Fiber Tensile Strength Research Articles

Effect of Curing Age on Pull-Out Response of Carbon, Steel, and Synthetic Fiber Embedded in Cementitious Mortar Matrix

Fiber-matrix interface bonding is an important area of concern in fiber-reinforced composites because it is directly related to the mechanical behavior of composites. In this study, interfacial bond properties of four types of fiber at different curing ages were investigated by analyzing fiber pull-out responses. Special attention was given to the fiber–matrix bonding behavior, including fiber tensile strength, average bond strength, equivalent bond strength, and average pull-out energy. Pull-out tests were conducted at 7, 14, 28, and 56 days of curing. Different failure modes in steel fiber, synthetic macrofiber, polyacrylonitrile (PAN)-based carbon fiber, and pitch-based carbon fiber were investigated. According to the pull-out force versus slip curves, different failure patterns were recorded based on the fiber type. Carbon fibers experienced a sudden drop after reaching the peak load, whereas the load decrease in steel and synthetic fiber was not as abrupt. Results also confirmed that steel fibers exhibited the highest pull-out load and energy absorption capacity followed by lower values for synthetic and carbon fibers. While monofilament of steel fiber was able to absorb 1,050 N·mm, monofilament of synthetic fiber and twisted bundles of carbon fibers could absorb 277 and 55 N·mm, respectively. However, the bond strength of straight carbon fibers was comparable to that of synthetic fiber and still lower than steel fiber. It was also derived from the experimental data that an increase in cement matrix age correlates to an improvement in fiber maximum pull-out load, bond strength, and tensile strength. These parameters were identified and compared in all fiber types.

Liquid Smoke Treatment for Natural Fibers: The Effect on Tensile Properties, Surface Morphology, Crystalline Properties, and Functional Groups of Banana Stem Fibers

This study aims to determine the effect of the treatment of banana stem fibers (BSF) with grade three liquid smoke on changes in the micromechanical properties of the BSF, single fiber tensile strength, morphology, crystal properties, and functional groups. This study used four variations of the specimen model, namely, fiber without treatment and immersion in liquid smoke for 1, 2, and 3 h. BSF with treatment was dried in an oven at 40 °C for 30 min. Several tests were carried out, including the tensile test for single fiber capacity of 50N standard ASTM 3379-02, Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), and Fourier Transform Infra-Red (FTIR) observation. The results showed that the highest increase in fiber strength occurred in P2J, which was 43.78%, with crystal intensity of 34.97%, compared to TP fiber. Treatment of fiber with liquid smoke can form a strong C-C elemental bond caused by the H2O degradation process in BSF so that the carbon atom (C) becomes solid; under conditions of excessive H2O degradation, the fiber strength will become brittle, however, liquid smoke can increase the fiber tensile strength. The morphology of the fiber changed where the untreated fiber was covered in lignin, while the treated fiber had a rectangular pattern of elongated lines, was porous, and the lignin was eroded. The fiber crystallization index increased due to changes in fiber structure, where the highest peak of TP BSF occurred at point two, while the highest peaks in BSF P1J, P2J, and P3J occurred respectively at points two and three. These results prove that the innovation of BSF treatment with liquid smoke can change the morphology, crystalline, and functional aspects of BSF, so that it becomes the choice of composite reinforcement material in the future, an option that is lightweight and environmentally friendly.

Prediction of Direct Tensile Strength of Bamboo Fiber Reinforced Concrete Using Artificial Neural Network

Bamboo is among the most economically-significant non-timber forest products in the Philippines, and its fiber can be used for concrete reinforcement, known as bamboo fiber reinforced concrete (BFRC). However, BFRC needs further exploration, and its direct tensile strength is an essential factor that needs to be studied. The present study assessed the direct tensile strength of BFRC utilizing finite element modeling (FEM) and Artificial Neural Network (ANN). A positive correlation was found between compressive and direct tensile strength of the BFRC. The optimum ANN model was obtained from the trial-error approach. This model has 5-5-1 (input-hidden neurons-output) network topology and uses the tan sigmoid transfer function for both input-hidden and hidden-output layer which brought the most accurate prediction. The Levenberg–Marquardt (LM) provided the best optimization performance among other algorithms. The best model has a mean squared error (MSE) of 0.0000287 and r values of 0.98619, 0.99936, 0.99516, and 0.98565 for training, testing, validating, and overall. Sensitivity Analysis shows that compressive can significantly change the system’s performance even with a small change in its parameter value.

Ultrasound‐assisted enzymatic scouring of jute optimised by response surface methodology and its natural dyeing

AbstractIndia is the largest producer of jute in the world and the use of this natural fibre in various value‐added applications is gaining momentum. The use of white biotechnology involving enzymes for the efficient processing of jute is considered to boost its productivity. The present investigation deals with the pretreatment of jute by using ultrasound‐assisted enzymatic scouring followed by bleaching and dyeing. The process showed optimum removal of impurities and improved water absorption capacity with minimal damage to fibre tensile strength. The process parameters and conditions were determined by response surface methodology, where weight loss of jute was kept as the main response. The optimised recipe obtained was 2.8% enzyme concentration, 1 g/L wetting agent at 55°C for 10 minutes at an ultrasound frequency of 40 kHz. The optimised recipe was compared with conventional high‐temperature long‐duration enzymatic scouring and was found to have an equal performance. Further, the scoured jute was dyed with a natural dye extracted from sappan wood and madder. Fourier Transform–infrared analysis was used for characterisation. The wash and light fastness of dyed jute yarn were evaluated and found to meet the industry norms.

Structural and Mechanical Properties of Hemp Fibers: Effect of Progressive Removal of Hemicellulose and Lignin

ABSTRACT Hemicellulose and lignin were progressively removed from hemp fiber by hydrolysis. SEM, FTIR, XRD analysis and tensile properties evaluation on technical fibers were carried out to understand the structural and mechanical properties of hemp fibers. Significant influence of hemicellulose and lignin content on tensile properties was verified by ANOVA. The fiber tensile strength and initial modulus were decreased with the extensive removal of hemicellulose, along with a constant increasing of elongation at rupture. Torsion and expansion were observed in hemp fibers. It was suggested that the internal structure destruction and reorganization in the ultimate fiber cells was the main reason for the variation of mechanical properties when hemicellulose was gradually dissolved. On the other hand, fiber individualization was achieved by lignin removal and contributed to the elevation of fiber tensile properties. The elongation at break of the hemp fibers decreased slightly with the removal of lignin. NaClO2 solution treatment affected the fiber cells slightly, but effectively changed the properties of the middle lamella jointing between the ultimate fiber cells. The mechanical properties of the hemp fiber were mainly decided by the shearing between single fibers caused by the plastic-like deformation of the middle lamella.

The greatness of the characteristics fiber pseudo stem outer layer of Musa acuminata origin lombok Indonesia as reinforcing polyester composite

Musa acuminata stem is an agricultural waste that has good economic potential. For this reason, efforts are needed to increase the saba banana tree not only as waste, but also to increase its function into natural fiber raw materials for polyester matrix composite reinforcement. The purpose of this study was to determine the characteristics of Musa acuminata stem fibre (MASF) from North Lombok Regency, Indonesia Country as a reinforcement for polyester matrix composites. In this study, the fiber (specimen), taken from pseudo stem Musa acuminata, which consists of three layers: outer, middle and inner stem. The ratting process is done mechanically using a fiber extraction machine. To remove impurities in the fiber, alkaline treatment was carried out, by soaking for 24 hours in a 5 % NaOH solution. To determine the characteristics, a scanning electron microscopy (SEM) test was carried out for MASF morphology analysis, chemical compound content testing, heat resistance testing, and fiber tensile strength testing. The results showed that the MASF of the outer layer pseudo-stem has a strong character. Fiber morphology is different, between the outer, middle and inner layers pseudo-stems. The cellulose content (73.12 %) was higher than the fiber of Fimbristylis globulosa, hemp, jute, rice straw, wheat straw, seaweed, sorghum straw, coir, and alpha grass. Less resistant to heat degradation because mass loss occurs at a constant rate up to 245 °C. The highest MASF, in the outer pseudo-stem layer it is 40–50 cm from the base stem. Its characteristics are better than other natural fibers so that its potential can be further developed as a reinforcement for polymer matrix composites

Improving Polypropylene Matrix Composites Reinforced with Aligned Hemp Fibre Mats Using High Fibre Contents.

The main goal of this study was to improve the mechanical performance of polypropylene (PP) matrix composites through high hemp fibre content. In order to achieve high fibre content, the possibilities of different polymer sheet thicknesses and stacking arrangements were investigated. It was found that decreasing the overall thickness of fibre mats between two polymer sheets within the stacking arrangements of composites and so decreasing the distance the polymer needs to travel improved the fibre wetting and therefore improved the tensile properties. The strongest composite produced had a fibre content of about 60 wt%. At this fibre content, tensile strength and Young’s modulus of the composites were found to be 3.0 and 6.9 times, respectively, higher than the control samples (polymer only samples), while figures for flexural strength and flexural modulus were 3.4 and 3.6, respectively.

Tensile, flexural and interlaminar shear strength of carbon fiber reinforced epoxy composites modified by graphene

Tensile, flexural and interlaminar shear strength of carbon fiber reinforced epoxy composites modified by graphene

Characteristic of Drying Shrinkage of Steel Fiber Reinforced Concrete by Tensile Strength of Steel Fiber

Characteristic of Drying Shrinkage of Steel Fiber Reinforced Concrete by Tensile Strength of Steel Fiber

Relationship between Compressive, Flexural and Split Tensile Strengths of Waste Copper Wire Fiber Reinforced Concrete

Concrete has low tensile strength, narrow ductile range and low crack resistance. Micro cracks in the concrete propagate quickly under loading, leading to brittle behaviour of the concrete. These cracks expose steel reinforcement to agents of corrosion. Adding steel fibres reduces the damage, but over a long period, the steel fibres corrode. This study used waste copper wire as fibre reinforcement in concrete to investigate the relationship between compressive, flexural and split tensile strengths. Grade 25 concrete was produced and cured for 7, 14 and 28 days before testing. One millimetre in diameter copper wire was used in the study. The fibre volume used was 0.5, 1.0 and 1.5%, respectively. The samples were tested for compressive, flexural and split tensile strengths. The results indicated a general increase in compressive, flexural and split tensile strengths of the concrete with an increase in waste copper wire fibre contents. Maximum compressive strength of 34.58 N/mm 2 was obtained at 1.5% fibre content and 28 days of curing. Flexural strength increases from 4.36 N/mm 2 at 0% fibre content and seven days curing to 6.68 N/mm 2 at 1.5% fibre content and 28 days curing. The split tensile strength increased fibre content from 2.72 N/mm 2 at seven days to 4.39 N/mm 2 at 28 days of curing. Mathematical models were produced for the relationships between compressive, flexural and split tensile strengths. The models have R 2 values greater than 70%, and the higher the value of R 2 , the better the model fits the data. This indicates that the model’s predictors influenced the variations in the responses.

Tension Strength and Fiber Morphology of Agave Cantala Roxb Leaves due to Liquid Smoke Immersion Treatment

In this work, we investigate the fiber tensile strength of the Agave cantala roxb leaves based on the treatment of immersion in liquid smoke which was obtained from mature coconut shells. Four different time variations of treatments, namely, one hour, two hours, three hours, and four hours, have been carried out. After the immersion, we investigated the chemical contents of the Agave cantala using scanning electron microscope (SEM) which is equipped by energy dispersive spectroscopy (EDS). Furthermore, the tension strength is tested using tensile strength plus 50 N. The test is applied for a single Agave cantala fiber. The results of the tensile test of single fiber showed an increase in tensile strength when compared with fiber tensile strength without immersion. The tensile strength of a single fiber of Agave cantala leaves increased with increasing duration of immersion time. After reaching a certain strength, however, the strength of the fiber decreases. The tensile strength of a single fiber without immersion is 192.85 MPa and the highest is 670.82 MPa for Agave cantala after immersion for three hours, with an elongation of 0.68 mm. By increasing the tensile strength of Agave cantala through liquid smoke immersion treatment, it can potentially improve its performance as a material composite reinforcement.

Effect of Surface Modification of Himalayan Nettle Fiber and Characterization of the Morphology, Physical and Mechanical Properties

Abstract The process of retting bast fiber plants for the production of long fiber has presented major challenges. Water retting, dew retting, chemical extraction, and micro-organism (fungi, enzymes) techniques were applied to the extraction of natural fibers. The two nettle samples were extracted with water retting for 14 days and dew retting for 4 weeks. This research investigated the effects on the traditional retting process of nettle fiber by fungi and bacteria formation in lignocellulosic. The latter biological extraction methods successfully degraded the lignin and pectin materials of the fiber and increases the cellulose content. These extraction methods produced high quality fiber and tensile strength at a low cost. This study determined the chemical, physical, and mechanical characteristics such as fiber cellulose, non-cellulosic content, tensile strength, tenacity, and elongation break to see how treatments affected them. The treated fiber surface morphology was characterized using scanning electron microscopy. To evaluate functional group alterations, Fourier-transform infrared spectroscopy was used on the fiber specimen.

Improved Shear Strength Prediction Model of Steel Fiber Reinforced Concrete Beams by Adopting Gene Expression Programming.

In this study, an artificial intelligence tool called gene expression programming (GEP) has been successfully applied to develop an empirical model that can predict the shear strength of steel fiber reinforced concrete beams. The proposed genetic model incorporates all the influencing parameters such as the geometric properties of the beam, the concrete compressive strength, the shear span-to-depth ratio, and the mechanical and material properties of steel fiber. Existing empirical models ignore the tensile strength of steel fibers, which exercise a strong influence on the crack propagation of concrete matrix, thereby affecting the beam shear strength. To overcome this limitation, an improved and robust empirical model is proposed herein that incorporates the fiber tensile strength along with the other influencing factors. For this purpose, an extensive experimental database subjected to four-point loading is constructed comprising results of 488 tests drawn from the literature. The data are divided based on different shapes (hooked or straight fiber) and the tensile strength of steel fiber. The empirical model is developed using this experimental database and statistically compared with previously established empirical equations. This comparison indicates that the proposed model shows significant improvement in predicting the shear strength of steel fiber reinforced concrete beams, thus substantiating the important role of fiber tensile strength.

High-Strength and High-Modulus Polyimide Fibers with Excellent UV and Ozone Resistance

A series of high-strength and high-modulus polyimide (PI) fibers containing benzimidazole and biphenyl units were synthesized from 2-(4-aminophenyl)-5-aminobenzimidazole (BIA), p-phenylenediamine (PDA), and 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA). The dry-spinning and hot-drawing processes were used to prepare PI fibers with various PDA/BIA molar ratios, wherein the chemical structures were identified by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Additionally, the relationship between the mechanical properties and aggregation structure of obtained PI fibers, varying with diamine ratios and hot-drawing ratios, was demonstrated by two-dimensional wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS), showing that the variation trend of mechanical property has a strong consistency with the nanoscale orientation factor calculated by the SAXS. The optimum tensile strength and modulus of PI fibers are 4.3 and 145 GPa, respectively, at a PDA/BIA molar ratio of 8/2. Moreover, after 168 h of UV irradiation and 175 h of ozone aging, this sample shows an excellent UV irradiation resistance and ozone aging resistance with retaining 94% and 95% of tensile strength of the pristine fiber. Meanwhile, the prepared PI fibers exhibit prominent thermal stabilities with the 10% weight loss temperature over 590 °C in a nitrogen atmosphere.

Continuous aluminum oxide-mullite-hafnium oxide composite ceramic fibers with high strength and thermal stability by melt-spinning from polymer precursor

Continuous aluminum oxide-mullite-hafnium oxide (AMH) composite ceramic fibers were obtained by melt-spinning and calcination from polymer precursor that synthesized by hydrolysis of the aluminum isopropoxide, dimethoxydimethylsilane and hafnium alkoxide. Due to the fine diameter of 8–9 µm, small grain size of less than 50 nm and the composite crystal texture, the highest tensile strength of AMH ceramic fibers was 2.01 GPa. And the AMH ceramic fibers presented good thermal stability. The tensile strength retention was 75.48% and 71.49% after heat treatment at 1100 °C and 1200 °C for 0.5 h respectively, and was 61.57% after heat treatment at 1100 °C for 5 h. And the grain size of AMH ceramic fibers after heat treatment was much smaller than that of commercial alumina fibers even when the heat treatment temperature was elevated to 1500 °C, benefited by the grain size inhibition of monoclinic-HfO2 (m-HfO2) grains distributed on the boundary of alumina and mullite grains.

Enhanced interfacial properties of hierarchical MXene/CF composites via low content electrophoretic deposition

The weak fiber-matrix interface is a bottleneck hindering the development of carbon fiber composites . In this work, an optimized electrophoretic deposition (EPD) approach was explored to improve the interfacial properties by depositing uniformly two-dimensional MXene (Ti 3 C 2 T x ) nanoparticles onto the surface of carbon fibers (CF). The MXene-CF hybrids were then used to fabricate continuous carbon fiber reinforced polymer (CFRP) composites. The results manifested that the presence of MXene nanoparticles on the CF surfaces could significantly increase the fiber surface energy and wettability , as well as their surface roughness. As a result, a remarkable increase of the interfacial strength and flexural properties of CFRP has been observed. The functionalized MXene–CF–epoxy composites witnessed a prominent enhancement of interlaminar shear strength (ILSS), flexural strength and monofilament tensile strength compared to their unfunctionalized counterparts. The versatile EPD strategy proposed herein, constitutes a promising approach for CFRP modification that can lead to significantly improved performance. • A homogeneous MXene attachment to the CF surface was achieved via a novel EPD process. • The EPD technique was optimized to prevent oxidation and agglomeration of MXene nanoparticles. • Enhancements of 75%, 50.4%, and 32.7% in ILSS, flexural strength, and single fiber tensile strength were obtained. • The interfacial strengthening mechanism was ascribed to mechanical interlocking, local stiffening, and hydrogen bonding.

Design of polysaccharidic Aloe vera gel incorporated PVA/tetracycline electrospun cell culture scaffolds for biomedical applications

In this study, hybrid nanofibrous 3D scaffolds containing Aloe vera (AV), polyvinyl alcohol (PVA) and tetracycline hydrochloride (TCH) are fabricated by electrospinning for cell culture applications. The role of polysaccharides present in AV gel is found to enhance the biocompatibility of the nanofibrous scaffolds. Different combinations of the polymers were selected to produce homogenous nanofibers with favorable mean fiber diameter and tensile strength. The surface morphology of the products was studied by SEM and it is found that the mean fiber diameter is decreased to about 188 nm upon addition of the AV component. The electrospun scaffolds were investigated by FT-IR spectroscopy to reveal the chemical structure of the samples and their crystallinity was studied by XRD. The hydrophilicity of the scaffolds was tested by optical contact angle measurements and their mechanical strength was examined by tensile strength tests. It is found that PVA is the main component contributing the mechanical stability of the scaffold structure. The fabricated scaffolds presented a more pronounced inhibitory effect against Gram-positive bacterial strains of S. aureus and B. cereus. Cell culture experiments using fibroblast L929 murine cells reveals that the AV/PVA/TCH scaffolds are promising for cell growth and the cells are capable of achieving a proper cell adhesion and proliferation. The cell viability experiment by MTT assay exhibits the contributing role of AV gel to L929 cell viability on the AV/PVA/TCH scaffolds.

Shear Strength Prediction of Slender Steel Fiber Reinforced Concrete Beams Using a Gradient Boosting Regression Tree Method

For the design or assessment of concrete structures that incorporate steel fiber in their elements, the accurate prediction of the shear strength of steel fiber reinforced concrete (SFRC) beams is critical. Unfortunately, traditional empirical methods are based on a small and limited dataset, and their abilities to accurately estimate the shear strength of SFRC beams are arguable. This drawback can be reduced by developing an accurate machine learning based model. The problem with using a high accuracy machine learning (ML) model is its interpretation since it works as a black-box model that is highly sophisticated for humans to comprehend directly. For this reason, Shapley additive explanations (SHAP), one of the methods used to open a black-box machine learning model, is combined with highly accurate machine learning techniques to build an explainable ML model to predict the shear strength of SFRC slender beams. For this, a database of 330 beams with varying design attributes and geometries was developed. The new gradient boosting regression tree (GBRT) machine learning model was compared statistically to experimental data and current shear design models to evaluate its performance. The proposed GBRT model gives predictions that are very similar to the experimentally observed shear strength and has a better and unbiased predictive performance in comparison to other existing developed models. The SHAP approach shows that the beam width and effective depth are the most important factors, followed by the concrete strength and the longitudinal reinforcement ratio. In addition, the outputs are also affected by the steel fiber factor and the shear-span to effective depth ratio. The fiber tensile strength and the aggregate size have the lowest effect, with only about 1% on average to change the predicted value of the shear strength. By building an accurate ML model and by opening its black-box, future researchers can focus on some attributes rather than others.

Mechanical Properties Evolution and Damage Mechanism of Kevlar Fiber under Ozone Exposure in Near-Space Simulation

The stratospheric airship, a long-term floating vehicle in near-space, has become a new hotspot in aerospace exploration. The airship’s envelope material is vulnerable to ozone exposure in near-space and degrades. This paper used typical Kevlar fiber as the research material for an ozone exposure experiment in a near-space simulated environment. The results showed that the elongation of the Kevlar fiber decreased and the elastic modulus increased after ozone exposure. The tensile strength of fiber decreased gradually with an increase in ozone concentration and exposure time. When ozone concentration increased from 0 pphm to 1000 pphm, the tensile strength of fiber decreased from 2397 MPa to 2059 MPa. With increasing ozone exposure time from 0 h to 1000 h under ozone concentration 1000 pphm, the tensile strength of fiber decreased from 2332 MPa to 1954 MPa. The hydrogen bonds and partial amide groups in the fiber structure were damaged, and the surface chemical functional groups of the Kevlar fiber were reassembled under ozone exposure. Low molecular weight oxidation products, including -COO- structures, formed on the surface of the Kevlar fiber. This work explores the ground simulation method in a near-space environment and enriches the service data of airship envelope materials.

Multi-scale model for time-dependent degradation of historic paper artefacts

The degradation of paper is due to complex physical and chemical processes that occur as the paper ages, and is enhanced by environmental factors, such as the temperature and relative humidity, and by intrinsic parameters, such as the acidity of the paper. The literature reports that a large percentage of historic documents, manuscripts, and paper objects in museums, libraries and collections is susceptible to degradation phenomena, which may ultimately affect their integrity and longevity. This contribution presents a novel computational model to predict the degradation and lifetime of historic paper. The approach is based on: i) a multi-physics modelling framework, which considers the relevant chemical and mechanical degradation processes and the influence by the ambient environmental conditions, and ii) a multi-scale description, which includes the effect of the intrinsic hierarchical structure of paper, from the fibre- and fibrous network levels to the effective macro-scale, paper sheet level. The paper fibres constructing the fibrous network are characterized by an age-dependent, chemo-mechanical constitutive behaviour. In particular, an evolution equation describes the reduction of the degree of polymerization of cellulose as a function of time and the specific environmental conditions, which in turn is used for determining the fibre tensile strength. The fibre stresses induced by hygro-expansion and hygro-contraction under a change in relative humidity are computed using a coupled hygro-mechanical model, and lead to brittle damage once the fibre tensile strength is reached. Accordingly, the chemical degradation of individual fibres affects the local damage development and stress distribution in the fibrous network, and thereby governs the material response at the paper sheet scale. Asymptotic homogenization is used to calculate the effective hygro-mechanical properties of the fibrous network. A set of numerical simulations is performed to predict the time-dependent degradation of historic paper under a range of temperature, relative humidity and acidity conditions. From these results, isochrone degradation maps are constructed that illustrate the expected lifetime of historic paper as a function of the ambient climate conditions and the acidity of the paper. Further, a practical, analytical degradation function is derived that can be used for a fast estimation of the time-dependent stiffness degradation of paper. The outcome of this work may help conservators to determine the optimal indoor climate conditions in museums, archives and libraries for limiting or delaying time-dependent degradation of historic paper artefacts.