Fiber Volume Percentage Research Articles

Simulative Prediction of Fiber-Matrix Separation in Rib Filling During Compression Molding Using a Direct Fiber Simulation

Compression molding of long fiber reinforced composites offers specific advantages in automotive applications due to the high strength to weight ratio, the comparably low tooling costs and short cycle times. However, the manufacturing process of long fiber composite parts presents a range of challenges. The phenomenon of fiber matrix separation (FMS) is causing severe deviations in fiber content, especially in complex ribbed structures. Currently, there is no commercial software that is capable to accurately predict FMS. This work uses a particle level mechanistic model to study FMS in a rib filling application. The direct fiber simulation (DFS) is uniquely suited to this application due to its ability to model individual fibers and their bending, as well as the interaction amongst fibers that leads to agglomeration. The effects of mold geometry, fiber length, viscosity, and initial fiber orientation are studied. It is shown that fiber length and initial fiber orientation have the most pronounced effects on fiber volume percentage in the ribs, with viscosity and part geometry playing a smaller role.

Isırgan Lifi-Fındık Kabuğu Unu Dolgulu Hibrit Kompozitlerin Mekanik Davranışının İncelenmesi

Polymer beam specimens produced with reinforcement of nettle fiber and fixed nut hazelnut flour at different volume ratios were opened initial notches with a / W = 0.2, 0.3 ratios after thermal curing. The volume percentage of nettle fiber in the composite is 2.5, 5, 7.5 and 10 percent. The grain size of hazelnut shell flour is 0-50μ and the volume ratio in the composite is 15% in all samples. Mode I fracture behaviors of compacted specimens from single sides, compact tensile and mechanical behavior were determined by three point bending test and impact test. The amount of crack opening was determined by the high-speed camera recorder. The bending test determined bending modulus and bending stresses. The morphological structure of the fractured surfaces obtained from the impulse test was revealed by sem views. It has been observed that the added hazelnut flour enhances the flexural modulus while reducing bending stress, fracture strength and impact resistance

Bond behavior of steel fibers reinforced self-stressing and self-compacting concrete filled steel tube columns

This paper investigates the bond behavior of steel fibers reinforced self-stressing and self-compacting concrete filled steel tube (FSSCFST) columns. A series of push-out tests on ninety CFST columns are conducted. The variables considered in the test are: (a) concrete type (self-compacting concrete and steel fibers reinforced self-stressing self-compacting concrete); (b) the thickness of steel tube (2.5–4.25 mm); (c) concrete strength (C40, C50 and C60); and (d) steel fibers volume percentage (0%, 0.6% and 1.2%). Experimental results show that the bond strength of FSSCFST specimens varies from 0.50 MPa to 2.51 MPa, which is generally higher than the self-compacting CFST specimens. Self-stress significantly improves the bond strength of CFST specimens, and the average improvement level is 42.7%. The bond strength firstly decreases and then increases with the increase of steel fiber volume percentage. Finally, formulas are proposed to predict the bond strength of FSSCFST columns, and the proposed formulas give a more accurate prediction than the existing design codes.

Behavior of steel fibers reinforced self-stressing and self-compacting concrete-filled steel tube subjected to bending

This paper described an experimental work for steel fibers reinforced self-stressing and self-compacting concrete-filled steel tube (FSSCFST) specimens subjected to bending. The study aimed to evaluate the effect of self-stress and steel fibers on the behavior of self-compacting concrete filled steel tube (SCCFST) specimens. Twenty-seven SCCFST specimens reinforced with steel fibers, self-stress or their couple were tested under bending. The variables considered in the test were self-stress, thickness of steel tube, concrete strength and steel fiber volume percentage. Experimental results showed that the FSSCFST specimens behaved in a relatively ductile manner, but steel fibers and self-stress failed to change the failure mode of CFST specimens. Self-stress can slightly increase the flexural capacity and lead to a higher flexural rigidity. Steel fibers can lengthen the elastic stage and improve the flexural capacity of FSSCFST specimens. This beneficial effect of steel fibers decreased with the increasing of steel tube thickness. A formula was proposed to predict the flexural capacity of FSSCFST specimens, and the comparison between predictions and experiment results proved the accuracy of the formula.

Study of dielectric properties of luffa–polylactide quadratic splint composites: The effect of cyclic absorption and desorption of water

This study reports on the effects of cyclic hot and cold water absorption on the dielectric properties of luffa–polylactide composites and their potential application as a quadratic mallet finger splint. The study was conducted for dry samples varying in fiber volume percentage from 0% to 20% with increments of 5%. The 15 vol% luffa–polylactide composites were subjected to the cyclic hot and cold water absorption. The changes in the dielectric constant, dissipation factor, and loss factor were measured in the 100 Hz to 1 MHz range. It was found that the higher the number of water cycles, lower the dielectric constant, dissipation factor, and loss factor. Cyclic hot water absorption showed a more significant effect on the dielectric properties than the cyclic cold water absorption. J. VINYL ADDIT. TECHNOL., 24:388–394, 2018. © 2017 Society of Plastics Engineers

Bond behavior between BFRP bar and recycled aggregate concrete reinforced with basalt fiber

This study investigated the effect on the bond behavior between BFRP bars and recycled aggregate concrete (RAC), which a total of 54 specimens for pull-out test and 162 specimens for mechanical properties were conducted. The parameters including RAC strength grade, chopped basalt fiber volume content and length, based on orthogonal test the bond stress-slip constitutive were proposed. According to the main results of experiment, the strength of RAC was higher than the other two factors in the effect of mechanical performance and ultimate bonding stress. Similarly, the influence of these factors on the free end slip that the length of chopped basalt fiber was the weakest, then the chopped basalt fiber volume percent was higher compared to RAC strength grade. Application of non-liner regression analysis in the bond stress-slip constitutive relationship with the experimental results and referred to the engineering practice.

PHYSICAL PROPERTIES OF FOAMED CONCRETE INCORPORATING COCONUT FIBRE

Nowadays, the high cost of conventional construction material becomes the dominating factor which affecting the housing system in our country. As an alternative method to overcome this disadvantage which is decreasing the strength of the building, it is important to do research on any alternating materials which will decrease the cost and increase the strength of concrete. This conventional construction material likewise made some problems to nature. But coconut fiber, which is natural fiber, makes no impact on environment furthermore increases the strength of concrete compares to other fiber. This paper focuses on the investigation and experimental analysis on the physical characteristics of lightweight foamed concrete (LFC) incorporating coconut fibers composites with different volume percentage of fibers 0.2 and 0.4. LFC is produced by cement paste or mortar in which air-voids are entrapped in the mortar by the suitable foaming agent. Two densities of LFC, 850 and 1200 kg/m³, were cast and tested. Approximately 0.75% of cement percentage of super plasticizer was used to enhance workability of the fresh mix. The results of the test showed that the both of physical properties of the concrete increases with curing age and quantity of coconut fiber.

Mechanical properties related to the microstructure of seven different fiber reinforced composite posts

PURPOSEThe aim of this in vitro study was to evaluate the mechanical properties (bending strength and hardness) of seven different fiber reinforced composite posts, in relation to their microstructural characteristics.MATERIALS AND METHODSTwo hundred eighty posts were divided into seven groups of 40, one group for each type of post analyzed. Within each group, 15 posts were subjected to three-point bending strength test, 15 to a microhardess meter for the Knoop hardness, and 10 to Scanning Electron Microscope in order to determine the diameter of the fibers and the percentage of fibers embedded in the matrix. To compare the flexural strength in relation to the type of fiber, matrix, and the hardness of the posts, a Kruskal-Wallis H test was used. The Jonckheere-Terpstra test was used to determine if the volume percent of fibers in the post influenced the bending strength.RESULTSThe flexural strength and the hardness depended on the type of fibers that formed the post. The lower flexural strength of a post could be due to deficient bonding between the fiber and the resin matrix.CONCLUSIONAccording to the results, other factors, besides the microstructural characteristics, may also influence the mechanical properties of the post. The feature that has more influence on the mechanical properties of the posts is the type of fiber.

On low-energy impact response of ultra-high performance concrete (UHPC) panels

This paper presents the experimental, numerical and analytical investigations carried out to understand the low-energy impact response of ultra-high performance concrete (UHPC) panels for different fiber volume, thickness and impactor energy. Concrete panels of sizes 350×350×10mm and 350×350×15mm were cast with three different fiber volumes — 0% (R1), 2% (R2) and 2.5% (R3). Two panels with mix R2 and one with mix R1 and R3 were cast for each impactor energy and panel thickness. The impact tests were performed with a 10mm diameter drop-weight hemispherical impactor of mass 5.41kg for three energy levels (10, 15 and 20J). The impact response of UHPC panels was predicted using finite element simulation and spring-mass models. The results obtained from FEM and spring-mass models corroborate well with those obtained from the experiments (R2 > 0.8 and mean absolute percentage error (MAPE)<20%). Based on the parametric study carried out to, peak impact load was found to be more sensitive to impactor energy and thickness of the panel than the percentage of fiber volume. In the end, a design flow chart is proposed to arrive at the optimum thickness of the UHPC panel subjected to impact loading.

Bond-slip constitutive relation between BFRP bar and basalt fiber recycled-aggregate concrete

In order to investigate the bond stress-slip constitutive relation between BFRP bar and basalt fiber recycled-aggregate concrete, 81 central pullout specimens were tested. Basalt fiber volume percent, fiber length and concrete strength grade were considered to be experimental variables to obtain the bond stress-slip curves. The results showed that adding basalt fiber into recycled-aggregate concrete will reduce the bond stress between BFRP bar and recycled-aggregate concrete but enhance the ductility of bond property; the bond stress increases with the increasing of fiber length and concrete strength grade. The bond stress-slip constitutive model was proposed and the results showed that the model is good in effect of fitting. The constitutive model can reflect the bonding mechanism between BFRP bar and basalt fiber concrete well, it also can provide reference for theoretical analysis and engineering applications of the bond and anchor property between BFRP bars strengthened recycled concrete.

Investigation of the mechanical properties of bagasse fiber-reinforced epoxy composite using Taguchi and response surface methodology

Fiber-reinforced polymer composites are widely used in various applications because of their mechanical properties and ease of manufacture. Fiber-reinforced plastics are being developed using synthetic fiber and natural fibers of bagasse, palm biomass, etc. In this study, the mechanical strength of bagasse fiber-reinforced epoxy composite was investigated using a Design of Experiment technique. The parameters of fiber volume percentage, alkali concentration, and treatment time with three levels were considered, and an L27 design matrix was developed using the Taguchi orthogonal array. The bagasse was first treated with sodium hydroxide solution (NaOH); subsequently, 27 specimens were developed for experimental investigation. The mechanical strength of newly developed bagasse fiber-reinforced epoxy composite was investigated using a three-point bending testing machine. The flexural strength was calculated using three-point bending strength for length versus load combination. The analysis and optimization was done using the Taguchi method, and a second-order mathematical model was developed using response surface methodology (RSM). A significant performance improvement in the flexural strength of the newly developed composite was found.

Preparation and Properties of Kraft Lignin-N-Isopropyl Acrylamide Hydrogel

Fiber-reinforced polymer composites are widely used in various applications because of their mechanical properties and ease of manufacture. Fiber-reinforced plastics are being developed using synthetic fiber and natural fibers of bagasse, palm biomass, etc. In this study, the mechanical strength of bagasse fiber-reinforced epoxy composite was investigated using a Design of Experiment technique. The parameters of fiber volume percentage, alkali concentration, and treatment time with three levels were considered, and an L27 design matrix was developed using the Taguchi orthogonal array. The bagasse was first treated with sodium hydroxide solution (NaOH); subsequently, 27 specimens were developed for experimental investigation. The mechanical strength of newly developed bagasse fiber-reinforced epoxy composite was investigated using a three-point bending testing machine. The flexural strength was calculated using three-point bending strength for length versus load combination. The analysis and optimization was done using the Taguchi method, and a second-order mathematical model was developed using response surface methodology (RSM). A significant performance improvement in the flexural strength of the newly developed composite was found.

Fabrication of FRP Spacers of Insulating Glass for Energy-Saving Eco-Friendly Home

The FRP(fiber reinforced plastics) spacer was fabricated to enhance the heat blocking and mechanical properties of insulating glass for energy-saving eco-friendly home. The fiber volume percent in ABS(acrylonitrile-butadiene-styrene) matrix was chosen as a main controlling factor. The various properties of FRP spaces were evaluated such as 3-point bending strength, thermal conductivity, and water absorption rate. And the aging test was performed at various temperatures for the spacer immersed in water. In conclusion, the optimum fiber volume percent, 25wt% of spacer was found that is enough for handling in construction process and appropriate for blocking the heat loss through the insulating glass window.

Research on the Molding Condition of 3D Braided Nozzle Throat Fabric

3D braided fabric lining mandrel weaving, throat is the key part of nozzle which should meet the requirements of molding. This paper based on the research between geometry and knitting yarn array of 3D braided nozzle fabric, proposed the basic conditions which influence the molding performance of nozzle. Theoretical derivation the formula of reasonable yarn array and cross-section parameters of yarn. Verify its correctness by actual production of 3D braided nozzle fabric. The CT scan image and the moire pattern of fiber volume percentage showed that the throat size of fabric and roundness well matched with mandrel, fiber volume percentage changed uniform which satisfied the requirement of engineering application.

Effect of porosity heterogeneity on the permeability and tortuosity of gas diffusion layers in polymer electrolyte membrane fuel cells

In this paper, we study the effect of porosity heterogeneity on the bulk hydrodynamic properties (permeability and tortuosity) of simulated gas diffusion layers (GDLs). The porosity distributions of the heterogeneous reconstructed samples are similar to those previously reported in the literature for Toray TGP-H 120™ GDLs. We use the lattice Boltzmann method to perform pore-level flow simulations in the reconstructed GDL samples. Using the results of pore-level simulations, the effect of porosity distribution is characterized on the predicted in- and cross-plane permeability and tortuosity. It was found that porosity heterogeneity causes a higher in-plane permeability and lower in-plane tortuosity, while the effect is opposite in the cross-plane direction, that is a lower cross-plane permeability and a higher cross-plane tortuosity.We further investigate the effect of adding poly-tetra-fluoro-ethylene (PTFE) & binder material to the reconstructed GDL samples. Three fiber volume percentages of 50, 75, and 100% are considered. Overall, increasing the fiber volume percentage reduces the predicted in- and cross-plane permeability and tortuosity values. A previously reported relationship for permeability of fibrous materials is fitted to the predicted permeability values, and the magnitude of the fitting parameter is reported as a function of fiber volume percentage.

Three-dimensional modelling of steel fiber reinforced concrete material under intense dynamic loading

This paper presents a new three-dimensional numerical model to study the dynamic response and failure mode of steel fiber reinforced concrete (SFRC) material under impact and blast loading. In the 3D numerical model, SFRC is assumed to be composed of two components, that is, the homogeneous concrete matrix with lower strength and the steel fibers with higher strength. The straight round steel fibers are assumed to be dispersed with random locations and orientations in the matrix and a 3D grid algorithm is introduced to generate the finite element analysis model. The interaction between fibers and matrix is modeled by the bonding and sliding contact algorithm. The mechanical behavior of SFRC material is simulated and a good agreement with the test data is observed. The verified numerical model is then employed to perform a series simulation of split Hopkinson pressure bar (SHPB) and split Hopkinson tensile bar (SHTB) in order to study the dynamic increase factor (DIF) of SFRC material with different fiber volume percentage (Vf) under high strain rate loading. And the influence of Vf on the dynamic properties of SFRC is analyzed. Further numerical studies of the SFRC specimens under contact detonation are carried out and compared with the test data. The result shows that the developed numerical model for SFRC could precisely predict the failure mode.

Serviceability limit states of high performance reinforced concrete beams with hybrid fibre

The article presents the results of research and analysis of reinforced high performance concrete beams with steel and polypropylene fibres at service load. The beams were bent in the 4-point model. Research was carried out for three different rectangular reinforced concrete beams in terms of the quantity and the type of reinforcement. The beam B1 was constructed conventionally with reinforced steel rods. The beams B2 and B3, instead of the compressive rods and the stirrups the fibre reinforcement of variable fibre volume percentage was applied. In the tests a non-contact system for three-dimensional measurements of deformation – ARAMIS was used. The analysis of the behaviour of the beams under static load for serviceability was based on: images of cracks, strain and force – displacement curves.

Sliding wear mechanisms of magnesium composites AM60 reinforced with Al2O3 fibres under ultra-mild wear conditions

Mg alloy based composites were fabricated using Al2O3 fibre preforms incorporated in a squeeze cast Mg–6% Al alloy (AM60). AM60–x% (Al2O3)f, where x=9, 11, and 26, samples were subjected to boundary lubricated sliding contact at 25°C and 100°C against AISI 52100 counterface within a load range of 1.0–5.0N. The test parameters emulated ultra-mild wear (UMW) corresponding to wear conditions observed in automotive engine blocks. Wear rates of Mg composites were 104 times less than that of the unreinforced alloy. AM60–9% (Al2O3)f showed the highest rate of material loss compared to AM60–11% (Al2O3)f and AM60–26% (Al2O3)f. In the UMW regime, damage to the composites occurred in the following sequence: (i) fibre fracture and fragmentation; (ii) sinking in of the fragmented fibres; (iii) damage to Mg matrix causing high rate of material loss. Contact stress calculations, based on a micromechanical model that considered the fibres as asperities, indicated that at 1.0N the initial contact pressure (2.8GPa) exceeded the fibre fracture strength in compression. The normal stress on fractured fibres increased as they continued to be fragmented during sliding and became embedded into the matrix causing plastic deformation and localised pile up formation around the fractured fibres. For AM60–26% (Al2O3)f the initial matrix hardness was high due to a large dislocation density created by thermal mismatch during fabrication and led to a greater degree of fragmentation compared to AM60–9% (Al2O3)f revealing that the composite with high Al2O3 fibre volume percentage less wear resistant than expected. FIB and TEM analyses of the worn surfaces of AM60–9% (Al2O3)f tested at 100°C indicated the formation of a tribolayer (oil-residue layer)- that mitigated the damage to Mg matrix tested for high sliding cycles making the AM6O-Al2O3 composites suitable for applications at these temperatures.

3D Braided Material Based on Space Group &amp;lt;i&amp;gt;R&amp;lt;/i&amp;gt;3 Symmetry

A unit cell geometrical structure was found with the use of symmetry operations corresponding to the point group C3. Based on the symmetry of space group R3, a 3D braided geometrical structure was obtained by transforming the unit-cell. The features corresponding to this braided structure were studied. The fiber volume percentage and variational tendencies of the material were predicted by establishing a geometric model.

Processing and Properties of Plate 3D Braided Material Based on Space Group&lt;i&gt; P&lt;/i&gt;¯3 Symmetry

A novel geometry structure of unit cell was deduced by using the point group S6 corresponding to symmetry operations. Based on the symmetry of space group P3, a new 3D braided material was obtained by transforming the new unit cell symmetrically. The plate processing corresponding to this geometry structure was studied. The fiber volume percentage and its variation tendency of the 3D braided material were predicted through establishing mathematical model.