Carbon Fiber-reinforced Epoxy Research Articles

Modelling damage in multidirectional laminates subjected to multi-axial loading: Ply thickness effects and model assessment

A meso-scale damage modelling framework for composite laminates is assessed against multi-axial experimental data obtained from specimens subjected to combined tension/compression and shear loading using a modified Arcan fixture (MAF). Two laminates made from unidirectional carbon fibre-reinforced epoxy plies of different thickness are considered to investigate the ply thickness effect on the damage behaviour of modified open-hole specimens. Intra-laminar damage is predicted using a continuum damage model combined with a fibre-aligned mesh, while cohesive zones are used to account for inter-laminar damage. The multi-axial open-hole specimen strength is predicted with a mean relative error of 15% across all the investigated lay-up and loading configurations, while the predicted damage maps show encouraging agreement with full-field measurements obtained using digital image correlation (DIC). However, the assessment reveals limitations of the assumption of small strains and rotations in the formulation of the model that lead to spurious model behaviour for shear-dominated damage modes.

Recycling of Carbon Fiber-reinforced Epoxy Resin-based Composites Using a Benzyl Alcohol/Alkaline System

High-efficiency recycling of carbon fiber-reinforced epoxy resin-based composites is difficult because of their three-dimensional network structure. In this article, a benzyl alcohol/alkaline system was used to recycle carbon fiber-reinforced epoxy resin-based composites cured by an anhydride. The degradation rate, mechanical properties and degradation mechanism of the recycled carbon fiber were determined by gas chromatography-mass spectrometry, Fourier transform infrared spectroscopy, liquid chromatography-mass spectrometry, scanning electron microscope and X-ray photoelectron spectroscopy. The experimental results indicated that there were two steps in benzyl alcohol/K3PO4 degradation system. The first was transesterification by benzyloxy selective attack to give small-molecule esters. Then the esters were saponified by the alkaline materials. After degradation, the stratification of resin and benzyl alcohol occurred, which was conducive to their separation. The optimal degradation time was 40 min under the weight ratio of alkaline material to benzyl alcohol of 1:10, atmospheric pressure, and temperature of 195 °C and the decomposition efficiency exceeded 90 %. A clean carbon fiber surface was obtained with an oxygen content comparable to that of the original carbon fiber. The tensile strength of the recycled carbon fiber was above 90 % of the original value.

Study on Properties of Z-pin-reinforced and Rivet-reinforced Composite T-joint: Experiment and Simulation

In this paper, the properties of z-pin and rivet reinforced composite T-joint are studied through experiment and finite element simulation, and the reinforcement effects of z-pin and rivet are compared. The composite T-joint is made of the carbon fibre reinforced epoxy resin bi-directional cloth. Z-pins and rivets are used to enhance the joint strength, and their total weight is equal. The influence of clamping span on the pull-out force is studied in the experiment of the z-pin-reinforced T-joint, and the bilinear interface elements are used to simulate the reinforcement of z-pin in finite element simulation, the exponential interface elements are used to simulate the bonding, and the linear springs to reinforcement of rivet. The results show that the reinforcement effect of the z-pin is better than that of the rivet when the weight of all z-pins is equal to that of all rivets: The maximum pull-out force and displacement of the z-pin-reinforced T-joint are 1.9 times and 4.9 times heavier than the rivet-reinforced T-joint, respectively; the z-pin can reinforce the whole lap area, while the rivet reinforcement is concentrated around itself. With the increase of the clamping span of the z-pin-reinforced T-joint, the pull-out force decreases, while the pull-out displacement increases, conversely.

Thermo-mechanical analysis of seawater-conditioned carbon/polymer composites reinforced with nanoclay/graphene nanoparticles

Increasing demand for the structural materials having high strength, lightweight, corrosion, and environmental resistance is the major reason to consider fiber-reinforced polymer composite (FRPC) materials instead of traditional materials. Synthetic nanoparticle-reinforced FRPC materials have proved to deliver superior performance in many high-end applications. In this study, carbon fiber-reinforced epoxy composites modified with montmorillonite nanoclay (MMT) and graphene nanoplatelets (GNP) were investigated. The prepared samples were subjected to seawater conditioning to exhibit the effect of environmental conditions on the properties of FRPC materials. Frequency sweep dynamic mechanical analysis (DMA) testing was performed in order to characterize the FRPC materials. The results indicated that dynamic mechanical properties of FRPCs were improved by incorporation of nanoparticles. MMT- and GNP-containing samples showed improvement of around 13% in glass transition temperature in the temperature sweep DMA test. Binary MMT/GNP-containing samples showed 10% improvement in glass transition temperature compared to unmodified carbon samples. Frequency sweep DMA test revealed the frequency-dependent properties of FRPCs. With increasing frequency, the storage modulus increased as the material had less time to respond to the applied load. However, at the same frequency, nanophased FRPCs showed higher modulus compared to baseline unmodified samples. Increasing demand for the structural materials having high strength, lightweight, corrosion, and environmental resistance is the major reason to consider fiber-reinforced polymer composite (FRPC) materials instead of traditional materials. Synthetic nanoparticle-reinforced FRPC materials have proved to deliver superior performance in many high-end applications. In this study, carbon fiber-reinforced epoxy composites modified with montmorillonite nanoclay (MMT) and graphene nanoplatelets (GNP) were investigated. The prepared samples were subjected to seawater conditioning to exhibit the effect of environmental conditions on the properties of FRPC materials. Frequency sweep dynamic mechanical analysis (DMA) testing was performed in order to characterize the FRPC materials. The results indicated that dynamic mechanical properties of FRPCs were improved by incorporation of nanoparticles. MMT- and GNP-containing samples showed improvement of around 13% in glass transition temperature in the temperature sweep DMA test. Binary MMT/GNP-containing samples showed 10% improvement in glass transition temperature compared to unmodified carbon samples. Frequency sweep DMA test revealed the frequency-dependent properties of FRPCs. With increasing frequency, the storage modulus increased as the material had less time to respond to the applied load. However, at the same frequency, nanophased FRPCs showed higher modulus compared to baseline unmodified samples.

A new approach to assess delamination in drilling carbon fibre-reinforced epoxy composite materials

The development of efficient, high-quality joining techniques is still considered an obstacle to the wide application of composite materials as structural components. Mechanical fastening is one of the most common joining techniques. However, this requires the composite material to be drilled, which introduces significant damage to the material. The improvement of drilling techniques is dependent on the accurate analysis of the induced damage. Moreover, concerning repair activities, the assessment of the machining-induced damage enables the determination of its significance, identifying the immediacy of repair. The delamination factors described in the literature quantify the damage but neither has achieved full acceptance to create international standards, which are yet to be defined. This work proposes a new approach to assess the delamination factor by using an image processing methodology, based on digital radiography, to characterize the drilling-induced damage. This approach reconsiders the assumptions made prior to the application of the delamination factor, by reducing the affected area to a quantified damaged area ratio. The obtained results highlight that the minimization of the quantified damage for the most irregular delamination shapes to a single, unequivocal value creates an unambiguous delamination factor for quantifying drilling-induced damage. Simultaneously, the preferential direction of the damage is identified. Additionally, since it is a fully automated method, it is an expeditious method that can be used in situ, being valuable either for manufacturing or repair activities.

Mechanical properties of multiwall carbon nanotubes/unidirectional carbon fiber-reinforced epoxy hybrid nanocomposites in transverse and longitudinal fiber directions

Unidirectional carbon fiber-reinforced epoxy (UCFRE) is suffering from weak transverse mechanical properties and through-thickness properties. The effect of different amount (0.1, 0.3 and 0.5 phr which is proportional to 0.09, 0.27 and 0.46 wt%, respectively) of multiwall carbon nanotube (MWCNT), on transverse tensile properties, flexural strength, fracture toughness in transverse and longitudinal fiber directions, interlaminar shear strength and lap shear strength of UCFRE has been investigated. Dicyandiamide was used as a thermal curing agent of epoxy resin. MWCNT was dispersed in the epoxy resin by ultrasonic instrument and their dispersion state was investigated by scanning electron microscopy (SEM). The curing behavior of epoxy resin and its nanocomposites was assessed by differential scanning calorimetry. Results show that transverse tensile strength, modulus and strain-at-break were increased by 28.5%, 25% and 14%, respectively by adding 0.1 phr of MWCNT. Longitudinal flexural properties of UCFRE was not changed by adding different amount of MWCNT. Although longitudinal flexural strength was increased by 5% by adding 0.1 phr of MWCNT. Fracture toughness in transverse and longitudinal fiber directions was increased by 39% and 9%, respectively at 0.3 phr of MWCNT. Results also show that interlaminar shear strength and lap shear strength were increased at 0.3 phr of MWCNT by 8% and 5%, respectively. These increases in mechanical properties were due to the good adhesion of fibers to the matrix, interlocking and toughening action of MWCNT as revealed by SEM.

Synthesis and Characterization of Multi-walled Carbon Nanotube from Pine Oil and Their Impact on Carbon Fibre Reinforced Epoxy Hybrid Nanocomposite

Synthesis and Characterization of Multi-walled Carbon Nanotube from Pine Oil and Their Impact on Carbon Fibre Reinforced Epoxy Hybrid Nanocomposite

Effects of adhesive modulus and curing conditions on curing behavior of silicate based ceramic coatings on carbon fiber reinforced resin matrix composites

Sodium silicate based ceramic coatings were prepared on the surface of carbon fiber reinforced epoxy resin matrix composite. The coatings were obtained by curing the mixture of silicate adhesive, SiO2 or Na2SiF6 as curing agent, and YSZ and Al2O3 as filler. The effects of adhesive modulus, curing agent, curing temperature and time on curing behavior of the coatings were investigated. The results indicated that the coating obtained from 2.7 modulus of silicate adhesive was dense, cohesiveness, uniform and continuous. As curing agent, SiO2 could promote curing better than Na2SiF6, achieving complete curing of the coating. And the coating containing SiO2 as curing agent was dense, flat and well adhered to the substrate. The curing behavior of coatings was significantly affected by curing temperature and time. The coatings could be cured completely with the increase of curing temperature. The best curing result was obtained at 100 °C curing temperature. Also the experimental results showed that the characteristics of coatings were improved to a certain extent by prolonging the curing time.

Improvement of solid particle erosion resistance of helicopter rotor blade with hybrid composite shield

In the present study, the solid particle erosion behavior of polyurethane (PU) tape (3M-8663) material, bidirectional carbon fiber reinforced epoxy (CF/EP) and glass fiber reinforced epoxy (GF/EP) composites has been characterized experimentally and numerically. In the experimental part, steady-state erosion rates of aforementioned materials have been evaluated at different impact angles (20°, 30°, 45°, 60°, and 90°) and different impact velocities (70, 110, 150, and 190 m/s), and compared with those of stainless steel (SS304) and pure nickel materials (Ni) which are commonly used for erosion shield of helicopter rotor blades. Tests were conducted at room temperature using silica (SiC) particles (average diameter of 175 µm) as an erodent. Erosion behaviors on the shield surface of the same materials were investigated numerically under different impact velocities (110, 150, 190, and 230 m/s) for a pitch angle of 0°. Numerical erosion simulations were realized with commercial ANSYS-Fluent software using the finite volume method, an erosion model, and a discrete phase method with the Eulerian-Lagrangian approach. The experimental results showed that the GF/EP and the CF/EP composites indicated the maximum erosion rate at the impact angles ranged from 60° to 90°, whereas the PU tape material exhibited the maximum erosion rate at the impact angle of 30°. The results also showed that the PU tape surface clearly provided much better erosion resistance than the GF/EP and CF/EP composite surfaces, and the hybrid erosion shield having the PU/SS304 surface significantly improved the erosion resistance of the helicopter rotor blade up to the impact velocity of 150 m/s. A good agreement was also observed between the experimental and the numerical results.

Fatigue performance of carbon fiber reinforced epoxy resin: A molecular simulation

In this work, mechanical behavior of multilayer graphene reinforced epoxy resin during fatigue was studied by molecular dynamic method. Transversely isotropic atom based model was established to simulate the carbon fiber reinforced plastics. The reinforced phase was multilayer graphene, and the matrix phase was epoxy resin. Performance degradation in the fiber direction (axial fatigue) and the vertical fiber direction (transversal fatigue) was studied, respectively. Mean stress was considered as the performance per cycle and the power function was employed to describe the tendency of performance degradation. Evolution of energy and structure in atomic scale was used to characterize the cause of performance degradation. The results showed that performance degraded slower in the fiber direction than that in the vertical fiber direction and faster in atomic scale than that in macroscopic experiment. Transformation of molecular structure, which could be represented by the radius of gyration (Rg) of molecular fragments, was one of the reasons that caused performance degradation. Besides, it could cause a change in microscopic energy. Both bond stretch energy and non‐bond interactional energy decrease obviously in the fiber direction while only non‐bond interactional energy decrease in the vertical fiber direction. This phenomenon indicates that existence of carbon fiber effectively slows down the rate of performance degradation in the fiber direction.

Development of fire retardant epoxy-based gelcoats for carbon fibre reinforced epoxy resin composites

This research article focuses on the development of multifunctional, flame retarded epoxy gelcoat formulations based on phosphorus-containing, intumescent flame retardant (FR). We prepared epoxy resin-based gelcoats with 5 %, 10 % and 15 % phosphorus (P) content using ammonium polyphosphate (APP), and compared their thermal stability, glass transition temperature, crosslinking reaction enthalpy and fire performance to the non-flame retarded reference and a commercial FR gelcoat. We coated carbon fibre reinforced pentaerythritol (PER)-based epoxy composites (non-FR, and FR) with these gelcoats in two thicknesses (0.5 mm and 1.0 mm). The APP-based gelcoats outperformed both the commercial reference and FR gelcoat in terms of thermal stability. When the APP concentration in the gelcoat was increased, the thermal stability and the limiting oxygen index (LOI) increased. All FR gelcoats reached the self-extinguishing (V-0) classification during the UL-94 test and showed remarkable char formation during the mass loss calorimetry (MLC) test even at a lower heat flux (25 kW/m2). In terms of heat release rate, the gelcoat with 10 % P from APP behaved similarly, while the formulation with 15 % P from APP outperformed the commercial FR gelcoat. The tendency in the fire performance of the coated composites was similar to the behaviour of the gelcoat matrices: above 10 % P content, the coated sample outperformed the commercial FR gelcoat. The addition of a liquid, organophosphorus flame retardant (resorcinol bis(diphenyl phosphate) (RDP), acting mainly in the gas phase) to the epoxy matrix of the composite resulted in the further decrease of heat release rate. Non-FR gelcoats considerably deteriorated the fire performance of the fibre reinforced composites, even when applied in a thickness of 0.5 mm. If a gelcoat layer is necessary on the surface of the composite part, a substantial increase in heat release must be considered, or an FR multifunctional gelcoat should be used as an alternative. We reached a 67 % reduction in peak heat release rate when we replaced a 1 mm thick non-FR gelcoat with a gelcoat containing 15 % P on the PER reference composite.

Enhanced Electrical Conductivity and Interlaminar Fracture Toughness of CF/EP Composites via Interleaving Conductive Thermoplastic Films

The poor electrical conductivity and interlaminar fracture toughness of carbon fiber reinforced epoxy (CF/EP) composites could reduce their reliability for aerospace applications. In this work, multi-walled carbon nanotubes (MWCNTs) doped polyethersulfone (PES) conductive thermoplastic films (CTFs) were prepared by solution casting method. The as-obtained composites were then interleaved into CF/EP prepregs to yield composite laminates. The effects of CTFs on the electrical conductivity and interlaminar fracture toughness of the as-prepared CF/EP composites were investigated. The results suggested an increase in conductivity of laminates by 104% and 84% in the transverse (Y) and through-thickness (Z) directions, respectively. The Mode I and Mode II interlaminar fracture toughness values were evaluated by double cantilever beam (DCB) and end-notched flexure (ENF) testing. The data revealed that the introduction of CTFs with 10wt% MWCNTs led to enhancement in Mode I and Mode II interlaminar fracture toughness of Composite laminates by 206% and 47%, respectively. The failure mechanism was investigated through microstructural and morphological changes in the composites studied by scanning electron microscopy (SEM). This work provides valuable guidance for the simultaneous enhancement of electrical conductivity and interlaminar fracture toughness of CF/EP composites.

Research on compression properties of unidirectional carbon fiber reinforced epoxy resin composite (UCFREP)

To research the axial compression properties of unidirectional carbon fiber reinforced epoxy resin composite (UCFREP), the compression experiments at different strain rates were carried out by using the MTS universal electronic testing machine and the equipment of split Hopkinson pressure bar (SHPB). Furthermore, the finite element analysis (FEA) was also used to study the compression properties of UCFREP with different conditions. The true stress-strain curves in quasi-static and dynamic compression were obtained, and the relationship between yield limit and strain rate was coupled. The microstructure of the failure area was observed by scanning electron microscope (SEM). A formula for predicting compression strength of combined buckling under the quasi-static condition was presented. The application range of Chang-Chang failure criterion was discussed by FEA, and the compression failure of UCFREP with different fiber directions was predicted. The results show that UCFREP has the obvious strain rate effect, the mechanical properties at dynamic compression are nonlinear. Shear is the main compression failure mode, which includes the shear cracking of matrix between fibers and the shear buckling of fiber. The direction of the fiber is the main factor that causes the shear cracking, such as the shear cracking shows the feature of 45° when the direction of the fiber is 45°. As a conclusion, increasing the shear strength of matrix and fiber will be a way to increase the compression strength of UCFREP. This paper could be used as a reference to develop the new constitutive model, especially considering the nonlinear effect.

Finite element analysis of space truss sandwich structure

In this paper, three kinds of carbon fiber reinforced epoxy resin (CF / EP) composites, including square, kagome and triangular grid sandwich structures, are analyzed by using ANSYS finite element analysis software. Through the comparison of the analysis results, the surface yield and core failure are the main failure mechanisms in three kinds of three-dimensional finite element models. The average bending loads of square, kagome and triangular grid sandwich structures are 18.0%, 19.7% and 24.6%, respectively. Therefore, the finite element analysis shows that more failures will occur due to the local collapse of the indenter.

An Experimental and Numerical Determination on Low-Velocity Impact Response of Hybrid Composite Laminate

In this study, experimental and numerical investigations were carried out in order to determine the mechanical properties and impact response of hybrid composite laminate. The hybrid composite laminate was formed from plain woven carbon fiber reinforced epoxy (CFRE) and plain woven glass fiber reinforced epoxy (GFRE) fiber using VARTM (vacuum-assisted resin transfer molding) process. The mechanical properties of the hybrid composites were determined using tensile test device with a 1 mm/min loading rate at room temperature. In addition, hybrid composites were subjected to low-velocity impact test under different impact energy levels (10, 20, 30, 40 J) for determining the impact response. Moreover, mechanical properties and impact responses of CFRE and GFRE laminates were also determined to compare to those of hybrid composite (HCGFRE). Microstructure analysis was performed to investigate the damage surfaces of the fiber and matrix in the composite material subjected to impact and tensile forces. In numerical analyses, composite damage model (Mat 54) was utilized in LS-DYNA® explicit finite element program to simulate the impact behavior of CFRE, GFRE and HCGFRE laminates. Consequently, the tensile test results showed that hybrid composite laminate behaved more ductile than carbon composite laminate and it exhibited more brittle behavior than glass composite laminate. Also, it was determined that absorbed energy and impact load capacity of HCGFRE composite laminate are between absorbed energy and impact load capacity of CFRE and GFRE composite laminate. It was determined that numerical results indicate a similar tendency with the experimental results.

Evaluation of modal parameters and static characteristics for composite mono leaf spring

The objective of this paper was to investigate and evaluate modal parameters and static characteristics for designed carbon/epoxy composite CFRP leaf spring made from carbon fiber-reinforced epoxy by comparing its finite element analysis FEA modal, harmonic and static results to that of conventional steel one under the same maximum full bump load. In ANSYS software, finite element modal, harmonic and static analysis for 3D models of conventional steel and designed composite mono leaf springs is carried out. FEA displacements for the steel and designed composite CFRP mono leaf springs at the maximum full bump load were 92.9 mm and 93.1 mm respectively. Compared to the steel mono leaf spring, the composite mono leaf spring has advantages; lower stresses, higher natural frequencies and higher safety in stresses of front and rear eyes. All these advantages let the composite leaf spring can be carried maximum full bump load with enough higher performance over steel one to avoid resonance and satisfy maximum stress failure criterion.

Interlaminar shear strength study of Mg and carbon fiber-based hybrid laminates with self-healing microcapsules

The present paper regards the shear strengthening of fiber metal laminates (FMLs) composed by surface treated magnesium and carbon fiber reinforced epoxy (CFRP) laminates. The effect of an intermediate layer consisting of isocyanate microcapsules (MCs), placed between the Mg and the CFRP layers, on the interlaminar shear strength (ILSS) of the composite is investigated, as well as the effect of the carbon fibers orientation in the laminate. Configurations involving fiber orientation at 0° and the presence of MCs at 1–1.5 wt% are shown to lead to the highest ILSS values and to less damage in the FML structure upon the ILSS testing. Interlocking and self-healing effects, derived from the presence of MCs, are at the origin of the shear strengthening phenomenon that occurs on those FMLs.

Effects of hot melt adhesives on the interfacial properties of overmolded hybrid structures of polyamide-6 on continuous carbon fiber/epoxy composites

This study aims to increase effectivity of the overmolding approach for thermoset/thermoplastics hybrid composites. The samples were prepared by overmolding of polyamide-6 (PA6) onto fully cured continuous carbon fiber-reinforced epoxy composites with the aid of hot melt adhesives. Specifically, the influence of hot melt adhesive application at the interface between the thermoset and thermoplastic parts of hybrid composites was investigated. The experimental scheme highlights the effects of hot melt type and adhesive layer thickness (ALT) on the performance of these hybrid joints. Thermoplastic polyurethane (TPU) based hot melt adhesive performed better adhesion characteristics among others (copolyesters, polyolefin) according to findings from lap shear test and DMA analysis. The fracture surfaces observed with optical microscopy and SEM also confirmed the synergistic effect of these parameters.

Surface Metallization and Ceramic Deposition on Thermoplastic-Polymer and Thermosetting-Polymer Composite Via Atmospheric Plasma Spraying

A spray coating technique is an excellent method for surface metallization and ceramic deposition to widen the application fields of irreplaceable engineering polymers. In this study, Al metallization and Al2O3 deposition on thermoplastic-polymers (polycarbonate, polyimide) and a thermosetting-polymer composite (carbon fiber reinforced epoxy) were conducted via atmospheric plasma spray (APS). Due to the susceptibility of polymers to thermal or mechanical damage, precise process control is required. It was shown that the engineering temperature range critically determines the process window of thermoplastic-polymers. An Al2O3 coating can be fabricated on polymers via an Al bond coat. Like a heat sink, the Al buffer layer enables polymers to endure process heating. In low thermally resistant polycarbonate (PC), only a low plasma energy source could be applied. Additionally, vaporization induced by Al droplet contact was a clear reason of the unstable weak interface between the coating and substrate. The coatings fabricated on polyimide (PI) substrates generally showed a continuous and clean interface with a moderate adhesion property. In the case of carbon fiber reinforced epoxy (CFRP), it is believed that carbon fibers acted as a heat sink such that considerable thermal damage of CFRP was not observed and there was not delamination of the coatings. However, fracturing of carbon fibers and epoxy resin by grit-blasting (surface pre-treatment) made the surface unstable. This led to the worst adhesion characteristics between the coating and CFRP substrate. It was demonstrated that because the available temperature range and surface condition are very sensitive compared to conventional metal substrates, advanced surface pre-treatment, precise process optimization, and additional cooling are required for successful deposition.

Comparison of novel surface treatments of Al 2024 alloy for al/cfrp adhesive bonded joints

The objective of this study is to investigate the effect of silane and fiber laser treatments on the shear strength and failure type characteristic ofAA2024-T3/unidirectional carbon fiber-reinforced epoxy composite [0]8 laminates (Al/CFRP) adhesively bonded joints. Epoxy-based paste 2 part adhesive (Loctite EA 9396 AERO) was used for adhesive joining. Chemical surface treatment was tested with three different silane concentrations (1, 3 and 5 vol%) applied to AA2024-T3 aluminum plates after cleaning. In addition, 50 W pulsed fiber laser was used to AA2024-T3 aluminum plates for laser treatment. For determining the optimum fiber laser parameters (laser power, frequency and scanning speed) L9 orthogonal array Taguchi method (3 variables and 3 levels) was used. The chemical composition of the fiber laser and silane treated AA2024-T3 sample's was analyzed using Fourier transform infrared spectroscopy – attenuated total reflectance (FTIR–ATR). Shear strength values of the Al/CFRP bonded joints were determined by using single lap shear tests. From the test results, the silane concentration of 3 vol% on AA2024-T3 aluminum plates had a significant effect on shear strength of Al/CFRP bonded joints (16.44 MPa) compared to untreated samples (6.46 MPa). In addition, it was determined that the laser treating parameters of scanning speed of 100 mm/s, frequency of 80 kHz and power of 50 W laser power achieved the optimum surface of AA2024-T3 to be strongly bonded with CFRP (23.68 MPa). After mechanical tests, failure modes were also observed by using the digital camera.