Hybrid CFRP Research Articles

Comparison of Material Performance through Experiments between CFRP and CFRP Hybrid and Steel

Comparison of Material Performance through Experiments between CFRP and CFRP Hybrid and Steel

Failure Behavior of Titanium/CFRP Hybrid Composites Under Tensile Loading

Carbon fiber reinforced polymer (CFRP) composites have found widespread use in various lightweight engineering applications, owing to their high stiffness and strength at low density. Nevertheless, they exhibit certain weaknesses, such as low bearing strength, leading to reduced impact resistance in CFRP components. In addressing this challenge, metal/CFRP composites have emerged as an alternative, leveraging the ductility of metals along with the high specific strength of the CFRP composites. In this study, tensile tests were conducted on the CFRP composite plates with 0°, 90°, and ±45° stacking sequences, and the corresponding load-displacement curves were obtained. The numerical simulation of tensile tests was conducted by the LS-DYNA software, and the numerical model was verified with the experimental results. Furthermore, numerical simulations were conducted to examine the influence of various metal types on the failure behavior of metal alloy/CFRP hybrid composite plates with different thicknesses under tensile loading. The results indicate that both the thickness of the hybrid CFRP composites and the type of metal have a substantial impact on the performance of metal-hybrid components. Additionally, a comparison between the tensile test results and numerical simulation results reveals a good agreement.

A Multiscale Modeling and Experimental Study on the Tensile Strength of Plain-Woven Composites with Hybrid Bonded-Bolted Joints.

CFRP hybrid bonded-bolted (HBB) joints combine the advantages of traditional joining methods, namely adhesive bonding, and bolting, to achieve optimal connection performance, making them the most favored connection method. The structural parameters of CFRP HBB joints, including overlap length, bolt-hole spacing, and fit clearance relationships, have a complex impact on connection performance. To enhance the connectivity performance of joint structures, this paper develops a multiscale finite element analysis model to investigate the impact of structural parameters on the strength of CFRP HBB joint structures. Coupled with experimental validation, the study reveals how changes in structural parameters affect the unidirectional tensile failure force of the joints. Building on this, an analytical approach and inverse design methodology for the mechanical properties of CFRP HBB joints based on deep supervised learning algorithms are developed. Neural networks accurately and efficiently predict the performance of joints with unprecedented combinations of parameters, thus expediting the inverse design process. This research combines experimentation and multiscale finite element analysis to explore the unknown relationships between the mechanical properties of CFRP HBB joints and their structural parameters. Furthermore, leveraging DNN neural networks, a rapid calculation method for the mechanical properties of hybrid joints is proposed. The findings lay the groundwork for the broader application and more intricate design of composite materials and their connection structures.

Numerical investigation of the bearing performance of Thin- and Thick-Ply hybrid laminates

This publication presents a numerical investigation of Thin-Ply Hybrid CFRP bolted joints. In addition to Thin- and Thick-Ply specimens, hybrid specimens are investigated by substituting a part of the 90° CFRP layers with stainless steel foils. The numerical investigations are based on preliminary experimental work, which showed that fibre kinking led to final failure. A modelling strategy that includes 3D stress states and fibre kinking is chosen. The influence of micro-damages such as matrix cracks decreases with decreasing layer thickness. Therefore, and to avoid high computational power, primarily micro-damages such as matrix cracks are not included. The results of the simulations of the Thin-Ply and the hybrid samples show a good agreement with the experimental results. By hybridisation, the bearing performance can be significantly increased. It is shown that the modelling approach of not including micro-damage is well applicable for thinner plies but reaches its limits for thicker plies.

Mechanistic Study of Failure in CFRP Hybrid Bonded-Bolted Interference Connection Structures under Tensile Loading.

Hybrid bonded-bolted composite material interference connections significantly enhance the collaborative load-bearing capabilities of the adhesive layer and bolts, thus improving structural load-carrying capacity and fatigue life. So, these connections offer significant developmental potential and application prospects in aircraft structural assembly. However, interference causes damage to the adhesive layer and composite laminate around the holes, leading to issues with interface damage. In this study, we employed experimental and finite element methods. Initially, different interference-fit sizes were selected for bolt insertion to analyze the damage mechanism of the adhesive layer during interference-fit bolt installation. Subsequently, a finite element tensile model considering damage to the adhesive layer and composite laminate around the holes post-insertion was established. This study aimed to investigate damage in composite bonded-bolted hybrid joints, explore load-carrying rules and failure modes, and reveal the mechanisms of interference effects on structural damage and failure. The research results indicate that the finite element prediction model considering initial damage around the holes is more effective. As the interference-fit size increases, damage to the adhesive layer transitions from surface debonding to local cracking, while damage to the composite matrix shifts from slight compression failure to severe delamination and fiber-bending fracturing. The structural strength shows a trend of initially increasing and then decreasing, with the maximum strength observed at an interference-fit size of 1.1%.

Strength Degradation Mechanism of CFRP and Aluminium Alloy Hybrid Bonded-Riveted Joints Under Salt Spray Environment

Strength Degradation Mechanism of CFRP and Aluminium Alloy Hybrid Bonded-Riveted Joints Under Salt Spray Environment

CFRP hybrid composites manufacturing and electromagnetic wave shielding performance-a review

CFRP hybrid composites manufacturing and electromagnetic wave shielding performance-a review

Innovative hybrid CFRP composite and Fe-SMA bonded systems for structural glass flexural strengthening

Contemporary architecture is increasingly embracing the use of structural glass for challenging applications. Glass industry has been adopting thermal toughening and lamination as advanced techniques to enhance tensile strength and avoid sudden failures. However, unexpected failure persists and hinders a more widespread application of glass, including as a structural material. Researchers have tested alternative glass composite systems, integrating reinforcements like steel, fiber-reinforced polymers (FRP), or iron-based shape memory alloy (Fe-SMA). This study explores an innovative concept that involves the simultaneous application of CFRP and Fe-SMA reinforcements via near-surface mounted (NSM) or externally bonded reinforced (EBR) techniques for glass strengthening. This system is shown to effectively prevent premature debonding, enhance post-cracking response, and ensure ductile failure modes, while being simple. Bending tests on large-scale laminated glass beams were performed to characterize the effectiveness of the system, while also the benefits of post-tensioning were investigated by inducing different prestressing levels in the glass strengthened elements. The paper first highlights the advantages of Fe-SMA reinforcements in glass composite systems through experimental evidence, followed by exploration of the proposed innovative hybrid CFRP composite and Fe-SMA bonded systems.

Multifunctional composite with hybrid carbon fiber and carbonaceous coconut particle reinforcement

The utilization of multifunctional composite materials presents significant advantages in terms of system efficiency, cost-effectiveness, and miniaturization, making them highly valuable for a wide range of industrial applications. One approach to harness the multifunctionality of carbon fiber reinforced polymer (CFRP) is to integrate it with a secondary material to form a hybrid composite. In our previous research, we explored the use of carbonaceous material derived from coconut shells as a sustainable alternative to inorganic fillers, aiming to enhance the out-of-plane mechanical performance of CFRP. In this study, our focus is to investigate the influence of carbonized coconut shell particles on the non-structural properties of CFRP, specifically electromagnetic interference (EMI) shielding, thermal stability, and water absorption resistance. The carbonized material was prepared by thermal processing at 400 °C. Varying proportions of carbonized material, ranging from 1% to 5% by weight, were thoroughly mixed with epoxy resin to form the matrix used for impregnating woven carbon fabric with a volume fraction of 29%. Through measurements of scattering parameters, we found that the hybrid composites with particle loadings up to 3% exhibited EMI shielding effectiveness suitable for industrial applications. Also, incorporating low concentrations of carbonized particle to CFRP enhances the thermal stability of hybrid CFRP composites. However, the inclusion of carbonized particle to CFRP has a complex effect on the glass transition temperature. Even so, the hybrid composite with 2% particle loading exhibits the highest glass transition temperature and lowest damping factor among the tested variations. Furthermore, when subjected to a 7-day water immersion test, hybrid composites with 3% or less amount of carbonized particle showed the least water absorption. The favorable outcome can be attributed to good interfacial bonding at the matrix/fiber interface. Conversely, at higher particle concentrations, aggregation of particles and formation of interfacial and internal pores was observed, ultimately resulting in deteriorated measured properties. The improved non-structural functionalities observed in these biocomposites suggest the potential for a more sustainable and cost-effective alternative to their inorganic-based counterparts. This advancement in multifunctional composites could pave the way for enhanced applications of biocomposites in various industries.

Publisher Correction: FE Modelling of Vibrational Parameters of Viscoelastic CNT–CFRP Hybrid Spherical Shell Structures

Publisher Correction: FE Modelling of Vibrational Parameters of Viscoelastic CNT–CFRP Hybrid Spherical Shell Structures

Surface functionalization of carbon fiber by hydrothermally synthesized ZnO nanostructures for mechanical strengthening of polymer composites

AbstractIn this work, the effects of ZnO nanostructure‐surface functionalized carbon fibers has been examined along with their impacts on mechanical attributes of resulting hybrid carbon fiber reinforced polymer (CFRP) composites. The procedure involves hydrothermally generating ZnO nanostructures on carbon fibers. To generate hybrid composites, the modified carbon fiber fabric is then utilized as reinforcement in a matrix made of bisphenol‐A epoxy resin and polymer. The electron microscopy technique was employed to study development phenomenon of nanostructures on the fiber. According to the findings, lengthening the growth treatment and increasing seeding cycles improves the rate of ZnO formation. However, the results are not significantly impacted by the growth solution's concentration. The weight change analysis, X‐ray diffraction, Fourier transform infrared spectroscopy, UV‐spectroscopy, and energy dispersive spectroscopy all provide additional support for these conclusions. In comparison to plain CFRP composites, the developed hybrid CFRP composites tensile properties and impact resistance are significantly better. The ZnO‐modified CFRP composites exhibit improvements in elastic modulus, tensile strength, and in‐plane shear strength of up to 46.44%, 48.63%, and 20.79%, respectively. The hybrid composites' capacity to absorb impact energy also rises by 76%. Based on these results, the developed hybrid composites exhibit promising properties for applications in industries such as aircraft and automobile manufacturing. They offer high impact strength, high modulus, lightweight characteristics, and low void content, making them desirable materials for these industries.Highlights Controlled growth of vertically aligned ZnO nanostructures on fiber surface has been accomplished using hydrothermal method. Characteristics of CFRP composites such as tensile strength, elastic modulus, in‐plane shear strength, and impact energy absorption, were significantly enhanced on inclusion of ZnO. The developed hybrid composites offer cost‐effective solutions with improved mechanical properties. High impact strength and modulus make them suitable for applications in aircraft and automobile industries. Achieved exceptional morphological structure and enhanced surface‐to‐volume ratio.

Compressive behavior and modeling of concrete wrapped by hybrid low-high elongation capacities FRP

This paper experimentally investigated the monotonic and cyclic compressive behavior of concrete confined with hybrid carbon fiber-reinforced polymer (CFRP) and large rupture strain (LRS) FRP. A total of 34 concrete cylinders wrapped by FRP were prepared and tested under monotonic/cyclic axial compression. The effects of FRP types and thickness on the failure mode, efficiency factor, hybrid effect, stress-strain response, and energy dissipation were carefully investigated. Test results verified that the hybrid confinement mechanism can fully utilize the advantages of both types of FRP and avoid their essential shortcomings. LRS FRP effectively improved the utilization of CFRP and increased the deformation and energy dissipation capacity of concrete. Hybrid inner CFRP and outer LRS FRP serve as a confinement device that can achieve a progressive failure mechanism for concrete. In addition, an analysis-oriented model was developed and constructed to simulate the monotonic stress-strain behavior of hybrid-wrapped concrete. This analysis-oriented model focuses on the lateral stress-strain relationship and the localized CFRP fracture effect. Finally, a cyclic stress-strain model of hybrid-wrapped concrete was developed using the analysis-oriented model as an envelope model. The proposed model can accurately capture monotonic/cyclic stress-strain behaviors.

Evaluation of Fastener Flexibility in Hybrid CFRP and Metal Joints Using the Finite Element Method

The fastener flexibility is one of the most important factors affecting the fatigue life of the joints. A three-dimensional model was established by ABAQUS software to simulate the load-displacement curve of a single shear fastener under tensile load. The fastener flexibility was calculated from the simulated curve and compared with the experimental results. The effects of the element type, hole gap, clamping clearance and clamping length on the prediction accuracy and fidelity of the finite element method (FEM) model were also investigated. It was shown that the simulation results agreed well with the experimental results. The modelling method was demonstrated to be usable for subsequent structural analysis and design.

Study on Effects of Geometric Parameters on Tensile Strength of Hybrid Bonded-Rived Joint of Fiber Reinforced Polymer Plates

Hybrid bonded-rived joint combines bonding and riveting and has become one of the most important connection forms in composite materials. This paper investigates and analyzes the influence of geometric parameters of CFRP hybrid bonded-rived joints on load-bearing strength. The finite element method is used to analyze the strength of the hybrid bonded/riveted joint between carbon fiber composite and metal under tensile load. The different ratios of the hybrid joint’s e/D, w/D, and w/e are analyzed. It is shown that e/D and w/D significantly impact damage loads and failure mode of the hybrid bonded/riveted joint. The increase of e/D will change the joint from shear-out to net tension failure, and the effect of w/D is opposite to that of e/D. Under the same bonding area, different w/e impacts the damage load of the joint, and the larger w/e makes the joint have a larger failure load, and the stiffness of the joint is also large.

Effect of Hybrid FRP Confinement on Tin Slag Polymer Concrete Compressive Strength

This study investigates the strength enhancement of Tin Slag Polymer Concrete (TSPC) under hybrid GFRP and CFRP confinement in comparison with mono GFRP and CFRP confinement on TSPC circular short column samples. Hybrid FRP confinement is prepared by wrapping TSPC with GFRP followed by CFRP both 1 layer using epoxy Sikadur 330 as matrix binders with 50 mm overlap. Compression test was performed on unconfined TSPC (TSPC-UC), TSPC with GFRP confinement (TSPC-GF), TSPC with CFRP confinement (TSPC-CF) and TSPC with hybrid FRP confinement (TSPC-HB) with 1mm/ min loading rate. The test results have revealed that the ultimate strengths are 59.19 MPa (TSPC-UC), 85.54 MPa (TSPC-GF), 108.77 MPa (TSPC-CF) and 124.59 MPa (TSPC-HB). The corresponding compressive strain measured at ultimate compressive strength is 0.0300 (TSPC-UC), 0.0453 (TSPC-GF), 0.0398 (TSPC-CF) and 0.0588 (TSPC-HB). Stress versus strain curve has shown that compared to TSPC-UC, externally strengthen sample with GFRP, CFRP and Hybrid FRP have enhanced TSPC strength with slight different behavior. TSPC-GF has less strength enhancement with larger strain while TSPC-CF provide larger strength enhancement but with lower strain. However, TSPC-HB has shown the highest strength enhancement with larger strain benefit from combined GFRP and CFRP properties. Failure mode of hybrid FRP confinement on TSPC (TSPC-HB) has shown combination of both FRP components failure mode (TSPC-GF and TSPC-CF) as in rupture pattern and delamination. The results of this study has provide findings on the effect of hybrid FRP confinement on TSPC circular column sample in close expectation based on literatures.

Evaluation of Flexural Behavior and Service Condition of GFRP and CFRP Hybrid Reinforced Concrete Beams

Evaluation of Flexural Behavior and Service Condition of GFRP and CFRP Hybrid Reinforced Concrete Beams

Damage Analysis of CFRP Hybrid Bonded-Bolted Joint during Insertion of Interference-Fit Bolt.

In this study, experiments and finite element analysis (FEA) were used to evaluate the impact of interference-fit sizes on CFRP hybrid bonded-bolted (HBB) joint damage during bolt insertion. The specimens were designed in accordance with the ASTM D5961 standard and bolt insertion tests were performed at selected interference-fit sizes (0.4%, 0.6%, 0.8%, and 1%). Damage to composite laminates was predicted using the Shokrieh-Hashin criterion and Tan's degradation rule via the user subroutine USDFLD, while damage to the adhesive layer was simulated by the Cohesive Zone Model (CZM). The corresponding bolt insertion tests were performed. The variation of insertion force with interference-fit size was discussed. The results showed that matrix compressive failure was the main failure mode. With the growth of the interference-fit size, more failure modes appeared, and the failure region expanded. Regarding the adhesive layer, it did not completely fail at the four interference-fit sizes. This paper will be helpful in designing composite joint structures and especially for understanding CFRP HBB joint damage and failure mechanisms.

Improving cyclic response of heat-damaged non-ductile RC joints using CFRP hybrid systems

The behavior of non-ductile, heat-damaged reinforced concrete (RC) beam column joints was investigated in this experimental research work. A hybrid system formed of carbon fiber-reinforced polymer (CFRP) sheets and strings was used to improve the cyclic response of these non-ductile, heat-damaged joints. To evaluate the cyclic performance of these joints, twelve RC beam-column joints were cast and classified into four categories: Three joints were kept without strengthening as control specimens. Three joints were strengthened with one layer of CFRP sheets and one NSM-CFRP string in the beam and in the column; three joints were strengthened with two layers of CFRP sheets and two NSM-CFRP strings in the beam and in the column; and three joints were strengthened with three layers of CFRP sheets and three NSM-CFRP strings in the beam and in the column. In addition, the joints were tested at three different temperatures, which are: ambient, 400 °C, and 600 °C. The experimental findings show a considerable improvement in the cyclic performance of non-ductile heat-damaged RC beam-column joints strengthened with a hybrid CFRP system (greater lateral displacement, higher load capacity, higher energy dissipation, higher displacement ductility, and slower secant stiffness degradation). Furthermore, the effectiveness of CFRP composites increases as the degree of heat damage increases.

Analysis of factors influencing absorbed energy in CFRP and Kevlar hybrid laminate subjected to low-velocity impact

ABSTRACT Fibre Reinforced Polymer (FRP) laminates absorb energy under elastic deformation. The matrix’s brittleness, causes the resilience to decrease, which causes delamination, matrix cracking, perforation, fibre breakage, and other problems. The amount of energy that the specimen absorbed during the entire impact test is the total absorbed energy which is influenced by impactor diameter, impactor velocity and fibre orientation. An attempt is made in this paper to investigate the effect of laminate thickness and the velocity at which the CFRP and Kevlar hybrid laminate is impacted. An explicit numerical analysis of low velocity impact damage behaviour of Hybrid and CFRP composite laminates has been performed for three different thickness by impacting the laminates at various velocities. An orthogonal array (L4) is prepared using two process variables and with three levels. A central composite design was used to obtain the response surface model. The developed mathematical model predicted the total absorbed energy of CFRP and Kevlar laminates subjected to low velocity impact. The results indicate that the change in thickness had no significant impact on the energy absorption while the variation in the impactor velocity had notable influence on the energy absorption of the laminate.

Experimental study on the effects of scale on the static and dynamic behaviour of Glulam and hybrid-Glulam beams

The research and development of timber and timber-hybrid systems depends heavily on the testing of large or full-scale structural components, which is often limited by laboratory space and budget constraints. Testing of small-scale samples is an alternative approach which can avoid costly experimental campaigns; however, little is known about evaluation of serviceability performance measures, including natural frequency and stiffness, which typically govern the design of elements in timber and timber-hybrid long-span systems. Downscale testing of timber is known to be susceptible to changes in material properties with size, the so-called ‘size effect’, but existing research into the size effect in timber focuses on strength rather than serviceability parameters. This work explores the effect of scaling down Glulam and hybrid carbon fibre (CFRP) reinforced Glulam beams, by comparing the dynamic and static performance of beams tested at both full-scale and approximately half scale. Outcomes of this experimental study indicate that serviceability parameters present small variations with scale, whereas strength parameters are affected by size effect in being consistently smaller in the full-scale samples when compared to their small-scale versions. It was also observed that tension-only reinforcement in hybrid CFRP–timber beams appeared to reduce the size effect in both static and dynamic parameters.