Different Volume Fractions Of Fibers Research Articles

A thermodynamically consistent physics-informed deep learning material model for short fiber/polymer nanocomposites

This work proposes a physics-informed deep learning (PIDL)-based constitutive model for investigating the viscoelastic–viscoplastic behavior of short fiber-reinforced nanoparticle-filled epoxies under various ambient conditions. The deep-learning model is trained to enforce thermodynamic principles, leading to a thermodynamically consistent constitutive model. To accomplish this, a long short-term memory network is combined with a feed-forward neural network to predict internal variables required for characterizing the internal dissipation of the nanocomposite materials. In addition, another feed-forward neural network is used to indicate the free-energy function, which enables defining the thermodynamic state of the entire system. The PIDL model is initially developed for the three-dimensional case by generating synthetic data from a classical constitutive model. The model is then trained by extracting the data directly from cyclic loading–unloading experimental tests. Numerical examples show that the PIDL model can accurately predict the mechanical behavior of epoxy-based nanocomposites for different volume fractions of fibers and nanoparticles under various hygrothermal conditions.

Mechanical properties of cement mortar with gamma-irradiated recycled plastic powder, pellet, and fiber

This study aimed to investigate the impact of gamma irradiated recycled polyethylene terephthalate (PET) pellets, powder, and fibers on the mechanical performance and ductility of cementitious mortar. The sensitivity to gamma irradiation was explored by varying the irradiation rate and total dose. The recycled PET additives employed in this experiment consisted of pellets and their different application forms: powder and fiber, containing 30 % recycled raw materials polymerized through a chemically recycled method. For comparison, plain mortar composite and virgin PET mortar composite were used as controls. When PET pellets partially replaced the aggregate, the compressive strength of the composite decreased significantly as the volume fraction of pellets increased. Conversely, specimens partially replaced by PET powder showed an overall increase in compressive strength compared to the control specimens, regardless of the volume fraction of powder, gamma irradiation rate, or total dose, with no change in ductility. To assess changes in tensile strength and ductility of the recycled PET fibers under different gamma irradiation rates and total doses, direct fiber tensile tests were conducted. The gamma-irradiated fiber specimens exhibited a slight increase in strength and ductility. This information allowed for the calibration of the tensile material constitutive relationship of PET fibers, which was subsequently used in nonlinear finite element analysis. The study also investigated the variation in direct tensile, compressive, and flexural strengths with different volume fractions of fiber. The results indicated that the strength enhancement was minimal, but the direct tensile and flexural tensile analyses predicted an enhancement.

Effect of hybrid steel-polypropylene fiber on punching shear behavior of flat slab with an opening

This research aimed to gain a better understanding of how the addition of fiber influences the punching shear capacity of two-way slabs by conducting an experiment into the structural behavior of flat slabs with and without a square opening using different volume fractions of hybrid steel-polypropylene fiber (0%, 0.9%, 1.05% and 1.8%). Ten 700 × 700 × 70 mm slabs were divided into five pairs, with two samples used as control samples (with and without openings), and eight other samples with different volume fraction of fibers. Results showed that an increase in fiber content enhanced the shear strength of the slabs. For example, as the volume fraction of hybrid fiber increased from 0.0 to 1.8%, the ultimate load increased by 52% for slabs without an opening and up to 42% for slabs with an opening.

Influence of rice husk fillers on mechanical properties of banana/epoxy natural fiber hybrid composites

Increasing environmental pollution, climate change, and the use of non-biodegradable or renewable resources have become major concerns for researchers in the modern industrialized world. It isbelievedthat if we are to build a sustainable future, we must address these issues while also protecting the capabilities of theforthcoming generations to achieve their own requirements. Compared to synthetic reinforcing fiber natural fiber has different advantages such as harmlessness, low densities, lower processing costs, and similar comparable strength. In this experiment banana fiber reinforced with the epoxy and rice husk bio filler hybrid composites were made and the Mechanical properties of for these hybrid composites were characterized. Different volume fractions of fiber with various composite samples were made by using the traditional hand layup method and pressure applied at moderate temperature. All the hybrid samples were tested under tensile, flexural, and impact loading, the interfaces of fiber matrix were evaluated and the fractured surface structures were analyzed using a Scanning electron microscope (SEM). From the results, it was observed that the composite samples with 30 % banana fibers and 10 % rice husk exhibited better mechanical properties when compared with the other composite compositions.

Mechanical and thermal analysis of coir fiber reinforced jute/bamboo hybrid epoxy composites

AbstractIn this current research study, nine different combinations of coir, jute, and bamboo reinforced epoxy composites were fabricated using casting technique. These composites were employed to mechanical tests such as flexural and impact tests, and analyzed the thermal stability through Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC). Moreover, the thermal conductivity and surface morphology was also studied for hybrid composites. The hybridization of more than one fiber with epoxy matrix resulted in better mechanical and thermal properties as compared to individual reinforcements, and this statement is agreed with the present research work as well as the research works reported in the literature. The hybrid composite with the maximum amount of jute fibers reinforcement with bamboo fiber (B2C0J8) exhibited maximum flexural and impact strengths of 92.521 MPa and 82.4 kJ/m2 respectively, which is due to the higher modulus and energy‐absorbing behavior of jute fibers, also it was an advantage of coir fibers absence having lower modulus and strength values. In thermal conductivity analysis, the marginal variations of values were observed with different volume fractions of fibers, and the maximum conductivity (0.317 W/m‐K) was obtained for B2C8J Composite having only coir and bamboo fiber reinforcements with epoxy matrix. The Thermogravimetric analysis results reveal that all nine types of hybrid composites possess nearly equal thermal stability, and slight variations in degradation temperatures were observed in the thermographs. The B2C1J7 hybrid composite was recommended for better mechanical and thermal properties, where it has 89.06 MPa of flexural strength, 78.6 kJ/m2 of impact strength, 0.233 W/m‐K of thermal conductivity and exhibited better surface morphology.

Tensile Properties of Additively Manufactured Continuous Glass Fiber Reinforced Onyx

Among all additive manufacturing techniques, fused deposition modeling (FDM) has been used the most extensively to fabricate continuous fiber reinforced polymers. Onyx, a short carbon fiber reinforced PA6 composite material developed by Markforged, has received widespread attention, and been employed as matrix in FDM-fabricated composites. This study investigates the tensile properties of continuous glass fiber (GF) reinforced Onyx (CGFRO) composites under quasi-static loading. CGFRO contains three different components, which are short carbon fiber in micrometer scale, continuous glass fiber and polyamide-d thermoplastic. The synergistic reinforcing behavior of these three components was evaluated experimentally by testing Onyx material, and CGFRO with different volume fractions of fibers (Vf). It was found that the failure mode of Onyx was different from that of GF/Onyx and the deformation modes of GF/Onyx varied with the volume fraction of glass fiber. The tensile properties of CGFRO increased with glass fiber volume fractions, where 42% Vf specimens exhibited the highest tensile modulus and strength of 10 GPa and 383 MPa, respectively, which are approximately nine times higher than that of Onyx parent material.

A hyperelastic-damage model to study the anisotropic mechanical behavior of coral-hydrogel bio-composite

In this research, a hyperelastic strain energy function was developed to investigate the anisotropic mechanical behavior of a soft bio-composite containing the coral collagen fibers and alginate hydrogel matrix. This hyperelastic function considers the matrix isotropic response, anisotropic behavior of soft crimpled fibers, and matrix-fiber interaction. The material parameters of the model were assumed as a function of the volume fraction of fibers to consider the fiber content. The published experimental data of matrix and bio-composites with different volume fractions of fibers in different directions were used to find the material parameters. A damage model was developed to take into account the damage of matrix, fibers, and fiber-matrix interaction. Results showed that the interaction contribution increases by increasing the volume fraction of fibers due to the crosslinks between the matrix and fibers. Moreover, by exceeding the fibers volume fraction from 20%, the anisotropic stiffening dominates the interaction stiffening in the longitudinal test owing to the load-bearing of soft fibers. Simulation results exhibited that cross-plied bio-composites show more uniform deformations than angle-plied bio-composites. Moreover, the damage results showed that the matrix plays a significant role in the failure of bio-composites.

Experimental Investigation on Dynamic Tensile Behaviors of Engineered Cementitious Composites Reinforced with Steel Grid and Fibers

Engineered cementitious composites (ECC) used as runway pavement material may suffer different strain rate loads such as aircraft taxiing, earthquakes, crash impacts, or blasts. In this paper, the dynamic tensile behaviors of the steel grid-polyvinyl alcohol (PVA) fiber and KEVLAR fiber-reinforced ECC were investigated by dynamic tensile tests at medium strain rates. The mixture was designed with different volume fractions of fibers and layer numbers of steel grids to explore the reinforcement effectiveness on the dynamic performance of the ECC. The volume fractions of these two types of fibers were 0%, 0.5%, 1%, 1.5%, and 2% of the ECC matrix, respectively. The layer numbers of the steel grid were 0, 1, and 2. The dynamic tensile behaviors of the PVA fiber and the KEVLAR fiber-reinforced ECC were also compared. The experimental results indicate that under dynamic tensile loads, the PVA-ECC reveals a ductile and multi-cracking failure behavior, and the KEVLAR-ECC displays a brittle failure behavior. The addition of the PVA fiber and the KEVLAR fiber can improve the tensile peak stress of the ECC matrix. For the specimens A0.5, A1, A1.5, and A2.0, the peak stress increases by 84.3%, 149.4%, 209.6%, and 237.3%, respectively, compared to the matrix specimen. For the specimens K0.5, K1, K1.5, and K2, the peak stress increases by about 72.3%, 147.0%, 195.2%, and 263.9%, respectively, compared to the matrix specimen. The optimum fiber volume content is 1.5% for the PVA-ECC and the KEVLAR-ECC. The KEVLAR-ECC can supply a higher tensile strength than the PVA-ECC, but the PVA-ECC reveals more prominent deformation capacity and energy dissipation performance than the KEVLAR-ECC. Embedding steel grid can improve the tensile peak stress and the energy dissipation of the ECC matrix. For the strain rate of 10−3 s−1, the peak stress of the A0.5S1 and A0.5S2 specimens increases by about 49.1% and 105.7% compared to the A0.5 specimen, and the peak stress of the K0.5S1 and K0.5S2 specimens increases by about 61.5% and 95.8%, respectively, compared to the K0.5 specimen.

Effect of polypropylene fibers on the development lengths of reinforcement bars of slabs

Ductile behavior is one of the most important earthquake indicators that must be possessed by structures. Because of the limited tensile strength of concrete, alternative materials such as structural nanosynthetic fibers as three-dimensional reinforcement bars have gained increasing popularity over several decades. However, the contribution of fibers to the development length of reinforcement bars has not been investigated. Therefore, an experimental study was conducted to investigate the effects of polypropylene fibers on the development lengths of reinforcement bars. Thirty-three reinforced concrete (RC) slabs at three different volume fractions of fibers of 0.0, 1.0 and 1.5 % at different embedment lengths of reinforcement bars were investigated under four-point flexural strength tests. Load-displacement curves, energy absorption capacities, ductility ratios and bond-slip relationships were obtained for different embedment lengths of reinforcement bars with three different amounts of fibers in RC concrete slabs. The test results revealed that the predominant effects of fibers on structural behavior pertained to the energy absorption capacities at plastic deformation. It was found that resisting more strains by reinforcement bars with the help of added polypropylene fibers resulted in the regaining of ductile behavior due to the reduced embedment lengths of the reinforcement bars.

Finite element estimation of the effective mechanical properties of coir fiber-reinforced high-density polyethylene

Natural fibers (NFs) have gained attention as replacement of synthetic fibers due to their advantages such as eco-friendliness, nontoxicity, and they are available in nature ensuring a continuous supply of the fibers. The aim of this study is to evaluate the elastic properties of NFs-reinforced polymer composites at different volume fractions of fiber using the finite element method. A micromechanical three-dimensional representative volume element with a square packing geometry was developed for the analysis. Results from the finite element analysis were validated with selected analytical models and were found to be in agreement.

The Effects of Natural Fiber Orientations on the Mechanical Properties of Brake Composites

ABSTRACT This research aims to study the usage of natural fibers as composite reinforcement and their effects on mechanical properties. Because asbestos fibers have negative impacts on the environment and public health, in the manufacture of brake composites they were replaced with natural fibers. Compared to synthetic fibers, natural fibers are cheaper, higher manufacturability, and a better contributor to mechanical properties. Pineapple leaf fibers were prepared by a water retting process, and coconut and areca fibers were prepared by a separation process after drying. The samples were prepared in the different volume fraction of fibers (2 vol% – 10 vol%) and fiber orientations adjusted as random, perpendicular, and angle of 45°. They were fabricated by hot isostatic pressing method, tested using Rockwell hardness tester, wear testing machine, and universal testing machine, and characterized using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The specimen in a fiber orientation of 45° performs the strongest tensile strength. The highest hardness (68 HRN) is found in the specimen with a volume fraction of 2 vol%, the lowest wear (1,64 × 10−4 mm2/kg) is obtained in the sample (10 vol%), and the highest tensile strength (14,5 MPa) is resulted by a specimen in angle orientation 45°.

Assessment of synergetic effect on microscopic and mechanical properties of steel‐polypropylene hybrid fiber reinforced concrete

AbstractFiber reinforced concrete (FRC) is presently being replaced with plain concrete for its superior performance. In most cases, FRC contains just a single kind of fiber. The utilization of at least two kinds of fibers in an appropriate mix can possibly improve the mechanical properties of concrete and result in performance synergy. This paper explores the effect of using steel fiber and polypropylene fiber for reinforcing the concrete to quantify the mechanical properties of the concrete composite. The purpose of this research was to analyze the flexural strength, tensile strength, sorptivity and elasticity modulus of steel, and polypropylene hybrid fiber composite. Crimped steel fibers in conjunction with polypropylene fiber at different volume fractions were utilized. A nondestructive methodology in light of ultrasonic pulse velocity measurements was utilized to evaluate the dynamic elastic modulus. The scanning electron microscope was used to assess the properties of the concrete mixtures, the interfacial bond between fiber and the concrete matrix. The results were analyzed to evaluate fiber synergy if any associated with different volume fractions of fiber. The paper identifies the volume fraction of hybrid fiber that demonstrates maximum synergy under the essential mechanical properties of steel‐polypropylene hybrid fiber reinforced concrete.

Performance assessment and optimization of hybrid composite patch repair of aircraft structure

PurposeIn this article, a novel hybrid composite patch consisting of unidirectional carbon fiber and glass fiber is considered for repair of the aircraft structure. The purpose of this paper is to assess the performance of hybrid composite patch repair of cracked structure and propose an optimized solution to a designer for selection of the appropriate level of a parameter to ensure effective repair solution.Design/methodology/approachElastic properties of the hybrid composites are estimated by micromechanical modeling. Performance of hybrid composite patch repair is evaluated by numerical analysis of stress intensity factor (SIF), shear stress, and peel stress. Design of experiment is used to determine responses for a different combination of design parameters. The second-order mathematical model is suggested for SIF and peel stress. Adequacy of the model is checked by ANOVA and used as a fitness function. Multiobjective optimization is carried out with a genetic algorithm to arrive at the optimal solution.FindingsThe hybrid composite patch has maintained equilibrium between the SIF reduction and rise of the peel stress. The repair efficiency and repair durability can be ensured by selection of an optimum value of volume fraction of glass fiber, applied stress, and adhesive thickness.Originality/valueThe composite patch with varying stiffness is realized by hybridization with different volume fraction of fibers. Analysis and identification of optimum parameter to reduce the SIF and peel stress for hybrid composite patch repair are presented in this article.

Effect of steel macro fibers on engineering properties of copperslag‐concrete

AbstractIn this paper, various engineering properties of the hardened concrete with copper slag and steel macro fibers are investigated. Normal grade concrete has been designed by varying the volume fraction of the fibers from 0.3 to 1.5% with higher aspect ratio (80). The setbacks of the concrete such as quasi‐brittle nature and low tensile strain capacity have been improved by adopting steel macro fibers along with copper slag. The study showcases the influence of macro fibers for five different volume fractions of fibers 0.3, 0.6, 0.9, 1.2, and 1.5% with higher length (60 mm) and diameter (0.75 mm) on the mechanical properties and microstructure properties of concrete by incorporating 40% of copper slag as partial replacement of fine aggregate. From the observed results, the addition of fibers and copper slag showed significant results on the mechanical properties of the concrete for the adopted low water–cement ratio of 0.35. The compressive strength, tensile strength, and flexural strength improved up to 16, 54, and 72% for the volume fraction of 1.5% of the fibers compared to the conventional concrete without any fibers. Relationship between the mechanical properties has been compared between the existing empirical relations and the experimental data. Microstructure analysis (Scanning Electron Microscopy and Energy Dispersive X‐ray Analysis) has been carried out to validate the bond performance and strength characteristics.

Production and mechanical characterization of Ni-coated carbon fibers reinforced Al-6063 alloy matrix composites

In this study, it aimed to produce carbon fiber (CF) reinforced aluminum metal matrix composite by squeeze casting method. In order to overcome the wetting problem between the aluminum matrix and the reinforcing agent, carbon fibers were coated with Ni coating with electroless technique. Different bath pH values and hypophosphite (HP), coating durations and bath temperature were investigated. SEM, EDS and XRD methods used to determine the characterize the layers. It has been observed that increasing the pH of the bath, coating time, bath temperature and amount of hypophosphite increases the thickness of the Ni coatings on the carbon fibers. Two different thicknesses of coatings were used with different volume fractions of fiber used to reinforce the 6063 aluminum as matrix alloy. Squeeze casting process was used for the production of the composites to increase the connection between the matrix and the carbon fibers. After achieving a good bonding, three-point bending, Charpy impact, and Vickers hardness tests were carried out to investigate the difference of at the mechanical properties. It was observed from the mechanical tests that while the hardness and the three-point bending strength was increasing the impact strength was decreasing after the carbon fiber addition. Also coating, in general, helping the mechanical properties, mechanical properties of composites are badly affected by higher coating thicknesses.

Possibilities to improve electromagnetic shielding of plaster composites adding carbon fibers

This paper studies size of electromagnetic shielding in plaster composites, using different volume fractions of carbon fibers. Conventional types of plaster, which are normally used in construction (i.e. cement, lime, gypsum and lime cement) were the main parts of the created composites The carbon microfibers with a length of 8 mm were added as reinforcing and simultaneously shielding element into plaster samples. The tested samples were created at three different volume fractions of the fibres and also into the base plaster for possibilities of their comparison. The results of carried measurement show that the electromagnetic shielding in the plaster composite grows with increasing fiber content in the tested ratio almost linearly.

Investigation Of Mechanical Properties And Tribological Behaviour Of Bagasse Fiber Reinforced Polymer Composite

Environmental awareness today motivates the researchers, worldwide on the studies of natural fiber reinforced polymer composite and cost effective option to synthetic fiber reinforced composites. With low cost and high specific mechanical properties, natural fiber represents a good renewable and biodegradable alternative to the most common synthetic reinforcement, i.e. glass fiber. Large varieties of sugar cane grow abundantly in many parts of India. Bagasse is considered to be a by-product of the milling process after production of sugar. Bagasse (fibrous residue) is essentially a waste product that causes mills to incur additional disposal costs. These fibers have many advantages over glass fiber or carbon fiber like renewable, environmental friendly, low cost, light weight and high specific mechanical performance. To study the mechanical properties of the composite, different volume fractions of fiber have been taken with in the range of 0-40%.These fibers were randomly distributed in the matrix. Usual hand lay- up technique has been adopted for manufacturing the composite. To have a good compatibility between the fiber and matrix, chemical modification of fibers such as Acetone and Alkali treatments has been carried out and catalyst(Aluminium dioxide) also added to the treated fiber.It was found that alkali treated fiber composite exhibits favourable strength and stiffness in comparison to acetone treatments. Moisture absorption behaviour of both treated and untreated fiber composite was also carried out .For studying mechanical properties of Bagasse fiber in thermosetting matrix composite different test were carried out such as impact test , flexural ,tensile ,hardness ,water absorption and wear test.

Effect of Fiber and Aggregate Size on Fracture Parameters Of High Strength Concrete

The present experimental investigation was to study the behavior of high strength concrete with different aggregate sizes and fiber variation influences on fracture characteristics. Total of 72 beams of various sizes are casted with different aggregate sizes (20mm, 16mm and 10mm) and with different volume fraction of fibers (0%, 0.5%, 1% and 1.5%). According to the notch depth ratios of different sizes of beams notches were made at centre of the beam. The casted and cured beams were tested on loading frame with three point loading. From the obtained results and graphs, the fracture parameters like fracture energy, brittleness number and failure stresses were analyzed by the size effect method (SEM). It was found that fracture energy (GF) and fracture toughness (KIC) increases from decreasing the aggregate size from 20mm to 10mm. By increasing the volume of fibers, brittleness number (β) decreases and fracture process zone (CF) increases.

Evaluation of maturity method for steel fiber reinforced concrete

The evaluation of steel-fiber reinforced concrete using the maturity method was investigated in this study. There were four different volume fractions of fibers (0, 0.5, 1 and 1.5 by volume of concrete) and three different curing temperatures (8°C, 22°C and 32°C) considered. The compressive strength and flexural strength were tested at 1, 3, 7, 10, 14 and 28 days for all of the volume fractions of fibers and at the different curing temperatures. The results show that as the volume fraction of fiber increased from 0 to 1.5%, the compressive and flexural strengths increased by 14% and 35%, respectively, compared to plain concrete. The maturity method was used to predict the compressive and flexural strengths. Four different equations (linear hyperbolic, parabolic hyperbolic, logarithmic and exponential) were used to predict the compressive and flexural strengths. All of the predicted models have good correlations with the experimental results for both compressive and flexural strengths. Moreover, to predict the compressive and flexural strengths using the maturity method, the apparent activation energies were calculated.

Experimental Investigation on Volume Fraction of Mechanical and Physical Properties of Flax and Bamboo Fibers Reinforced Hybrid Epoxy Composites

The aim of this paper is to study the effect of volume fraction on mechanical and physical properties such as tensile, flexural, impact, interlaminar shear strength, void content and water absorption of flax and bamboo fibers reinforced hybrid epoxy composites. Flax and bamboo fibers reinforced epoxy resin matrix hybrid composites have been fabricated by compression molding techniques. The hybrid composites were fabricated with different volume fraction of fibers. SEM analysis on the hybrid composite materials was performed to analyze the bonding behavior of materials and internal structure of the fractured surfaces. The effect of chemical treatment of flax and bamboo fibers was verified by FTIR analysis. The results showed that the tensile, impact, flexural and ILSS are maximum for 40:0 (flax: bamboo) hybrid composites. The void content decreased for 20:20 (flax:bamboo) composites due to tightly packed flax fiber and more compatibility towards epoxy resin.