Carbon Fibre Reinforced Polymer Tubes Research Articles

Comparative study of dynamic parameters for damage identification of carbon fiber reinforced polymer tube

AbstractThe primary objective of the paper is the numerical and experimental investigation related to the damage recognition effects for CFRP tubes of four dynamic parameters. Four damage identification indexes consisting of natural frequency‐based index, Mode Shape‐based index (MS), Mode Shape Curvature‐based index (MSC), and Modal Flexibility Curvature‐based index (MFC) are established by analyzing the dynamic parameter data obtained before and after damage occurs. The performances of dynamic parameters are thoroughly discussed in the context of numerical simulations and experiment. The results indicate that the effect of natural frequency is not as significant as that of mode shape. MFC has the most notable effectiveness out of the four indexes. The simulation peak index pair is predicted to rise from 0.3 to 0.6 as the damage in the simulation model increases by 25% from 12.5%, indicating that MFC can feedback the damage degree. Moreover, the circumferential curvature index exhibits superior performance compared to the axial curvature index. To enhance the accuracy of the axial curvature index, it is proposed to increase the number of measuring sites along the tube's long direction.Highlights Damage identification indexes of four dynamic parameters are established. Discuss the identification ability of dynamic parameters by simulation and test. Two numerical models of CFRP tube with delamination damage are established. Impact and modal tests are executed to study the ability of four indexes.

Experimental investigation on the low‐velocity impact response and the residual strength of CFRP tubes

AbstractWith the help of the high‐speed camera and self‐designed fixture, it was investigated that the effects of the impactors in a variety of shapes on the mechanical behavior and failure mode of carbon fiber‐reinforced polymer (CFRP) tubes with a range of inner diameter during the low‐velocity impact (LVI) of four impact energies. Then, the three‐dimensional digital image correlation (3D‐DIC) system was carried out to monitor the damage evolution of the LVI‐damaged specimens under compressive and flexural loading. In addition, the residual compressive and flexural strength of all kinds of cases were compared and discussed. The results show that the increase in wall thickness can improve the LVI, compression‐after‐impact (CAI), and flexure‐after‐impact performance. The failure mode of compression changes to brittle fracture failure at the impact circumferential region. The CAI strength of the specimen damaged by a flat impactor is 23.89% less than that of a hemispherical one, but there is little difference in flexural loading.Highlights Mechanical behavior on in & post LVI of CFRP tubes varying wall thickness and impactor. Due to point‐line contact for flat impactor, two peak forces are in the F‐D curves. LVI property and residual strength are improved with the increase of wall thickness. Compressive failure mode is brittle fracture at the impact circumferential area. Flexure‐after‐impact strength mainly depends on the no‐impact surface of tubes.

Load–Displacement Behaviour and a Parametric Study of Hybrid Rubberised Concrete Double-Skin Tubular Columns

Rubberised concrete has emerged as a material of interest to the research community with the mission of creating sustainable structural members and decreasing the burden of waste tyre rubber. The potential benefits of replacing natural aggregates with rubber particles to obtain greater energy absorption and ductility are proven in the literature. To negate the reduction in capacity due to the addition of rubber particles, single- and double-skin confinements were proposed and successfully tested by researchers. Hybrid rubberised double-skin tubular columns (RuDSTCs) were recently trialled and tested by the authors. Each of these hybrid RuDSTCs had a filament-wound carbon fibre-reinforced polymer (CFRP) outer tube and an inner steel tube with rubberised concrete as the sandwich material between the two tubes. To explore the axial behaviour of such a column, this paper develops a finite element modelling strategy and carries out a comprehensive parametric study of the hybrid RuDSTC with 0%, 15%, and 30% combined aggregates replaced with rubber particles. This methodology is validated by experimental results, and a good agreement is found. Hybrid RuDSTC models are developed in four groups with different material and geometric parameters, in addition to those corresponding to the experimentally tested column, to explore the effects of the thickness ratio, hollow ratio, steel tube yield strength, and CFRP tube diameter with a special focus on the transition of the characteristic bilinear stress–strain curve of the hybrid RuDSTCs. The results show the smooth transition of the stress–strain curve with increasing rubber content after the yielding of steel, which indicates better ductility of the rubberised columns. The novel hybrid RuDSTCs can provide a promising sustainable solution with greater capacity compared with their unconfined counterparts. Better strain and enhanced ductility of the hybrid RuDSTCs compared with non-rubberized hybrid DSTCs enable their use in seismic-prone regions and mining infrastructure.

Effect of delamination on the dynamic characteristics of thin‐walled carbon fiber‐reinforced polymer tube

AbstractThin‐walled carbon fiber‐reinforced‐polymer (CFRP) tubes are susceptible to damage, which impacts their dynamic characteristics. This paper investigates the influence of delamination damage on the dynamic properties of thin‐walled CFRP tubes through finite element simulation and experimental methods. A transversely isotropic principal model is employed to establish the geometric model. Delamination damage is induced using the cohesive zone model and the secondary stress criterion. Both circumferential and elliptical delamination cases are studied. The modal test is conducted using the hammer excitation method. It is observed that the finite element model aligns with the experimental results. It is discovered that the larger the delamination size, the lower the natural frequency for a given damage location. The location of the delamination within a single layer has minimal effect on the natural frequency. The natural frequency exhibits a symmetrical pattern of decreasing and then increasing as the delamination shifts from the sides toward the center layer. Positional information is discernible in the modal shape, which can be utilized for delamination detection and localization.Highlights The damage model is built by transversal isotropic equation and cohesive unit. Finite element model is built with various delamination sizes and locations for two cases. Modal tests are performed on CFRP tubes and obtained good accuracy. Effect of delamination size and location on dynamic parameters is discussed.

Mesoscale study on the mechanical properties and energy absorption characteristics of aluminum foam-filled CFRP tubes under axial compression

This study investigates the axial compression mechanics and energy absorption characteristics of aluminum foam-filled carbon fiber-reinforced polymer (CFRP) tubes from both experimental and simulation perspectives. Quasi-static compression experiments of aluminum foam specimens, single CFRP tubes and aluminum foam-filled CFRP tubes are carried out. Based on the experimental results, compression simulations are conducted to investigate the structural deformation and the energy absorption characteristics of aluminum foam-filled CFRP tubes at the mesoscale. The effects of structural parameters on the compression mechanics and energy absorption characteristics of aluminum foam-filled CFRP tubes are explored.

Bond behaviour between CFRP, GFRP, and hybrid C-GFRP tubes and seawater sea sand concrete after exposure to elevated temperatures

The paper provides an overview of the current research on bond performance between fibre-reinforced polymer (FRP) tubes and SWSSC and investigates the bond strength of SWSSC-filled FRP tubes after exposure to different temperatures using push-out tests. A total of 27 samples, including glass FRP (GFRP), carbon FRP (CFRP), and glass-carbon hybrid FRP (HFRP) tubes, were tested to determine the effect of elevated up to 250 °C temperatures on the bond performance of the samples. It was observed that exposure to elevated temperatures increased the bond strength of all the tubes. The GFRP and CFRP tubes exhibited the strongest and weakest bond strengths, respectively. Since the inner layer of the HFRP tube was composed of CFRP, the bond strength of HFRP was found to be more similar to that of CFRP samples than GFRP samples. The study concluded that the bond strength of all the samples was predominantly influenced by the surface roughness of the inner tube rather than the fibre type.

On axial crushing behavior of double hat-shaped CFRP and GFRP structures

This study aimed to investigate the energy-absorbing mechanisms of composite structures subjected to quasi-static and dynamic axial crushing loads. Double hat-shaped composite tubes were prepared using carbon fiber-reinforced polymer (CFRP) and glass fiber-reinforced polymer (GFRP) composite materials. The results indicated that these composite tubes exhibited a progressive end-crushing mode and had a comparable load-carrying capacity at a crushing velocity of 2 mm/min. When the loading rate was increased to 6.1 m/s, a 23.3% reduction in the energy absorption of the CFRP structures was observed; whereas the energy absorption of the GFRP structures remained relatively constant. A stacked-shell finite element model, which considered the effects of strain rate on intra-layer and inter-layer properties, was developed to simulate the axial crushing behavior of the CFRP and GFRP tubes. The predictions made by the finite element model were found to correlate well with the tested crushing process, force–displacement curves, and final failure mode. The mechanical properties of the composite materials were also observed to play a critical role in the energy-absorbing mechanisms, contributing to the distinct crushing responses of the CFRP and GFRP structures. The results of this study are expected to help clarify the differences in the energy-absorbing mechanisms between CFRP and GFRP tubes, thereby contributing to the crashworthiness design of composite energy-absorbing structures.

A New Electrical Resistance Measurement Method of Carbon Fiber-Reinforced Polymer Tubes Based on C⁴D Technique

This work introduces the capacitively coupled contactless conductivity detection ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{C}^{{4}}\text{D}$ </tex-math></inline-formula> ) technique into nondestructive testing (NDT) of carbon fiber-reinforced polymer (CFRP) and proposes a new resistance measurement method of CFRP tubes. The proposed method does not require direct contact between the electrodes and the carbon fiber. Therefore, the electrical resistance of CFRP can be measured without the treatments required by traditional electrical methods that may lead to surface or structural damage. The equivalent circuit model of the new method is established, and the challenges are analyzed. Simulation and experiment are conducted with woven fabric CFRP tubes to verify the feasibility of the proposed method, including the range of workable frequency, the effectiveness of the circuit model, and the capability of damage detection. Research results show that a relatively high working frequency is required to accurately measure the interested resistance and sense the resistance change. By selecting a workable frequency, the effectiveness of the circuit model is verified. Research results indicate that the stray capacitance between the electrodes has little effect on resistance measurement, and the capacitor–resistor–capacitor model is still applicable. Research results also verify the feasibility of the proposed method for damage detection. It is able to sense the resistance change resulted from the damage of CFRP, either the conductivity changes in simulation or actual cutting damage in experiment.

A probabilistic study into the influences of fiber angle orientations on energy absorption performance of carbon fiber-reinforced polymer composite tubes

The influence of fiber orientations on the crashworthiness of carbon fiber-reinforced polymer (CFRP) composite tubes was investigated to fill in the knowledge gap regarding the effects of fiber angle on the energy-absorbing potential of these tubes. This study adopted the Hammersley sequence sampling (HSS) method to generate a quasi-random distribution of the design objectives. Then, LS-DYNA was utilized for numerical quasi-static crushing tests to measure the specific energy absorption (SEA) and the crushing force efficiency (CFE) of a quasi-static CFRP tube at different fiber angles. The Kriging method was implemented to generate a surrogate model. Finally, Pareto results were extracted deterministically and probabilistically using the NSGAII algorithm. Fiber orientation angles are naturally exposed to uncertainties in the manufacturing process; thus, the main contribution of the study is illustrating the effects of fiber angle orientations on the energy-absorbing characteristics of CFRP tubes while incorporating uncertainties into the optimization procedure. Interestingly, the optimum fiber angle orientations revealed the potential advantage of using non-conventional angle-ply layouts by improving the CFE by up to 4% compared with the initial design configuration. The results also demonstrated the capability and superior performance of the optimization procedure in finding the global optima, and the necessity of conducting a probabilistic examination in similar studies.

Freeze-thaw behaviour of basalt fibre reinforced recycled aggregate concrete filled CFRP tube specimens

This paper is focused on the behaviour of basalt fibre reinforced recycled aggregate concrete (BFRC) short specimens confined by carbon fibre reinforced polymer (CFRP) tubes under freeze–thaw conditions. The main parameters investigated are the replacement rate of recycled coarse aggregate (RCA), the number of freeze–thaw cycle (FTC), the related temperature range, and the shape of short specimen section. The failure mode, dynamic elastic modulus, ultimate bearing capacity and the load–strain response of the specimens are studied. The results show that the failure mode and the load–strain response of CFRP tube confined recycled aggregate concrete (RAC) specimen have insignificant change due to FTCs. However, with the increase of the FTCs, the bearing capacity of the specimen decreases, and the specimen with square cross-section is much more sensitive than that of the circular cross-section counterpart. The smaller the range of freeze–thaw temperature changed, the smaller loss of the dynamic modulus and the smaller decrease range of the ultimate bearing capacity after FTCs.

Mechanical performance of marine concrete filled CFRP-aluminum alloy tube columns under axial compression: Experiment and finite element analysis

This study presents the mechanical performance of marine concrete filled carbon fiber reinforced polymer (CFRP)-Aluminum alloy tube columns (CFRP-CFAT) through axial compression experiment and finite element analysis. 18 specimens were tested including 3 marine concrete filled aluminum alloy tubes (CFAT) and 15 CFRP-CFATs. The effects of the CFRP pasting position (outer and inner CFRP) and the number of CFRP layers were investigated. The typical failure pattern of specimens without inner CFRP was waist drum failure of aluminum alloy tube and concrete crushed, aluminum tube and concrete of specimens with inner CFRP were shear failure, the CFRP of all specimens was fractured. CFRP and aluminum alloy tube have fine deformation coordination performance. With the confinement of CFRP, the ultimate bearing capacity and energy absorption capacity of CFRP-CFATs were increased by up to 60.0% and 37.3%, respectively, also effectively inhibited the damage development of specimens. Moreover, a finite element model was developed, a parametric study was carried and a model for calculating the ultimate bearing capacity of CFRP-CFAT was proposed. The simulated results and calculated results were consistent with experimental results.

Finite Element Simulations of the CFRP Retrofitted Hollow Square Columns

ABSTRACT This article describes the finite element analysis of concrete columns with a hollow square reinforced which restricted with a square Carbon-Fiber-Reinforced polymer (CFRP) tube. In this study, about sixteen square hollow core columns were investigated. These columns were classified into four sets. The set number one was the reference set which involved four unconfined reinforced columns with traditional steel helices and longitudinal steel bars. The columns of the 2nd category have a similar configuration as the set number one except that these columns were restricted outwardly by the CFRP tube. The columns of the set number were restricted outwardly by a CFRP tube and restricted inwardly by a steel tube. Finally, the columns of the 4th category do not have a steel reinforcement where they produced with only an outer CFRP tube and an inner steel tube. These columns were exposed to various loading conditions: concentric, eccentric (22 and 44) mm, and four bendings' points. It was investigated that the CFRP tube confinement faintly improved the columns’ strength. Moreover, the use of a steel tube as inner confinement in the columns with a hollow section led to improve the structural performance and ductility.

Deformation and fracture behaviors of cylindrical battery shell during thermal runaway

Thermal runaway is one of the catastrophic failure modes of lithium-ion cells. During thermal runaway in cylindrical cells, sidewall shell rupture has been identified as a contributing factor for thermal runaway propagation in battery packs. Herein, the deformation and fracture behaviors of the battery shell during thermal runaway are investigated based on in-situ and ex-situ characterization as well as physics-based modeling. The deformation and fracture modes of the battery shell with/without Carbon Fiber Reinforced Polymer (CFRP) sleeves are identified. In the simulation, the strain introduced by thermal expansion of the system is considered, as well as the thermal and strain rate effects on the plastic stage. The final cell shell modeling is validated by cell thermal runaway tests. Results reveal the quantitative relation between shell deformation behaviors and the pressure and temperature distribution. Both the experiment and model demonstrate the effectiveness of adding a tight-fitting CFRP sleeve around the cell in limiting the side-wall rupture of the shell. The use of CFRP tubes introduces a novel phenomenon in the context of uneven temperature distribution. Results shed light on the mechanistic analysis of a cell side-wall rupture during thermal runaway and provide essential guidance for the next-generation safe battery design.

Optimal finite element modeling of filament wound CFRP tubes

The complexity of fiber patterns within the layers of a Carbon Fiber Reinforced Polymer (CFRP) composite made with the filament winding technique has an active effect on the mechanical properties of the layer and respectively of the whole structure. While the approximation of mechanical properties in classic laminated composites is a relatively well-researched subject, there is a lack of information on filament wound cylindrical composites. Due to its material variability, filament wound CFRPs require certification results through numerical - experimental validation. Thus, in this work, an optimal modeling procedure of filament wound CFRP tubes is presented. The main goal is to acquire the lamina mechanical properties that could reliably be used in further finite element analyses with implications in critical practical applications with linear and nonlinear characteristics. At first, a homogenization method is applied to obtain the nominal values of layer properties. Next, a simple tensile test, conforming to ASTM 3039 standards, was repeatedly carried out using a representative sample of CFRP specimens, measuring experimental strain data. A stochastic state-of-the-art single objective optimization algorithm coupled to a robust finite element analysis solver is employed in order to finely tune the lamina material parameters minimizing the residual between experimental measurements and numerical predictions. Lastly, three tensile-based validation tests of stepwise difficulty and varying layer orientation, thickness, internal diameter, width and loading conditions are carried out, efficiently confirming the reliability of the characterized lamina material properties. Comparison of experimentally measured and optimal model’s numerically predicted strain response time histories in both linear elastic deformations as well as in nonlinear large deformations under progressive failure response strongly supported the efficacy and effectiveness of the proposed methodology.

Damage Detection of CFRP Filament Wound Tubes Using Electrical Resistance Measurement

The electrical resistance measurement method was used for damage detection of Carbon Fiber Reinforced Polymer (CFRP) tubes during torsion and flexural loading. The symmetrical convex octagon shape specimens were manufactured using a filament winding technology. The specimens were manufactured with Integrated Loop Technology (ILT) joints at the ends in a single production step. This configuration of tubes with ILT joints allows very effective load transfer and it is also efficient from the manufacturing point of view. This type of components could be used in construction of robotic arms for automated processes. Possible collisions and resulting overloading can cause damage to the composite tubes. Such damage could be overlook due to cabling, coating and casing covering the surface of the robotic arms. In addition to the above, the requirement for a smooth surface must also be met. Therefore, possible way how to easily detect serious damage of CFRP tubes was investigated, together with a testing of a novel approach to an electrical contact manufacturing. The electrical contacts for damage monitoring were made of carbon fiber tows with electrically connected endings. They were integrated to the composite structure during filament winding process. Four specimens were loaded by flexural loading and two specimens were loaded by torsional loading. All specimens were loaded by three cycles of operational loading and then loaded to final fracture. It was shown that the presented type of electrical connection to the structure is feasible, does not disturb the surface of the sample and does not affect the ultimate strength of the specimen. According to our measurements, operational loading could be monitored only to a limited extend using the electrical resistance measurement. This is because the fracture damage caused significant change in measured electrical resistance of the specimen for both torsional and flexural loading. The presented measurement configuration with electrodes made of integrated carbon fibers is suitable for further investigation in the field of fracture damage detection of carbon fiber wound profiles.

Behavior of CFRP-Confined Sand-Based Material Columns under Axial Compression.

This paper presents an innovative pumpable standing support designed for underground mines located in the arid and semi-arid deserts of the Gobi region with a shortage of water resources. The exterior shell of this pumpable standing support is made of carbon fiber-reinforced polymer (CFRP), while the infill material is a sand-based material (SBM). As the novel backfill material, SBM is the combination of high-water cementing material and desert sand. A series of experimental tests were conducted to obtain the mechanical response mechanism of this novel pumpable standing support under uniaxial compression. Test variables investigated in this research covered the water-to-powder ratio of the cementing material, the mixing amount of sand, and the thickness of the CFRP tube. Test results confirmed that the CFRP-confined SBM columns exhibited typical strain hardening behavior with the acceptable axial deformation. It was also demonstrated that using high-strength cementing material, a thicker CFRP tube, and a high mixing amount of sand effectively increased the bearing capacity of the CFRP-confined SBM column. Except for the exemplary structural behavior, the consumption of high-water cementing materials of the novel pumpable standing support is smaller than that of its counterparts made of pure cementing material, when specimens with the same mechanical performance are compared.

Post Tensioned CFRP tubes for improved energy absorption

Thin-walled tubes made of CFRP (Carbon fiber reinforced Polymer) are being increasingly used as CC (Crush Cans) due to their higher specific energy absorption capacity in the automotive domain for absorbing impact energy during a frontal crash. Finite element analysis (FEA) based computational methods have matured over the years with increased accuracy and acceptable correlation with experimental results. FEA-based computational studies when used appropriately can reduce the number of physical tests and prototypes required besides accelerating the overall cycle design time. The present work proposes an FEA based design validation approach for the evaluation of post-tensioned crush can design that can absorb more impact energy compared to a normal CFRP thin tube. The FEM based method uses a combination of multiple simulation techniques to predict the behavior of a post-tensioned tube. The post-tensioning in the present work has been proposed in the form of internal pressure for the thin tube. It was found that a safe value of pressure, when applied as a post-tensioning load, can improve the energy absorption capacity without increasing the weight of the tube.

Blast responses of carbon-fiber reinforced polymer tubular columns filled with seawater sea-sand concrete

Concrete-filled fiber-reinforced polymer tubular (CFFT) columns are advanced structures in civil engineering due to their advantages of high strength, good corrosion resistance, and strong stability. In this study, four groups of columns were designed, with three groups of CFFT columns cast with carbon-fiber reinforced polymer (CFRP) tube and seawater sea-sand concrete (SSC) reinforced with glass fiber reinforced plastic (GFRP) bars and one group of reference SSC columns. Quasi-static compression and field explosion experiments were conducted to investigate their quasi-static and dynamics mechanical performances. The damage of exploded columns was evaluated by direct radiography (DR) inspection and residual bearing capacity testing. The quasi-static compression capacity of the CFFT column is about twice of the summation of the load bearings of the CFRP tube and the SSC column with the help of the constraint effect of the CFRP tube. An improved model was proposed to predict the compression capacity of the CFFT column considering the strength of the CFRP tube. The CFRP tube attenuates the spalling failure of SSC columns and transfers the damage to concrete tensile crack and CFRP damage. The innovative CFFT column filled with GFRP bars reinforced SSC exhibits immense potential in marine protective structures.

Confinement of Concrete by Fiber Reinforced Polymer Tube: A Review

Researchers studied a lot of strengthening techniques of concrete, one of which is the technology of concrete confinement. This technique is common to utilize fiber fabric impregnated with epoxy resin adhesive. Relevant applications mainly include strengthening the existing structure and new structural construction. This paper presents a review of previous studies on the confinement of concrete using fiber-reinforced polymer (FRP) tubes. Four main parameters were investigated in this study: the number of layers of FRP tubes, cross-sectional shape and slenderness ratio, material types of FRP tubes, and concrete types. The results of the investigation showed that increasing the number of FRP tubes resulting in a significant improvement in the behavior of confined specimens, circular cross-section specimens exhibited better behavior than square. Also, the behavior of confined square specimens improvement with increasing the angular radius. A carbon fiber reinforced polymer tube is better than (aramid, glass, and basalt) fibers. Finally, the concrete confining technique significantly improved the behavior of specimens regardless of the type of concrete confined, and the effect of confining decreases with the increase of compressive strength of the concrete confined.

Behavior of High Strength Concrete Filled Square Steel Tube Stub Columns with Inner CFRP Tube Under Biaxial Eccentric Compression

This paper studies the contribution of CFRP (carbon fiber-reinforced polymer) to the mechanical behavior of high strength concrete-filled square steel tube (HCFST) under biaxial eccentric compression. The new type of composite member is composed of an inner CFRP tube and an outer steel tube with concrete filled in the two tubes. The finite element analysis was made by ABAQUS on the behavior of high strength concrete filled square steel tubular columns with inner CFRP circular tube subjected to bi-axial eccentric loading. The results obtained from the finite element analysis were verified with the experimental results. In addition, the load-deflection curves in the whole process were calculated and analyzed, which can be divided into three segments: Elastic phase, plastic phase, descending phase. Based on the load-deflection curves, the stresses analysis on the core concrete, CFRP tube and steel tube were conducted. The confinement effect of the CFRP tube improves the ductility of HCFST-CFRP stub column. CFRP ratio and eccentricity affect the ultimate bearing capacity of HCFST stub column. Finally, a calculation formula of ultimate bearing capacity was proposed in the paper.