Reinforced Polymer Materials Research Articles

A Study on Strength and Failure of Fabric Reinforced Polymer Composites

A Study on Strength and Failure of Fabric Reinforced Polymer Composites

Application of edge detection based on hexagonal image structure to delamination detection of carbon fiber reinforced polymer material

Delamination is one of the most critical damage modes in carbon fiber reinforced polymer (CFRP) materials, and is invisible to the naked eye. Although delamination defect images of CFRP materials can be obtained through ultrasonic tomography, it is still difficult to accurately identify the position and contours of defect images. In this study, four different delamination defect images of CFRP composite plates were obtained through a finite element simulation and fan-beam ultrasonic tomography. A hexagon algorithm based on interpolation is proposed that transforms the reconstructed defect images from square pixels into hexagonal pixels. The interpolation algorithm is based on the overlap between the square and hexagonal pixels. As the experiment results verify, the use of the hexagonal structure-based morphological method for edge detection significantly reduces the recognition error from 7.74% to 0.148% in comparison with a traditional quadrilateral structure. The experimental results also showed that this method can effectively reduce the artifact interference and obtain complete and accurate target edge information more effectively than a square structure.

Deformation of and Interfacial Stress Transfer in Ti3C2 MXene-Polymer Composites.

Transitional metal carbides and nitrides (MXenes) have promise for incorporation into multifunctional composites due to their high electrical conductivity and excellent mechanical and tribological properties. It is unclear, however, to what extent MXenes are also able to improve the mechanical properties of the composites and, if so, what would be the optimal flake size and morphology. Herein, Ti3C2Tx MXene is demonstrated to be indeed a good candidate for mechanical reinforcement in polymer matrices. In the present work, the strain-induced Raman band shifts of mono-/few-/multilayer MXenes flakes have been used to study the mechanical properties of MXene and the interlayer/interfacial stress transfer on a polymer substrate. The mechanical performance of MXene was found to be less dependent upon flake thickness compared to that of graphene. This enables Ti3C2Tx MXene to offer an efficient mechanical reinforcement to a polymer matrix with a flake length of >10 μm and a thickness of 10s of nanometers. Therefore, the degree of exfoliation of MXenes is not as demanding as other two-dimensional (2D) materials for the purpose of mechanical enhancement in polymers. In addition, the active surface chemistry of MXene facilitates possible functionalization to enable a stronger interface with polymers for applications, such as strain engineering and mechanical enhancement, and in materials including membranes, coatings, and textiles.

Three-Dimensional Permeability of Thick-Section Glass Fabric Reinforced Polymer Composite by Vacuum-Assisted Resin Infusion Molding

Abstract Determination of permeability of thick-section glass fabric preforms with fabric layers of different architectures is critical for manufacturing large, thick composite structures with complex geometry, such as wind turbine blades. The thick-section reinforcement permeability is inherently three-dimensional and needs to be obtained for accurate composite processing modeling and analysis. Numerical simulation of the liquid stage of vacuum-assisted resin infusion molding (VARIM) is important to advance the composite manufacturing process and reduce processing-induced defects. In this research, the 3D permeability of thick-section E-glass fabric reinforcement preforms is determined, and the results are validated by a comparison between flow front progressions from experiments and from numerical simulations using ansys fluent software. The orientation of the principal permeability axes were unknown prior to experiments. The approach used in this research differs from those in literature in that the through-thickness permeability is determined as a function of flow front positions along the principal axes and the in-plane permeabilities and is not dependent on the inlet radius. The approach was tested on reinforcements with fabric architectures which vary through-the-thickness direction, such as those in a spar cap of a wind turbine blade. The computational simulations of the flow-front progression through-the-thickness were consistent with experimental observations.

Investigation of the Effect of Vibration on the Bearing Capacity of Composite Materials

Polymer coatings are increasingly used in mechanical engineering. In particular, sheet composite elements are created on their basis. But the question of the influence of vibration loads on the bearing capacity of composite structures remains relevant. This work presents the results of an experimental study of the operation of composite structures when exposed to vibration loads. The choice of the parameters of the test bench is due to the frequencies of natural vibrations of the specimens under study. The frequencies were determined using generally accepted approximations. A test bench was developed for carrying out measurements. A vibration-absorbing foundation was used, a support frame with the element was attached on elastic suspensions to the outer frame. A scheme for cutting sheet elements for tensile testing was developed. Nine sheet elements made of reinforced polymer material were tested. The influence of the number of loading cycles on the material ultimate strength is investigated. It was established that the presence of a reinforced polymer coating leads to a decrease in the vibration amplitude when approaching the resonance frequencies. This is due to the internal deformation of the polymer coating. After removing the vibration load, no cracks were found on the specimens.

Application of Edge Detection Based on Hexagonal Image Structure to Delamination Detection of Carbon Fiber Reinforced Polymer Material

Abstract Delamination is one of the most critical damage modes in carbon fiber reinforced polymer materials, and is invisible to the naked eye. Although delamination defect images of carbon fiber reinforced polymer materials can be obtained through ultrasonic tomography, it is still difficult to accurately identify the position and contours of defect images. In this study, four different delamination defect images of carbon fiber reinforced polymer composite plates were obtained through a finite element simulation and fan-beam ultrasonic tomography. A hexagon algorithm based on interpolation is proposed that transforms the reconstructed defect images from square pixels into hexagonal pixels. The interpolation algorithm is based on the overlap between the square and hexagonal pixels. As the experiment results verify, the use of the hexagonal structure-based morphological method for edge detection significantly reduces the recognition error from 7.74% to 0.148% in comparison with a traditional quadrilateral structure. The experimental results also showed that this method can effectively reduce the artifact interference and obtain complete and accurate target edge information more effectively than a square structure.

Effect of Carbon Nanofibers (CNF) on The Crystallization Kinetics of Polyphenylene Sulfide (PPS)

The presence of a reinforcement in polymeric materials can cause alterations in their physical properties, and increase the crystallization rate of their polymeric matrix. Therefore, this research work was oriented toward the incorporation of different percentages of carbon nanofibers (0.6-1-3 and 5%) in a PPS thermoplastic matrix, with the purpose to establish and understand each one of the variables that control crystallization kinetics. The results showed a gradual decrease in crystallization times for contents of up to 5% of CNF, where carbon nanofibers act as nucleation sites, accelerating the crystallization process. According to the values obtained in the Avrami exponent, these fell within a range that oscillates from 2.5 to 3 for pure PPS and PPS/1%CNF which indicates that the presence of carbon nanofibers does not have an effect on the nucleation mechanism of polyphenylene sulphide crystalline phase, thus suggesting crystallization with heterogeneous nucleation and two-dimensional growth with circular geometry

Novel pulse compression favorable excitation schemes for infrared non-destructive testing and evaluation of glass fibre reinforced polymer materials

Infrared thermography (IRT) has been extensively used in the field of non-destructive testing and evaluation (NDT&E) as a condition monitoring tool in commercial as well as industrial applications. It is a fast, non-contact, whole field and quantitative technique for NDT&E applications by mapping the thermal profile over the test sample. This paper presents a novel three-dimensional analytical model for characterization of glass fibre reinforced polymer (GFRP) sample having flat bottom hole defects. The capability of the proposed method is highlighted with recently introduced pulse compression favorable thermal wave imaging modalities. Further, the analytical results have been validated with simulated and experimental studies on the proposed frequency modulated thermal wave imaging (FMTWI), Barker coded thermal wave imaging (BCTWI) and digitized frequency modulated thermal wave imaging (DFMTWI) techniques to analyze the performance of the defect detectability by taking normalized correlation coefficient as a figure of merit. Obtained results clearly shows the capabilities of the DFMTWI over the FMTWI and BCTWI using correlation based matched filter post-processing approach.

Biosensing Efficiency of Nanocarbon-Reinforced Polyacrylonitrile Nanofibrous Matrices

The reinforcement of polymer matrices with nanocarbon fillers is highly attractive for electrochemical biosensing (due to enhanced electrical conductivity). Further processing by electrospinning results in versatile nanofibrous mats. This study compares the biosensing performance of composite polyacrylonitrile nanofibers (PAN NFs) electrospun with different carbonaceous fillers (fullerene, carbon nanotubes, graphene). Morphological characterization of the composite NFs is performed by scanning electron microscopy (SEM) and correlated with the performance of the biosensing matrices. Glucose oxidase (GOD) is employed as model enzyme by immobilization through cross-linking. Optimum nanofiller content was evaluated at 2.0 wt%. for carboxyl functionalized-multiwall carbon nanotubes- NFs (highest sensitivity of 61.5 mAM−1cm−2 and limit of detection (LOD) of 2.0 μM), whilst reduced graphene oxide- NFs exhibited 49.3 mAM−1cm−2 sensitivity with the lowest LOD of 1.6 μM within the most extended linear range (up to 20 × 10−3 M). Insignificant effect of interferent sugars led to real sample recovery close to 100%.

Hierarchical Composite Materials

Conventional continuous fiber reinforced polymer composites (FRP) have extensively been used as structural elements in a myriad of sectors, such as civil, transport, energy and marine, among other, due to their superior mechanical properties, low weight and ease of processing. However, the relatively weak compression and interlaminar properties of these composites limit their application field. Interest is, therefore, growing in the development of hierarchical or multiscale composites, in which, a nanoscale filler reinforcement is utilized to alleviate the existing limitations associated with the matrix dominated properties. The majority of the work has focused on carbon nanotubes, CNTs due to their extraordinary intrinsic properties. In addition to their outstanding mechanical properties, CNTs possess excellent electrical and mechanical properties, making them attractive materials as reinforcement for polymer matrices. CNTs provide both intralaminar and interlaminar reinforcement, thus improving delamination resistance and through thickness properties, without compromising in-plane performance. In recent years, there has been an increasing interest in the use of graphene as reinforcement of polymer nanocomposites. Compared to CNTs, graphene has advantages such as lower cost, higher surface area and a greater ease of processing. Graphene is more easily dispersed in the resin and causes a lower viscosity increase, which can facilitate the impregnation of the fibers. In this work, the fabrication and characterization of hierarchical composites are analyzed through the inclusion of graphene to conventional continuous carbon fiber reinforced epoxy composites by vacuum-assisted resin transfer molding.

Low Velocity Impact Behavior of Fabric Reinforced Polymer Composites– A Review

Low Velocity Impact Behavior of Fabric Reinforced Polymer Composites– A Review

Epoxyorganosilane Finishing Compositions for Fibrous Fillers of Thermosetting and Thermoplastic Binders.

The development of universal finishing compositions for fibers of various natures is an urgent task for polymer composite materials science. The developed finishes can be used for the fiber reinforcement of polymer matrices with a wide range of surface free energy characteristics. Epoxy systems modified with diaminesilane in a wide concentration range were examined by optical interferometry, FTIR spectroscopy, DSC and the sessile drop technique. It was shown that the partial curing of epoxy resin by diaminesilane at room temperature under an inert atmosphere, followed by contact with air, leads to a significant increase of the surface free energy of the system. Varying the concentration of diaminesilane allows us to effectively regulate the surface free energy of the composition. This makes it possible to use fibers finished with epoxyaminosilane compositions in composite materials based on a various thermosetting and thermoplastic binders with a surface tension of up to 75 mJ/m2.

Analysis of lightning ablation damage performance of glass fiber reinforced polymer\xa0materials

Glass fiber-reinforced polymer materials have been effectively used in civil aviation aircraft, but due to low electrical conductivity, a large area of ablation damage will occur after lightning strikes, which greatly threatens the safety of civil aircrafts. Based on this, the coupled electrical-thermal finite element analysis model for a lightning ablation damage of glass fiber reinforced polymer materials is established, and the analysis results are compared with the experiment, and the error rate is 1.26%, which verifies the accuracy of the model. In addition, different influencing factors are analyzed to study the lightning protection characteristics of glass fiber reinforced polymer on carbon fiber-reinforced polymer laminates. The results show that glass fiber reinforced polymer materials have low lightning resistance, but they can effectively reduce the lightning ablation damage area of carbon fiber reinforced polymer laminates under the joint protection of them and aluminum coating. However, they have different protective effects on different protective forms of laminates. Among them, the thickness of aluminum coating has a higher impact on the lightning protection efficiency of full spraying aluminum protective laminates, and the thickness of glass fiber reinforced polymer materials has a higher impact on the lightning protection efficiency of local spraying aluminum protective laminates.

Lignocellulosic fiber reinforced composites: Progress, performance, properties, applications, and future perspectives

AbstractEnvironmental awareness across the world has motivated researchers to focus their attention on the use of cellulosic fiber as reinforcement in polymer matrices. Lignocellulosic fibers are an abundantly available resource in all countries, which is cheap and easily renewable. Also, due to their properties, cellulosic plant fibers exhibit a great potential for use in polymer reinforcement. As a result, considerable research and development efforts have been directed towards the use of cellulosic fibers as a reinforcing material in composites. The use of cellulosic fiber reinforced composites has continuously increased during recent years, which benefits the cultivation of fiber plants and the economy of the country. This research area continues to be of interest to both industry and academia, the use of cellulosic fibers in composite applications being investigated throughout the world. Cellulosic fiber reinforced composites are reasonably strong, lightweight, harmless to human health and the environment, and biodegradable, hence they have the potential to be used in various applications. Recent progress in cellulosic fiber composites research has illustrated their great potential as structural components in automobiles, aerospace structures, construction, and building, and so forth. This study is an effort to create awareness about the research works that have been published in the field of natural fiber composites. This review briefly illustrates the main paths and results of major research published in the field of natural fiber reinforced polymer composites. The topics covered include the aspects of fiber treatment to improve the mechanical properties of the composites, manufacturing methods, performance of hybrid composites, effect of laminate configuration, and many different applications of natural fiber composites. By presenting a systematic view of the work performed in this area so far, this review will hopefully serve as a starting point for the development of new ideas in the research on natural fiber polymer composites.

Soft magnetic composites of carbon fibers decorated with magnetite in an epoxy matrix

ABSTRACT The chemical precipitation was used to obtain carbon fibers (CF) with surface modified by magnetite particles (Fe3O4). Processing was carried out by employing up to three subsequent coating stages of ultrasonic treatments. After each sonication stage, the coating was 17, 33, and 47 wt. % of the total weight of the modified fibers. Raman spectroscopy indicates the presence in the coating of a mixture of iron II and III states. As-decorated fibers were used to fabricate composites with an epoxy resin (ED-20) matrix cured with PEPA. The quantity of the carbon fiber filler was of 1, 3, and 6 wt %. At room temperature, the saturation magnetization of the soft magnetic samples was 0.37, 0.83, and 1.72 emu/g for the indicated compositions. Carbon fiber reinforced polymer materials with extra functions such as magnetic in this case, are expected to be useful in applications from the power and energy industries.

ENHANCING OF FLEXURAL STRENGTH OF WEB OPENING REINFORCED GEOPOLYMER BEAMS BY USING FRP STRIPS

This study is devoted to inspect the flexural behavior of Geopolymer reinforced concrete beams with “large” web transverse opening and strengthened by three kinds of Fiber Reinforced Polymer materials. The implemented experimental program comprised casting eight beams under static and “one stage” repeated load, two of these are normal concrete beams and the others are Geopolymer beams. These beams are divided into two groups, the first comprised four beams of solid and beams “with transvers web opening” under static load for normal and Geopolymer concrete beams. The second group are of four Geopolymer beams that one of them is “un strengthened and having transvers web opening” while the others are also have transvers web opening but strengthened by different kinds of Fiber Reinforced Polymer materials sheets that installed vertically aligned and accompanied with the 90mm diameter large circular web opening. The strengthening materials included are Carbon Fiber Reinforced Polymer, Glass fiber Reinforced Polymer and Hybrid (one layer of Glass + one layer of Carbon) reinforced polymer sheets. The results showed that for the ultimate load capacity was decreased by 9.96% for holed normal concrete beam if compared with solid normal concrete solid beam while such capacity was decreased 2.25% and 11.89% for solid and holed Geopolymer beams respectively. In addition to that, the maximum load capacity is also decreased by 8.16%, 10.20% and 12.25% for Glass, Carbon and Hybrid fiber reinforced polymer strengthened beams if compared with reference beams “holed un strengthened beam” subjected to cyclic load.

Laser selective ablated multistep interfacing for enhanced adhesive bonding joints of carbon fiber reinforced polymer materials

Carbon fiber reinforced polymer (CFRP) has been widely used in the aviation field, especially, in the skin structure of civil aircraft. However, the damage is inevitable in service time and the effective repair methods of CFRP are, especially, important. In this paper, a high-efficiency and high-strength multistep interface adhesive structure was designed and prepared by laser selective ablation for CFRP skin maintenance. The micromorphology and surface chemical composition were analyzed under different laser treatment parameters. The tensile shear strength test as well as impact strength test of CFRP multistepped adhesive bonding joints showed that the value of shear strength and impact strength were 86.29 Mpa and 9.43 kJ/m2, respectively, which increased about 11% and 15%, respectively, when compared with the conventional mechanical milling interface. The results showed that the resin matrix between carbon fibers was removed neatly by laser ablation treatment, which lead to the enlarged adhesive contact area and improved comprehensive mechanical properties of the CFRP joints.

Polymeric materials reinforced by noncovalent aggregates of polymer chains

AbstractMechanical performances are among the most fundamental properties that dictate the applicability and durability of polymeric materials. Reinforcement of polymeric materials is eternally pursued to broaden the applications of polymers with light‐weight, low‐cost and easy‐processing advantages. Noncovalent aggregates of biomacromolecules have been found to play a significant role in the mechanical properties of many natural materials, such as the spider silk. Increasing numbers of reports have demonstrated that the in situ formed noncovalent aggregates of polymer chains in polymeric systems are highly effective for enhancing the mechanical properties of artificial polymeric materials, in terms of strength, stiffness, toughness, and/or elasticity. The in situ formed noncovalent aggregates act as additional crosslinking domains and well‐dispersed “hard” nanofillers in the polymer networks, significantly strengthening, stiffening and/or toughening the polymeric materials. Moreover, the noncovalent crosslinking of polymer chains favors the development of healable and recyclable polymeric materials, thanks to the reversible and dynamic properties of noncovalent bonds. This review provides an overview of the recent advances on the enhancement of the mechanical properties of different polymeric materials by the in situ formed noncovalent aggregates of polymer chains. It is expected to arouse inspirations for the development of novel polymeric materials with extraordinary mechanical performances and functionalities.

Fully bio-based agro-waste soy stem fiber reinforced bio-epoxy composites for lightweight structural applications: Influence of surface modification techniques

Present days, the world needs more sustainable and eco-friendly materials to replace and reduce the use of synthetic materials to prevent pollution. In this regard, the agro-waste after soy cultivation is identified as a sustainable resource of raw material and can be used as reinforcement in polymer matrices. The current research focuses on the effect of surface modification in agro-waste soy stem fibers and their composites. The fibers were collected, cleaned, processed, and subjected to chemical treatment. The chemical analysis showed an increased ratio of cellulose % in the soy fibers when compared to untreated fibers. The silane treatment showed improvement in the thermal stability of soy fibers and reduced the coefficient of thermal expansion in silane treated composite. The X-ray diffraction test shows that there was a 22.57% increase in the crystalline index due to oxalic acid treatment. The chemical treatments also influenced the crystal size of the soy fibers which had direct impact on the water absorption nature of the developed composites. The mechanical performance of the composites is evaluated through tensile, flexural, impact, and interlaminar shear strength according to the ASTM. The silane treated fibers in the composites showed a better mechanical performance compared to untreated and other chemical treatment. However, oxalic acid treatment showed better mechanical performance when compared to traditional NaOH treatment. The increase in wettability nature influenced the mechanical strength and water-resistant nature of the composite. The complete results state that the silane treatment on the soy stem fiber showed the best performance followed by the oxalic acid and alkali treatment when compared to the raw fibers. From the results, it is observed that the Agro-waste soy fiber is a sustainable and renewable resource of raw material that can be used as reinforcements in polymer matrices for lightweight structural applications.

Electromechanical-Mode Coupling Model and Failure Prediction of CFRP under Three-Point Bending

Carbon fiber reinforced polymer materials (CFRP) cause CFRP to bend or fail when subjected to external loads or impacts. In the case of static three-point bending, using the conductive properties of the carbon fiber inside the CFRP, the overall damage detection and failure prediction can be carried out by electromagnetic methods. The eddy current coil is used to realize real-time monitoring of damage, and the measured voltage value can be mapped to obtain the load of the sample. This paper conducts theoretical analysis and experimental verification, and obtains the relationship between CFRP stress damage and spatial conductivity change, and proposes a CFRP electromechanical coupling model under quasistatic three-point bending. Combined with the theory of electrically ineffective length, the CFRP three-point bending electromechanical coupling model was revised. Experimental results prove that the revised model can describe the load-conductivity change trend of three-dimensional braided CFRP more accurately, which provides a theoretical basis for monitoring the structural health of CFRP through electromagnetic methods.