Increasing Fiber Volume Research Articles

Cracking behavior and energy consumption of Steel Fiber Concrete Encased Steel beams

Steel Fiber Concrete Encased Steel (SFCES) beams were subjected to bending to investigate the effect of steel fibers on the behavior of Steel Reinforced Concrete beams with or without steel reinforcement. 18 SFCES beams reinforced with steel fibers, steel reinforcement, or both were cast. The parameters considered in the experiment were (a) the volume percentage of steel fiber (0%, 1%, and 2%), (b) the shear span to depth ratio( s/d = 2.5 and 3.5), (c) the stirrups spacing (180 mm and 360 mm), and (d) the presence or absence of longitudinal reinforcement (2Φ8+2Φ10).The cracking load, crack development, energy dissipation capacity, and ductility of the specimens were investigated. The results illustrate that the cracking load F c, the total energy consumption, and the energy ductility increase with increasing steel fiber volume, and the average improvement with a steel fiber volume increase of 1% can reach 36.5%, 21.2%, and 28.67%, respectively. However, this strengthening effect of steel fibers was weakened due to the addition of steel reinforcement. The influence of the steel fiber volume and reinforcement configuration on each stage of energy consumption was mainly concentrated in the elastic ( E 1) and failure stages ( E 3). Finally, mathematical equations were proposed to predict the cracking load and crack width of the SFCES specimens, which were verified by comparing the predictions with the experiment results.

Effect of fibre arrangements on tensile properties of 3D printed continuous fibre-reinforced thermoplastic composites

ABSTRACT Continuous fiber reinforced thermoplastic composites (CFRTPCs) with advantages of great mechanical properties and green recyclability, have been widely used in aerospace, transportation, sports and leisure products, etc. This study applied the 3D printing process for the integrated rapid manufacturing of CFRTPCs. The volume fraction and distribution arrangement of fiber reinforcement were designed to evaluate the effect of fiber arrangements on tensile properties of the printed composites. The experimental results proved that some outer and inner defects reduced the surface smoothness and tensile properties based on the analysis of macro and micro morphology. The fiber distributed evenly contributed to the dimensional precision and stability, as well as tensile properties. With the increasing fiber volume, the elastic modulus and ultimate tensile strength both approximately increased while the strain at break decreased. This work promises a significant contribution to the abilities of designing fiber arrangements to control tensile properties of 3D printed CFRTPCs.

Effect of High Contain Sustainable Steel Fiber on Properties of Reactive Powder Concrete

An experimental work was carried out to investigate some mechanical properties of Reactive Powder Concrete (RPC). These properties include Compressive strength, Flexural strength, Water Absorption and Density. The effect of the high volume of steel fiber on these properties were carefully studied, the steel fibers volume fraction (0%, 14%, 28% by volume of concrete) layer and (0%, 7%, 14% by volume of concrete) random. Used silica fume content 10% as a partial replacement by weight of cement and super plasticizer known (Sika Visco Crete-5930). The experimental results showed that as the steel fiber volume increase from 0% to 28% (layer) lead to decrease in compressive strength while increase in tensile strength, water absorption and density. The steel fiber volume from 0% to 14% (random) lead to decrease in compressive strength while increase in tensile strength, water absorption and density.

Shear strength of steel fiber self-compacting concrete beams

The use of self-compacting concrete has increased for several reasons over recent decades but, mainly due to its high fluidity, which dispenses of the need for concrete vibrators, ease of casting, higher quality and better compacting, allowing the production of slender pieces, with a higher reinforcement ratio. However, even self-compacting concrete exhibits brittle failure behavior and low tensile and shear strength, issues that can be mitigated with the use of steel fibers. Aiming to investigate the shear strength in self-compacting concrete beams with steel fibers, this study presents a database collected from 113 experimental tests in the literature. Using the Root Mean Square Error (RMSE) and the Collins’ Demerit Points Classification (DPC), five code-based equations and ten experimental based equations for the prediction of the shear capacity of SFRC beams were evaluated. The results show that, unlike concrete without the addition of fibers, increase in aggregate dimensions decreases the shear strength with the use of steel fibers in SCC beams. Additionally, the increase in fiber volume corresponds to an increase in concrete shear strength with a maximum compressive strength of 50 MPa. The results also demonstrate that the Root Mean Square Error (RMSE) is better for evaluating the precision but not the safety of the shear strength prediction equations, which are better determined by Collins’ Demerit Points Classification (DPC). Code-based equations for ultimate shear strength prediction of fiber reinforced concrete beams presented results with satisfactory safety and economy.

Modeling and simulation of the elastic properties of natural fiber‐reinforced thermosets

AbstractThis paper presents an analysis on the elastic characteristics of luffa and palm natural fiber composites (NFC) with epoxy and ecopoxy matrixes, taking into account the impact of fiber volume fractions. Furthermore, longitudinal modulus, transverse modulus, shear modulus, and Poisson's ratio were predicted using representative volume elements (RVEs) with chopped random and unidirectional fiber arrangements. However, analytical approaches such as rule of mixture, Chamis, Halpin–Tsai, and Nielsen were considered for validating and comparing the findings of finite element analyses. Hence, it was found that increasing fiber volume fraction increased the elastic properties of palm/epoxy, palm/ecopoxy, and luffa/epoxy NFCs, but decreased that of luffa/ecopoxy NFC. Addition of palm fibers in ecopoxy and epoxy had stronger effect than luffa on enhancing the elastic properties of the final structure. However, greatest elastic characteristics observed through analytical and numerical models were obtained for ecopoxy matrix with 0.5 palm fibers. A strong agreement was observed between the results obtained from analytical approaches and RVE unidirectional model. Chamis model exhibited higher outcomes compared to the considered analytical techniques, while Halpin–Tsai model showed the least values.

Preparation, microstructure and mechanical properties of tungsten fiber reinforced LaAlCuNi metallic glass matrix composites

In this paper, Wf/La62Al14Cu12Ni12 bulk metallic glass composites (BMGCs) were successfully prepared by a new forward melt infiltrating method. Compared with Wf/Zr-based BMGCs, the preparation of Wf/La62Al14Cu12Ni12 BMGCs is simpler and more convenient. In the experimental part, quasi-static compressive behaviors of composites with different fiber volume fractions were systematically investigated. The volume fraction of the tungsten fiber was found to have remarkable influence on compressive properties and fracture modes of the composites. The introduction of tungsten fiber can significantly improve the strength of composites, strikingly, the composite with fiber volume fraction of 60% shows a significant plastic strain of 11.7% as well as a high fracture strength of 1600 MPa. With the increasing fiber volume fraction, the failure mode of the composites switches from shear of amorphous matrix to splitting. In addition, the relationship between compressive strength and fiber volume fraction of Wf/La62Al14Cu12Ni12 BMGCs and Wf/Zr(Vit1)-based BMGCs was studied, and we found that the theoretical compressive strength of those two composites is approximately consistent with the experimental counterparts. Although the matrix strength of the two varieties of composites has a huge difference, the compression plasticity of composites shows a similar change with the increasing fiber volume fraction.

Contribution of fiber alignment on flexural properties of UHPC and prediction using the Composite Theory

This paper investigates the effect of fiber alignment on the flexural properties of ultra-high performance concrete (UHPC) made with different steel fiber lengths (6, 13, and 20 mm) and volumes (1%, 2%, and 3%). Fiber alignment of prismatic samples was secured using a flow-induced casting method. Test results indicated that prismatic samples cast using the flow-induced method can enable 35% greater fiber orientation compared to those prepared using a conventional casting method that results in random fiber orientation. Such improvement in fiber orientation led to 60% and 80% higher flexural strength and toughness, respectively. At a fiber volume of 2%, the increase in fiber length from 6 to 20 mm can result in 45% and 195% greater flexural strength and toughness, respectively, for samples with flow-induced fiber alignment. With the increase in fiber volume from 1% to 3% for 13-mm long fibers, such enhancements were 55% and 40%, respectively. Similar flexural properties can be obtained for UHPC made with 1% of the longer fibers when the flow-induced casting method is employed compared to those prepared using the conventional casting method at 3% of the shorter fibers. The flexural-to-tensile strength ratio of UHPC increased with the increase in fiber length, volume, and orientation. For a given fiber length and volume, the flexural-to-tensile strength ratio increased linearly with the increase in fiber orientation. When the variations in flexural-to-tensile strength ratios are considered as a function of fiber length, volume, and orientation, flexural strength of UHPC can be predicted with a maximum spread of 15% using the Composite Theory.

Tests on workability and strength of high strength-flowable concrete containing PET waste fiber

This study describes two workability tests, compressive strength and tensile strength tests of high strength flowable concrete containing plastic fiber prepared from polyethylene terephthalate (PET) waste bottles. For the high fluidity mix Vebe time and V-funnel time tests were carried out. Results show that there is a Vebe time increase with PET fiber addition to concrete being increased with increasing fiber volume and fiber length. V-funnel time was found to reduce when up to 0.75% fiber volume is added to concrete, followed by an increase for larger fiber volumes. When fiber length is increase, there is more time increase, but in general, V-funnel time increase was lower than that of Vebe time, indicating a different influence of PET fiber on the compatibility and flowability. The measured V-funnel time for all mixes was found to conform to the limits of European specifications on the flowability of self compacting concrete. Small descending in compressive strength was recorded for RPET fiber reinforced concrete that reached 15.74 % for 1.5 percent fiber content with 10 mm fiber length. Attractive results was recorded in split tensile strength of RPET fibrous samples which resulted in improvement up to 63.3 % for 1.5 percent of 40 mm fiber length content.

Progressive damage analysis of an adhesively bonded composite T-joint under bending, considering micro-scale effects of fiber volume fraction of adherends

In this study, a numerical study on failure assessment and stress distribution on the adhesive region in a composite T-joint under bending load case is investigated using cohesive zone method (CZM). The Finite Element Model (FEM) has been verified with experimental results. To study the load transfer capability of the T-joint, five different adhesives are considered in the adhesive region and the effect of geometrical parameters such as stringer thickness, corner radius, and adherend thickness as well as micromechanical properties of reinforced fiber composite adherends are investigated. Effective properties of two composite adherends including Carbon-Epoxy (IM7/8552) and Glass-Epoxy (E-glass/Epon 828) with various fiber volume fractions are estimated using a 3D representative volume element (RVE) and employing period boundary conditions (PBC) through Python scripts in ABAQUS. The results show that the fiber volume fraction of composite adherends has a significant effect on failure behavior. For instance, increasing fiber volume fraction of carbon/epoxy composite from 0.4 to 0.7 resulted in a 78% increase in elastic stiffness and a 41% enhancement in maximum load-bearing capacity. Among different adhesive types used in this study, FM300 resulted in the strongest structure and S7752 led to a more ductile T-joint.

A micromechanical temperature-dependent vibration damping model of fiber-reinforced ceramic-matrix composites

In this paper, a micromechanical temperature-dependent vibration damping model of fiber-reinforced ceramic-matrix composites (CMCs) is developed. Temperature-dependent damage mechanisms of matrix cracking, interface debonding and slip, and fibers fracture contribute to the vibration damping of damaged CMCs. The temperature-dependent fiber and matrix strain energy and dissipated energy density are formulated of composite constituent properties and damage related micro parameters of matrix crack spacing, interface debonding and slip length, and broken fibers fraction. Theoretical relationships between temperature-dependent composite damping, temperature and temperature-dependent damage mechanisms are established. Effects of composite constituent properties (i.e., fiber volume, interface debonding energy, interface shear stress and interface frictional coefficient) and composite damage state (i.e., matrix crack spacing) on temperature-dependent composite vibration damping of SiC/SiC composite are analyzed. When the fiber volume increases, the composite vibration damping decreases, and the temperature for the peak value of the composite vibration damping increases, mainly due to the decrease of the interface debonding and slip fraction. Experimental temperature-dependent composite vibration damping of 2D SiC/SiC composite at the temperature range of 293–1373 K are predicted using the developed micromechanical vibration damping model. Experimental vibration damping of 2D SiC/SiC composite increases with temperature, and the theoretical predicted composite vibration damping for different vibration stress of σ = 5, 6, and 7 MPa are obtained and agreed with experimental data, and the predicted interface debonding and slip fraction increases with temperature.

A micromechanical vibration damping model of fiber-reinforced ceramic–matrix composites considering interface debonding

A micromechanical vibration damping model of fiber-reinforced ceramic–matrix composites is developed considering interface debonding. The relationship between the stress-dependent composite damping and interface debonding is established. Effects of material properties and damage-related parameters on the vibration damping of fiber-reinforced CMCs are discussed. Experimental vibration damping with interface debonding of C/SiC composites is predicted. When the vibration frequency increases from f = 1–5 Hz, the vibration damping decreases due to the increasing dynamic interfacial shear stress and low frictional dissipated energy in the debonding region. The composite vibration damping decreases with increasing fiber volume, matrix crack spacing and interface shear stress, and increases with fiber radius and fiber elastic modulus. When the interface debonding energy increases, the vibration damping decreases when the interface partial debonding and approaches the same value when the interface complete debonding, and the vibration stress for complete interface debonding increases.

Prediction of Elastic Properties of Short Fibers Reinforced Composites (Dept.T)

window.dataLayer = window.dataLayer || []; function gtag(){dataLayer.push(arguments);} gtag("js", new Date()); gtag("config", "UA-72322659-1");

Diverse angle-length-width model for 3D/4D/5D steel fiber reinforced concrete under tension

The most important characteristic of steel fiber reinforced concrete (SFRC) is its excellent post-cracking behavior. An analytical diverse angle-length-width model (DAM) was proposed to calculate the tensile stress-crack width (σ-w) constitutive behavior of SFRC members subjected to tension and to evaluate its post-cracking behavior. In the proposed model, the tensile stress in SFRC members with end-hooked steel fibers was generated from the straight fiber part, the end-hooked fiber part, and the concrete part. The effects of straight and end-hooked parts were separately considered, and three cases for different crack width ranges were analyzed for each part. The model was derived by considering all of the possible fiber inclination angles, fiber embedded lengths, and crack widths. It was found that SFRC members with new types of 4D and 5D steel fibers possessed a higher tensile stress than those with 3D steel fibers, and the tensile stress intensity increased with the increasing fiber volume fraction. Finally, the accuracy of the model was verified by comparing the values by DAM with the experimental results based on the sectional analysis.

Preliminary Material Evaluation of Flax Fibers for Prosthetic Socket Fabrication.

Composite prosthetic sockets are typically made of fiberglass or carbon fiber. These fibers have good mechanical properties, but relatively poor vibration damping. Flax fibers are claimed to have exceptional vibration damping properties, with the added benefit of being a natural renewable resource and a cost-effective alternative to synthetic fibers. Flax fibers could prove beneficial for prosthetic sockets, providing lightweight sockets that reduce vibrations transmitted to the body during movement. This research used impact testing (impulse hammer and custom drop tower) on flat and socket shaped composite samples to evaluate composite layer options. Sample vibration dissipation was measured by a combination of accelerometers, load cells, and a dynamometer. Composite sockets made purely of flax fibers were lighter and more efficient at damping vibrations, reducing the amplification of vibrations by a factor of nearly four times better than sockets made purely of carbon fiber. However, the bending stiffness, elastic moduli, and flexural strength of flax sockets fabricated using the traditional socket manufacturing method were found to be ten times lower than theoretical values of flax composites found in the literature. By increasing fiber volume fraction when using the traditional socket manufacturing method, the composite's mechanical properties, namely, vibration damping, could improve and flax fiber benefits could be explored further.

Evaluating the effect of variable fiber content on mechanical properties of additively manufactured continuous carbon fiber composites

Fiber volume fraction is a driving factor in mechanical properties of composites. Micromechanical models are typically used to predict the effective properties of composites with different fiber volume fractions. Since the microstructure of 3D-printed composites is intrinsically different than conventional composites, such predictions need to be evaluated for 3D-printed composites. This investigation evaluates the ability of the Voigt, Reuss, and Halpin–Tsai models to capture the dependence of modulus and strength of 3D-printed composites on varying fiber volume fraction. Tensile coupons were printed with continuous carbon fiber-reinforced Onyx matrix using a Markforged Mark Two printer. Specimens were printed at five different volume fractions with unidirectional fibers oriented at either [Formula: see text] to obtain longitudinal, shear, and transverse properties, respectively. It is shown that the Voigt model provides an excellent fit for the longitudinal tensile strength and a reasonable fit for the longitudinal modulus with varied fiber content. For the transverse direction, while the Reuss model fails to capture the transverse modulus trend, the Halpin–Tsai model provides a reasonable fit as it incorporates more experimental parameters. Like conventional composites, addition of fibers degrades the transverse strength, and the transverse strength decreases with increasing fiber volume fraction. The shear modulus variation with fiber content could not be fitted reasonably with either Halpin–Tsai model or Reuss model.

Effect of Stochastic Loading on Tensile Damage and Fracture of Fiber-Reinforced Ceramic-Matrix Composites.

In this paper, the effect of stochastic loading on tensile damage and fracture of fiber-reinforced ceramic-matrix composites (CMCs) is investigated. A micromechanical constitutive model is developed considering multiple damage mechanisms under tensile loading. The relationship between stochastic stress, tangent modulus, interface debonding and fiber broken is established. The effects of the fiber volume, interface shear stress, interface debonding energy, saturation matrix crack spacing and fiber strength on tensile stress–strain curve, tangent modulus, interface debonding fraction and fiber broken fraction are analyzed. The experimental tensile damage and fracture of unidirectional and 2D SiC/SiC composites subjected to different stochastic loading stress are predicted. When fiber volume increases, the initial composite strain decreases, the initial tangent modulus increases, the transition stress for interface debonding decreases and the initial fiber broken fraction decreases. When fiber strength increases, the initial composite strain and fiber broken fraction decrease.

Estimation of effective properties of composite sandwich panels with negative Poisson's ratio by using variational asymptotic multiscale method

According to the anisotropy and non-homogeneity of composite sandwich panels with negative Poisson's ratio (NPR), the variational asymptotic method combined with multiscale technology (VAMM) is used to analyze its effective properties. Firstly, in the microscale, the effective properties of the unidirectional fiber reinforced composite (UDFRC) forming the facesheets are obtained by means of asymptotic homogenization analysis, which can be used as lamina properties. Then, in the mesoscale, an asymptotic analysis of the typical unit cell is carried out to deduce the effective plate properties (A, B, and D matrices) of composite sandwich panels with NPR according to the heterogeneity of the structure. Finally, the influence of the layup configurations and fiber volume fractions of UDFRC on the equivalent plate properties of composite sandwich panels with NPR is analyzed. Numerical results show that the 3D responses of composite sandwich panels with NPR using VAMM are in agreement with those of 3D FEM model, while in a much more efficient manner. The layup configurations of facesheets have great influence on the equivalent plate properties of the structure. Furthermore, the degree of anisotropy and negative Poisson's ratio of the whole structure decrease with increasing fiber volume fraction of UDFRC.

Fiber Volume Fraction Influence on Randomly Distributed Short Fiber Tungsten Fiber‐Reinforced Tungsten Composites

For future fusion reactors, tungsten (W) is currently the main candidate for the application as plasma‐facing material due to its several advanced properties. To overcome the brittleness of W, randomly distributed short W fiber‐reinforced W (Wf/W) composites have been developed using field‐assisted sintering technology (FAST). Herein, Wf/W materials with different fiber volume fraction (20–60%) are manufactured by FAST process to study the fiber volume fraction influence on the composite properties. Wf/W with ductile fibers and brittle fibers is produced using different tool setups during the production. Three‐point bending tests on prenotched samples, 4‐point bending tests, and tensile tests have been performed to determine the fracture behavior and flexural/tensile strength of the material. Wf/W materials with 30–40% fiber volume fraction exhibit a promising pseudoductile behavior, similar to fiber‐reinforced ceramic composites. However, Wf/W with 20% and >50% fiber volume fraction shows only a limited extrinsic toughening effect. In terms of flexural strength, with increasing fiber volume fraction, the tensile/flexural strength does not show a clear increasing tendency, or even lightly decreases.

Toughness Characterization of Fiber Reinforced Concrete Beam using Fracture Mechanics

The study of fracture mechanics was very much essential because it gives clear idea of arising and propagation of cracks, cause for failure, life of structure, etc. The main aim of this research was to study the fracture behavior of fiber reinforced concrete which was reinforced with polypropylene fiber. The fiber used in concrete with different volume fraction like 0.5%, 0.75% and 1% of total volume of cementitious material. The specimens were prepared with different grades of concrete with different dosage of fiber and then subjected to three point bending test. Using test results the fracture properties like fracture energy, flexural strength; stress intensity factor, fracture toughness and stiffness were found. The experimental results showed that effectiveness of polypropylene fiber for different grades of concrete that is normal, medium and high strength concrete increases with increase in fiber volume and also the fracture properties of fiber reinforced concrete increases with increase in fiber volume and effectiveness of fiber was found for dosage of about 0.75-1% volume.

Study the behavior of Slurry infiltrated fibrous concrete (SIFCON) under impact loading

SIFCON, as a type of fiber reinforced concrete (FRC), has a unique and superior properties in the areas of both ductility and energy absorption and the impact resistance is recognized as one of the significant properties of SIFCON.The main object of present study is to determine the influence of SIFCON mortar type and fiber volume fraction on the behavior of SIFCON under impact loading. For SIFCON mortar, supplementary cementitious materials [Class F fly ash (FA) and silica fume (SF)] were used as a partial replacement by weight of cement. The percentage of FA replacement was (20%) and of SF replacement was (10%). Hooked end steel fibers were used with different fiber volume fraction (6, 8.5, and 11) %, the test was carried out using disc specimen (152 mm diameter by 63 mm thick). The test results were compared with those of fiber reinforced mortar (FRM) containing 2% fiber volume fraction, as a reference (control) mix. The test results show that in general, there is a significant improvement in impact resistance of all SIFCON mixes with increasing fiber volume fraction. SIFCON mix containing SF and FA and 11% volume fraction exhibited the highest impact resistance, and the energy required for completing failure was increased by 11.87 times, when compared with the control mix at 90 days.