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This study delves into the bearing response of two types of Fiber Metal Epoxy Laminates (FMLs): Glass Fiber/Stainless Steel laminates and Glass Fiber/Jute/Stainless Steel laminates, where a portion of glass fiber is replaced with jute. The primary focus is to assess the impact of introducing natural fiber (jute) into FML on its pin‐type bearing performance, considering various edge‐to‐hole ratios (e/D), width‐to‐hole ratios (W/D), and stacking orders. The study aims to understand how these parameters influence the bearing load and failure modes of the laminates. Observations reveal that variations in e/D and W/D ratios, along with the stacking arrangement of materials in the FMLs, exert a significant influence on the ultimate load‐bearing capacity of the pinned joint. It is observed from the study that, for the two stacking sequences considered, the load bearing capacity of the FMLs with W/D ratio 6 is greater than those with W/D ratio of 4 by a maximum of 23.06%. Moreover, if the weight fraction of the glass fiber content in the FML is reduced, the ultimate load bearing capacity of the FML also gets curtailed to a maximum extent of 44%. The experimental findings suggest that the prepared fiber metal laminate, characterized by lower weight, cost‐effectiveness, and enhanced environmental friendliness, exhibits a substantial capacity to withstand bearing loads. Consequently, it emerges as a promising candidate for the construction of structures such as storage silos, offering a balanced combination of structural performance and sustainability. Highlights: FML bearing performance: Glass/Stainless versus Glass/Jute/Stainless.Influence of e/D and W/D ratios on pin‐type bearing.Stacking order impact on load‐bearing capacity.Lightweight, cost‐effective, and eco‐friendly FMLs.Promising for silo construction: structural and sustainable. [ABSTRACT FROM AUTHOR]

In the present study, the sound transmission loss (STL) through the air-filled rectangular double-walled cross-ply fiber metal laminated (FML) nanoplates under simply supported and clamped boundary conditions is studied using the nonlocal strain gradient theory (NSGT) and third-order shear deformation theory (TSDT). NSGT is complemented with hardening and softening material effects, which can significantly enhance the accuracy of small-scale results. The sound velocity potential and Hamilton's principle are employed to derive the coupled size-dependent vibroacoustic equations. The Galerkin method is exploited to solve vibroacoustic equations and obtain the STL. The developed solution is examined in terms of its accuracy and precision via a comparison with other available data in existing research. The effects of different parameters such as boundary conditions, nonlocal and strain gradient parameters, lay-ups, incident angles, and acoustic cavity depth on the STL through the double-walled FML nanoplates are investigated. [ABSTRACT FROM AUTHOR]

In selective laser etching for the interfacial strengthening of Fiber Metal Laminates (FMLs), the wettability of customized structured features significantly affects their overall mechanical properties. For two-level features, their complicated geometry makes the evaluation of wettability difficult, which introduces challenges to feature design. In this study, a sandwich FMLs comprising an AA2024-O metal skin and a plain-woven carbon-fiber fabric core is investigated. Three types of two-level feature interfaces are designed and introduced into the FMLs structure. To understand the effect of two-level features on the resin flow and dynamic wetting progress in resin transfer molding, two-phase flow Computational Fluid Dynamics numerical models coupled with porous media and level-set numerical methods are built. The feasibility of the numerical simulation in the qualitative analysis was verified by comparing the results with those of the testing porosity values from X-ray scanning. In addition, the mechanisms of pore formation and transportation are revealed. These results indicate that the deeper groove structure in the etched features plays an important role in discharging residual air and determining the transformation of pores to reduce porosity. The permeability orientations of the porous media and surface structure both have significant impacts on the flow behavior and formation of pores. [ABSTRACT FROM AUTHOR]

Fiber Metal Laminates (FML) are hybrid composites comprising metals and Fiber Reinforced Plastics (FRP). FMLs are the most widely used in aerospace, defence and automotive sectors due to their superior qualities like light weight, tensile, compression, flexural, excellent fatigue and impact resistance. The properties like strength-to-weight ratio, susceptibility to corrosion and good heat conduction of FML make it suitable for subsea applications. Commonly, FML with a combination of aluminium (Al), titanium (Ti), stainless steel (SS) alloys and FRP are widely used for ocean applications. Compared to other FML, the SS alloy-based FML is typically used in subsea applications as it has more creep and excellent corrosion resistance. In India, under the Ocean Acoustics programme of the National Institute of Ocean Technology (NIOT), an autonomous underwater Ambient Noise Measurement System (ANMS) has been developed and deployed in the shallow waters of Indian seas for the past 12 years to study the background noise prevailing in the sea. To accommodate electronics and power packs for the measurement of ambient noise at an ocean depth of 100 m, subsea housing with stainless steel 316L (SS316L) material for a pressure rating of 1 MPa has been developed. The objective of this study is to develop the FML with SS316L and FRP for reducing the weight of the housing. Based on the literature studies and Classical Laminate Theory (CLT), the FML has been fabricated as a 0.45 m (450 mm) panel with a sequence of SS316L as outer layers and E-glass fibre and carbon as the inner layers. The total thickness of the laminates is 0.006 m (6 mm). The developed FMLs are processed with water jet cutting machines to carry out various testing such as tensile, compression and flexural, which are relevant to the characterization of FML and the experimental results are described in the paper.

Hybridizing natural and synthetic fibers is thought to be an alternate technique for achieving the desired balance between the mechanical performance and sustainability of fiber metal laminates (FMLs). The aluminum (Al)/pineapple leaf fiber (PALF)/carbon fiber (CF) reinforced epoxy composites with five stacking sequences were fabricated by the vacuum-assisted resin transfer molding (VARTM) method. The effects of the hybridization and layering sequence on mechanical and viscoelastic properties have been investigated by the hardness, interlaminar shear strength (ILSS), and Izod impact test, along with dynamic mechanical analysis (DMA). The study found that A1 (ACPCA) showed significant improvements over non-hybrid AP (APPPA), with 86.50% better ILSS and 59.59% higher impact strength. Compared to A2 (APCPA), A1’s ILSS and impact strength were 26.26% and 38.38% better, respectively, due to two CF layers. Hybrid FML A3 (CPAPC) had the lowest impact strength at 97.77 kJ/m2 among FMLs with aluminum outer layers. DMA tests showed all hybrids were stiffer than non-hybrid AP, with A1 having superior viscoelastic properties. This suggests PALF and CF in natural fiber metal laminates (NFMLs) could be promising for automotive applications.

This study looks at the mechanical and free vibration properties of glass laminated with functionalized aluminium reinforced epoxy. NaOH, K2Cr2O7, Fe2(SO4)3. XH2O, and C8H18O3Si were employed to functionalize aluminum. The flexural, impact, and shear strengths, as well as their failures, were investigated using electron microscope images. The impulsive hammer approach was applied to investigate laminate vibration behaviour. The results showed that the flexural strength (623.83 MPa), impact strength (76.41 J/mm2), and shear strength (55.31 MPa) of C8H18O3Si functionalized laminates outperformed those of other functionalized laminates. The improvement of mechanical properties was due to the change in interfacial adhesion. This is dependent on the functionalization of aluminium used in stacked laminates. Moreover, C8H18O3Si functionalized laminates exhibit a higher natural frequency and higher damping than other functionalized laminates. This natural frequency and damping are enhanced due to the strong mechanical interlocking between polymer and metal adhesion. It was noted that the same laminates have higher toughness than other laminates because of the high impact energy obtained. [ABSTRACT FROM AUTHOR]

To investigate the enhancement mechanism and effect of laser treatment on the performance of an interface between a carbon-fiber-reinforced polymer and magnesium (CFRP/Mg), finite element simulations and experiments were conducted to demonstrate the macroscopic and microscopic failure processes of the laser-treated interface. Based on the high controllability of the groove parameters in laser machining, the quantitative relationship between the texture parameters and the shear properties of the CFRP/Mg interface was analyzed. In addition, shear tests and simulations of the laser-treated interfaces with different groove parameters were performed. Increasing the groove depth and decreasing the groove spacing effectively improved the shear strength of the CFRP/Mg interface. In addition, the reliability of the interface cohesion parameters obtained using the representative volume element model was verified by experiments and simulations, which is important for the application of laser technology to composite laminates. [ABSTRACT FROM AUTHOR]

The hybridization of natural and synthetic fibers is an alternate method to balance the performance and environmental friendliness of fiber metal laminates (FMLs). This research aims to fabricate hybrid aluminum (A)/ carbon fiber (C)/ pineapple leaf fiber (P) reinforced epoxy FMLs with different stacking sequences by the vacuum-assisted resin transfer molding (VARTM) technique. The fabricated hybrid FMLs were subjected to tensile, flexural, thermogravimetric analysis (TGA), and water absorption tests. The tensile and flexural strength of hybrid A1 (ACPCA) surpassed those of non-hybrid AP (APPPA) by 252.77% and 165.08%, respectively. The thermal test shows that the hybrid FMLs A1 with higher CF content leads to better thermal stability than A2 (APCPA). In addition, from the water absorption test, the AP and A2 FMLs, with PALF as outer layers of core materials, absorbed moisture exceeding 6% after 10 weeks, compared to AC (ACCCA) and A1 with CF as outer layers of core materials, which only reached up to 2.88% and 4.22%, respectively. From this study, it is worth pointing out that the hybrid A1 showed comparable performance to non-hybrid AC. Thus, the appropriate hybridization of synthetic and natural fibers can broaden the scope of the practical application of FMLs with improved environmental friendliness in the automotive industry. [ABSTRACT FROM AUTHOR]

A detailed experimental investigation was carried out for the high-velocity ballistic response of AA 1100-H14 based carbon-fiber metal laminates (FMLs). FMLs with different metal volume fractions and the same thickness of carbonepoxy fiber laminates were tested to examine the surface and internal damage. The ballistic performance parameters, namely % escalation in absorbed energy, specific energy absorbed, ballistic limit, specific perforation energy, first cracking energy, and global deformation profile, were studied and a comparison was drawn with pure carbons fiber reinforced epoxy composite laminates. Despite having greater thickness, pure carbon fiber-reinforced epoxy composite laminates absorbed less impact energy than FMLs and failed catastrophically. For FMLs, the % escalation in the absorbed energy and the specific energy absorption kept increasing with the increasing impact velocity until the onset of perforation. Once the perforation started, both these parameters showed a decreasing trend. Thick FMLs absorbed a good amount of energy, leading to projectile recoil suffering minimal damage. The ballistic velocity, specific perforation energy, and first cracking energy on the front and rear face of FMLs layers showed an increasing trend. The minimum for the thinner and maximum for the thicker FMLs attributed to the large thickness and more metal volume fraction. Contrary to the large deformation of the impacting points, pure carbon fiber-reinforced epoxy composite laminates showed very minimal deformation as compared to FMLs. The brittle nature of the epoxy resin resisted the deformation to a large extent leading to less energy absorption. Highlights • High-velocity ballistic response of AA 1100-H14 based carbon-FMLs was investigated. • Ballistic performance parameters of FMLs were studied and was compared with carbons fiber reinforced composite laminates. • The ballistic limit of FMLs showed a direct dependence its thickness and metal volume fraction. • In the absence of any metallic layer, pure carbons fiber reinforced composite laminates absorbed less impact energy. [ABSTRACT FROM AUTHOR]

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Following the principle of constrained-layer damping (CLD), fiber-metal-elastomer laminates (FMELs) offer a high potential for damped lightweight structures, overcoming the undesirable vibration characteristics of conventional lightweight materials. While proven to be versatile and efficient, the damage-tolerance of such laminates is unexplored. This study for the first time in literature addresses the damage-tolerance of this efficient damping mechanism using a combined experimental and numerical approach. Results of experimental low-velocity impact tests on different configurations of FMELs are presented. In subsequent numerical modal analyses, different types of damage, namely delaminations, intra-ply damage and permanent deformation, are modeled and their influence on the vibrational behavior is investigated. While all types of damage influence the natural frequencies and modal damping ratios with a strong mode dependency, all laminates retain a high amount of modal damping with losses typically not higher than 15%. The results obtained reveal, that CLD is an efficient intrinsic damping measure in FMELs even in the presence of different types of damage. The key contributions of this paper include the thorough experimental characterization of low-velocity impact damages in different configurations of FMELs as well as the numerical assessment of those in frequency-domain simulations.

In a multi-layered shielding material, the sequence of the arrangement of the layers affects the extent of insulation to acoustic waves. In the current work, hybrid composite laminates have been taken up comprising 10 sequences, employing metallic faceplate (AA6061), paperboard, ballistic-grade aramid, and ultra-high molecular weight polyethylene (UHMWPE) fabrics with an epoxy binder. In the theoretical studies, an analytical model for the transmission loss function has been developed by incorporating the multiple wave reflection principle in combination with interface-wise acoustic impedance grading. The analytical model has been validated using the transmission loss functions from numerical and experimental studies on the different sequences. The numerical simulation has been carried out using the harmonic acoustic analysis module, on Ansys R19.0. The experimentation has been carried out on an impedance tube. The results from the analytical model are in good agreement with the experimental and numerical simulation results, the analytical model can be used for predicting the transmission losses of composite laminates.

In addressing the difficulty of forming Fiber Metal Laminates (FMLs), a laminate composed of a 0.1 mm-thick 304 Stainless Steel Foil (SSF) and Carbon Fiber Reinforced Plastics (CFRP) as the base material is prepared using a specific process. Subsequently, forming limit diagrams are obtained through hemispherical bulge forming experiments to investigate the forming performance of FMLs laminates. The damage phenomena of various forming specimens during the thermal stamping process are analyzed. Based on different damage forms, corresponding theoretical models are established to simulate and predict the forming damage modes of FMLs through simulation. The research results indicate that the stamping formability of FMLs is influenced by the damage tolerance of the thin stainless steel foil. During the thermal stamping process, FMLs may experience delamination, fracture/crack of the thin stainless steel foil, and rupture/tearing/wrinkling of the prepreg. To address these issues, cohesive elements, GTN-M-K damage, and Hashin damage models are established, providing a reasonable simulation prediction of the stamping damage phenomena of FMLs. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Fiber Metal Laminates (FML) are hybrid composites comprising metals and Fiber Reinforced Plastics (FRP). FMLs are the most widely used in aerospace, defence and automotive sectors due to their superior qualities like light weight, tensile, compression, flexural, excellent fatigue and impact resistance. The properties like strength-to-weight ratio, susceptibility to corrosion and good heat conduction of FML make it suitable for subsea applications. Commonly, FML with a combination of aluminium (Al), titanium (Ti), stainless steel (SS) alloys and FRP are widely used for ocean applications. Compared to other FML, the SS alloy-based FML is typically used in subsea applications as it has more creep and excellent corrosion resistance. In India, under the Ocean Acoustics programme of the National Institute of Ocean Technology (NIOT), an autonomous underwater Ambient Noise Measurement System (ANMS) has been developed and deployed in the shallow waters of Indian seas for the past 12 years to study the background noise prevailing in the sea. To accommodate electronics and power packs for the measurement of ambient noise at an ocean depth of 100 m, subsea housing with stainless steel 316L (SS316L) material for a pressure rating of 1 MPa has been developed. The objective of this study is to develop the FML with SS316L and FRP for reducing the weight of the housing. Based on the literature studies and Classical Laminate Theory (CLT), the FML has been fabricated as a 0.45 m (450 mm) panel with a sequence of SS316L as outer layers and E-glass fibre and carbon as the inner layers. The total thickness of the laminates is 0.006 m (6 mm). The developed FMLs are processed with water jet cutting machines to carry out various testing such as tensile, compression and flexural, which are relevant to the characterization of FML and the experimental results are described in the paper. [ABSTRACT FROM AUTHOR]

The study's main objective is to design and develop pressure vessels in underwater applications using Hybrid composites-Fibre Metal Laminates (FML) so that the weight will be reduced. The proposed pressure vessel accommodates electronics in the underwater ambient noise measurement system under an external hydrostatic pressure of 1 MPa (10 bar). The research study aims initially to design and develop a pressure vessel with stainless steel 316 L and subsequently design a pressure vessel with hybrid composites with a combination of composite materials of E-glass and carbon/epoxy materials with a metal alloy stainless steel 316 L. The pressure vessel has been optimised with varying metal and composite percentage combinations. The cylinder's wall thickness has been pivotal in optimizing pressure vessel design. Classical Laminate Theory (CLT) transforms the FML pressure vessel or cylinder into a rectangular plate. As preliminary measures, FML specimen with a size of 0.45 m square laminate and 0°orientation has been developed with 50 % metal layer and 50 % fibre composites, and corresponding mechanical tests have been carried out as per the standards. The tensile strength of the developed FML is 420 MPa compared to base metal (SS316 L) strength of 556 MPa, and similarly, Flexural and Impact properties have shown a higher level when compared to other types of FMLs. [ABSTRACT FROM AUTHOR]

Purpose: Fiber metal laminates (FML) are a new composite, particularly the CAJRAL type laminate, consisting of aluminium and a carbon/jute/epoxy composite. The present work aims to develop low-density Fiber metal laminates (FML) with good mechanical properties for aerospace applications. Design/methodology/approach: FML combines the good characteristics of metal, such as ductility and durability, with the benefits of fibre composite materials, such as high specific strength, high specific stiffness, good corrosion resistance and fatigue resistance. The present work introduces an FML consisting of aluminium and Carbon/Jute/epoxy layers. The FML was produced by the hand lay-up technique. The aluminium sheets were surface-treated with the sobbing method. Two combinations of laminate sequencing were selected: Ca 0°/Ca 45°/Al/Ju 45° and Ca 0°/Al/Ca 0°/Al/Ju 0°. Findings: The structure characterisation after bending tests is shown and discussed. The three point-bending tests are conducted according to ASTM D 2344 standard specifications. Sample-1 (Ca 0°/Ca 45°/Al/Ju 45°/Ju 45°/Al/Ca 45°/Ca 0°) is a better result. Research limitations/implications: Preliminary studies have shown that the metal layers in the laminates and the composite carbon layer, particularly in the bend area of the laminate, significantly impact the nature of the damage. Laminate indicates the complexity of the degradation process of these materials. Practical implications: The orientation of the reinforcing fibres influences the degree of the laminate structure and affects the ability to form laminates. An important factor influencing the properties of the laminate as a whole is to provide high adhesive properties of the compositemetal connections. Originality/value: By replacing aluminium with jute. It is observed that the tensile and flexure stresses of the CAJRAL with Ca 0°/Ca 45°/Al/Ju 45°/Ju 45°/Al/Ca 45°/Ca 0° are more compared with Ca 0°/Al/Ca 0°/Al/Ju 0°/Ju 0°/Al/Ca 0°/Al/Ca 0°. [ABSTRACT FROM AUTHOR]

The interlayer bonding ability is a crucial indicator of thermoplastic fiber metal laminates (FMLs). Using different preparation strategies and adhesive thicknesses, a series of fiber metal laminates were prepared from 2024-T3 Al alloy, unidirectional carbon fiber prepreg tapes, and films of polyether ether ketone. The span-thickness ratio for this type of laminates was examined and characterized to identify the most suitable span-thickness ratio. The effects of adhesive layer thickness on the interlaminar properties of FMLs were investigated, and the failure processes were analyzed by microscopic observation. The results show that lower span-thickness ratios have better applicability in thermoplastic carbon fiber aluminum alloy laminates. The adhesive layer presence significantly affects interlaminar properties independent of its thickness, and the FMLs with unidirectional alignment and anodized treatment possess stronger shear resistance. [ABSTRACT FROM AUTHOR]

In a multi-layered shielding material, the sequence of the arrangement of the layers affects the extent of insulation to acoustic waves. In the current work, hybrid composite laminates have been taken up comprising 10 sequences, employing metallic faceplate (AA6061), paperboard, ballistic-grade aramid, and ultra-high molecular weight polyethylene (UHMWPE) fabrics with an epoxy binder. In the theoretical studies, an analytical model for the transmission loss function has been developed by incorporating the multiple wave reflection principle in combination with interface-wise acoustic impedance grading. The analytical model has been validated using the transmission loss functions from numerical and experimental studies on the different sequences. The numerical simulation has been carried out using the harmonic acoustic analysis module, on Ansys R19.0. The experimentation has been carried out on an impedance tube. The results from the analytical model are in good agreement with the experimental and numerical simulation results, the analytical model can be used for predicting the transmission losses of composite laminates. [ABSTRACT FROM AUTHOR]

Numerical analyses offer a cost-effective and efficient alternative to experimental investigations, and Finite Element (FE) models have become a popular tool to simulate the behavior of Fiber metal laminates (FMLs) under impact loads. This study verified the reliability of the proposed FE models to predict the perforation response of ‎the FMLs investigated under low-velocity impact loadings. The validation of ‎the FE models was assessed through comparison with the corresponding results of the ‎experimental work. The results showed that the proposed simulations are capable of predicting the dynamic response of the laminates investigated with a high degree of success. The parametric studies were conducted on 2/1 titanium FMLs based on 2-ply composite cores and 2/1 aluminum FMLs based on 4-ply composite cores under impact with a variety of loading conditions. The developed FE models were then used to explore the structural behavior of the fiber metal laminates investigated with an extended variation of parameters, i.e., projectile striking angle, impact locations, the geometry of the projectile, and velocity. The results of the FE models are presented in terms of load-displacement traces, energy absorption, and failure modes. The findings of this study contribute to the understanding of the structural behavior of FMLs under impact loads and can inform the design and optimization of FMLs for various engineering applications. The use of FE models provides a cost-effective and efficient means of exploring the structural behavior of FMLs under different impact conditions, which can reduce the need for costly and time-consuming experimental investigations.

Abstract Fiber metal laminates (FMLs) are widely applied as protective structures in various high-tech industries owing to their excellent impact resistance. This paper presents an explicit finite element (FE) simulation to investigate the dynamic damage behavior of carbon fiber-reinforced aluminum laminates (CRALLs) under combined explosion and fragment loading. Johnson-Cook model is utilized to capture the damage response of aluminum material; 3D Hashin failure criteria are applied to predict the damage evolution of fiber composite material considering the high strain rate effect; cohesive elements are incorporated to simulate the inter-laminar delamination phenomena. The effectiveness of the proposed numerical model is verified through a comparison with available experimental data in ballistic impact conditions. In addition, a thorough analysis of the dynamic behavior and damage mechanism of FMLs is conducted, and the impact performance is extensively discussed in terms of the influences of explosion distance and explosion mass. This work serves as a valuable reference for future numerical studies on the explosive impact resistance of other FMLs structures. [ABSTRACT FROM AUTHOR]

Fiber metal laminates (FMLs) are made by sandwiching a fiber-reinforced composite between thin layers of metal. FMLs are modern materials utilized in the manufacture of automobiles and aircraft because of their improved mechanical behavior compared to conventional metallic alloys. In the current study, different fabrics, that is, jute (J), glass (G), carbon (C), basalt (B), and aramid (A) were used as reinforcing components for composites that were sandwiched between two aluminum (Al) alloy sheets as a metal component in the proposed FMLs. The effect of hybridizing J-reinforced composite with different declared fabrics on the tensile response of the designed FMLs was experimentally investigated. The proposed FMLs were created using manual lay-up and compression casting techniques. Complex proportional assessment (COPRAS) was adapted to find the best FMLs structure that achieved the optimum tensile properties. The Al/2C/4J/2C/Al and Al/8J/Al structures were ranked first and last, respectively, based on COPRAS results. [ABSTRACT FROM AUTHOR]

The inferior delamination resistance and out‐of‐plane performance of fiber metal laminates (FMLs) are of serious concerns. This work employs two modification methods, namely metal surface's chemical pre‐treatment and nano Al2O3 embedded interpenetrating polymer network (IPN) formation for improving the delamination resistance of aluminum and glass fiber‐reinforced polymer (GFRP) composite‐based FMLs. The synergetic effect of the two modification techniques resulted in high degrees of improvement in delamination resistance that were ~28% for critical strain energy release rate during mode‐I interlaminar fracture toughness (ILFT), that is (GIC) and ~37% for GIIC. Simultaneously, the flexural strength, tensile strength, and interlaminar shear strength improved by ~23%, ~17%, and ~24%, respectively. Scanning electron microscopy, atomic force microscopy, and surface energy measurement studies showed that the chemical pre‐treatment significantly influenced the surface morphology, surface roughness, and surface energy responses of aluminum, respectively. Fractographic study validated the effect of modification methods on the failure behavior under various testing modes. [ABSTRACT FROM AUTHOR]

In this paper, the tensile mechanical behavior and progressive damage morphology of glass-fiber-reinforced magnesium alloy laminate for different numbers of holes in a temperature range of 25–180 °C were investigated. In addition, based on extensive tensile tests, the tensile mechanical behavior and microscopic damage morphology of porous-glass-fiber-reinforced magnesium alloy laminates at different temperatures were observed by finite element simulation and scanning electron microscopy (SEM). Finally, the numerical simulation and experimental results were in good accordance with the prediction of mechanical properties and fracture damage patterns of the laminates, the average difference between the residual strength values of the specimens at ambient temperature was 5.57%, and the stress–strain curves were in good agreement. The experimental and finite element analysis results showed that the damaged area of the bonded layer tended to expand with the increase in the number of holes, which has a lesser effect on the ultimate tensile strength. As the temperature increased, the specimens changed from obvious fiber breakage (pull-out) and the resin matrix damage mode to matrix softening damage and interfacial delamination fracture damage. As the testing temperature of the specimens increased from 25 °C to 180 °C, the tensile strength of the specimens decreased by an average of 51.59%, while the tensile strength of the specimens showed a nonlinear decreasing trend. The damage mechanism of porous-glass-fiber-reinforced magnesium alloy laminates at different temperatures is discussed in this paper, which can provide a reference for engineering applications and design. [ABSTRACT FROM AUTHOR]

Fiber metal laminates (FMLs) are widely used in a variety of protective structures due to their excellent impact resistance. In the present work, a nonlinear finite element (FE) model is developed to investigate the damage behavior of carbon fiber reinforced aluminum laminates (CRALLs) under high velocity fragments impact. The strain rate effect of composite ply is involved and the intra-laminar damage is predicted based on 3D Hashin criteria; Johnson-cook model is employed to simulate the high velocity fragments impact response of aluminum layer; cohesive elements are introduced to describe the inter-laminar delamination phenomena. The proposed FE model is verified with the available experimental data in ballistic impact condition and then implemented to predict the fragments impact behavior of FMLs. The dynamic response and damage mechanism of FMLs are analyzed and the effects of explosion distance, explosion mass and impact angle on the impact performance are discussed in detail. [ABSTRACT FROM AUTHOR]

The cutouts are commonly found in fiber metal laminates to facilitate to pass electrical wires, water/fuel lines and sometime to facilitate easy access and inspection. Sometimes, such cutouts need to be reinforced by providing stiffener around the cutouts to avoid pre-mature failures. This article addresses the effects of reinforced cutouts and non-linearly varying edge loads on the vibration and buckling performance of inter laminar hybrid fiber metal laminates (HFMLs) by utilizing finite element approach. Toward this a 9-noded heterosis plate element has been used to discretize both plate and stiffener by taking into account the effect of shear deformation and rotary inertia. The stiffener considered in this study is spread in nature. The displacement compatibility by the plate and stiffener is maintained by using transformation matrix. The effect of eccentricity of the spread stiffener is also incorporated within the transformation matrix. Since the stress distribution within the plate is highly non-uniform in nature, the dynamic approach has been used to solve the buckling problems. The present study consists of aluminum metal face sheets bonded with four layered symmetric hybrid cross-ply laminates, in which six different hybrid configurations have been considered. The performance of each hybrid configuration along with different sized and positioned reinforced cutouts is well investigated under various nonlinear loading conditions. [ABSTRACT FROM AUTHOR]

Significant fluid–structure interaction is present in fiber metal laminate forming with a low viscous matrix. A modular, process-inspired test setup is presented for one-dimensional saturated and unsaturated infiltration experiments for fiber metal laminates. Permeability measurements for different fabric orientations, fabric layers, and fiber volume contents show low scatter and good repeatability for fiber volume contents up to 65%. Fiber metal laminate specimens were formed by exchanging the mid-segment of the test setup with a punch and die. The stiffness differences between metal and fabric lead to remarkably high compactions in the bending radii, significantly reducing the flow during infiltration. Contrary to resin transfer molding processes, no formation of resin-rich zones along bending edges occurs due to the high normal pressures from metal forming. A numerical forming simulation was developed to predict the local fiber volume content. Comparing the experimental results with the numerical simulation shows that the high fiber volume content in the radii almost exclusively impacts the overall permeability. Implications for fiber metal laminate processing and modeling are outlined. [ABSTRACT FROM AUTHOR]

The development of automotive components with reduced greenhouse gas (GHG) emissions is needed to reduce overall vehicle emissions. Life Cycle Engineering (LCE) based on Life Cycle Assessment (LCA) supports this by providing holistic information and improvement potentials regarding eco-efficient products. Key factors influencing LCAs of automotive components, such as material production, will change in the future. First approaches for integrating future scenarios for these key factors into LCE already exist, but they only consider a limited number of parameters and scenarios. This work aims to develop a method that can be practically applied in the industry for integrating prospective LCAs (pLCA) into the LCE of automotive components, considering relevant parameters and consistent scenarios. Therefore, pLCA methods are further developed to investigate the influence of future scenarios on the GHG emissions of automotive components. The practical application is demonstrated for a vehicle component with different design options. This paper shows that different development paths of the foreground and background system can shift the ecological optimum of design alternatives. Therefore, future pathways of relevant parameters must be considered comprehensively to reduce GHG emissions of future vehicles. This work contributes to the methodological and practical integration of pLCA into automotive development processes and provides quantitative results. [ABSTRACT FROM AUTHOR]

Fiber metal laminates have been widely used as the primary materials in aircraft panels, and have excellent specific strength. Bending deformation is the most common loading mode of such components. An accurate theoretical predictive model for the bending process for the carbon reinforced aluminum laminates is of great significance for predicting the actual stress response. In this paper, based on the metal-plastic bending theory and the modified classical fiber laminate theory, a modified bending theory model of carbon-fiber-reinforced aluminum laminates was established. The plastic deformation of the thin metal layer in laminates and the interaction between fiber and metal interfaces were considered in this model. The bending strength was predicted analytically. The FMLs were made from 5052 aluminum sheets, with carbon fibers as the reinforcement, and were bonded and cured by locally manufacturers. The accuracy of the theory was verified by three-point bending experiments, and the prediction error was 8.4%. The results show that the fiber metal laminates consisting of three layers of aluminum and two layers of fiber had the best bending properties. The theoretical model could accurately predict the bending deformation behaviors of fiber metal laminates, and has significant value for the theoretical analysis and performance testing of laminates. [ABSTRACT FROM AUTHOR]

The amalgamation of metallic alloys and fiber-reinforced composites has helped Fiber Metal Laminates (FMLs) like Carbon fiber reinforced aluminum laminates (CARALL) and Glass laminate aluminum reinforced epoxy (GLARE) overcome the limitations of standalone metals and composites. As a result, they have found increasing applications in the aircraft and defense industries. Moreover, the inhomogeneous nature and poor machinability of the materials make hole drilling a challenging task. Therefore, to enhance drilling performance, the paper reports a systematic analysis on the effect of spindle speed and axial feed on key performance measures, including thrust force, machining temperature, surface roughness, hole size, burr size, and chip morphology. Experimental outcomes indicate a significant reduction in the thrust force while utilizing higher spindle speed (4000 rev/min) and lower axial feed (0.1 mm/rev), while the surface finish improved under high feed conditions (0.4 mm/rev). The analysis revealed that machining temperature increased with the employment of higher spindle speed and lower axial feed. Higher spindle speeds and axial feeds are desirable from the perspective of hole accuracy as they help produce holes within H9 diameter tolerance. Burr size was verified to be larger at the hole exit compared to hole entry, with the size of the burr increasing with an increase in spindle speed and axial feed. The results show that the axial feed was the significant variable affecting chip size followed by spindle speed. Higher axial feed (0.4 mm/rev) and spindle speed (4000 rev/min) helped improve the chip breakability, thus helping in better chip evacuation.

Fiber metal laminates (FMLs) are widely used in various fields such as automotive and aerospace due to their high stiffness and strength-to-weight ratios. Moreover, they also have high fatigue resistance. In some applications such as aircraft structures, it is crucial to do dynamic analysis of the FMLs structure. FMLs compose of aluminium and fiberglass reinforced polymers (FRPs) are used in this study. The aim of this study is to investigate the effect of shape mode and aspect ratio on the stress distribution of FML by using finite element analysis software. Ten initial mode shapes and the aspect ratio of 1:1.5, 1:2, and 1:2.5 are used as the environmental conditions of the FMLs. The results indicate that the mode shape will change the stress distribution and the maximum stress position. Besides, the results have shown that a wider FMLs plate will increase the maximum stress and deformation. The maximum to minimum stress distribution occurs on the outer aluminium surface, the inner aluminium surface, and the FRPs surface, respectively.

The transportation industry needs lightweight structures to meet economic and environmental demands. Composite sandwich structures offer high stiffness and low mass, making them ideal for weight reduction in high-speed trains. The objective of this research is to develop a method of weight and cost optimization for floors of high-speed trains. The studied sandwich floor structure consists of Fiber Metal Laminates (FML) face sheets and a honeycomb core. Different variations of FMLs were investigated to define the optimal sandwich structure for minimum weight and cost. The Neighborhood Cultivation Genetic Algorithm (NCGA) was used to search the design space, and the Finite Element Method (FEM) was used to construct the optimal design of the train car floor panel. The FEM and optimization results had a maximum difference about 11%. The study concluded that using face sheets made entirely of Fiber-Reinforced Plastic (FRP) or Fiber Metal Laminates (FMLs) resulted in significant weight savings of approximately 62% and 32%, respectively, compared to a sandwich structure made entirely of aluminum, but a lighter structure was associated with higher cost. The main contribution of this study is the elaboration of a multi-objective optimization method that utilizes a wide range of constituent materials and structural components in order to construct weight- and cost-optimized sandwich structures. [ABSTRACT FROM AUTHOR]

To shorten the preparation cycle of Al/PEEK/CFRP laminates fabricated by Al sheets, peek films, and CFRP prepreg and reduce energy consumption during the preparation process to ensure the highest quality laminates, a novel forming process based on self‐resistance electric (SRE) heating was proposed. Considering the tensile properties, fracture morphology, and void content comprehensively, the influence of current intensity (11.5, 12.5, 13.5 A) on the forming quality of laminates was explored. This optimized electric heating process was compared with the traditional heating process with respect to forming time, energy consumption, and the performance of the prepared samples. The results show that when the current is 12.5 A, the molding quality of the samples prepared by the SRE process is better than that of the traditional process. In addition, the SRE process significantly reduces forming times and saves energy. This SRE heating method provides a new process optimization pathway for the preparation and formation of fiber metal laminates and exhibits great prospects for future research. [ABSTRACT FROM AUTHOR]

Fiber‐metal laminates (FMLs) are attracting much attention from researchers as emerging aerospace materials. In this paper, 1060‐H112 aluminum alloy‐carbon/glass fiber laminates were prepared by vacuum bagging method. Subsequently, based on tensile, three‐point bending and low‐velocity impact experiments, the quasi‐static mechanical properties as well as the dynamic response to impact of the two fiber laminates were investigated. The results show that the carbon fiber metal laminate (CARALL) has stronger tensile strength and inter‐ply tensile consistency, while the glass fiber metal laminate (GLARE) has better bending resistance. The impact response of CARALL and GLARE is closely related to the impactor shape and impact energy. The peak loads of the FMLs increased with increasing impact energy over the range of impact energies tested. However, the peak load of CARALL is more sensitive to the impact energy, while the deformation of GLARE is more sensitive to the impact energy. With complete penetration of the impactor into the target, the fibers of GLARE were ductile fracture and fibers of CARALL were brittle fracture for the blunt impactor impact, while the fibers of both GLARE and CARALL were ductile fracture for the hemispherical impactor impact. Under the impact of both impactors, two types of FMLs showed matrix broken, delamination, and local debonding. [ABSTRACT FROM AUTHOR]

During deep drawing processes of fiber metal laminates, such as the newly developed in-situ hybridization process, fibers and metal sheets come into contact while the dry fabric is infiltrated by a reactive matrix system. The viscosity of the matrix increases as polymerization starts during deep-drawing. In the in-situ hybridization process, a dry fiber metal laminate is deep drawn while a thermoplastic matrix system is injected into the glass fiber fabric layer in a resin transfer molding process. During forming of the fiber metal laminate, friction occurs in tangential direction to the metal sheet. The friction plays the main role in preventing the elongation of the sheets in the deep drawing process. Therefore, the measurement of friction coefficients between fibers and metal sheets is essential. In this paper, the friction between sheet metal and dry or infiltrated glass fiber fabric under high contact pressures of 1.67 MPa, as occurring in deep drawing processes, is characterized. A modified strip drawing test setup is used to analyze the coefficient of friction under a constant high contact pressure. Compression tests were performed to show that Coulomb friction can be assumed. Different types of glass fiber fabrics and liquids with defined viscosities are used. It was found that fluids with higher viscosity decrease the friction coefficients in the interface, which is physically explained. For the in-situ hybridization process, it is deduced that with low viscosities, a better infiltration is achieved, while higher viscosities reduce the friction coefficient for better formability. [ABSTRACT FROM AUTHOR]

In the face of fierce competition in the automotive market, severe environmental problems, and the consistent enhancement of consumer demands for vehicle performance, research and development for new automotive materials have increased. Fiber metal laminate (FML) is a representative hybrid composite in recent years but the application of FMLs in the automotive industry is still rare. In order to boost the strengths and applications of FMLs, a lot of effort has been put into enhancing their mechanical properties. In this review article, up-to-date information on the mechanical performance of FMLs for automotive components is presented. The mechanical testing methods, materials selection, structure design, fabrication methods, and the application of hybrid FMLs were explored. The objective of this review article is to study different factors that influence the mechanical properties of FMLs and provide some optimization directions from various aspects. From recent research, there will be great opportunities for hybrid FMLs utilizing natural fibers and bio-polymers in the automotive field in the future.

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.

Owing to the increasing demand for high performance and lightweight materials, fiber metal laminates (FMLs) have become the alternative materials to replace metallic alloys. When the environmental friendliness of the materials is taken into consideration, plant fibers have shown an excellent potential to be employed as the reinforcements in FMLs. This work describes the mechanical behavior of kenaf and pineapple leaf fibers (PALF) reinforced metal laminates with various fiber contents, ranging from 10 wt% to 50 wt%. Fiber metal laminates were formed through the coalescence of metallic skin layers with the composite as the core. The mechanical tests were then conducted to study the tensile, flexural and Charpy impact properties of the structures. From the findings, it was concluded that both the kenaf and PALF based FMLs showed the optimum mechanical properties when the fiber content was fixed at 30 wt%. In addition, PALF based FMLs had shown higher mechanical properties over kenaf based FMLs. At a fiber content of 30 wt%, the tensile and flexural strength of PALF based FMLs were respectively 6.18% and 3.44% higher than kenaf based FMLs. In terms of impact properties, the impact strength of PALF based FMLs was 5.06% and 40.73% higher than kenaf based FMLs in the flatwise and edgewise orientations.

In this article, the pipeline design is introduced. The new pipe structure is made of new fiber metal laminates with the unidirectional composite and sheet metal (Ti–Ni alloy). Many pipe structures are in the heating environment such as in or around the engine, which will also cause the heating-up structure. If the shape memory alloy (SMA) fiber is added to the composite lamination, it can be seen that with the increase of temperature, the stiffness of the structure is increased and so is its frequency. The changed frequency of the structure can avoid the excitation frequency in this way, which effectively inhibits the resonance. In dynamic analysis, it can also show that the pipeline with the SMA fiber has good performance for vibration reduction and noise attenuation. Additionally, the convergence of the meshing model and the effect of the thickness of the SMA material on vibration and noise reduction are also discussed.

The aim of this study is to investigate the effects of metal‐composite interface (MCI) adhesive quantity on the energy absorption and failure behavior of fiber metal laminates (FMLs) under ballistic impact. The dynamic shear and ballistic impact tests were systematically conducted, and CT scan was employed to quantitatively investigate the damage and failure mechanisms of the FMLs. The results reveal that the dynamic shear strength of MCI initially increases and then remains constant with the increase in the adhesive quantity at a constant strain rate. Moreover, the MCI adhesive quantity has a certain influence on the impact energy absorption of FMLs, and the degree of influence is related to the impact velocity. At an impact velocity of 360 m/s, the difference of energy absorption is maximal, approximately 14.7%. The distribution of total debonding area changes with increase in the adhesive quantity. When the impact velocity is 212 m/s, compared to FMLs with the lowest adhesive quantity, the total debonding area of FMLs with the highest adhesive quantity decreases by 774.57 mm2 (9.20%), otherwise the debonding area near the rear aluminum alloy sheet increases by 595.94 mm2 (58.99%). [ABSTRACT FROM AUTHOR]

The low-velocity impact resistance of fiber metal laminates (FMLs) is investigated. FMLs with titanium alloy Ti-6Al-4V sheets and glass fiber/epoxy layers are fabricated using the hand layup technique, exhibiting the same total metal layer thickness. A drop tower is used to produce a low-velocity impact on the FMLs. FML with outermost metallic layers exhibits comparatively higher lateral spreading and interlayer delamination opening contrary to FML with more metallic layers. This is also observed in high-velocity impact. The low-velocity impact resistance of titanium-based FMLs seems higher than aluminum-based FMLs. This is also noticed in high-velocity impact for former and latter FMLs. [ABSTRACT FROM AUTHOR]