Type Of Fiber Metal Laminates Research Articles

Thermophysical characterization of innovative and recyclable composites, being developed and considered for battery boxes mass production

This paper describes the results of preliminary thermophysical characterization carried out on recyclable & biobased Fibre Metal Laminates (FML) for lighter, more sustainable & safer battery box production, with higher fire resistance. These FMLs are designed to be suitable for the low and medium end automotive. In particular, the specific heat and the thermal conductivity of four different types of FMLs were analysed and assessed depending on temperature. The results show increasing trends of specific heat by increasing temperatures and thermal conductivity values increasing both with temperature and the density of the samples. Further studies will be carried out both to optimise the composition of the FMLs and to provide extensive assessment of the thermal and mechanical properties of the solutions so as to guarantee high thermal and mechanical performances and durability of battery boxes for electric vehicles.

Experimental study on the impact resistance and damage tolerance of thermoplastic FMLs

This study aimed to enhance the impact resistance of fiber metal laminates (FMLs) and achieve lightweight optimization by incorporating a new thermoplastic resin, a titanium alloy and ultra-high-molecular-weight polyethylene (UHMWPE) fiber to produce a novel type of FMLs (PEFMLs). The impact resistance of PEFMLs was analyzed through low-velocity impact tests conducted at different energy levels. Subsequently, the residual compression-after-impact (CAI) strength of the PEFMLs was evaluated through compression tests on the impacted specimens. The experimental findings revealed that PEFMLs exhibited subcritical failure when subjected to impact energies less than 35 J, with a penetration energy threshold of 55 J. Higher impact energies resulted in larger damage areas and increased plate buckling of PEFMLs, consequently leading to reduced CAI strength. The presence of metal, thermoplastic resin and UHMWPE in the PEFMLs effectively dissipated a substantial amount of impact energy while maintaining their structural integrity during both the impact and compression processes.

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.

An experimental and numerical investigation on low velocity impact response of GLAREs

Glass fiber aluminum laminates (GLAREs) are a type of fiber metal laminates (FMLs) that are widely used in the aviation industry. The present article aimed to carry out the numerical and experimental study of the damage mechanism initiation and development in the FMLs subject to low velocity impact. In the experimental part, the drop weight impact test was conducted at four energy levels of 8, 11.5, 15, and 18.5 J on the GLARE laminates. The first crack in the aluminum layer was observed at 18.5 J in the lower aluminum layer. In the numerical simulation, the user-material subroutine VUMAT, including the three-dimensional Hashin damage initiation criterion and the modified progressive damage evolution model, was coded and implemented in the ABAQUS/Explicit finite element package to predict damage initiation and development. The numerical simulations were validated by the experimental results in terms of force–time, force–displacement, and absorbed energy-time curves. The optical microscopy (OM) and scanning electron microscopy (SEM) images of the specimen cross-section were produced to detect the FML damage pattern. The numericalsimulation andexperimentalresults showed to be in good agreement.

The comparison of the veritable response to impact load of conventional and Thin-Ply types of fibre metal laminates

Impact resistance is one of the critical issues for thin-walled structures made of composite materials used e.g. in aerospace fuselage elements. There are two strategies to improve the impact behaviour of composites. One of them involves thin-ply technology, and the second employs fibre metal laminates. The aim of this paper is to explain the response of Aluminium/Thin-Ply-Glass laminates to a wide range of impact energies in comparison with conventional Aluminium/Glass laminates by using deep and multi-criteria experimental evaluation. As demonstrated, the failure mechanisms are similar for both types of laminates. However, the noted differences in the order and importance of individual failure modes may affect damage propagation. The major factor of the earlier perforation initiation process of thin-ply FMLs in comparison to conventional FMLs is the domination of bending stress instead of tensile stress.

Novel thermoplastic fiber metal laminates manufactured with an innovative acrylic resin at room temperature

In the current study, the mechanical characteristics of a new generation of thermoplastic fiber metal laminates (FMLs) manufactured by vacuum-assisted resin infusion (VARI) at room temperature are investigated. For this end, Ti-6Al-4V alloy sheets, ultra-high molecular weight polyethylene (UHMWPE) fabric, carbon fabric, and two hybrid laminates with different layups are manufactured by a novel liquid methyl methacrylate (MMA) thermoplastic resin, Elium®. Prior to fabricating and testing, a multi-step surface treatment is followed to improve the bonding strength between the titanium alloy sheets and fiber-reinforced polymer composite (FRPC) laminates. ASTM standard tests are conducted in tension, compression, shear (both intralaminar and interlaminar) as well as flexural to evaluate the mechanical characteristics of the newly developed hybrid titanium composite laminates (HTCLs). The results are compared with those of equivalent monolithic composites as well as traditional FMLs in the literature to determine the possibility of replacing epoxy resins with Elium® for fabricating different types of FMLs, namely HTCLs. In addition, the results are verified by a recently developed homogenization method, that is the mechanics of structure genome (MSG), which is used in parallel with the rule of mixture (ROM) to verify the experimental results of HTCLs and their constitutive FRPC laminates. The results show equivalent mechanical properties of the newly developed HTCLs compared to those of traditional thermoplastic HTCLs with the advantages of fabricating at room temperature, increasing the production rate, eliminating the residual thermal stresses, and the requirement for post-stretching HTCL panels.

Examination on Mechanical Behavior and Drilling Analysis of Fiber Metal Laminates

Fiber Metal Laminates (FML) are a class of composites that are recently employed to substitute sole metals in various applications like aerospace applications. In this investigation, a new type of FML was successfully fabricated using compression moulding in which Aluminium and ceramics mat are stacked in the presence of epoxy resin. To improve the bonding by ensuring the flow of resin through the laminates, drilling with various pattern on the Aluminium sheet and ceramic mat were performed before subjected to compression to form FML. Aluminium sheets with Zig-zag pattern performed in a better way due to the improvements in bonding. In addition, drilling operation was done on the FML to ensure the de-lamination resistance and machinability. The drill bit before and after drilling was inspected by using optical microscope to understand the machinability behaviour of the FML.

An Experimental Study on Impact Resistance of Different Layup Configuration of Fiber Metal Laminates

Fiber metal laminates (FMLs) are composed of thin metal sheets and fiber-reinforced composite layers. Compared to monolithic aluminum alloys, FMLs combine lower density, higher fatigue resistance, and improved damage tolerance. The present study aimed to investigate the low-velocity impact induced by drop-weight instrument and the tensile strength on various lay-up configurations of FMLs fabricated. FML samples were composed of two layers of aluminum 2024-T3 and two layers of epoxy resin, which were reinforced with carbon fabric, glass fabric, and Kevlar fabric made in pairs. In addition, another type of FMLs was developed with carbon/Kevlar fabric under the same circumstances. Force-time histories of impact forces were recorded, and the damaged specimens were inspected using optical microscopy in terms of the impact side, nonimpact side, and cross-sectional side. Experimental results indicated that the maximum impact force corresponded to the FMLs that were composed of Kevlar fabric on the impact side and glass fabric on the non-impact side. In addition, the highest tensile strength and Young’s modulus among FMLs belonged to FML with Kevlar fabric and glass fabric.

Impact of Fiber Metal Laminates - Literature Research

Abstract The paper refers the general idea of composite materials especially Fiber Metal Laminates (FMLs) with respect to low-velocity impact incidents. This phenomenon was characterized by basic parameters and energy dissipation mechanisms. Further considerations are matched with analytical procedures with reference to linearized spring-mass models, impact characteristics divided into energy correlations (global flexure, delamination, tensile fracture and petaling absorbed energies) and set of motion second order differential equations. Experimental tests were based on analytical solutions for different types of FML - GLARE type plates and were held in accordance to ASTM standards. The structure model reveals plenty of dependences related to strain rate effect, deflection represented by the correlations among plate and intender deformation, separate flexure characteristics for aluminium and composite, contact definition based on intender end-radius shape stress analysis supported by FSDT, von Karman strains as well as CLT. Failure criteria were conformed to layers specifications with respect to von Misses stress-strain criterion for aluminium matched with Tsai-Hill or Puck criterion for unidirectional laminate. At the final stage numerical simulation were made in FEM programs such as ABAQUS and ANSYS. Future prospects were based on the experiments held over 3D-fiberglass (3DFG) FMLs with magnesium alloy layers which covers more favorable mechanical properties than FMLs.

Strength properties of aluminium/glass-fiber-reinforced laminate with additional epoxy adhesive film interlayer

This paper studies the strength analysis of two types of fibre-metal laminates (FMLs), with a different way of preparing the adhesive coupling between 2024-T3 aluminium alloy sheets and a polymer/fibre layer. In the first variant, the 3 M structural adhesive film AF 163-2 K is used as an intermediate layer between prepreg and adherends. The adhesive layer is co-cured with prepreg and adherends. In the second FML variant, coupling between adherends was produced using epoxy resin. Two types of strength test, – i.e., tensile/shear test and 90° peel test – were used to measure the adhesion between the layers of FML composite. To measure the joint strength the tensile test was used. The fracture mode and the fracture surfaces were examined and discussed using a scanning electron microscope. The application of the adhesive film as an additional binding agent caused an increase in laminate elasticity. In this way, the strength and fatigue life of the joint increased. The main advantage of adhesive film application was a significant increase in the peel strength of laminate, which reached 289.4%. As a result of this, bonded laminates are very susceptible to normal stresses. However, the application of the additional adhesive film in the analysed 2/1 laminate lay-up increased the mass of the laminate by about 10%. Furthermore, a significant increase in the FML peel strength was achieved, with the increased cost of the additional adhesive film at about 20%.

Influence of fiber type on the impact response of titanium-based fiber-metal laminates

This investigation examines the influence of fiber type on the failure of titanium-based fiber metal laminates (FMLs). Two types of FMLs, comprising fiber-based composite layers, sandwiched between titanium sheets, were subjected to impact by a 12 mm steel sphere at various velocities ranging from 100–400 m/s. The first FML incorporated carbon fiber reinforced plastic (CFRP) layers, whereas the second had hot-pressed ultra-high-molecular-weight polyethylene fiber (UHMWPE, Dyneema®HB50) layers as the sandwiched component. FML specimens were clamped between annular plates, which exposed a circular target, and impacted at the center by spherical projectiles. Optical images of the deformation and failure induced in the two types of FMLs were captured by a high-speed camera, and the respective responses compared; the ballistic limit and energy absorbed were also determined. The results indicate that the ballistic performance of the Ti/HB50 system is superior to the Ti/CFRP combination, in terms of ballistic limit and energy absorption. However, this difference diminishes when the impact velocity exceeds 1.5 times the ballistic limit. The rolling direction of the titanium sheet plays a significant role in the amount of energy absorbed, through its influence on the deformation/failure mode of the FMLs.

Flexural Behaviour of CFRP/MG Hybrid Laminates with Different Layers Thickness

Three different types of fibre metal laminates (FMLs) with varying layers thickness, consisting of carbon fibre reinforced polymer (CFRP) prepregs and magnesium alloy sheets, were prepared by a hot-press process. The flexural behaviour of the FMLs were investigated using a three point flexural test method, to investigate the effect of layer thickness on flexural behaviour of FMLs while maintaining a constant metal volume fraction and constant overall thickness in the design process. The results show that the flexural modulus of the FMLs decreases in an almost linear manner with the decrease of layer thicknesses, yet no clear differences were observed in the flexural strength. Decreasing the layer thickness causes the transition of failure zone from compression region to tension region, which results in the appearance of two similar peak stresses.

Interfacial fracture of the fibre-metal laminates based on fibre reinforced thermoplastics

Abstract As the adhesion quality plays an important role in determining the mechanical performance and environmental stability of most types of fibre-metal laminates (FMLs), investigating the interfacial fracture properties becomes one of the key factors for the improvement. Adhesion of a self-reinforced polypropylene (SRPP) and glass fibre reinforced polypropylene (GFPP) based FML is evaluated experimentally. Single Cantilever Beam (SCB) tests were performed to access interfacial fracture energy (Gc) of the bi-material laminates and their associated interlayer materials. Simulations mimicking the experiments were also performed. The energy needed to fracture was obtained experimentally and also via stress intensity factor from the simulations. The test results show that good adhesion between the aluminium and fibre reinforced thermoplastics can be achieved using a sulphuric acid anodising surface pre-treatment. Further examination has shown that the edges of the test samples highlighted the presence of significant fibre bridging in the SRPP and plastics deformation in the GFPP.

Assessment of impact response of fiber metal laminates

Series of low velocity impact tests were carried out on different types of fibre metal laminates (GLARE®) with varying material constituents. Impact damages in the laminates and their extent were analysed. Relationship between the configuration as well as the properties of the laminates with different material constituents and the impact response in terms of indent was derived. This relationship resulted in an empirical method predicting the dent depth under low velocity impact in laminates with different configurations. The method is valid as long as there is reference impact data obtained on a composite material with the same constituents and identical boundary conditions.

The high-velocity impact response of thermoplastic–matrix fibre–metal laminates

The high-velocity impact response of fibre metal laminates based on a woven polypropylene fibre reinforced polypropylene, termed a self-reinforced polypropylene, and a glass reinforced polypropylene has been investigated. Two types of aluminium alloy were considered, these being the 2024-O and 2024-T3 alloys. Tests on these composite–metal hybrids were undertaken using a gas gun over a wide range of incident impact energies. In this study, attention focused specifically on the perforation threshold. Following impact, the fracture mechanisms in the two types of fibre metal laminates were elucidated by sectioning and polishing samples through the point of impact and also by measuring the residual deformation of the hybrid plates. Cross-sections of the failed samples highlighted significant plasticity within the volume of these hybrid materials, indicating that considerable energy had been absorbed in plastically deforming the aluminium and composite plies. The impact resistances of the various laminates were compared by determining their specific perforation energies. Here, it was shown that fibre metal laminates based on the glass reinforced polypropylene composite offer a slightly higher perforation resistance than the self-reinforced polypropylene fibre metal laminates. Also, the fibre metal laminates based on the stronger 2024-T3 alloy out-performed their 2024-O counterparts. Finally, the perforation resistances of the fibre metal laminates were predicted using the previously reported Reid–Wen impact perforation model. Good agreement was observed between this impact model and the measured experimental data.

Mechanical behavior of basalt fiber-reinforced and basalt fiber metal laminate composites under tensile and bending loads

This article examines the mechanical behavior of Basalt fiber-reinforced epoxy (BFRE) and a new type of fiber metal laminates (FMLs) composed of steel, aluminum, and BFRE named as Basalt fiber metal laminate (BFML) under tensile and bending loads. To study the effect of fillers in epoxy, the micro glass powder (MGP) was only added into the epoxy resin in BFRE composites at various volume fractions. It was found that the MGP had no significant effect on tensile strength, but it raised the stiffness and decreased the failure strain of BFRE. On the other hand, bending strength increased by adding MGP. BFML showed superiority in energy absorption via tensile strength. This FML had flexibility much higher than that of BFRE. Adding MGP or metal layer to basalt-reinforced composites improved the mechanical properties in tensile and bending loads. Selective bending specimens of BFRE are studied by SEM to show the positive role of MGP in raising the bending strength and further analysis of the nature of fracture surfaces. High fragmentation of matrix was obvious.

Estimating the failure strength of fiber metal laminates by using a hybrid degradation model

Different analytical formulations are reported in recent works to model the failure strength and the progressive failure of different fiber metal laminates (FMLs). Although the basis for all these formulations is classical lamination theory (CLT), the models differ with each other while modeling the stiffness degradation. A common analytical formulation that is independent of configuration of the laminate will be very helpful for the designers in this field. Present work is aimed to develop such a model with the help of a hybrid degradation scheme, which uses constant degradation factors based on the condition of the adjacent lamina. This hybrid degradation scheme has helped to model the occurrence of multiple failures inside a lamina during failure progression. The formulation is tested with three types of FMLs and the results show that the formulation is very much helpful in predicting the failure strength and progressive failure.

Damage Behaviour of Ti/GFRP Laminates under Low-Velocity Impact Loading

In the present paper, the impact responses and overall damages of Fibre-Metal Laminates based on titanium alloys and glass fibre-reinforced polymers (Ti/GFRP) as Ti/FRP laminate system were evaluated. Low-velocity impact tests using a drop-weight tower were conducted for the cross-plied GFRP laminates and the Ti/GFRP laminates, and the impact responses during impact loading were obtained. Impact damages such as cracks in titanium layer and delamination of titanium-GFRP interface or matrix cracks and interlaminar delamination in GFRP layer were observed from the impact direction. From the experimental evidence, it was found that the Ti/GFRP laminates showed same impact damage modes as of other types of Fibre-Metal Laminates. Internal damages in the Ti/GFRP laminates were restrained by the reinforcing effect of titanium and adhesive layer compared to the cross-plied GFRP laminates. The Ti/GFRP laminates showed two patterns of the impact responses and damages with the threshold impact energy of about 4.8J. With higher impact energy than this threshold, single crack was presented in titanium layer at non-impacted side. The interlaminar delamination area in GFRP layer increased sharply due to the occurrence of this crack. Numerical analysis model that represent the impact behaviour of the Ti/GFRP laminates using finite element method was suggested based on the damage observations. The impact responses obtained by the dynamic analyses agreed well with the experimental results. The calculated area of interlaminar delamination in GFRP layer as a function of impact energy showed same behaviour as seen in the experiments. As a consequence, it was shown by the analysis as well that the drastic increase in the internal damage area of the Ti/GFRP laminates was induced by the fracture in outer titanium layer under the out-of-plane impact loading.

Mechanical properties of a novel fiber–metal laminate based on a polypropylene composite

Fiber–metal laminates (FMLs) are a relatively new type of material developed from the need to develop high performance lightweight structures with excellent properties under tensile, flexure and impact conditions. The first generation of FMLs was based on thermosetting matrices, typically epoxy resins. Recently, new types of FMLs are emerging as a result of the demand for more efficient and lightweight materials for use in the automotive and aerospace industries. This study characterizes the mechanical properties of a new type of thermoplastic-matrix FML based on a self-reinforced polypropylene (SRPP) composite and an aluminum alloy. This FML is manufactured in a simple compression-molding process, allowing it to subsequently be re-shaped according to operational requirements. This paper presents the findings of a study conducted to investigate the mechanical properties for this lightweight thermoplastic FML, investigating its properties in tension, flexure and impact.

Evaluation of residual strength of notched fiber metal laminates

Fiber metal laminates (FML) are a family of hybrid materials consisting of alternating layers of thin metal sheets and fiber-reinforced epoxy prepregs. In contrast to aluminum alloys, the presence of notches in FML causes significant strength reductions. The objective of this study was to evaluate the residual strength of fiber-reinforced metal laminates with a circular open hole. Mechanical testing was performed to determine the unnotched tensile properties and notched strength of bi-directionally reinforced fiber metal laminates. The influence of specimen dimension and notch size on residual strength and notch sensitivity of fiber metal laminates was investigated. A modified point stress criterion was introduced to predict the residual strength of fiber metal laminates with open hole. An excellent agreement between experimental results and model prediction was obtained. The residual strength predicted from this modified model also correlated very well with the experimental data in the literature for various other types of fiber metal laminates. A computer simulation based on finite element method was performed to study stress concentration and stress concentration around notch. Failure modes, damage initiation and progression of notched fiber metal laminates are also characterized and discussed.