Fiber Composite Materials Research Articles

Study of the thermal and moisture aging effect on the residual mechanical properties of a structural composite material

The main aim of work is experimental research and description of the mechanical behavior regularities and strength properties degradation of a fibrous structural composite material under combined mechanical and thermal effects and aging in aggressive (operational) environments. Data on the various environments influence such as process water, seawater and machine oil at different durations (15, 30, 45 days) and temperatures (22°С, 60°С and 90°С) on the destruction processes of the composite and the realization of various mechanisms of damage accumulation on during quasi-static tests for interlayer shear. The paper presents the experimental data obtained by the acoustic emission technique. The results of a sample's microstructure study obtained using a stereo microscope before and after thermal and moisture aging in aggressive environments.

Study of the laminas’ stress-strain state for cross-ply composites with the [± 45°]2s lay-up: tensile tests

In this paper we have analysed the relations that allows one to determine the components of strains and stresses in the orthotropic axes of layered fiber reinforced composite materials in tensile and compression experiments for test specimens with the [±45°]2s lay-up. In particular, such relations were compiled on the assumption that in a cross-ply fiber composite two adjacent layers with the [±φ] lay-ups can be considered as one symmetrically reinforced layer with orthotropic properties. To establish the degree of accuracy of these relationships and assumptions, numerical experiments were carried out to determine the parameters of the stress-strain state of specimens consisting of two and four monolayers of a unidirectional fibrous composite material with the [±45°]2s lay-up. The analysis has been performed in the ANSYS finite element analysis program system in a linear formulation of two- and three-dimensional problems. It is shown that in the central zone of the specimen, the theoretical-experimental methodology based on the above mentioned relations has a sufficient degree of accuracy. Based on the analysis of results of three-dimensional problems, the formation of a linear torque in the specimen, which causes the twisting of some zones of the specimen along its length, has been revealed.

Production Technology of Ecological High Performance Fibre Composite Construction Materials

Eco materials derived from natural plant fibres and mineral binders are an alternative solution for modern ecological construction. This research is devoted to developing production technology for ecological high-performance fibre composite materials based on hemp shives and magnesium binder. The proposed composite wall structures consist of outer envelope layers made from dense hemp composite and middle insulation layer made from a lightweight hemp composite. The article describes the process of manufacturing a hemp composite boadr and the process of creating a three-layer structure of the outer wall. Used mix compositions are based on previously elaborated mix compositions based on magnesium oxychloride cement (MOC) binder and hemp shives. This study presents the case study of testing samples from hemp composite boards produced in actual industrial conditions. During an experiment, 20% magnesium oxide was replaced as an alternative binder, such as metakaolin and fly ash. The purpose of modifying the compositions of the composite is to increase the water resistance of the material and improvement of the hydraulic properties of the material, as it was previously found that this material is hygroscopic concerning the high humidity of the ambient air.

A review of recent developments in structural applications of natural fiber-Reinforced composites (NFRCs)

Natural fiber-reinforced composites (NFRCs) are expected to find growing applications in near future, especially in Europe where stringent environmental codes are being legislated and public pressure for their enforcement is increasing. Study has shown that NFRCs are also gaining recognition among civil engineers as a viable alternative to traditional materials for use as concrete reinforcement in load-bearing structural members as in building frames and bridge decks. The present review strives to provide a brief overview of NFRCs, state-of-the-art developments in their manufacture, and examples of their structural applications. Another aspect of the review involves investigation of the challenges facing the use of fiber composite materials in civil engineering. These include the high manufacturing costs, difficulties associated with appraisal of its potential benefits, uncertainties about their properties, lack of understanding among civil engineers of the material and its service life, and the relatively small battery of standards developed for the composite industry. Finally, the study will conclude with the prospects of bio-composite applications and the emerging trends in novel bio-composites for future structural applications.

Sustainable waste cotton and pigeon pea stalk fibers composite materials for acoustics and thermal properties

This study focuses on the development and characterization of pigeon pea stalk/cotton fibers mixed with a blend ratio of 50/50, 70/30, 30/70, 60/40, 100/0 waste cotton and 0/100 waste pea stalk composites are equipped with a compression molding system. The entire composite samples are tested for acoustics, thermal and physical parameters as per the American Society for Testing and Materials standard (ASTM). The sound absorption coefficients (SAC) were measured according to ASTME1050 by an impedance tube method, and the SAC over six frequencies 125, 250, 500, 1000, 2000, and 4000 Hz were calculated. The result revealed that the composite samples that are prepared from cotton/pigeon pea waste have confirmed more than 80% of the SAC and the waste composites provided the best insulation, sound absorption, moisture absorption, and fiber properties. The effect exposed that composites materials arranged from cotton/pea stalk waste fiber have established further than 75% by the sound immersion measure and the waste 28% composites handed the fashionable Appropriation, sound immersion, humidity immersion, and fiber materials. The waste cotton/pigeon pea stalk composite samples have satisfactory moisture resistance at high humidity situations without disturbing the insulation properties.

Mechanical properties research of carbon fibre composites incorporating nanoclay and graphene

Study purpose is to determine the interactions between the widely-used graphene and nanoclay on carbon fiber composite materials. They are produced using the vacuum infusion method by reinforcing the nanoclay and graphene, which have a montmorillonite structure organized at various ratios via homogenizer, into the resin that is to be applied to carbon fiber layers. Eczac?ba?? EsanNANO 1-140 was used as nanoclay, and GRAFEN NG5 of the Nanografi Co. Ltd. was used as graphene. The graphene ratio was kept constant by taking reference from antecedent studies. Tensile test was applied to the produced samples. Graphene in the resin is expected to increase the saturation in the layers and improve mechanical properties. After nanoclay ratio exceeds a certain limit, it acts negatively rather than positively in the tensile test, their cracked roads are then rendered easier to traverse by them combining. This is why there is a certain bell-shaped curve in the strain values measured in samples. The result that gives the optimum values is sought after. Additionally, there are studies previously conducted with polymer matrix composite, from which samples that could reach to certain strains or to higher yield stress values in certain intervals are obtained. By increasing the strength and toughness of the graphene and nanoclay resin, they gain more rigidity, which raises an expectation of increment to be observed in the yield and tensile strengths.

Damage-failure transition staging in carbon fiber composite materials under quasistatic and cyclic loading with acoustic and digital image correlation analysis

Damage-failure transition staging in carbon fiber composite materials under quasistatic and cyclic loading with acoustic and digital image correlation analysis

A comprehensive review of natural fiber reinforced composite and their modern application

The industrial sector heavily depends on materials. According to the Kyoto Protocol, enterprises are becoming more and more interested in obtaining carbon credits through lowering air pollution. Therefore, green composite materials must be used in place of conventional materials to complete the carbon credit. Natural fiber-reinforced composite materials are now widely utilized in contemporary industrial sectors for example sports, automotive, medicine, aerospace, electronics, food packaging, and energy storage where engineered heterogeneity has been developed and utilized to achieve specific engineering functions. Because of its exceptional mix of thermal, mechanical, and dielectric qualities as well as environmental benefits including renewability and biodegradability, natural cellulosic fiber composite materials are becoming more and more popular for a variety of industrial applications. Natural cellulosic fiber-reinforced composite mechanical and thermal properties as well as for natural fibers mechanical properties and thermal properties also interpreted in this article.

A Review on Use of FRP Mesh and Bamboo Fiber Composite Material for AAC Block Masonry Wall Strengthening and Water Resistance

Abstract: For the purpose of strengthening masonry walls, externally bonded composite materials offer a desirable solution. Current studies in this area demonstrate that the use of fiber-reinforced polymers (FRPs), which are externally bonded composite materials, improves the strength, stiffness, and ductility of the wall under loads while maintaining the wall's integrity at failure

Mechanical Properties of Fiber-Reinforced Polymer (FRP) Composites at Elevated Temperatures

Many materials are gradually softened with increasing temperatures in the fire, which will cause severe damage. As a new fiber-reinforced polymer (FRP) composite, the change in mechanical properties of nanometer montmorillonite composite fiber-reinforced bars or plates at elevated temperatures has not been investigated. To obtain a more comprehensive study of the mechanical properties of FRP composites at high temperatures, experimental research on the nanometer montmorillonite composite fiber material under the tensile rate of 1 mm/min was conducted at target temperatures between 20 °C and 350 °C. Finally, the failure mode of the FRP composites after the tensile test was analyzed. The results demonstrate that the elevated temperatures had a major impact on the residual mechanical properties of fiber-reinforced polymer (FRP) composites when the exposed temperatures exceeded 200 °C. Below 200 °C, the maximum decrease and increase in the fracture load of fiber reinforced polymer (FRP) composites were between −34% and 153% of their initial fracture load. After exposing to temperatures above 200 °C, the surface color of fiber-reinforced polymer (FRP) composites changed from brown to black. When exposed to temperatures between 200 and 300 °C, the ultimate load of fiber-reinforced polymer (FRP) composites significantly increased from 731.01 N to 1650.97 N. Additionally, the stress−strain behavior can be accurately predicted by using the proposed Johnson−Cook constitutive model. The experimental results studied in this research can be applied to both further research and engineering applications when conducting a theoretical simulation of fiber-reinforced polymer (FRP) composites.

Thermal analysis of natural fiber reinforced composites

Natural fiber composite materials grabs attention in modern industrial world. Evaluation of mechanical and thermal properties of composite requires lot of experimentation. In this paper an attempt is made to predict mechanical and thermal properties of natural fiber composite from mathematical relations. Different natural fibers and epoxy matrix were considered for the property prediction. Mechanical and thermal properties of composites were predicted using Halpin-Tsai and Chamis model respectively. Most common natural composite in traditional boat construction is wood. Here NFRP material is used as an alternative to wood. Stress concentration occurs on marine structures due to openings provided for electrical and plumping lines. In order to simulate the structural stability with NFRP material, a rectangular plate is selected for the study. The predicted properties used to study effect of thermal variation of plate with hole. Finite element model was developed to study the stress concentration over different hole diameter. L/D ratio is selected as the parameter for the study. L/D ratio versus stress plot revealed that structure is unsafe if the ratio is above 6.

An experimental evaluation of a new eco-friendly insulating material based on date palm fibers and polystyrene

The purpose of this study is to minimize the environmental impact and to reduce the cost of petroleum-derived polystyrene by the use of date palm leaves remnants in the production of polystyrene/date palm fiber composite materials (PS-DPF). Moreover, this new material must have mechanical properties and thermal insulation comparable or superior to those of virgin polystyrene (VPS) or other insulating materials. Three types of fibers are used to make samples with fillers of 10%, 20%, and 30% (by weight), namely untreated fiber (UDPF), fiber treated by alkalinisation (ADPF), and fiber treated by benzoylation (BDPF). The melt-mixing method and hot compression molding were used for the production of the composites. Various morphological, mechanical, and thermophysical tests were carried out on the produced composites. From scanning electron microscopy (SEM) micrographs, it was determined that the dispersion of filler and its interfacial interactions with the matrix were improved due to a reduction in the OH group present on the fibers, as validated by the Fourier transform infrared spectroscopy analysis (FTIR). X-ray diffraction (XRD) studies indicate that ADPF has the highest crystallinity index. The PS-DPF composites exhibited satisfactory tensile strength within the range of 14–27 MPa, flexural strength within the range of 31–44 MPa, and tensile and flexural modulus within the range of (2.9–5.9 GPa). The results revealed that alkaline and benzoylated treatment treatments increase the tensile and flexural strength while slightly decreasing the tensile and flexural modulus. Both chemical treatments demonstrated a similar impact on these attributes. Thermogravimetric analysis (TGA) results indicated that samples of PS filled with 30% untreated and treated fibers have the maximum thermal stability compared to VPS, with a slight advantage for the untreated sample when residues are taken into account. The thermal conductivity (λ) of the composites produced was low (0.118–0.141 W/m.K) at 18°C, and its variation was incompatible with the bulk density (ρ), which varied from 860 to 980 kg/m3, and decreased with the incorporation of fibers. Moreover, replacing one-third of the composition of conventional building materials with a PS-DPF composite has shown promise for applications such as thermal insulation, with a reduction in thermal conductivity of up to 50%. The composite materials created have revealed their potential application as thermal insulators, which encourages the frequent exploitation of waste in date-producing countries.

EVALUATION OF THE THERMAL AND MOISTURE AGING INFLUENCE IN AGGRESSIVE ENVIRONMENTS ON THE CHANGE IN THE OF THE MECHANICAL BEHAVIOR OF FIBERGLASS BY A SHORT BEAM BENDING TESTS BASED ON ACOUSTIC EMISSION TECHNIQUE

The work is aimed at experimental research and description of the mechanical behavior and degradation of the fibrous structural composite material strength properties during thermal and moisture aging in aggressive (operational) environments of different duration and temperatures. The object of the study was STEF structural fiberglass. STEF is a laminated fiberglass reinforced plastic obtained by hot pressing of glass fabric impregnated with a thermosetting binder based on combined epoxy and phenol-formaldehyde resins. After preliminary aging under various temperature-time conditions, fiberglass samples were tested at normal temperature for interlayer shear. To study the defect initiation and propagation during the deformation of fiberglass after preliminary aging under various temperature-time conditions and environments, the acoustic emission method is used in this work, which makes it possible to study the deformation stage structure and track the processes associated with the formation of defects in the structure of the fibrous composite. Influence of various media, such as industrial water, sea water and machine oil, at different durations (15, 30, 45 days) and temperatures (22°, 60° и 90 °С) on the processes of composite destruction and the implementation of various mechanisms damage accumulation during quasi-static interlaminar shear tests were obtained and analyzed. The paper presents the test results obtained by the acoustic emission signals processing. The data illustrating the stages of damage accumulation are presented and described, and the main mechanisms of damage to the composite structure under loading are analyzed. The results of a study of the microstructure of samples obtained using a stereomicroscope before and after thermal and moisture aging in aggressive media are described.

Parallel optimization of design and manufacturing—Carbon fiber battery pack for electric vehicles

According to the requirement of “structural design and manufacturing feasibility” of the electric vehicle battery pack, the design of carbon fiber composite material instead of metal material is studied in this paper. Firstly, the cross-section performance of the composite battery pack was determined by the principle of equal stiffness. Moreover, the different layups were verified from a manufacturing point of view and the advantages and disadvantages of the three improvements, linear shear, V-shear, and V-shear + linear shear, were compared. Secondly, the three steps of free size optimization, size optimization, and layup sequence optimization were carried out for the lower box to find the lightest structure; the upper box was directly reinforced with a “King” type to alleviate the excessive amplitude. The total mass of the final pack is 14.09 kg, with a weight reduction rate of 56%. Finally, the volume-of-fluid (VOF) method in ANSYS Fluent is chosen to simulate the curing process. The molding results of four injection methods are discussed, while resin viscosity and pressure are considered to find the optimal process parameters. The work in this paper provides a reference for the lightweight application of composite materials in new energy vehicles.

Selection of piezoeloectric material and fiber volume fraction to maximize the electrical power produced by macro-fiber composite energy harvesters

A piezoelectric Macro fiber composite (MFC) materials developed in the last decade found widespread applications such as vibration sensing, actuation and structural health monitoring. Unlike conventional ceramic piezoelectric materials (PZT), these composites show many advantages such as flexibility, reliability and high actuation capacity. However, increasing their energy harvesting capabilities still remains a challenge. Modeling and simulation of electrical energy harvesters using MFC patches provide a mean for geometrical optimization and appropriate choice of the MFC composite. This paper proposes a linear analytical model for prediction of the electro-mechanical response of bimorph harvesters using MFC patches. Homogenization technique is used to describe the equivalent piezoelectric properties of the composite structure of the MFC patch. This paper investigates the effect of the volume fraction of the fibers and the material choice of the piezoelectric fibers and epoxy matrix on the generated electrical power. It has been found that an increased fiber volume fraction causes a decrease of the voltage, the power and the velocity amplitudes for a range of load resistance. However, an increase in the fiber volume fraction FVF is achieved by an increase of the current amplitude for a range of load resistance. Maximum amount of power is generated by the bimorph MFC harvester for an FVF of 86% which corresponds to the reference configuration. The piezoelectric fiber material has a significant influence on the output power. In fact, the SONOX-P502 generated the greatest electrical power. However, the material of the matrix has a negligible effect on the generated power.

Structural Characteristics and Sound Absorption Properties of Waste Hemp Fiber

In order to realize high-efficiency and high-value recycling of waste hemp fibers, the macromolecular structure, the supramolecular structure, and the morphological structure of waste hemp fibers were investigated by using Fourier transform infrared spectroscopy, X-ray diffractometry, upright metallurgical microscopy, and scanning electron microscopy. According to its structural characteristics, the sound-absorbing mechanism of waste hemp fiber was analyzed, and the reason for the good sound-absorbing performance of waste hemp fiber was clarified. The acoustic impedance transfer function test was used to analyze and compare the sound-absorbing performance of waste hemp fiber and several other fiber aggregates that could be used in the field of sound-absorbing, and the sound-absorbing performance of a waste hemp fiber composite material was tested. The research revealed that: the sequence of sound-absorbing performance of several fiber aggregates was cotton fiber, waste hemp fiber, wool fiber, and polyester fiber; that waste hemp fiber had excellent high-frequency sound-absorbing performance, with a maximum sound absorption coefficient of 0.95; and that the maximum sound absorption coefficient of the waste hemp fiber composite reached 0.93. Therefore, the waste hemp fiber has excellent sound-absorbing properties and has high application value in the field of sound absorption.

Analysis of load-bearing capacity factors of textile-reinforced mortar using multilayer perceptron and explainable artificial intelligence

With the aging of reinforced concrete structures, textiles, which are fiber composite materials, have been gaining attention for structural strengthening and replacement of steel reinforcements. The application of textile-reinforced mortar (TRM) is one method of strengthening structures using textiles. Various factors affect the performance when structures are strengthened with TRM; it is affected by the physical properties of the material, such as tensile strength and elongation, and external factors, which vary depending on the design condition, such as textile geometry and strengthening method. Therefore, it is necessary to develop an accurate method that considers the influence of various external factors for evaluating the load-bearing capacity in flexural of TRM-strengthened RC beam. A total of 100 experimental data were learned using a multilayer perceptron (MLP) deep learning model with 24 features, which were analyzed using explainable artificial intelligence, shapley additive explanations (SHAP). The MLP model exhibited a high performance, with a coefficient of determination of 0.9677, indicating the complex correlation between the given features. Regarding the influence of external factors on yield strength, the weft fiber spacing had a negative impact with high influence, and the warp fiber spacing was found to have a very low effect. The anchorage and the number of layers seemed to have a positive impact; however, the effect was small.

Design, molding, manufacturing and testing of wave-transparent functional composite missile wings

In this paper, a fiber-reinforced resin matrix composite missile wing with a wave-transparent function is studied, which has the function of wave-transparent and meets the requirements of the mechanical properties of the missile during flight, and the missile wing structure is made of aluminum alloy, carbon fiber composite material, and glass fiber composite material, and the weight reduction is about 30.3% compared with the overall aluminum alloy structure of the missile wing. In the design process, the finite element simulation method is used, the plastic deformation of aluminum alloy is fully considered, and the antenna is built into the airfoil of glass fiber composite material, which successfully realizes the wave-transparent function of the missile wing and provides a new design idea for the composite wing.

Novel reactive benzoxazine resins using renewables: Leveraging inherent chemistries to produce novel thermoset materials

Novel thermoset tannin-based oxazolidine materials have been prepared in a one pot reaction combining condensed tannins with N,N-alkyldiamines and various aldehydes. Reaction stoichiometry was important in O,N-oxazole hetereocycle formation with N-methylene coupling and ammonium ion formation also observed. For this tannin-diamine system, a tannin :1,6-hexanediamine:formaldehyde mole ratio of 1:1:2 was favoured for oxazole product formation, cure and material properties. Thermal analysis (DSC, DMTA) established that these materials exhibit benzoxazole crosslinking reactivity, with higher alkyldiamine contents found to contribute to greater cure onset temperatures that ranged between 130 and 180 °C. Consolidated, crosslinked tannin-diamine materials exhibit consistent mechanical properties at elevated temperatures (>200 °C). Tannin-diamine materials could be combined with wood fibre , either as a powder or aqueous dispersion, to give composite materials (30–40 % fibre fractions, o.d.) with similar high temperature mechanical properties. Substitutions of glyoxal or furfural for formaldehyde produced comparable tannin-diamine products exhibiting similar material performance when hot-pressed. These tannin-based benzoxazoles have potential for utilisation as a matrix or binder with natural fibre reinforcements and composite materials. • Tannin-based oxazolidine materials have been synthesised via a one pot reaction. • Condensed tannins react with N,N-alkyldiamines and aldehydes to form O,N-oxazoles. • O,N-oxazoles are formed via N-methylene coupling and ammonium ion formation. • Tannin-based benzoxazoles exhibit similar crosslinking as synthetic oxazole systems. • Tannin-diamines can be consolidated either pure or with fibre to form composites.

The Study of the Influence of Temperature and Low Frequency on the Performance of the Laminated MFC Piezoelectric Energy Harvester

MFC (Microfiber composite) piezoelectric transducers are one of the smart composite materials used among others in alternative energy sources and autonomous wireless sensors which exploit vibrational energy. This work presents the theoretical and experimental investigations of the integration of MFC piezoelectric transducers on epoxy glass fiber composite material and explores the capacity of power generation based on a variety of ambient temperatures and frequencies. The study examined the use of ambient vibrational energy to power small electronic devices of wireless sensor networks which eliminates the need for external power, periodic battery replacement costs, and chemical waste from conventional batteries. The test was conducted using a laboratory stand equipped with a thermal chamber and an Instron ElectroPulse waveform generator which induces a concentric cyclic load to the laminated beam. Laminated MFC was loaded with a low–frequency range, controlled displacement under different moderate temperatures. The test was conducted at temperatures ranging from 25 to 60 degrees Celsius and at frequencies ranging from 5 to 25 Hz. The results show that the voltage generated by the transducer is highly affected by both temperature and frequency of excitation.