Microscopic images and schematics illustrate the toughening mechanism of anodising and GNPs, including the enhancement of aluminium/resin interface and fibre/resin interface and the enhancement of resin matrix properties.

Study of Low-Velocity Impact Behavior of Hybrid Fiber-Reinforced Metal Laminates.

In this paper, the low-velocity impact behavior and damage modes of carbon/glass-hybrid fiber-reinforced magnesium alloy laminates (FMLs-H) and pure carbon-fiber-reinforced magnesium alloy laminates (FMLs-C) are investigated using experimental, theoretical modeling, and numerical simulation methods. Low-velocity impact tests were conducted at incident energies of 20 J, 40 J, and 60 J using a drop-weight impact tester, and the load-displacement curves and energy-time curves of the FMLs were recorded and plotted. The results showed that compared with FMLs-C, the stiffness of FMLs-H was slightly reduced, but the peak load and energy absorption were both greatly improved. Finally, a finite element model based on the Abaqus-VUMAT subroutine was developed to simulate the experimental results, and the damage modes of the metal layer, fiber layer, and interlayer were observed and analyzed. The experimental results are in good agreement with the finite element analysis results. The damage mechanisms of two kinds of FMLs under low-velocity impacts are discussed, providing a reference for the design and application of laminates.

Experimental and simulation analysis of the effect of GNPs on the mechanical and interfacial properties of CF/PEEK-Ti fiber metal laminates

In this study, graphene nanoplatelets (GNPs) were used to improve the interfacial and mechanical properties of carbon fibre-reinforced polyetheretherketone-based titanium alloy laminates (CF/PEEK-Ti) and molecular dynamics (MD) simulations were used to investigate the mechanism by which GNPs improve CF/PEEK-Ti, collectively known as fibre reinforced metal laminates (FMLs). In addition, surface anodising of titanium (Ti) sheets was used further to enhance the interfacial bonding properties of the FMLs. The experimental results showed that the flexural and shear strengths of the anodised FMLs were increased by 77.7% and 29.5%, respectively, compared with those of the Ti plates without surface anodisation. Based on this, different levels (0–1.5 wt.%) of GNPs were added to the FMLs matrix, and test results showed that FMLs containing 0.5 wt.% GNPs had the best flexural and shear strengths, 108.9% and 130.8% higher than untreated FMLs without GNPs. In addition, an in-depth microscopic analysis was carried out to understand the enhancement mechanism of GNPs on FMLs. Finally, MD simulations were used to analyze the role and mechanism of GNPs in this system. The results show that the addition of GNPs can increase the interfacial energy of FMLs. In other words, the interfacial mechanical properties of FMLs are improved. The effect of the dispersion of GNPs on the interfacial properties of FMLs was also investigated. The polyetheretherketone (PEEK) matrix could be significantly improved by well-dispersed GNPs. These findings provide insight into designing high-performing composites for various engineering applications.

Debonding Defect Detection by Applying Pulsed, Lock-in and Linear Frequency Modulation Thermal Excitation Methods in the Inspection of Fiber-Reinforced Metal Laminates

Debonding Defect Detection by Applying Pulsed, Lock-in and Linear Frequency Modulation Thermal Excitation Methods in the Inspection of Fiber-Reinforced Metal Laminates

The Experimental Study on the Mechanical Properties of Fiber-Reinforced Metal Laminates Using an Innovative Heat-Solid Integrated Forming Technology

In the forming process of fiber-reinforced metal laminates (FMLs) product, the exploratory compound forming technology, including hot stamping of aluminum alloy and laying process of fiber prepreg which is named HFQ-FMLs was proposed to solve the puzzles such as weak rigidity, low strength and integration deformation with large difficulty, and the feasibility and mechanical properties of the innovative forming process were studied. Firstly, based on the modified metal volume fraction formula, the theoretical values of the mechanical properties of the HFQ-FMLs plates were calculated. Compared with the experimental results, the minimum error is 1%, proving that the HFQ-FMLs technology scheme is feasible. Secondly, three kinds of metal sheets with different heat treatments and specimens by HFQ-FMLs were carried out for the tensile tests, the mechanical properties distributions were demonstrated, and the influence regularity of the strain rate and rolling direction on the stress analysis was considered at the same time. As can be seen from the distribution of yield strength and tensile strength, the yield stress of metal sheets obtained by HFQ-FMLs technology along the 45° is superior to the raw material and can increase by 46% under strain rate = 0.01 s−1. While, because the vacuum thermal curing treatment makes the aluminum alloy happen double aging, the metal sheet strength dropped, and the jointing strength between the metal and fiber prepreg became weak too, which made the strength limit of the new material improve weakly. Thirdly, the fractured style of the FMLs under different conditions was studied qualitatively. It is helpful to achieve the development rule of defects, optimize the craft route, and avoid deformation failure.

Reinforcing interlaminar interface of carbon fiber reinforced metal laminates by graphene

Fiber metal laminas (FMLs) are disadvantaged by weak interlaminar strength limiting their application where dynamic loads are expected. In this study, graphene platelets (GnPs) were employed to strengthen the interlaminar interface in carbon fiber (CF) metal laminates. GnPs within range of 0–1 wt% were added into epoxy resin via ultrasonication. GnPs-based FML samples were prepared by wet lay-up method and tested under flexural loading, short beam shear and single lap shear. The reinforcing mechanism and failure modes were investigated. The results show that 0.5 wt% of GnPs increases the flexural strength and interlaminar shear strength by 39.7% and 53.2%, respectively. In addition, molecular dynamics (MD) simulations concluded that the addition of low content of GnPs increases the elastic modulus of the matrix and improves the resin adsorption on the surface of carbon fiber and Al sheets. The results from both the experimental and MD simulation indicate that adding GnPs can effectively improve the interlaminar mechanical properties of FMLs. In principle, the research method in this paper can be applied to the study of FMLs with other nanomaterials.

Experimental Research on the Thermal-Consolidation Compound Forming of Thermosetting Fiber Metal Laminates Design for Complex Structures with Variable Curvature

The glass fiber-reinforced metal laminates (GLARE) cannot be used to form complex laminate structures in the aerospace industry, because there is substantial variation in the plasticity of the heterogeneous materials. Hence, a compound process for composite materials based on the thermoforming technology for aluminum alloy and fiber-reinforced metal laminates (FMLs)-forming technology was proposed; it contains solution heat treatment, thermoforming, quick cold die quenching, artificial aging integrated process (HFQ), and the thermal consolidation of fiber-reinforced metal laminates, and it is named the HFQ-FMLs forming process. In order to test and judge the effect of the heat treatment on the properties of the materials obtained by the new technology, the pure metal sheet and the three kinds of HFQ-FMLs composite laminates fabricated with the different layup method were assessed with the Vickers hardness test and the Charpy impact test at the same time, and they were labeled #1, #2, #3, #4, respectively. In the Charpy impact test, in order to obtain accurate data, the shape and fixing position of the specimen was optimized so that the gap direction was parallel to the loading direction. After the heat treatment, the properties of the aluminum alloy were improved, the hardness will affect the energy absorption of the laminates, and the relationship between the thickness, hardness and impact properties will be analyzed. The hardness test results are 39.9 HV, 37.5 HV, 37.4 HV, 37.1 HV which indicates the pure metal sheet had the greatest hardness, and the greater the thickness of fiber layer, the lower was the hardness of the HFQ-FMLs composite laminate. The impact resistance of the HFQ-FMLs composite laminates was about two times of the pure metal sheet for the same thickness, and the values are 2.3 J, 4.8 J, 4.8 J, 4.8 J, respectively. In addition, the method of laying the fiber layer had no effect on the impact resistance of the composite laminates. For the novel composite laminates subjected to different cutting processes, the scanning electron microscope (SEM) results for the incision morphology suggest that the water cutting process ensures the structural integrity of the composite laminates after the edges’ and holes’ cutting procedures, and the performance maintains continuity.

Effect of graphene nanosheets on interlaminar mechanical properties of carbon fiber reinforced metal laminates

Aiming at the problem of weak bond strength between CARALL metal/resin/fiber layers, this paper proposes a new preparation method to improve the bond strength between CARALL layers. In this method, Graphene platelets (GnPs) with different mass fractions (0%, 0.1%, 0.3%, 0.5% and 1.0%) are uniformly dispersed in epoxy resin by ultrasonic dispersion method, and using the wet layup method completes the production of CARALL. Carry out the I type fracture toughness test, explore the influence of GnPs on the CARALL interlaminar performance, and carry out the test of the tensile and flexural properties of CARALL to study the influence of GnPs on the mechanical properties of CARALL. The enhancement mechanism of GnPs and the failure mode of CARALL specimens were observed by SEM and optical images. The results show that when the amount of GnPs added is 0.5%, CARALL has the best interlaminar strength and mechanical properties. When 0.5% GnPs is added, the type I fracture toughness is increased by 79%; the tensile strength, Young's modulus, and strain rate at break are increased by 14.5%, 11.0%, and 15.5%, respectively; the flexural strength and flexural strain rate are increased by 20.5% and 89.7%, respectively. This is because adding GnPs to the epoxy resin can disperse the load carried by CARALL, and use its own fracture, pull-out and debonding mechanisms to absorb energy, and further improve the interlayer mechanical properties of CARALL.

Effect of graphene nanoplatelets on water absorption and impact resistance of fibre-metal laminates under varying environmental conditions

This work investigated the effect of graphene nanoplatelets (GNPs) on the water absorption and impact resistance of fibre-reinforced metal laminates (FMLs) under hygrothermal and salt spray environments. Containing GNPs of 0.1, 0.3, 0.5 and 1.0 wt%, the resulting nanocomposite FMLs were investigated for 28 days of aging in the environments. The salt-spray environment was found to pose a more serious effect on FMLs than the hygrothermal environment. The addition of GNPs at 0.3 wt% effectively reduced the water absorption of FMLs by 57.6% whilst improving their impact resistance by 150.6% in comparison with pure FML in the case of treatment by the salt-spray environment. The water absorption reduction is caused by GNPs creating a tortuous path for diffusion of water molecules and restricting the intermolecular motion of the epoxy molecules. The impact resistance improvement can be attributed to GNPs improving the modulus and crack-resistance of the epoxy matrix and thus the interfacial bonding of FMLs.

Novel sandwich structure of composite-metal laminates based on cellulosic woven pineapple leaf fibre

Fibre metal laminates (FMLs) are the contemporary sandwich materials that have been employed in the aerospace industries. The commercially available synthetic fibre based FMLs have shown excellent fatigue, impact and specific properties over those of metallic alloys. In order to explore the potential of environmental friendly cellulosic based materials, this research work aims to characterise the mechanical properties of novel woven pineapple leaf fibre reinforced metal laminates which were prepared through the hot compression moulding technique. For the comparison purpose, the mechanical properties of woven pineapple leaf fabrics and pineapple leaf fibre reinforced composite laminates were determined as well. It was concluded that the pineapple leaf fibre reinforced metal laminates evidenced salient mechanical and specific properties over pineapple leaf fabrics and composites. The specific tensile strength of metal laminates was 230.87% and 62.21% higher than those of the pineapple leaf fabrics and composite laminates whereas the specific flexural strength of metal laminates was 174.91% higher than composite laminates. Besides that, metal laminates also showed an impact strength of 91.49 kJ/m2 which was 143.13% greater than that of the composite laminates. The results indeed showed that the pineapple based FMLs could be considered as the promising and sustainable sandwich materials in future structural applications.

Interlaminar fracture toughness analysis of fiber reinforced metal laminates based on APDL

Fiber Reinforced Metal Laminates (FRMLs) are widely used in modern industry because of excellent comprehensive properties. However, due to the existence of the interface, there will be delamination damage in their use process. Interface is the weakest part of fiber reinforced metal laminates. The bonding strength at the interface is determined by the fracture toughness of the interface. It is an important mechanical property index of fiber reinforced metal laminates. It is usually measured by a single cantilever beam test. In this paper, the finite element model of fiber reinforced metal laminate was constructed based parametric design language APDL of ANSYS to simulate the fracture roughness tests of FRMLs using element birth-death technology. The results show that the numerical simulation is very close to the experimental results. The numerical simulation is a very effective method to determine the interlaminar fracture toughness of fiber reinforced metal laminates.

Innovative Manufacturing and Application of Fiber Metal Laminate Pipe

Fiber-reinforced metal laminate tube (FMLT) is a multi-layered ultra-hybrid material that cures at fixed pressure and temperature after alternating metal laminates and fiber composites. As with the production process similar to the second-generation GLARE fiber-reinforced metal layer, the management layer of the formed composite layer should have good impact resistance characteristics, and can also be used in the impact-resistant structure of the aircraft, the landing cushion structure of the aircraft, and the body collision Device to protect aviation materials.The composite pipe fittings are made by hydraulic forming technology, which lays a good foundation for the small-scale fine processing of the pipe. In addition, use speckle models and other virtual software simulation models (such as various related software and related formulas) to monitor data before and after hydroforming of fiber-reinforced metal layer tubes, it lays a good data foundation for the hydroforming of pipes and subsequent experiments.The development and performance testing of GLARE composite tube hydraulic forming technology is of great significance to the development of lightweight and safety in the aviation industry and the automobile industry.

Research of Different Processes for Forming Fiber Metal Laminates

The paper presents the results of forming rifts in five-layer fiber reinforced metal polymer laminates by electromagnetic forming. During the experimental studies the discharge energy of the electro-magnetic machine was varied in such a way as to achieve different depths of the rift. Samples obtained by electro-magnetic forming were compared with control samples obtained by forming using a rubber pad under static loading. The strain state of the samples was analyzed using an digital image correlation system Vic-3D. The experimental research of fiber reinforced metal laminates forming under the influence of pulse magnetic field has shown the possibility of formability increasing due to change of strain state: the rift zone is dominated by compressive circumferential strains, rather than tensile radial strains as during conventional rubber pad forming.

A Survey of Scrutinizing Delaminated Composites via Various Categories of Sensing Apparatus

Scrutinizing delaminated composites is extensively conducted based on measurements of various types of nondestructive sensing apparatus, classified herein as systems of thermographic inspection, piezoelectric inspection, optical interferometric inspection, electromagnetic testing, ultrasonic testing, and visual testing. The development of the subject has been reviewed during 2000–2017. Not only does the substantial corresponding literature strongly indicates numerous increasing industrial demand for composites, including carbon fiber-reinforced polymer, glass fiber-reinforced polymer, and fiber-reinforced metal laminate, but also the significant potential of composites to delaminate when subjected particularly to impact, machining operation or manufacturing imperfections. Conducting a study on the corresponding literature, the subject of delamination inspection within composites is found to be a dynamic, mature field, while lacking a thorough literature review. Therefore, the present study addresses the mentioned gap regarding various sensation systems utilized so as to detect internal anomalies in composites for the review arrangement. To that end, the literature inclusion in terms of citation times is electronically adopted associated with an appropriate combination of keywords. The study may be considered as a comprehensive, up-to-date review covering all delamination inspection techniques founded on sensation systems, thus benefiting the readers with information in an organized configuration.

Progressive Failure Monitoring of Fiber-Reinforced Metal Laminate Composites Using a Nondestructive Approach

Fiber-reinforced metal laminate (FRML) composites are currently used as a structural material in the aerospace industry. A common FRML, glass layered aluminum reinforced epoxy (Glare), possesses a set of mechanical properties which was achieved by designing its layup structure to combine metal alloy and fiber-reinforced polymer phases. Beyond static and dynamic mechanical properties at the material characterization phase, however, the need exists to develop methods that could assess the evolving material state of Glare, especially in a progressive failure context. This paper presents a nondestructive approach to monitor the damage at the material scale and combine such information with characterization and postmortem evaluation methods, as well as data postprocessing to provide an assessment of the failure process during monotonic loading conditions. The approach is based on multiscale sensing using the acoustic emission (AE) method, which was augmented in this paper in two ways. First, by applying it to all material components separately in addition to actual Glare specimens. Second, by performing testing and evaluation at both the laboratory scale as well as at the scale defined inside the scanning electron microscopy. Such elaborate testing and nondestructive evaluation results provided the basis for the application of digital signal processing and machine learning methods which were capable to identify data trends that are shown to be correlated with the evolution of failure modes in Glare.

Tensile and Flexural Performance of Polypropylene Based Oil Palm Fibre Reinforced Metal Laminates

In this research, the effects of fibre composition on the tensile and flexural performance of Oil Palm Fibre Metal Laminates have been experimentally investigated. OPFMLs are constituted of aluminium 6061 and oil palm empty fruit bunch fibre reinforced polypropylene composite. OPFMLs with four different fibre weight compositions (10%, 20%, 30% and 40%) were manufactured in 2/1 configuration. OPFMLs and their respective composite layers were prepared through hot press moulding compression technique using hot press machine. The mechanical properties of OPFMLs were characterised by tensile and flexural tests in accordance with ASTM D3039 and ASTM D790 respectively. Results showed that tensile and flexural performances of OPFMLs depend on fibre composition in the composite layer. It was found that increase in fibre composition increased the tensile strength but decreased the flexural strength. OPFMLs with 40 wt% showed the highest tensile strength of 65.99MPa whereas OPFMLs with 30 wt% showed the highest flexural strength of 152.45MPa. The optical microscopic images showed damage mechanisms in OPFMLs for different fibre weight composition, which includes delamination and debonding.

The effects of stacking configuration on the response of tensile and quasi‐static penetration to woven kenaf/glass hybrid composite metal laminate

The hybridization of natural and synthetic fibers in composite materials has gained the attention in the research field due to environmental awareness. Therefore, this study focuses on the effects of fiber stacking configuration on the tensile and quasi‐static penetration of kenaf/glass hybrid fiber metal laminates (FMLs). Kenaf/glass reinforced polypropylene FMLs with two different hybrid stacking configurations were prepared using hot compression process. Non‐hybrid kenaf and glass fiber reinforced metal laminates were also prepared for comparison. The tensile test was conducted according to ASTM E8, while the quasi‐static penetration test was carried out in accordance with ASTM D 6264 using 12.7 and 20 mm hemispherical indenters. The fractured surface of FMLs due to tensile loading was examined using scanning electron microscope, while optical micrograph was used to investigate the failure mechanism of quasi‐statically penetrated laminates. From the results, FMLs with the glass plies at the outer layers of composite (H1) showed a positive hybrid effect as they displayed better tensile and penetration resistance, compared to the non‐hybrid kenaf and glass reinforced FMLs. Furthermore, it could be seen that the overall performance of FMLs decreased as the kenaf content in the laminates further increases for hybrid FML. POLYM. COMPOS., 40:568–577, 2019. © 2017 Society of Plastics Engineers

Numerical verification on formability of metallic alloys for skin structure using multi-point die-less forming

Recently, a trend towards lightweight components in the automobile and aircraft industries has developed as one of the primary paths to improve the fuel consumption rate and reduce environmental pollution. Therefore, various sheet materials such as composite and fiber reinforced metal laminates, and metallic alloys are used to satisfy this trend. However, to ensure good impact performance of the automotive structural components and to reduce the production cost, metallic alloy sheets are thought to be the most attractive for sheet blank materials. In this study, the formability of the selected metallic alloys sheet materials such as AA3003-H14, AZ31B, DP600, is investigated on multi-point dieless forming (MDF). For verifying the formability, wrinkling and dimple occurrence, a limit index is newly proposed for convex and saddle target shapes based on: cushion thickness, curvature radius, bank thickness, and punch stroke. Numerical simulations are performed on ABAQUS commercial software with consideration of the springback behavior. An ordinary Kriging model prediction technique is applied to replace the computationally expensive finite element simulation to find the wrinkling and dimple occurrence limit. For forming limit index validation, one optimal case is conducted, and the simulation and experimental result show the product is wrinkling and dimpling free.

Fracture toughness of a corrugate interface between two dissimilar materials

The finite element analysis technique and the cohesive zone model are used to build a physical model of fibre reinforced metal laminates with a corrugate interfacial structure between metal and polymer to analyse the law of interfacial fracture toughness. The results suggest that an interface with a patterned structure has a relatively higher interfacial resistance ability than an interface with a common flat structure within limits. The ratio of stress intensity factor (KIC/K0) nearly increases linearly when the ratio of amplitude to wavelength (A/λ) is larger than 0·25; moreover, the variational trend of KIC/K0 is not linear when A/λ is smaller than 0·25, even the value is less than 1·0. The aforementioned results illustrate that the interfacial fracture toughness changes with the size and morphology regularly at some ranges and have some guidelines for experimental design of surface treatment.