Fiber Volume Percentage Research Articles

Evaluation of Mechanical and Water Absorption Behavior of Natural Fiber-Reinforced Hybrid Biocomposites

ABSTRACT The virtues of hybrid composites are higher performances and improved mechanical properties as compared to polymer composites. Hence, it have been extensively used in various applications. However, only a few works reported on the performance of natural fiber-reinforced biocomposite. In this study, the experimental work has been carried out to investigate the mechanical properties, such as tensile, flexural and impact, of randomly oriented Calotropis gigantea Fiber (CGFs) & Palmyra fiber (PFs)-reinforced Phenol-Formaldehyde (PF) hybrid biocomposites. The samples have been prepared by varying the fiber percentages and fiber length by using hand layup method. The fabricated specimens were tested as per ASTM standard. The results illustrate that the addition of palmyra fiber with Calotropis gigantea fiber composites improved the mechanical properties of hybrid composite. Hybridization of Calotropis gigantea Fiber (CGFs) & Palmyra fiber (PFs) was effective at higher fiber volume percentage composites. Variation in fiber length shows effective results in mechanical properties. The water absorption of the composites increased with the increase in the fiber volume percentage, all the composites attained equilibrium state after 120 hours. To understand the failure mechanism of composites during mechanical testing, the failed specimens were examined using Scanning Electron Microscopic (SEM) images. Also, the failure modes and their effects were discussed.

Influence of Barchip fiber on early-age autogenous shrinkage of high strength concrete

High strength concrete (HSC) is vulnerable to early-age cracking owing to a low water-to-cement (w/c) ratio. Barchip fibers have been utilized to reduce the autogenous shrinkage of concrete. The relationship between autogenous shrinkage and ultrasonic velocity of HSC reinforced with Barchip fibers was studied utilizing the non-contact shrinkage test. Results indicated that the autogenous shrinkage and ultrasonic velocity of concrete decreased with the volume percentage of Barchip fibers increasing. Besides, models for predicting early-age autogenous shrinkage strain were proposed considering the fiber volume percentage and age based on the results of ultrasonic velocity.

Computational Analysis of Punching Shear Models of Steel Fiber Reinforced Concrete Slabs

A computational analysis is presented to predict the ultimate and cracking shear strength of steel fiber reinforced concrete slabs. Different models are suggested considering the effect of concrete compressive and tensile strength, amount of flexural reinforcements, yield strength of the reinforcement bars and steel fiber properties (volume percent, aspect ratio, and type of steel fibers). The predicted results are compared with the experimental data found in literature and found good agreement.

Influence of steel fibers on the behavior of spirally RC short columns

This study provides an experimental test to examine the behavior of spirally reinforced short columns with circular sections, strengthened by steel fibers. The volume percentage of steel fibers was (0.5, 1.0, 1.5) %. Four series comprising a total of 16 column specimens (600 mm length × 150 mm diameter) were loaded to failure under axial concentric compression load. The findings of this work are as follows: for the control specimens (columns without steel fibers), the spiral pitch influence was significant: as compared to spiral pitch of 100 mm, reducing the spacing to 75 mm, 50 mm, and 25 mm increased the ultimate load capacity by 7.6%, 11.5% and 18.4%, respectively. The steel fibers effect was very significant in increasing the ultimate load capacity of the columns. For 100 mm spiral pitch columns, these increases reached to 24.6%, 36.3% and 49.9% for the columns with 0.5%, 1.0% and 1.5% steel fibers volume percentages, respectively in comparison to the control specimen. The columns with lesser amount of spirals (less internal confinement) were strengthened by the steel fibers more than the ones with greater number of spirals. For 1.5% steel fibers volume percentage, the column with 100 mm spiral pitch was strengthened by 49.9% with steel fibers. In contrast, the one with 25 mm spiral pitch increased in strength with steel fibers by 41.4%.

Dynamic buckling optimization of laminated aircraft conical shells with hybrid nanocomposite martial

Dynamic buckling optimization in laminated truncated nanocomposite conical aircraft shell in moisture and temperature environments as well as magnetic fields is considered in this article. The structural layers are hybrid nanocomposite consist of polymer, carbon nanotubes (CNT) and carbon fibers based on Halpin-Tsai model. Utilizing theory of Mindlin, the final equations are solved and derived by method of Bolotin and differential quadrature method (DQM). In the optimization process utilizing improved meta-heuristic algorithm basis Grey Wolf optimization (GWO), the instability and frequency of the structure are utilized to define the subjective and objective functions. The GWO is improved using an adjusting randomly process with normal distribution. The main contribution of this study is maximizing the inequality and frequency constraint to control its instability. In the optimization procedure, the cone semi vertex angle, moisture and layers number change are optimized and the temperature influences, carbon fiber volume percentage, magnetic field and CNT radius are considered. The outcome shows that the proposed improved GWO may provide better abilities to search the global conditions compared to GWO because of rising flexibility to study optimum conditions of this complex problem. It is observed that the optimum frequency of system without retrofitting by CNTs is lower than the case of ωCNT≠0.

Effective flexural rigidities for RC beams and columns with steel fiber

Influences of different variables that affect the effective flexural rigidity of reinforced concrete (RC) members are not considered in the most seismic codes. Furthermore, in the last decades, the application of steel fibers in concrete matrix designs has been increased, requiring development of an accurate analytical procedure to calculate the effective flexural rigidity of steel fiber reinforced concrete (SFRC) members. In this paper, first, a nonlinear analytical procedure is proposed to calculate the SFRC members\' effective flexural rigidity. The proposed model\'s accuracy is confirmed by comparing the results obtained from nonlinear analysis with those recorded from the experimental testing. Then a parametric study is conducted to investigate the effects of different parameters such as varying axial load and steel fiber are then investigated through moment-curvature analysis of various SFRC (normal-strength concrete) sections. The obtained results show that increasing the steel fiber volume percentage increases the effective flexural rigidity. Also it\'s been indicated that the varying axial load affects the effective flexural rigidity. Lastly, proper equations are developed to estimate the effective flexural rigidity of SFRC members.

Damage and stiffness research on steel shape steel fiber reinforced concrete composite beams

In this work, an experimental research has been performed on Steel Fiber-Steel Reinforced Concrete (SFSRC)specimens subjected to four-point bending tests to evaluate the feasibility of mutual replacement of steel fibers and conventional reinforcement through studying failure modes, load-deflection curves, stiffness of characteristic points, stiffness degradation curves and damage analysis. The variables considered in this experiment included steel fiber volume percentage with and without conventional reinforcements (stirrups or steel fibers) with shear span depth ratios of S/D=2.5 and 3.5. Experimental results revealed that increasing the volume percentage of steel fiber decreased the creation and propagation of shear and bond cracks, just like shortening the stirrups spacing. Higher crack resistance and suturing ability of steel fiber can improve the stability of its bearing capacity. Both steel fibers and stirrups improved the stiffness and damage resistance of specimens where stirrups played an essential role and therefore, the influence of steel fibers was greatly weakened. Increasing S/D ratio also weakened the effect of steel fibers. An equation was derived to calculate the bending stiffness of SFSRC specimens, which was used to determine mid span deflection; the accuracy of the proposed equation was proved by comparing predicted and experimental results.

Neurofuzzy modelling of moisture absorption kinetics and its effect on the mechanical properties of pineapple fibre-reinforced polypropylene composite

Natural fibres possess low density, less abrasiveness, good strength and sound absorption capacity and its significance lies in being renewable and biodegradable. The mechanical characteristics and moisture absorption of pineapple fibres reinforced with polypropylene resin are focused in this study. Chopped fibres and unidirectional fibre mats of pineapple were reinforced with polypropylene resin to make pineapple fibre/polypropylene composites. The length of the pineapple fibres and the orientation of the layup of the fibre mats are varied to make composite specimens and the mechanical properties are tested. Moisture absorption studies were carried out and it was confirmed to follow Fickian diffusion. A total of 384 samples were tested and it was observed that all the samples reached its saturation in moisture absorption before 720 h and the strength was inversely proportional to the moisture absorbed. Specimens reinforced with unidirectional fibre mats of alternate orientation possessed high strength irrespective of the moisture absorbed when compared to the specimens reinforced with chopped fibres of random orientation. Neuro fuzzy modelling using ANFIS tool box in MATLAB was used to correlate the static mechanical properties of pineapple fibre-reinforced polymer under different moisture conditions, fibre orientations, fibre volume percentage, fibre size, etc.

The potential of rising husk fiber/native sago starch reinforced biocomposite to automotive component

This work aims to examine the mechanical and thermal behavior of rising husk fiber/starch reinforced epoxy polymer composites. Experiments are carried out to study the effect of fiber and filler volume percentage on the mechanical, and thermal behavior of epoxy-based polymer composites. The volume of fibre and filler is varied by 10%,20%,30%, 40%, and starch 5% and 10% and 1.5%, respectively. The specimens are fabricated by using hand layup technique. The specimens are expurgated according to ASTM standards. The effects of rising husk fiber and filler were examined under different thermal conditions. The mechanical results show that the addition of fiber increased the impact characters of epoxy resin, whereas the addition of starch shell filler increased the termal conductivity of the composite. We found that the results show that the stacking sequences of rising Husk/starch fibers have a significant impact on thermal conductivity. Composites with the stacking sequence mode RH40 with 15 % starch exhibit the highest thermal conductivity 2.6 W/m·K an enhancement of 472,72% over the thermal conductivity of the PC resin (0.55 W/m·K) it is significant

Structural analysis of natural fiber reinforced polymer matrix composite

The conventional structural material used in construction industries like aluminum, wood and steel are depleting now a day. In this work an attempt has been made to fabricate a hybrid natural fiber composite material reinforced with vinyl ester resin. Composite are made-up with various volume percentage of Sisal and Luffa fiber by compression molding. The mechanical behavior of composite material such as tensile, impact test and flexural test are carried out as per ASTM standard. The ANSYS analyzed result shows that the mechanical properties of the composite materials have a good agreement with the conventional structural aluminum material.

Potensi Pengembangan Komposit Berpenguat Serat Kulit Gaharu Sebagai Material Pengganti Fiberglass Pada Pembuatan Dashboard

The development of industrial in the utilization of composites as a substitute of metal materials that are used is fiberglass. However, fiberglass is considered not environmentally friendly because difficult to decipher. The technology advances, it is now widely used from composite materials with natural fibers.This research was conducted to obtain data about mechanical ability in the tensile strength, impact strength and physical form of Gaharu skin fibers using polyester matrix BQTN 157 with volume fraction variations made by hand lay-up method. This research is expected to be useful in automotive, manufacturing industry and household appliances are environmentally friendly. The maximum value of tensile strength is 34.574 MPa in 45% fiber volume fraction. However, there is a decrease in the tensile strength value in the 50% fiber volume fraction, which is 22,635 MPa, this is due to the large amount of fiber content so that the matrix spread to the fiber is uneven. The maximum impact strength value is 62.76 kJ / m2 at 50% fiber volume percentage. Based on the results of testing the comparison of the fiber and matrix volume fractions greatly affect the tensile strength and impact. The results show tensile and impact tests have met the plastic standards used car dashboards.

An Investigation of the Failure Mechanisms of a Polymer Matrix Composite Crew Oar

Rowing, or crew, is a constantly evolving sport with an impressive history of equipment advancements, including the use of advanced polymer matrix composites as construction materials for boats and oars. While the use of composites undoubtedly improves the performance of the equipment, the complexity of such a material makes it difficult to establish the cause of failures observed during practice and competition. In particular, composite oars, which are ubiquitous in competitive rowing, have the potential for catastrophic failure. The present effort at investigating the failure mechanisms of a composite oar involved metallographic examinations of the fracture surface using a scanning electron microscope (SEM)/energy-dispersive X-ray spectroscopy (EDS), as well as finite element stress analyses using ANSYS software. From a cross section analysis, the fiber volume percentage of the oar was measured to be 58.2%. Finite element modelling results suggested that oar failure was not the result of a discrete load, which implies that cyclic loading and structural defects were likely the primary contributing factors. A visual fracture analysis revealed surface defects introduced due to improper handling. No chemical degradation was found in the vicinity of the fracture site; however, degradation in the form of congelifraction (freeze–thaw of trapped water) was found to be a possibility. Based on the aggregate results of this investigation, recommendations for suppliers are provided in terms of manufacturing process and for sporting organizations at large with respect to improved storage and transportation of oars to reduce the likelihood of fatigue failures during training and competitions.

An innovative design approach in three-dimensional printing of continuous fiber–reinforced thermoplastic composites via fused deposition modeling process: In-melt simultaneous impregnation

In this study, an innovative method was devised and implemented to produce continuous glass fiber–reinforced thermoplastic composites via a fused deposition modeling three-dimensional printer to enhance the mechanical properties of the printed products. In the extrusion-based, or filament-based, additive manufacturing process, namely, fused deposition modeling, the parts are basically formed via deposition of the material in the molten state, and thus embedding continuous fiber, in a solid form, is highly challenging. Hence, a nozzle system was designed and manufactured to feed the continuous fiber into the molten polymer simultaneously, which is called, here, in-melt simultaneous impregnation. With the presence of continuous fibers in the nozzle outlet, the feed of filament was calculatedly adjusted in the G-codes depending on the fiber volume percentage, to produce sound flow, and consistent deposition. Composite products were produced with various geometrical shapes. Via analysis and close control of the filament feeding, as a critical requirement to produce a sound printed product, composites with various fiber volume percentages were printed. Also, the mechanical properties of the printed parts with 30% by volume of glass fiber were measured. The results of the tensile test indicated that the continuous fibers were appropriately and effectively embedded that could result in remarkable increases in tensile strength and modulus of the samples, higher than 700%. The resulted values of tensile modulus were consistent with the values calculated via the rule of mixture. In addition, scanning electron microscopic images of the fracture sections suggest a sound adhesion between fibers and the matrix.

Effect of steel fiber on the shear strength of reactive powder concrete

Nowadays, research about concrete technology has led to a concrete with high performance (ultra-high concrete). Various innovations are also used to support the ultra-high concrete. In concrete engineering, we always avoid shear failure due to its brittleness. In this study, innovative additives will be used in the form of fiber steel fiber with the aim to increase the shear strength of the concrete powder. Tests in the laboratory will be carried out on samples of fiber-reinforced concrete beam specimens and to study the effect of increasing shear strength due to the addition of fiber (steel fiber), the variable is aspect ratio (fiber length versus fiber diameter) varied 75, 100, 125,165,180 and volume aspects ( 0.1%, 0.2%, 0.3, 0.4, 0.5%, 0.6%). And the greater the percentage of steel fiber volume can increase the shear strength, the greater the fiber-reinforced concrete, but the workability will be lower. In order for workability to remain good, the recommended fiber volume is 0.3% and the aspect ratio using the critical length of the fiber compared to the diameter of the fiber.

An approach to develop printable strain hardening cementitious composites

New additive manufacturing methods for cementitious materials hold a high potential to increase automation in the construction industry. However, these methods require new materials to be developed that meet performance requirements related to specific characteristics of the manufacturing process. The appropriate characterization methods of these materials are still a matter of debate. This study proposes a rheology investigation to systematically develop a printable strain hardening cementitious composite mix design. Two known mixtures were employed and the influence of several parameters, such as the water-to-solid ratio, fibre volume percentage and employment of chemical admixtures, were investigated using a ram extruder and Benbow-Bridgwater equation. Through printing trials, rheology parameters as the initial bulk and shear yield stress were correlated with variables commonly employed to assess printing quality of cementitious materials. The rheology properties measured were used to predict the number of layers a developed mixture could support. Selected mixtures had their mechanical performance assessed through four-point bending, uni-axial tensile and compressive strength tests, to confirm that strain hardening behaviour was obtained. It was concluded that the presented experimental and theoretical framework are promising tools, as the bulk yield stress seems to predict buildability, while shear yield stress may indicate a threshold for pumpability.

Prediction of Fiber Reinforced Concrete Strength Properties by Micromechanics Method

High strength steel fiber reinforced concrete (HSSFRC) was prepared with the help of steel fiber. 0.5%, 1.0%, and 1.5% steel fiber by volume of concrete specimen was used in concrete for present investigation. Compressive strength test and flexural strength test were conducted on cubical and prismatic specimens respectively.The main objective of the research work is to validate the experimental out comes by a numerical technique such as micromechanics approach. A high strength steel fiber reinforced concrete whose compressive strength is greater than 60 N/mm2 was prepared and tested on concrete testing machine. Flexural strength test was conducted on universal testing machine to evaluate the bending properties of concrete. It was observed that with increase in the percentage of steel fiber volume the compressive strength and flexural strength also increases. However the workability of concrete declines and concrete is no longer in working condition. Micromechanics technique helps to predict the strength properties which save time required for casting and such technique was found to be beneficial.

Determination of shear strength of steel fiber RC beams: application of data-intelligence models

Accurate prediction of shear strength of structural engineering components can yield a magnificent information modeling and predesign process. This paper aims to determine the shear strength of steel fiber reinforced concrete beams using the application of data-intelligence models namely hybrid artificial neural network integrated with particle swarm optimization. For the considered data-intelligence models, the input matrix attribute is one of the central element in attaining accurate predictive model. Hence, various input attributes are constructed to model the shear strength “as a targeted variable”. The modeling is initiated using historical published researches steel fiber reinforced concrete beams information. Seven variables are used as input attribute combination including reinforcement ratio (ρ%), concrete compressive strength (f′c), fiber factor (F1), volume percentage of fiber (Vf), fiber length to diameter ratio (lf =ld) effective depth (d), and shear span-to-strength ratio (a/d), while the shear strength (Ss) is the output of the matrix. The best network structure obtained using the network having ten nodes and one hidden layer. The final results obtained indicated that the hybrid predictive model of ANN-PSO can be used efficiently in the prediction of the shear strength of fiber reinforced concrete beams. In more representable details, the hybrid model attained the values of root mean square error and correlation coefficient 0.567 and 0.82, respectively.

Mechanical, wear and thermal behaviour of hemp fibre/egg shell particle reinforced epoxy resin bio composite

The aim of this work is to examine the mechanical, tribological, and thermal behaviour of hemp fibre reinforced egg shell epoxy polymer composites. Experiments are carried out to study the effect of fiber and filler volume percentage on mechanical, wear, and thermal behaviour of epoxy based polymer composites. The volume of fibre and filler is varied by 30%, 40%, and 50% and 0.25%, 0.5%, and 1.0%, respectively. The specimens are fabricated by using hand layup technique. The specimens are expurgated according to ASTM standards. The mechanical tests such as hardness, tensile, impact and flexural strength are evaluated and abrasive wear behaviour of the specimen was investigated using a pin-on-disc machine. The thermal stability was evaluated using a thermo gravimetric analyzer. The effects of hemp fibre and filler were examined under different mechanical and thermal conditions. The mechanical results show that the addition of fibre increased the load bearing characters of epoxy resin, whereas the addition of egg shell filler increased thermal stability of the composite.

Axial compression behavior of hybrid fiber reinforced concrete filled steel tube stub column

Previous studies indicate that the use of hybrid fiber has the potential to improve the properties of concrete. This paper investigates the effect of steel-polypropylene hybrid fiber on the axial compression behavior of concrete-filled steel tube (CFST) columns. Sixteen hybrid fiber reinforced concrete filled steel tube (HFRCFST) stub columns are tested under axial load. The variables considered in the tests are the steel fiber volume percentage and polypropylene fiber quality percentage. The failure mode, ultimate capacity, ductility and energy dissipation capacity of HFRCFST column are investigated. Experimental results show that hybrid fiber has negligible effect on the failure mode and ultimate capacity, delays the failure process and improves the energy dissipation capacity. The fiber hybridization has a favourable reinforcement effect on the ductility over the sum of the individual single fibers. Therefore, using hybrid fiber reinforced concrete is a more effective method to improve the ductility of the CFST columns than single fiber.

Axial compression behavior of circular recycled concrete-filled steel tubular short columns reinforced by silica fume and steel fiber

This paper presents an experimental work for short circular steel tube columns filled with normal concrete (NAC), recycled aggregate concrete (RAC), and RAC with silica fume and steel fiber. Ten specimens were tested under axial compression to research the effect of silica fume and steel fiber volume percentage on the behavior of recycled aggregate concrete-filled steel tube columns (RACFST). The failure modes, ultimate loads and axial load- strain relationships are presented. The test results indicate that silica fume and steel fiber would not change the failure mode of the RACFST column, but can increase the mechanical performances of the RACFST column because of the filling effect and pozzolanic action of silica fume and the confinement effect of steel fiber. The ultimate load, ductility and energy dissipation capacity of RACFST columns can exceed that of corresponding natural aggregate concrete-filled steel tube (NACFST) column. Design formulas EC4 for the load capacity NACFST and RACFST columns are proposed, and the predictions agree well with the experimental results from this study.