Carbon Fiber Reinforced Aluminum Laminates Research Articles

Enhancing carbon fiber reinforced aluminum laminates with cellulose paper interlayers: experimental characterization of tensile, flexural, and interlaminar fracture toughness

ABSTRACT The mechanical properties of fiber metal laminates (FML) are influenced by several various factors. Interface adhesion plays a particularly crucial role in interlaminar strength. Enhancing the interlaminar strength of carbon fiber reinforced aluminum laminate (CARALL) composites present a persistent challenge due to inherent weaknesses between metal and composite elements. Therefore, this study focuses on improving the interlaminar performance of CARALL composites by introducing cellulose paper interlayer at the metal/composite interface. The cellulose paper interlayer offers the advantage of being cost-effective and sustainable. Cellulose paper-interleaved CARALL composites were fabricated by vacuum bagging method and exhibited noteworthy improvements in mechanical properties. Comparative analysis with pristine samples revealed substantial enhancements, including a 15% increase in tensile strength, a remarkable 42% improvement in flexural strength, and a significant enhancement in mode-I fracture toughness by 65%. Furthermore, the cellulose paper interleaving played a crucial role in stabilizing fracture formation at the fiber-matrix interface, with mode II fracture toughness witnessing a 3% increase. Visual examination revealed the underlying toughening processes occurring in the interfacial area. This innovative approach of interleaving laminated composites with cellulose paper emerges as a sustainable and effective strategy, demonstrating the potential to fortify and toughen the interlaminar zones of CARALL composites.

Numerical investigation on dynamic behavior and damage mechanisms of fiber metal laminates subjected to combined explosion and fragments loading

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.

Molding preparation and tensile properties test of carbon fiber reinforced aluminum laminates

Molding preparation and tensile properties test of carbon fiber reinforced aluminum laminates

Progressive Damage Behaviour Analysis and Comparison with 2D/3D Hashin Failure Models on Carbon Fibre-Reinforced Aluminium Laminates.

It is known that carbon fibre–reinforced aluminium laminate is the third generation of fibre metal materials. This study investigates the response of carbon fibre–reinforced aluminium laminates (CARALL) under tensile loading and three-point bending tests, which evaluate the damage initiation and propagation mechanism. The 2D Hashin and 3D Hashin VUMAT models are used to analyse and compare each composite layer for finite element modelling. A bilinear cohesive contact model is modelled for the interface failure, and the Johnson cook model describes the aluminium layer. The mechanical response and failure analysis of CARALL were evaluated using load versus deflection curves, and the scanning electron microscope was adopted. The results revealed that the failure modes of CARALL were mainly observed in the aluminium layer fracture, fibre pull-out, fracture, and matrix tensile fracture under tensile and flexural loading conditions. The 2D Hashin and 3D Hashin models were similar in predicting tensile properties, flexural properties, mechanical response before peak load points, and final failure modes. It is highlighted that the 3D Hashin model can accurately reveal the failure mechanism and failure propagation mechanism of CARALL.

Comprehensive experimental investigation on drilling multi-material carbon fiber reinforced aluminium laminates

The amalgamation of metallic alloys and fiber-reinforced composites has helped Fiber Metal Laminates (FMLs) like Carbon fiber reinforced aluminum laminates (CARALL), and Glasslaminatealuminum-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 challenging. Therefore, to enhance drilling performance, the paper reports a systematic analysis of 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 finishes 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 the 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 improve chip evacuation.

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.

Experimental and Numerical Simulation Studies of Failure Behaviour of Carbon Fibre Reinforced Aluminium Laminates under Transverse Local Quasi-static Loading

This paper investigated the failure behaviour of medium thick carbon fibre reinforced aluminium laminates (CARALL) panels under transverse local quasi-static contact crush experimentally and numerically. Four types of CARALL specimens with a 3/2 configuration were manufactured by hot-pressing process using two type of aluminium alloys (2024-T3, 7075-T6 aluminium alloy) and CFRPs with different lay-up ([0°/90°/0°]3, [45°/0°/-45°]3). Three dimensional Hashin progressive failure model in quadratic strain form with damage evolution laws defined by subroutine VUMAT based on ABAQUS was used to simulate the composite layers. The bilinear cohesive contact model was used to predict interfacial failure. Aluminium alloys were defined by Johnson-Cook model. Numerical predictions composing of load-deflection curves and failure mode were matched closely with experimental results. The results of the analysis shown that delamination in CFRP/Al interfaces was the initial damage of the tested CARALL panels. Matrix failure occurred after the delamination closely. The maximum load bearing was determined by fracture of aluminium alloy. Fibre breakage was responsible for complete failure of specimens.

Strength and failure behavior of carbon fiber reinforced aluminum laminates under flexural loading

The current work investigates the influences of different surface modifications on the flexural characteristics of carbon fiber reinforced aluminum (AA2024-T3) laminates fabricated at 3/2 sequence. Among all types of surface modifications, mechanical abrasion by 220-grit paper shows highest flexural strength. The flexural load of Al/0°/Al/0°/Al configuration is about 19% higher in comparison with mechanical abrasion (220-grit paper) with chemical treatment due to higher interfacial strength. However, corrosion resistance is improved about 30 times in the later modification. In-situ imaging reveals that failure of Al/0°/Al/0°/Al laminates initiates by micro-buckling of carbon fiber whereas matrix cracking initiates the failure in Al/90°/Al/90°/Al laminates.

Impact Response and Damage Characteristics of Carbon Fiber Reinforced Aluminum Laminates Under Low Velocity Impact Loading

CARALL hybrid material has been extensively used in the aircraft structure due to their competitive impact strength. Low velocity impact test is utilized to evaluate the impact and damage properties for such material. It is also employed to observe complex damage mechanisms. A numerical modelling is an alternative way for impact assessment. This paper investigates the impact and damage properties under low velocity impact using numerical modeling and experimental work. A three-dimensional (3D) finite element (FE) model was devolved and validated with two studies from the literature. This model was meshed with solid elements. It was subjected to 2.4 m/s impact velocity and to 10 J impact energy. Absorbed energy, penetration, impact load and damage morphology were obtained. The impact energy was efficiently absorbed by the material. Both aluminum alloy layers underwent plastic deformation whereas the fiber layer failed. A macroscopic cross-sectional morphology was presented using the FE model. An agreement between the numerical and the experiment results were achieved and discussed.

Experimental and numerical investigation into the impact resistance of aluminium carbon laminates

Carbon fibre-reinforced aluminium laminates are relatively new fibre-metal laminate materials. Their properties include low density, high resistance and rigidity, and high fatigue strength. This study aimed to evaluate the CARALL response to low-velocity impact, based on experimental tests and numerical analyses of damage initiation and propagation mechanisms. These experimental tests and numerical simulations involved the use of both quantitative and qualitative criteria for assessing the FML damage under dynamic load. It was shown that the mechanism of laminate damage is fairly complex and related to the internal degradation of the composite material with characteristic permanent deflection of the FML. Matrix fractures, carbon-fibre cracking, and delamination were found to be the main modes of damage. The delamination observed at the interfaces of specific multidirectional plies of the composite material and the delamination at the metal-composite interfaces were the critical damage modes of the FMLs. The proposed FEM, including its user-developed failure criteria and cohesive zone, can be used to further examine the influence of various parameters describing FMLs and other adhesive-bonded materials in an effective and reliable manner.

High Velocity Impact Response of Aluminum- Carbon Fibers-Epoxy Laminated Composites Toughened by Nano Silica and Zirconia

This research work investigated the effects of SiO2 and ZrO2 nanoparticles type and content incorporated into an epoxy matrix on the high velocity impact behavior of carbon fiber reinforced aluminum laminates (CARALL). CARALL specimens consisted of a 0/90/90/0 stacking sequence of a carbon-epoxy composite containing 0, 1, 3, 5 and 7 wt% of each of nanoparticles sandwiched between two layers of aluminum 2024-T3. To observe the toughening effects of the nanoparticles on the fracture surface of the impacted CARALL, a typical field emission scanning electron microscope (FESEM) was employed. Impact energy absorption of CARALL was at most increased by 18 % and 12 % with the nanoparticles content of 5 wt% SiO2 and 3 wt% ZrO2, respectively. Overloading of the nanoparticles content up to 7 wt% resulted in the creation of nanoparticles aggregated sites associated with loss in the energy absorption capacity. FESEM fractography procedure also showed that the crack deflection and pinning were the most recognizable toughening mechanisms exhibited by nanoparticles. Overall, the controlled addition of SiO2/ZrO2 rigid nanoparticles to CARALL was found to be a promising method for improving the high velocity impact energy absorption of CARALL.

Performance evaluation of CFRP/Al fibre metal laminates with different structural characteristics

FMLs (fibre metal laminates) are a kind of hybrid material consisting of composite material layers alternating to metal sheets, that present high mechanical characteristics. The aim of the present work deals with the flexural behaviour of CARALL (carbon fibre-reinforced aluminium laminates) specimens; in fact, the influence of both the layer thickness and the adhesion interface between CFRP layer and aluminium sheets was analysed. Four different laminates, bonded with structural adhesive or with prepreg resin only and with one or two metal sheets (but maintaining the composite/metal volumetric ratio at a constant value), were tested according to the three points bending scheme. The experimental tests evidenced that the flexural strength increased in absence of the adhesive layer and with a single metal sheet. Moreover, some micrographs of the fractured specimens were taken to determine the failure mechanism.

Investigation of the mechanical behavior of CARALL FML at high strain rate

Fiber metal laminates (FMLs) are hybrid composite structures made of thin sheets of metal alloys and plies of polymeric materials reinforced with fibers. Among various FML, CArbon Fiber Reinforced ALuminum Laminates (CARALLs) are appreciated because of their excellent impact resistance and energy absorption property; for the correct design of components that are intended to exploit such capabilities, the mechanical characterization is very important, not only in quasi-static but also in high strain rate conditions. With this regard, CARALL has received less attention if compared with other FMLs; moreover, conflicting results are found in the literature, as the actual properties depend on a number of parameters. Each type of FML requires a dedicated test campaign for a correct characterization.Hence, this work shows the mechanical characterization of a newly developed CARALL, manufactured in the laboratories of the Wayne State University, that makes no use of adhesives film among layers. Quasi-static and dynamic tensile tests have been carried out on CARALL sheet samples.The dynamic tests were made by a direct version of Split Hopkinson Bar (SHB) at an average strain rate of 300 s−1; in the work, the difficulty of achieving accurate strain measurements in such tests was also analyzed, concluding that a direct strain measure by image analysis is essential. A finite element model was also used to confirm the validity of the adopted approach.Finally, the specific CARALL here considered is not strain rate sensitive in terms of material strength; on the contrary, it shows a different failure mode if subjected to dynamic rather than quasi-static loading.

Impact behavior analysis of carbon fiber reinforced aluminum laminates based on a micro-mechanical damage model

A micro-mechanical damage model is proposed to investigate the low-velocity impact behavior of carbon fiber reinforced aluminum laminates (CARALL). This proposed method is able to study the failure mechanisms of fiber and matrix based on their individual micro stresses, which is more precise than other macro stress damage models. Stress amplification factors are adopted to realize the rapid micro stress calculation of key points in fiber and matrix, and combined with physical failure criteria the progressive degradation of composite stiffness is realized. A nonlinear elasto-plastic model is adopted to study the deformation and fracture of aluminum sheet. The cohesive zone model with a bilinear traction-separation relation is adopted to study the delamination initiation and propagation. The finite element model of impacted CARALL is established on ABAQUS/Explicit platform, and a user-defined material subroutine (VUMAT) is written to implement this proposed model. The predicted structure responses and damage mechanisms show good agreements with experimental results, which helps to obtain the profound understanding of this new kind of hybrid material.

Finite element simulation of damage in fiber metal laminates under high velocity impact by projectiles with different shapes

Fiber metal laminates (FMLs) have been widely used in many high-tech industries as protective structures because of their excellent impact resistance. The damage constitutive model that accurately characterizes the complex damage modes and failure processes of FMLs is the base to study the ballistic impact problems by numerical simulation. In this paper, a nonlinear finite element model based on continuum damage mechanics is established to investigate the damage modes and failure mechanisms of carbon fiber reinforced aluminum laminates (CRALLs) under high velocity impact. Johnson-Cook material model and a 3D rate-dependent constitutive model are applied to identify the in-plane damage in aluminum and fiber composite layers respectively; cohesive elements governed by bilinear traction-separation constitutive model are implemented to simulate the inter-laminar delamination induced by impact. The ballistic performance and damage characteristics of CRALLs under high velocity impact by projectiles with different shapes are studied in detail. The obtained numerical results correlate well with the available experimental data thus validates the proposed finite element model, which also provides an appropriate reference for numerical studies of high velocity impact issues in other FMLs.

Characterization of progressive damage behaviour and failure mechanisms of carbon fibre reinforced aluminium laminates under three-point bending

In this study, the failure behaviour of a 3/2 carbon fibre reinforced aluminium laminates (CARALL) under three-point bending were investigated experimentally and numerically. Two different progressive failure models were compared for modelling the composite layers: the Abaqus in-built two-dimensional model and a combined three-dimensional Puck failure model with strain-based damage evolution laws implemented by explicit finite element subroutine Abaqus-VUMAT. Interfacial failure was simulated by the bilinear cohesive contact model and aluminium layers were described using Johnson-Cook model. Experiments including load-deflection curves and micro-observation using scanning electron microscope were performed to validate the numerical predictions. Results indicated that the VUMAT model is more accurate in predicting the flexural mechanical response and failure mechanisms than the in-built two-dimensional model during the whole loading stages. In addition, influences of stacking structures between aluminium and composite layers on the flexural behaviour were explored based on validated numerical methods.

Mechanical properties of carbon fibre reinforced aluminium laminates using two different layering pattern for aero engine application

ABSTRACTThe properties of carbon reinforced fibre with aluminium alloy 2024-T3 sheets of different sequence were studied. The aim of the research is to analyse and compare the mechanical properties of two different layering sequences of the composite. The composites uses hand lay-up method in its fabrication in a mould. Tensile, compressive and flexural strength were investigated in the study using an Instron 3382 Universal Testing Machine according to their ASTM standard. There is about 11%, 7% and 53% increase on tensile strength, tensile modulus, and elongation at break for carbon fibre reinforced aluminium laminates with aluminium alloy at front and rear face. This was also true for flexural strength of the two composites; where a greater value was obtained for the aluminium alloy at front and rear face of the composite with the same compressive strength and lower difference on compressive modulus. Therefore, the study show that the two composites have good mechanical properties that can withstand a load in fire designated zone of an aircraft engine.

Effect of Resin Rich Veil Cloth Layers on the Uniaxial Tensile Behavior of Carbon Fiber Reinforced Fiber Metal Laminates

The influence of stacking sequence and resin rich (polyester veil cloth) layers, which were used to improve the adhesion between carbon fiber/epoxy (CFRP) and aluminum layers (AL), on the uniaxial tensile response of carbon fiber reinforced aluminum laminates (CARALL) was investigated in this research study. The metal volume fraction was varied to prepare two types of CARALL laminates having a 3/2 configuration with the help of a vacuum press without using any adhesive film. Numerical simulations were performed by utilizing commercially available finite element (FE) code, LS-Dyna to predict the tensile response of these laminates with initialization of predicted thermal residual stresses that developed during curing of laminates. Delamination failure was considered in the numerical simulation by utilizing the well-known B-K mixed-mode damage propagation model. It was found that addition of epoxy resin rich (polyester veil cloth) layers used for enhancement of interfacial bond adhesion and to ensure no separation between AL-CFRP layers increased the tensile strength of CARALL laminates.

The Influence of the Thickness and Areal Density on the Mechanical Properties of Carbon Fibre Reinforced Aluminium Laminates (CARAL)

A novel composite material consisting of a laminate of several thin aluminium sheets bonded with layers of carbon fibre mat/epoxy resin. Carbon fibre reinforced aluminium laminates (CARAL) offer specific advantageous properties such as better strength, fatigue, impact, corrosion resistance, fire resistance and weight savings. CARAL is a kind of fibre metal laminate system. In the present work, CARAL was prepared and experimental tests were conducted to evaluate the influence of the thickness and areal density on the mechanical properties of CARAL. Mechanical properties such as, the tensile strength and flexural strength of the laminates were increased with the increase in thickness and areal density. CARAL with four aluminium layers and three carbon fibre mat layers have superior strength than the laminates with lesser number of layers due to thickness of laminates and areal density.

An experimental investigation into the high velocity penetration resistance of CFRP and CFRP/aluminium laminates

Carbon fibre-reinforced composite materials are of high potential as protective casing in the aerospace area, acting as an effective solution to lighten components against the collision. The high velocity penetration resistance abilities of unidirectional CFRP laminates and two carbon fibre reinforced aluminium laminates CRALL2/1 and CRALL3/2 (fabricated from T700S CFRP layers combined with aluminium alloy 2024-T3 layers) were evaluated by the ballistic tests with a flat, hemispherical or conical nosed projectile. Revealed from ballistic tests that fracture modes, ballistic limits and specific energy absorptions of CRALLs and CFRP were sensitive to nose shapes. Higher ballistic limits and specific energy absorption ability were performed by CRALLs than monolithic CFRP impacted by all shapes due to the strain rate hardening effect and failure conversion effect. In particular situation of flat nose projectiles penetrating, the specific energy absorption of the CRALL3/2 was 8% higher than that of monolithic aluminium alloy 2024-T3 at same thickness. The CRALLs may then be designed as effective lightweight structures to protect frames against collision in the aerospace area and outperform the traditional single CFRP laminates.