Carbon Fibre Reinforced Polymer Tubes Research Articles

Development of a 25kN <i>In Situ</i> Load Stage Combining X-Ray Computed Tomography and Acoustic Emission Measurement

Combination of material testing methods such as X-ray computed tomography with in-situ load stages allows for detailed analysis of damage formation and progression in fibre-reinforced composites. X-ray computed tomography is highly suited to volumetrically analyse the damage evolution induced by the load stage for tensile testing after subsequent load increments. Simultaneous acoustic emission monitoring allows identifying the occurrence of particular failure mechanisms and allows stopping the loading procedure for volumetric scanning. However, typical commercial designs focus on a broad range of materials and are not necessarily optimized for high load capacity at high voxel resolution or the possibility to attach acoustic emission sensors to the test sample. Accordingly, we designed a new load stage to fit larger samples up to 180 mm in length and 18 mm in width, which also allows two piezoelectric acoustic emission sensors to be directly applied on the sample. In order to test fibre reinforced laminate samples with a relevant cross-section, the support structure of the load stage is made of a carbon fibre reinforced polymer tube, which withstands a maximum load of 25 kN and still stays reasonably X-ray transparent. With an outer diameter of 27 mm, a computed tomography scan with a resolution down to 2.6 μm is still possible for these laminate cross-sections. This allows to study in detail how matrix and fibres behave under loads in laminates, which are comparable to specimen sizes by typical test standards. As example, we present results from glass fibre-reinforced epoxy samples with a [±45°]5layup and carbon fibre-reinforced epoxy samples with a [0,90,90,0] layup.

Hierarchical design, manufacture and crushing behaviors of CFRP tubular energy absorbers

Hierarchical topology is introduced to construct weight-efficient carbon fiber reinforced polymer (CFRP) tubular energy absorbers through filling small-diameter tubes into large-sized tubes. Crushing behaviors of the thin-walled tubes and the hierarchical tubes are investigated through quasi-static compression experiments and compared with each other. Large-diameter and long thin-walled tubes always fail at brittle modes with limited energy absorption (EA). The hierarchical tubes are crushed progressively and have excellent EA, for the mean crushing force (MCF) exceeds half of the peak force (PF) and the crushing distance is larger than half of the tube length. The improvement in the EA is attributed to the interactions among substructures at different levels which induce a ductile crushing mode. Taking into account the priority of low density, the hierarchical CFRP tubes are weight-efficient absorbers.

Rate and temperature dependent relations for CFSTs and CFFTs subject to post-impact fire conditions

Experimental research on the behaviour of conventional construction materials subject to extreme loading condition of post-impact-fire has indicated the effect of rate dependent loading history on the temperature performance of these materials. In order to analyse and design structures to withstand such combined loading, it is desirable to develop models that can reflect the mechanical properties of materials under initial impulsive loading and subsequent elevated temperature. In this study, a rate-pre-damage-temperature dependent empirical expression is proposed to predict the residual strength of partially damaged steel-concrete and fibre rein-forced polymer-concrete composite materials, in the form of concrete-filled steel tubes (CFST) and Concrete filled carbon-fibre reinforced polymer tubes (CFFT), at high temperatures up to 600 °C. The developed model is calibrated and validated on the basis of actual experimental data published by the authors. The proposed expression proves to be capable of successfully reproducing material strengths by considering the extent of high strain rate induced pre-damage together with temperature exposure.

Finite element simulation for predicting the behaviour of carbon fibre tubes for automotive side structure

Digital product development for carbon fibre reinforced polymer (CFRP) parts needs reliable simulation methods to predict the performance. The objective of this study to find the best simulation method to predict the behaviour of CFRP tube when subjected to lateral/bending forces. LS Dyna Explicit finite element code is used for simulation. CFRP square tube is subjected to three Point bend test experiment. The force displacement curves are obtained. The deformation pattern, cracks and failures are also closely observed. Various methods of Finite Element Simulation are explored. Each simulation method is compared with experimental results. Finite element simulation method with Layered Thin Shell and delamination modelling using mixed mode material cohesive zone is found to be best validating with experimental results. This method is proposed to be used in the design and development of Carbon fibre parts for automotive structures. This can reduce time and cost involved in prototyping and testing.

Finite element simulation for predicting the behaviour of carbon fibre tubes for automotive side structure

Digital product development for carbon fibre reinforced polymer (CFRP) parts needs reliable simulation methods to predict the performance. The objective of this study to find the best simulation method to predict the behaviour of CFRP tube when subjected to lateral/bending forces. LS Dyna Explicit finite element code is used for simulation. CFRP square tube is subjected to three Point bend test experiment. The force displacement curves are obtained. The deformation pattern, cracks and failures are also closely observed. Various methods of Finite Element Simulation are explored. Each simulation method is compared with experimental results. Finite element simulation method with Layered Thin Shell and delamination modelling using mixed mode material cohesive zone is found to be best validating with experimental results. This method is proposed to be used in the design and development of Carbon fibre parts for automotive structures. This can reduce time and cost involved in prototyping and testing.

Study of automotive side sill/rocker by using carbon fibre reinforced polymer tubes

ABSTRACTVehicle side crash is a critical crash event where the vehicle is crashed by a movable car or vehicle may hit a tree or pole. Minimising the intrusion into the occupant space is important to protect the occupant. In side pole crash, vehicle rocker (sill) plays an important role in resisting the load due to the crash. The objective is to study the functional performance and potential mass reduction in the vehicle sill/rocker area by use of carbon fibre reinforced polymer (CFRP) tubes. The study is divided into three parts. First part investigates the behaviour of CFRP square section tubes in a three-point quasi-static bending in comparison to conventional steel structure using finite element method. By keeping the resistance force offered by a steel section as the baseline resistance value, different combination of CFRP tubes and metal holding brackets are evaluated and compared with the baseline. In the second part, CFRP tube is simulated in dynamic three-point bending test and compared with quasi-static simulations in order to check the influence of inertial effects on the CFRP tube behaviour. In the third part, the best performing design variants from the three-point quasi-static bending simulations are used in the sill or rocker of a vehicle and evaluated in full vehicle US NCAP pole impact load case. The full vehicle crash simulations for side pole impact is compared between the baseline with the steel reinforcement and design variants with the CFRP tube. Resistance force levels, intrusion and structural integrity are the key parameters on which this comparison is made. It is concluded that using CFRP tubes does not reduce the performance in terms of structural integrity and intrusion levels in typical side crash scenario like a US NCAP side pole impact. It can also be concluded that there is potential for mass reduction. Further investigation into the assembly feasibility is suggested as future work.

Seismic behavior of concrete bridge columns confined with fiber-reinforced polymer stay-in-place formwork

One of the applications of fiber-reinforced polymers in bridge construction is stay-in-place formwork. Fiber-reinforced polymer stay-in-place formwork, in the form of preformed tubes, provides easy form assembly, protection of steel reinforcement and concrete against corrosion and chemical attacks while also improving the strength and ductility of structural elements in earthquake resistant construction. Experimental research was conducted to investigate the seismic performance of fiber-reinforced polymer stay-in-place formwork for bridge columns. Tests of large-scale specimens were conducted under simulated seismic loading. The experimental program included circular and square columns confined with carbon fiber–reinforced polymer tubes. The results indicate that the use of carbon fiber–reinforced polymer tubes increases column inelastic deformability significantly. Bridge columns under low levels of axial compression exhibit inelastic drift capacities in excess of 4% before failing in flexural tension due to the rupturing of longitudinal reinforcement. These observations and experimental results were used to develop a displacement-based design procedure for concrete confinement for fiber-reinforced polymer–encased concrete columns. This article presents an overview of the experimental program and the design approach developed.

Concrete Filled Carbon FRP Tube (CFRP-CFFT) columns with and without CFRP reinforcing bars: Axial-flexural interactions

Abstract The axial and flexural behaviors of Concrete Filled Carbon Fiber Reinforced Polymer Tube (CFRP-CFFT) columns have received significant research attention in the last two decades. One of the most attractive advantages of Carbon FRP (CFRP) tube is the high confinement which results in substantial increase in peak axial and flexural loads and deformations. Despite large research efforts, the behavior of CFRP-CFFT with and without CFRP reinforcing bars under different applied axial load eccentricity has not yet been adequately investigated. This study investigates the experimental and analytical axial-flexural ( P − M ) interactions of CFRP-CFFT columns with and without CFRP reinforcing bars. A total of 12 specimens of 204–205 mm outer diameter and 800–812 mm height were tested under concentric axial load, 25 mm and 50 mm eccentric axial loads and four-point load. The effectiveness of CFRP reinforcement (tube and bar) was observed to be reduced with the increase in the applied axial load eccentricity. Analytical P − M interactions were constructed using available FRP confined concrete design codes which matched well with the experimental P − M interactions. The parametric study showed that the actual confinement ratio, orientation of fibers and CFRP bar reinforcement ratio have significant influences on P − M interactions of CFRP-CFFT specimens.

Flexural behavior of high strength concrete filled square steel tube with inner CFRP circular tube

This paper investigates the flexural behavior of high strength concrete filled square steel beam with inner CFRP (carbon fiber-reinforced polymer) circular tube by the ABAQUS/Standard solver. In addition, eight specimens were fabricated and tested to investigate the pure flexural behavior. The test data was used to verify the Finite Element Analysis (FEA) modeling and good agreement was achieved in general. Furthermore, the influences of steel yielding strength, concrete strength, steel ratio and the thickness of CFRP on the flexural performance of the specimens were analyzed by FEA. According to the analysis of bending moment versus strain curves, the materials of CFRP, steel and concrete worked well together subjected to pure bending before the CFRP tube ruptured. The results presented in this paper show that these composite beams have a very ductile response because the concrete is confined by the CFRP tube and the steel tube. The beams’ flexural response, including the flexural stiffness and the ultimate load, can be substantially improved by the inner CFRP tube. The parametric studies provide information for the development of formulae to calculate the moment capacity. A comparison of experimental failure loads with the predicted failure loads in accordance with the formulae showed good agreement.

Behavior of CFST columns with inner CFRP tubeunder biaxial eccentric loading

This paper presents the results of an experimental study on the behavior of a new type of composite FRP-concrete-steel member subjected to bi-axial eccentric loading. This new type of composite member is in the form of concrete-filled square steel tube slender columns with inner CFRP (carbon fiber-reinforced polymer) circular tube, composed of an inner CFRP tube and an outer steel tube with concrete filled in the two tubes. Tests on twentysix specimens of high strength concrete-filled square steel tube columns with inner CFRP circular tube columns (HCFST-CFRP) were carried out. The parameters changed in the experiments include the slenderness ratio, eccentric ratio, concrete strength, steel ratio and CFRP ratio. The experimental results showed that the failure mode of HCFSTCFRP was similar to that of HCFST, and the specimens failed by local buckling because of the increase of lateral deflection. The steel tube and the CFRP worked together well before failure under bi-axial eccentric loading. Ductility of HCFST-CFRP was better than that of HCFST. The ultimate bearing capacity of test specimen was calculated with simplified formula, which agreed well with test results, and the simplified formula can be used to calculate the bearing capacity of HCFSTF within the parameters of this test.

Tests on seawater and sea sand concrete-filled CFRP, BFRP and stainless steel tubular stub columns

This paper presents an experimental study on concrete-filled circular tubes that consisted of seawater and sea sand concrete (SWSSC), stainless steel (SS) tube, carbon fibre reinforced polymer (CFRP) tube, and basalt fibre reinforced polymer (BFRP) tube. A total of 38 stub columns, which included 12 hollow section tubes, 12 fully SWSSC-filled tubes and 14 SWSSC-filled double-skin tubes, with four combinations of inner and outer tubes, were tested under axial compression. Tensile coupon tests and “disk-split” tests were conducted to obtain the material properties of SS, CFRP and BFRP. Ultimate strain of SWSSC-filled tubes and stress-strain curves of the confined concrete were characterised in the study. The effects of some key parameters (e.g., tube diameter-to-thickness ratio, cross-section types, outer tube types, and inner tube types) on the confinement effects were also discussed. Comparisons were made among CFRP, BFRP and glass fibre reinforced polymer (GFRP) in terms of confinement to SWSSC. The capacity prediction formulae previously proposed by the authors for SWSSC filled GFRP tubes were found to be reasonable for estimating the load carrying capacity of SWSSC filled CFRP and BFRP tubes.

Behavior of glass and carbon FRP tube encased recycled aggregate concrete with recycled clay brick aggregate

In literature, there are few studies which investigated compressive behavior of fibre reinforced polymer (FRP) tube confined recycled aggregate concrete (RAC) where the recycled aggregates (RAs) mainly came from demolished old concrete components. Study which considered FRP tube confined RAC using recycled clay brick aggregates (RCBA) originating from demolished brick masonry components is rare. Thus, this paper reports a systematic study on axial compressive behavior of FRP tube encased RAC containing RCBA (termed as FRP-confined RAC-RCBA). The experimental variables considered are, i.e., replacement ratio of RCBA (r=0, 50, 70 and 100%), FRP tube thickness (nf=2, 4 and 6 layers) and type of fibre material (GFRP and CFRP). This study shows that both GFRP and CFRP tubes enhanced strength and deformation of the confined RAC-RCBA specimens remarkably. The ultimate compressive stress of the confined specimens decreased with an increase of RCBA replacement ratio but their axial deformation kept approximately constant. Failure mode and the compressive stress-strain behavior of G/CFRP-confined RAC-RCBA were similar to these tube confined normal aggregate concrete (NAC) and the ultimate compressive strength of G/CFRP tube confined RAC-RCBA specimens enhanced with an increase in FRP tube thickness. The CFRP-confined specimens showed higher ultimate strength but lower ultimate axial strain than those of GFRP-confined specimens. The applicability of eight widely used confinement models, i.e., 5 design-oriented and 2 analysis-oriented models, for FRP-confined NAC to FRP-confined RAC-RCBA was also evaluated.

Axial and flexural behavior of unreinforced and FRP bar reinforced circular concrete filled FRP tube columns

Fiber Reinforced Polymer (FRP) composites have emerged as a viable alternative of steel reinforcement due to higher ultimate tensile strength to weight ratio and corrosion resistance of FRP composites. Concrete Filled Fiber Reinforced Polymer Tube (CFFT) technique for new column construction has attracted significant research attention. This paper investigated the axial and flexural behavior of Concrete Filled Carbon FRP Tube (CFRP CFFT) columns with and without CFRP bar and concrete filled Glass FRP (GFRP) tube columns with and without GFRP bar. The test results of 16 circular CFFT and four steel Reinforced Concrete (RC) specimens of 203–205mm diameter and 800–812mm height have been reported in this paper. The test results showed a larger reduction in the confinement effectiveness of FRP tube than steel helices under increasing applied load eccentricity. FRP bar reinforced CFFT specimens exhibited higher axial loads, flexural loads, and deformations at peak loads than unreinforced CFFT and steel RC specimens. Experimental axial load-bending moment interaction curves of tested specimens also showed the improved performance of FRP bar reinforced CFFT specimens.

Effect of thickness of inner carbon fibre reinforced polymer tubes on axial compressive behaviour of steel-concrete-carbon fibre reinforced polymer-concrete columns

Steel-concrete-carbon fibre reinforced polymer-concrete columns (SCCC columns) have been introduced as a new form of hybrid columns by first author. An SCCC column consists of an outer steel tube, an inner carbon fibre reinforced polymer tube, an annular concrete between two concentric tubes and a core concrete encased in carbon fibre reinforced polymer tube. This paper presents the results of a test study that was conducted to investigate the effect of thickness of inner carbon fibre reinforced polymer tube on the axial compressive behaviour of SCCC columns. Four SCCC columns with carbon fibre reinforced polymer tubes of two different thicknesses of 0·167 mm and 0·334 mm in addition to two reference columns without carbon fibre reinforced polymer tube were prepared. All the six short columns, each 260 mm in diameter, 780 mm in height, were manufactured and tested to failure under pure axial compression. Test results demonstrate that the circular hybrid SCCC columns are of excellent axial compression behaviour, and that increasing the thickness of inner carbon fibre reinforced polymer tube can increase the ultimate axial load capacity and ultimate axial strain of SCCC columns remarkably.

Static property analyses based on finite element method and torsion tests on carbon fibre composite motor drive shaft

A carbon fibre-reinforced polymer drive shaft consisting of a carbon fibre/epoxy composite tube connected to two adhesively bonded steel flanges was designed. Next, finite element method was used to analyse the carbon fibre-reinforced polymer shaft's static torsional properties. The finite element method results showed that the carbon fibre-reinforced polymer tube was capable of withstanding the designed maximum torque of 6701·8 Nm according to the Tsai-Wu failure criterion. Static torsion and torsional fatigue tests were conducted on the carbon fibre-reinforced polymer shaft specimen, at the applied maximum torque of 5492 Nm and 184 300 fatigue cycles. As the shaft did not sustain any damage, it was concluded that the design of the carbon fibre-reinforced polymer shaft was feasible.

Influence of overlap configuration on compressive behavior of CFRP-confined normal- and high-strength concrete

This paper presents the findings of an experimental investigation on the effect of overlap configuration on carbon fiber-reinforced polymer (CFRP)-confined normal- and high-strength concrete. A total of 33 specimens were prepared and tested under monotonic axial compression. All specimens were cylinders with 152 mm diameter and 305 mm height and confined by CFRP tubes. Two different concrete mixes were examined, with average compressive strengths of 52.0 and 84.7 MPa. The effect of overlap configuration was examined by manufacturing the specimens with different properties at the overlap region including overlap length, continuity and distribution. Axial and lateral behavior was recorded to observe the axial stress–strain relationship and hoop strain behavior for concentric compression. Ultimate axial and lateral conditions are tabulated and stress–strain curves have been provided. Detailed plots of hoop strain development and lateral confinement pressure at ultimate are presented. The results indicate that FRP overlap length has no significant influence on strain enhancement ratio (e cu /e co), but an increase in overlap length leads to a slight increase in strength enhancement ratio (f′ cc /f′ co), with these observations equally applicable to both continuously and discontinuously wrapped specimens. The results also indicate that continuity of the FRP sheet in the overlap region has some influence on the effectiveness of FRP confinement. Furthermore, it was observed that the distribution of FRP overlap regions for discontinuously wrapped specimens can influence the axial compressive behavior of these specimens in certain overlap configurations. Finally, it is found that the distribution of lateral confining pressure around specimen perimeter becomes less uniform for specimens with higher concrete strengths and those manufactured with overlap regions that are not evenly distributed.

Compressive behavior of concrete confined by CFRP and transverse spiral reinforcement. Part A: experimental study

This study presents the results of an experimental investigation of 18 short concrete columns confined by carbon fiber-reinforced polymer (CFRP) and transverse spiral reinforcement (TSR) under uniaxial compression. Longitudinal rebars are not installed in the specimens in order to eliminate their confinement effect to concrete which affects the analysis of 3-D compression of concrete. The paper only consider for FRP and spiral reinforcement confinement in transverse direction. Two key experimental parameters were investigated: the thickness of the CFRP tube (0.167, 0.334, and 0.501 mm) and the spacing of the TSR (25 and 50 mm). The failure mode, axial and transverse stress–strain relationship, confinement effectiveness, Poisson’s ratio and dilatation performance of the specimens were discussed. Test results show that the ultimate strength of concrete has a linear proportional enhancement with an increase in the FRP layer in each TSR category and a decrease in the TSR spacing in each FRP layer category. The ultimate load carrying capacity of the confined concrete depends on the confinement pressure during failure in terms of ultimate strength and axial strain.

Experimental Study of Concrete-filled Carbon Fiber Reinforced Polymer Tube with Internal Reinforcement under Axially Loading

Comparing with the circular concrete columns confined with fiber reinforced polymer (FRP) wrap or tube, the rectilinear confined columns were reported much less. Due to the non-uniform distribution of confining pressure in the rectilinear confined columns, the FRP confinement effectiveness was significant reduced. This paper presents findings of an experimental program where nine prefabricated rectangular cross-section CFRP tubes with CFRP integrated crossties filled concrete to form concrete-filled FRP tube (CFFT) short columns and three plain concrete control specimens were tested. All specimens were axially loaded until failure. The rest results showed that the stress-strain curves of CFFTs consisted of two distinct branches, an ascending branch before the concrete peak stress was reaches and a second branch that terminated when the tube ruptured, and that the CFFTs with integrated crossties experienced most uniform confinement pressure distribution. Test research also found that the stress-strain curves of CFFTs indicated an increase in ductility. These demonstrate that this confinement system can produce higher lateral confinement stiffness. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6035

Long-term durability of tri-axial woven CFRP tube structure extended along the spin axis of spinning platforms for the SCOPE mission

This study investigates the strength and long-term durability of a spin-axis extensible rigid antenna element, made of tri-axial woven carbon fiber-reinforced polymer (CFRP), for a spinning spacecraft. Due to a slight deviation between the spin axis and antenna-extended axis with the spin, the antenna is subjected to centrifugal body force; the centrifugal force enhances the antenna deflection. A relationship between centrifugal force and antenna deflection is derived from beam theory. As the apparent material modulus decreases with time, the deflection increases simultaneously. The time dependence of mechanical properties of the tri-axial woven CFRP is hence examined by a creep test. The time-dependent failure criterion of the antenna is then examined using a flexural durability test. Based on the beam theory and experimental results, we examine the long-term reliability of applying the tri-axial woven CFRP to extensible rigid antenna for the spinning spacecraft, especially for SCOPE mission; it is verified that the current design tolerance for the mission assures certain durability for long-term usage.

Axial Compressive Behavior of Circular High-Strength Concrete-Filled FRP Tubes

AbstractConcrete-filled fiber-reinforced polymer (FRP) tubes (CFFTs) have received significant research attention over the last two decades. However, experimental studies on the behavior of CFFTs filled with high-strength concrete (HSC) remain very limited. This paper presents the results of an experimental study on the axial compressive behavior of 83 monotonically-loaded circular CFFTs. The effects of fiber type, concrete strength, specimen size, and manufacturing method on the compressive behavior of CFFTs were investigated. The CFFTs were manufactured with carbon FRP (CFRP), high-modulus CFRP (HMCFRP), or aramid FRP (AFRP) tubes, and their average unconfined concrete strengths ranged between 34–110 MPa. The diameters of the test specimens ranged from 75–300 mm with all specimens maintaining a 2∶1 height-to-diameter ratio. The effect of the CFFT manufacturing method was investigated through AFRP specimens that were manufactured through either an automated filament winding or manual wet layup technique....