•The CARALL’s are characterised by high resistance to dynamic load.•The delamination at the interfaces were one of the critical form of damage.•The proposed model can be used to effective examination ...of the FML’s to impact.
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.
•Theoretical solution for predicting dynamic response of CARALL under off-center impact is developed.•Establishment and simplification method of yield criterion for hybrid plastic hinges is ...proposed.•Theoretical model reveals the energy absorption mechanism of CARALL under off-center impact.
Carbon fiber reinforced aluminum laminate (CARALL) composed of multi-layer CFRP and aluminum has better toughness and impact resistance than composite laminates due to the existence of metal. This work investigates the energy absorption mechanism and creatively proposes a theoretical analysis model to predict the dynamic response of CARALL under off-center impact. Firstly, based on a simplified ideal rigid-plastic material model, a unified yield criterion and its simplified method for hybrid plastic hinges are proposed. Then, the analytical solution for maximum transverse displacement and impact force of CARALL under off-center impact is established. Finally, it is verified by the simulation and discussed in detail. The results show that the established theoretical method can predict the structural response under low-velocity impact.
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•Manufacturing of different Fiber Metal Laminate (FMLs) through VARTM process.•Use of Anodizing process on Aluminum metal surface.•Interlaminar Shear strength (ILSS) characterization of FMLs under ...different displacement rates.
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.
This paper investigates the low velocity impact behavior of the carbon fiber aluminum laminates (CARALL). The purpose of the research is to study the applicability of carbon fiber in FMLs and the ...effect of the properties of aluminum alloy on the low velocity impact response of CARALL. A user-defined material subroutine (VUMAT) is used to define Hashin’s 3D damage constitutive model of composite. The numerical simulations using the progressive damage model have a good agreement with the test results of Glare in the impact incident. Simulation results reveal that CARALL represents the better impact resistance property than Glare due to the high strength and stiffness carbon fiber reinforced plastic (CFRP). The numerical simulations using the proposed damage model successfully predict the impact mechanical behavior of CARALL. In addition, finite element models are developed to investigate the effect of the impact resistant of CARALL panels with different aluminum alloys, namely 1060-O, 2024-T3, 6061-T6 and 7075-T6. It is shown that the impact resistance of CARALL is improved by increasing the yield strength of aluminum alloy.
Abstract A reliable strategy to enhance the bonding ability in carbon reinforced aluminum laminates (CARALL) is proposed, which is based on the mechanical interlocking effect generated by the surface ...slot structure of aluminum alloy enhances the structural interface between fibers/resins and aluminum alloy. The characteristic of slot structure is determined, and the strengthening mechanism of bonding interfaces is revealed. The CARALL samples with slot structure are fabricated via an hot pressing process. The micro texture morphologies, mechanical, interlayer bonding properties under different conditions are studied. The results indicate that forming a slot structure on the aluminum surface is beneficial for improving the interfacial bonding performance. Compared with the non‐slotted structure, the interlayer type II fracture toughness of the slotted structure is increased by 112.99%. The slotted structure can reduce the defects at the interface between the layers and improve the interface bonding force. In this work, the interlaminar shear strength (ILSS) of the slotted structure sample was 27.08% higher than that of the non‐slotted structure sample. Highlights A slotted structure was proposed to solve the problem of insufficient bonding strength. A slotted structure consistent with the direction of adjacent fibers is designed. The interlayer type II fracture toughness of the slotted structure is increased by 112.99%. The final crack propagation of the slotted structure sample is reduced by 40%. The final failure area of the slotted structure sample is reduced by 53.85%.
Fibre Metal Laminates are characterized by low density, high static and fatigue strength, high impact resistance and good corrosion resistance. Currently some new solutions of FML which will contain ...carbon fibre reinforced polymer layers with aluminium (CARALL laminates) are tested.
The purpose of the study was to investigate the influence of the thermal cycles on interlaminar shear strength and microstructure of aluminium-carbon fibres laminates modified by additional glass interlayer.
Six different variants of laminates were tested. The 1500 thermal cycles were used. Before and after thermal cycles, the Interlaminar Shear Strength tests were conducted to compare the shear properties of CARALL and CARALL with thin glass interlayer. No delamination, cracks of matrix or fibres were observed after thermal cycles. The interlaminar shear tests have shown that the strength is not dependent on thermal cycles. However, some differences in microstructure of FML after ILSS were noted. Laminates without thermal cycles were damaged more often by delamination at the metal/composite interphases in the middle region of sample (directly under the stamp), whilst the laminates after thermal cycles were damaged also by delamination at the metal/composite interphases but the delamination mostly originated from the edges of the samples. National Science Centre, Poland UMO-2014/15/B/ST8/03447.
Functionalized multi-walled carbon nanotubes were deposited on the carbon fabric using ultrasonic-assisted electrophoretic deposition. The effect of carbon nanotubes (CNTs) deposition time and ...morphology on the mode I interlaminar fracture resistance of carbon reinforced aluminum laminates (CARALL) was investigated. The formation of a proper network of CNTs on the carbon fabric favorably deviated the crack growth into the carbon fabric layer and intensified the fiber bridging during the delamination. The CNT coating on the carbon fiber in conjunction with the alkaline-acid treatment on the Al substrate significantly promoted the interlaminar fracture initiation and propagation energies and stabilized the fracture behavior.
This paper aims to explore the off-center low-velocity impact response and damage characteristics of carbon fiber reinforced aluminum laminate (CARALL). Progressive damage finite element models of ...CARALL considering the stiffness degradation and damage evolution of carbon fiber reinforced plastic (CFRP) were established using a user subroutine and verified by off-center impact tests with different impact energies. The motion propagation, damage, and spatial distribution of dynamic responses of CARALL impacted in different locations are studied. The results indicate that increase in impact distance from center dissipates more energy due to the more severe damage and failure of CFRP, while the off-center impact have a negative effect on the plastic energy absorption of metal compared with center impact. A quantitative expression is proposed to describe the spatial distribution of the maximum transverse displacement.
Abstract Carbon Fiber Reinforced Aluminum Laminated (CARALL) composites are widely used in aircraft structures due to their ability to be produced in different shapes with desired properties and ...their high impact resistance properties. As with other layered composite materials, processing of CARALL composites by conventional manufacturing methods results in many damage mechanisms such as fiber breakage, deformation in the hole region, stress concentration, resin‐fiber separation and microcracks. One of the modern manufacturing methods, Abrasive Water Jet (AWJ), is a processing method in which the material is removed by abrasion and almost any material can be cut without thermal degradation. There are no experimental studies in the literature on the drilling of CARALL composites by modern manufacturing methods. The aim of this study is to investigate the impact of machining parameters on the output variables (kerf taper angle (K) , roundness error (Re) and material removal rate (MRR) ) as well as the effect of fiber orientation on the drilling of CARALL composites with different fiber orientations on an AWJ machine. PROMETHEE‐GAIA weighted by Entropy Weighting Method were used to ascertain the optimum levels of control factors. CARALL composites with different fiber orientations were drilled with an 8 mm diameter AWJ with three different water pressures, three different nozzle feed rates. With PROMETHEE‐GAIA multi‐criteria optimization method, the optimum levels of the factors that provide both minimum Re and K values and maximum MRR value were obtained with twill woven material, 1680 mm/min feed rate and 1680 bar water pressure. Highlights CARALL composite materials with two different fiber orientations (twill weave and UD) were used. CARALL composite materials were drilled at different machining parameters. Abrasive water jet was used in drilling experiments. Optimum drilling parameters were determined to achieve minimum roundness error, minimum kerf angle and maximum material removal rate. PROMETHEE‐GAIA was used as a multi‐criteria decision‐making method.
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