Application Of CFRP Research Articles

Study on increasing load capacity of wooden arch bridge by CFRP strengthening: experimental and numerical Verification

The wooden arch corridor bridge is a typical representative of Chinese wooden bridges, holding significant historical research value. Currently, these bridges face issues of severe component deformation and insufficient load-bearing capacity. To address these problems, this study employs CFRP reinforcement on the components of wooden arch corridor bridges to reduce deformation and enhance load-bearing capacity. Experimental research on CFRP reinforcement has yielded the elastic modulus of the bonding interface. Given the lack of an accurate numerical model for wooden arch corridor bridges, this study establishes a precise numerical model by setting parameters based on load test data from wooden arch corridor bridges. The elastic modulus obtained from the experiments is input into the numerical model for analysis. The results indicate that CFRP exhibits excellent reinforcement performance, with the load-bearing capacity of the reinforced damaged components still reaching 75%–85% of their original capacity, while the load-bearing capacity of the reinforced undamaged components increases to 130%–140% of their original capacity. The failure modes of the CFRP-reinforced wooden components suggest that allowing for some gaps in the bonding of CFRP can enhance overall ductility. The application of CFRP to wooden arch corridor bridges also demonstrates favorable reinforcement effects, increasing the load-bearing capacity of the arch surface by approximately 20%, thereby providing a theoretical basis for the reinforcement of wooden arch bridge frameworks.

The Effect of CFRP Application on the Strength and Dynamic Characteristic of Unreinforced Masonry Wall

The Effect of CFRP Application on the Strength and Dynamic Characteristic of Unreinforced Masonry Wall

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.

Parametric design and modeling method of carbon fiber reinforcement plastic-laminated components applicable for multi-material vehicle body development

Abstract Combined application of steel, aluminum, and carbon fiber reinforcement plastic (CFRP) is the main direction of future lightweight body development. However, the anisotropy and additional lamination design variables of CFRP parts pose significant challenges for the development of multi-material bodies. This study establishes a parametric design method for the variable-thickness lamination scheme based on non-uniform rational B-splines, it can be coupled with existing parametric design methods for structural shapes to formulate a complete parametric design and modeling of CFRP components. On this basis, a homogenized intermediate material property is derived from classic laminate theory by introducing lamination assumptions, it enables a stepwise multi-material body optimization method to solve the challenge that components’ material design variables switching between CFRP and alloy will introduce/eliminate lamination design variables iteratively, posing a great optimization convergence difficulty. The proposed parametric modeling method for CFRP components was validated by experimental tests of a fabricated roof beam, and the proposed optimization method was applied to a vehicle body, achieving 15.9%, 23.9%, 18.6%, and 12.2% increase in bending and torsional stiffness and modal frequencies; 20.2%, 9.3%, and 12.7% reduction of weight and peak acceleration in frontal and side collisions. This study enables the forward design of multi-material bodies compatible with CFRP parts.

Effect of hygrothermal aging on compression behavior of CFRP material with different layups

This study investigates the mechanical degradation mechanism and statistical analysis of residual compressive strength of three lay-up laminates under more than one-year seawater environment. Fick and Langmuir model were used to describe the moisture absorption process with a maximum moisture equilibrium content of 3.78% and various characterization methods were used to reveal the microstructural evolution of CFRP during aging. Experimental results demonstrate that the multiple fiber directions in the MD specimens provide additional moisture absorption channels, leading to a stronger wicking effect and a higher equilibrium moisture content. The layups can significantly affect the compression failure mode after long-term aging. The compressive strength of the cross-ply and multidirectional laminates decreased by 50% while that of unidirectional laminates decreased by 28%, and surface cracking is easily observed in the aged specimens. An empirical prediction model based on the Langmuir model and experimental data was proposed and verified by the data from the literature, with at least a 10% improvement in prediction accuracy. Meanwhile the three-parameter Weibull distribution was used to describe the residual compressive strength after hygrothermal aging and tested by Kolmogorov-Smirnov test. It is expected to provide insight for the application of CFRP in seawater environment.

Model-based analysis of temperature-dependent dynamics in CFRP spindle unit

The application of CFRP to machine tool structures can potentially improve their dynamic characteristics and energy efficiency owing to its highly specific material properties. The different thermal characteristics of CFRP and steel in spindle units likely induce unique thermal deformation, which affects the bearing dynamics. This research proposes a modeling method of CFRP spindle unit dynamics via generalized multipoint receptance coupling with contact characteristics at the spindle-holder interface. The temperature-dependent mechanical properties are analyzed by parameter identification from the model. The translational stiffness and damping of bearings in the CFRP spindle increase with temperature increase at high rotational speed.

A criticism on strengthening glued laminated timber beams with fibre reinforcement polymers, numerical comparisons between different modelling techniques and strengthening configurations

The application of CFRP for strengthening timber structures has proven its efficiency in enhancing load-bearing capacity and, in some cases, the stiffness of structural elements, thus providing cost-effective and competitive alternatives both in new design and retrofitting existing historical buildings. In this study, glued laminated timber beams strengthened with CFRP were examined. A number of test beams with different reinforcement configurations and beam sizes were selected from the literature. These beams were analysed with three different methods as numerical, theoretical and code perspective. For the numerical method, a 3D nonlinear finite element model which includes damage and fracture mechanics was constructed. All test beams were studied with different methods and results were compared with respect to initial flexural stiffness, midspan vertical displacement and failure load. The effectiveness of methods and strengthening configurations were stated and suggestions for practical application of FRP-strengthened timber beams were presented.

Interfacial Bond-Slip Model for CFRP Plate Externally Bonded to Corroded Steel Plate

The purpose of this study is to establish the interfacial bond-slip model for CFRP plate externally bonded to corroded steel plate. The present bond-slip models for CFRP materials bonded to uncorroded steel plate were first reviewed. Thirty-four double-lap joints were tested to investigate the effect of corrosion duration and adhesive thickness on the bond behavior between CFRP plates and corroded steel plates, and the bond-slip curves for the bonding interface with different adhesive thickness and corrosion duration were obtained combined with the CFRP plate strain distribution data. A new bond-slip model for CFRP plate externally bonded to corroded steel plate was proposed, and the expression of the characteristic parameters, which included the maximum bond resistance τf, the relative slip at the peak bond stress s1, the fitting parameter α, and the interfacial fracture energy Gf, were also developed based on the careful regression analysis of the present data. The influence of the corrosion duration and construction adhesive thickness on the bond-slip relationship were accounted together and expressed as a new parameter; that is, the effective adhesive thickness teff. The comparison between the predicted values and experimental results indicated that the proposed bond-slip model can be applied to reproduce the structural response of the CFRP plate-corroded steel plate double-lap joint with reasonable accuracy. The outcome of this study can provide meaningful references and essential data for the reliable application of CFRP strengthening systems in the performance improvement of corroded steel structures.

Behavior of CFRP-strengthened RC beams with circular web openings in shear zones: Numerical study

In practice, especially the basement floor beams are drilled and damaged by the users. In some cases, this damage to the beams can be significant for the load-bearing element and the whole structure. In this study, the behavior of reinforced concrete beams with circular openings and the failure types resulting from strengthening these beams with CFRP are parametrically investigated. The diameter of the opening/beam height ratio (D/H), concrete compressive strength, stirrup spacing, the position of the opening to the beam support, the type of CFRP application, CFRP ply orientation, and the number of CFRP layers were selected as parameters. Numerical models were verified using 9 specimens having different circular openings with/without CFRP strengthening and the analyses of 95 numerical models with the selected parameters were carried out utilizing the finite element program, ABAQUS. The ultimate load capacity, ductility, stiffness, energy dissipation capacity and failure modes of the beams were determined. As a result of the study, it was observed that there was no significant loss in ductility for the beams with D/H ≤ 0.3 and the number of CFRP layer and type of application did not have a significant effect on D/H ≤ 0.44. However, for the beams with D/H > 0.64, the CFRP application that completely surrounds openings should be preferred instead of partial CFRP strengthening. In addition, the concrete strength is an effective parameter for the beams with D/H ≤ 0.44. The effect of the stirrup spacings in the beam on the ductile behavior was also limited with the increase in the hole diameter. The number of CFRP layers should theoretically be 4 for an effective strengthening in beams with D/H > 0.44. Finally, U wrapping is recommended instead of using full wrapping. It has been seen that the location and diameter of the hole are very important parameters in the failure type of the beam.

Evaluation of mechanical properties of CFRP modeled by FDM

Knee joint diseases have been increasing in recent years due to the aging of society and the increase in the sports population. Knee braces used in treatment play a role in immobilizing and stabilizing the knee joint and reducing the direct burden on the knee joint. Therefore, the development of knee braces using CFRP material by fused deposition modeling (FDM), one of the additive manufacturing (AM) methods, is expected. The application and development of CFRP for knee orthoses requires safe design that considers the weakest points in terms of the shape of the various parts used in the orthoses and the walking motion. However, the mechanical properties of CFRP materials using FDM have not been clarified. In this study, the effects of carbon fiber content and orientation on the flexural strength of FDM-molded CFRP were investigated. 4-point flexural strength tests revealed that the carbon fiber layer was distributed throughout the entire structure, and that the higher the fiber content, the higher the strength. Therefore, it is suggested that an even arrangement of the fiber and resin layers increases the bending strength.

An Analysis of CFRP Application in the Construction of Rail Vehicles

The aim of this article is to provide crucial information on CFRP composites and examples of their use in rail vehicle construction. The first part outlines the key characteristics of CFRP composites and compares their properties with conventional structural materials. Implementation examples of this group of composites for structural components of rail vehicles are discussed further. The final section of the article analyses the reasons for introducing composites of this type into the engineering practice of railways. Keywords: CFRP composites, carbon fiber, rail vehicle body, mass reduction

Seismic behavior of CFRP confined rectangular CFST columns using high-strength materials: Numerical analysis and restoring force model

The concrete-filled steel tube (CFST) columns using high-strength materials have the advantages of small sections and high capacity. However, the high-strength steel tube is susceptible to local buckling which will affect the seismic performance of CFST columns. The experimental study on seismic performance of CFRP confined rectangular CFST columns using high-strength materials indicated that the reinforcement of CFRP improves the bearing capacity and energy dissipation capacity efficiently. Based on the experimental investigation, the refined finite element model (FE model) of the CFRP confined high-strength rectangular CFST column was established in ABAQUS and verified in this paper. Parametric analysis was carried out to learn the influence of important factors such as material strength, width-to-thickness ratio, number of wrapped CFRP layers, and axial compression ratio. By combining the experimental research and parametric analysis, the restoring force model of FRP confined high-strength rectangular CFST column was proposed. The restoring force model could accurately predict the load–displacement curve and provided theoretical support for the design and application of CFRP confined high-strength rectangular CFST column.

Numerical investigation on the fatigue life of non‐cracked metallic plates repaired with bonded CFRP

AbstractIn Europe, a large number of old riveted metallic bridges approach the end of their fatigue life. Past research has shown that the application of CFRP can be very efficient in delaying the crack growth rate of deficient structural elements with existing crack. However, little attention is given to the fatigue resistance of non‐damaged metallic members approaching the end of their fatigue life. This is particularly relevant for old metallic riveted bridges, where many critical components do not have existing cracks. This paper presents a numerical investigation on the fatigue behavior of non‐cracked metallic plates bonded with CFRP using epoxy resin. Nonlinear finite element analyses are performed using the commercial software ABAQUS. The cyclic elasto‐plastic behavior and the fatigue strain life of puddle iron metal are obtained from previous experimental results conducted on specimens extracted from Luiz I Bridge (Porto, Portugal). Debonding failure of the adhesive joint is simulated through the use of cohesive zone model with traction separation law. The cohesive behavior was calibrated using fracture mechanic tests results on the adhesive, conducted in a previous related study. The fatigue crack initiation life was estimated using local approach based on material fatigue strain life. Fatigue resistance curves that relate the number of cycles to failure and the applied nominal stress for unreinforced and reinforced elements are derived. The results show that the application of CFRP can significantly increase the fatigue crack initiation life of a metallic structural component significantly.

Performance Evaluation of CFRP Strengthened Corrosion-Proof Columns

The application of FRP composites in recent years has attracted much attention. Lightweight, high strength, and corrosion resistance are among the properties that make this material available in various forms in construction engineering. The present study analyzed the performance of carbon fiber-reinforced accelerated corrosion-proof box. Nine columns without corrosion and cross-corrosion reinforcement were tested in laboratory and software. Syntax reinforcement was applied locally to the damaged area with respect to a transverse and longitudinal layer. The results of the axial test showed that, due to corrosion, the damaged site was weakened by the loading and severe resistance decreased, and the range of damage points due to the axial load was highly deformed compared to the initial state. The damage caused on both sides of the steel column had a significant effect on reducing the hardness and deformation of the steel columns; it is worth noting that the corrosion on both sides of the steel column had the most variations among the samples. Application of CFRP with 2 layers in the damaged steel columns resulted in increased bearing capacity and hardness in the affected area due to corrosion so that reinforcement of these columns by carbon fibers improved the axial strength.

Modeling Reinforced Concrete Beam with Reinforced Internal Failure by FRP and Comparing It with Laboratory Sample

Diagnosing type and amount of deficits in beams and structure is highly important in terms of performance and impact. Despite of paramount studies on CFRP application, its usage as Strips can be mentioned as one of the most important ways. Using Half Scale in building structure and lab beams would provide more adducible results. Considering type of breakdown and its progress, the growth cracks on the surface of beams is different. In all constructions, the manner of implementation and the quality of materials are two important principles in terms of performance and efficiency of the structure. In present study, type breakdown in the beam of reinforce concrete is addressed in a nondestructive manner. In this technique, by using finite element method in identifying beam breakdown without creating an unstable condition, one can achieve a nondestructive situation in experiments which is significantly cost – effective. Hence, 16 250mm × 250mm × 2100mm concrete beams were built and divided into two groups with and without FRP composite. Each group has a control beam and remained samples have breakdown in concrete and rebar. Prepared beams were put in a 4 – point experiment and, upon gathering and analyzing relevant data, beams prototyping was begun. By using finite element method, all beams were prototyped in lab. The findings from prototyping and lab analyses are compared in the format of load – location change graph. One can consider the results of prototyping as a proper approximation of lab samples.

Analysis of carbon fiber reinforced with resin epoxy using FEM analysis

Application of CFRP has been increased from the past as they offer much enhanced properties with less weight as compared to traditional metal such as cast iron. This development is the new spear head of the material technology due to its incomparable potential. This paper investigate the variation in the properties of CFRP with the variation in the Fiber mass percentage. ASTM standard test specimen are utilized and test is carried out with the help of Ansys Academic software. The primary objective of this paper is to evaluate equivalent stress, strain and total deformation of the composite under same load.

Experimental analysis of reinforced concrete shear deficient beams with circular web openings strengthened by CFRP composite

In this study, two methods of CFRP applications were utilized to strengthen the shear deficient beams with circular holes and a comprehensive experimental program consisting of 11 ½ scaled specimens was undertaken. The beams with hole diameter (D)/beam height ratio (H) of 0.30, 0.44, 0.64 ratios, symmetrically drilled in shear span were tested under vertical loading. D/H ratio of 0.30 did cause not only a decrease in load carrying capacity but also increased the ductility of the beam. However, significant decreases in load carrying capacities were observed as the hole diameters increase. The load carrying capacity and ductility were significantly improved owing to different CFRP configurations. The fact that the hole diameter and CFRP strengthening method are very important parameters for strengthening is observed. No CFRP strengthening alternative was successful in the beams with a D/H ratio of 0.64. A detailed macro and micro damage analyses are presented.

Numerical Modeling of Square Steel Members Wrapped by CFRP Composites

HSS (Hollow Structural Steel) tubular members used in buildings and bridges for structural application is rapidly developing technique in the recent era. Since, they have many advantages over RC structural members. This paper presents the application of CFRP on HSS tubular members under axial compression. Typical failure occurred during axial loading was local buckling, and this could be reduced by wrapping CFRP sheets around the HSS tubular columns were investigated experimentally. Eight steel samples are used in this test. Among eight specimens, two are unwrapped and the remaining six columns are externally wrapped by CFRP. CFRP sheets are used as strips, and the width of the sheets are constant. The spacing between the CFRP sheets is also constant. All columns are tested in column tester till the maximum to understand their failure modes, Ultimate load, load Vs. Displacement, Stress- Strain behaviour and Ductility index. Finally, results obtained from the experimental investigation could be validated with ANSYS software. The ultimate load and displacements from ANSYS validation are closely match with test results.

Experimental Study on Behavior of Bench-Scale Steel Structure Retrofitted with CFRP Composites under Ambient Vibration

Usage of FRP composites for the retrofitting purpose of the structures against the harmful effect of dynamic loads are gaining popularity, it is used in a wide variety of disciplines including civil engineering. Thus, there is a great need to study the behavior of FRP composites for strengthening purposes of structures using empirical methods. In this study, a bench-scale steel structure model was strengthened with CFRP composite and tested using operational modal analysis. To conduct operational modal analysis a bench-scale earthquake simulator and ambient vibration emulator were used. Same steel structure model was tested without strengthening procedure. Obtained dynamic responses (maximum-minimum displacements and accelerations before and after application of CFRP) of steel structure model have compared to each other. This study shows that floor displacements of the model have been decreased along the height of the structure up to 41.43 %. Therefore, the results of the experiment confirm the effectiveness CFRP composites for the strengthening of steel structures.

Experimental Study on Behavior of Bench-Scale Steel Structure Retrofitted with CFRP Composites under Ambient Vibration

Usage of FRP composites for the retrofitting purpose of the structures against the harmful effect of dynamic loads are gaining popularity, it is used in a wide variety of disciplines including civil engineering. Thus, there is a great need to study the behavior of FRP composites for strengthening purposes of structures using empirical methods. In this study, a bench-scale steel structure model was strengthened with CFRP composite and tested using operational modal analysis. To conduct operational modal analysis a bench-scale earthquake simulator and ambient vibration emulator were used. Same steel structure model was tested without strengthening procedure. Obtained dynamic responses (maximum-minimum displacements and accelerations before and after application of CFRP) of steel structure model have compared to each other. This study shows that floor displacements of the model have been decreased along the height of the structure up to 41.43 %. Therefore, the results of the experiment confirm the effectiveness CFRP composites for the strengthening of steel structures.