Fiber-reinforced Composite Materials Research Articles

Use of fiber-containing materials in restorative dentistry

It is aimed at providing chewing function in restorative treatment in dentistry, to protect the tooth structure based on the minimally invasive approach and to meet the aesthetic expectations of the patient. Studies including application techniques are carried out to improve the mechanical and physical properties of composite resins and to reduce polymerization shrinkage. The success of composite restorations has increased with the use of fibers and fiber-reinforced composite resin materials, and the indications of composite resins as direct restoration material have expanded thanks to the production of newly developed fiber-reinforced composite resin materials and their use with the biomimetic restoration technique. In this review, information about the properties and types of fiber structures, advantages, disadvantages, and application areas is explained.

Experimental examination of the axial compression conduct of filament-wound cylindrical composite tubes at different wall thicknesses and orientation angles

This study presents the results of experimental research on the behavior and stretching of hollow cylindrical epoxy tubes made of glass, carbon, and kevlar fibers subjected to axial compression load. Hollow cylindrical tubes were fabricated by fiber winding method using glass, carbon, and kevlar fiber-reinforced composite materials. In this study, hollow cylindrical composite tubes with constant outer (Ø17 millimeters), two different inner diameters (Ø12 and Ø13 millimeters; 2 ve 2,5 millimeters wall thickness), and 80 millimeters in height. Experimental research was carried out for two dissimilar wall thicknesses and four fiber orientation angles. The compressive strengths of all samples were investigated experimentally by applying loads in the axial direction. Twenty-four configurations of composite specimens were fabricated (three reinforcement materials, four winding angles, and two wall thicknesses) to research the impact of axial compression stress. Experimental results revealed that polymer reinforcement material, fiber winding angle, and wall thickness have a significant impact on the compressive stress of cylindrical composite tubes as a result of applied load in the axial direction. The conclusions show that the compressive stress of all reinforcement rises as the orientation angle and wall thickness increase under an axial compression load, and the compressive stress reaches a maximum when the orientation angle is 90° under an axial compression load. It was observed that the axial compressive stress was highest in glass/epoxy samples with 217 MPa, followed by carbon/epoxy samples with 173 MPa and kevlar/epoxy samples with 145 MPa, respectively. The axial compressive stress of all samples was highest at a 90° orientation angle and lowest at a 15° orientation angle. were found to have low values. It was observed that the axial compressive stress value increased in all reinforcement materials as the wall thickness increased.
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Inter-fibre failure under biaxial loads in glass–epoxy composite materials: Effect of the presence of a nearby fibre

Fibre-reinforced composite materials are especially prone to transverse failure. It appears at the lamina level following the mechanism known as matrix/inter-fibre failure. This mechanism of damage is associated with the appearance of fibre–matrix debonds (interface cracks), as shown in previous numerical micromechanical studies. After the nucleation, growth and kinking into the matrix, these interface cracks give rise to the final macro-failure.When compared to uniaxial loading, the growth stages of this mechanism of damage (analysed in light of Interfacial Fracture Mechanics) show some alterations under different combinations of biaxial loads. This work gives a step forward and focuses on the micromechanical BEM study of the evolution of an interface crack in the presence of a neighbouring fibre.Thus, after considering a transverse tensile load (nominally responsible for the failure) a secondary transverse load is also applied (tensile or compressive, perpendicular to the primary load). When considering the two-fibre BEM model, the results obtained lead to identifying the neighbouring fibre locations that act as accelerative agents on failure progression and establishing the effect of the biaxial load on them. Specifically, when a secondary tensile load is applied, the presence of the nearby fibre (for most of its positions) confirms the slight inhibition of the mechanism of failure for biaxial tensile loads already referred to in previous single-fibre studies by the authors. As the secondary tensile load increases, it tends to mitigate the effect of the presence of the neighbouring fibre that was previously observed for uniaxial tensile load. The opposite effects are found when a secondary compressive load is considered, which intensifies the alterations of the presence of the neighbouring fibre on the interface crack growth. Experimental evidence on some aspects is provided confirming the associated conclusions derived from the numerical models.

Insight into the wear properties of fiber fabric surface-enhanced composite under water lubrication

Water-lubricated bearings are subject to abrasive wear, leading to performance degradation. Herein, the use of PTFE and UHMWPE fibers was investigated to improve surface tensile strength and explore wear mechanisms. Through finite element analysis and friction and wear experiments, it is hereby demonstrated that fiber reinforcement significantly improves surface tensile strength and reduces surface wear compared to non-reinforced materials, and the wear of the bronze plates is reduced as well. Meanwhile, fiber-reinforced composite materials suppress the development of wear in a certain amount of time and exhibit outstanding frictional performance.

Identification of NOL-Ring Composite Materials' Damage Mechanism Based on the STOA-VMD Algorithm.

This research utilized the sooty tern optimization algorithm-variational mode decomposition (STOA-VMD) optimization algorithm to extract the acoustic emission (AE) signal associated with damage in fiber-reinforced composite materials. The effectiveness of this optimization algorithm was validated through a tensile experiment on glass fiber/epoxy NOL-ring specimens. To solve the problems of a high degree of aliasing, high randomness, and a poor robustness of AE data of NOL-ring tensile damage, the signal reconstruction method of optimized variational mode decomposition (VMD) was first used to reconstruct the damage signal and the parameters of VMD were optimized by the sooty tern optimization algorithm. The optimal decomposition mode number K and penalty coefficient α were introduced to improve the accuracy of adaptive decomposition. Second, a typical single damage signal feature was selected to construct the damage signal feature sample set and a recognition algorithm was used to extract the feature of the AE signal of the glass fiber/epoxy NOL-ring breaking experiment to evaluate the effectiveness of the damage mechanism recognition. The results showed that the recognition rates of the algorithm in matrix cracking, fiber fracture, and delamination damage were 94.59%, 94.26%, and 96.45%, respectively. The damage process of the NOL-ring was characterized and the findings indicated that it was highly efficient in the feature extraction and recognition of polymer composite damage signals.

Investigation of Workability and Mechanical Properties of PVA Fiber-Reinforced Phosphogypsum-Based Composite Materials.

To address the poor characteristics of low strength and poor toughness in phosphogypsum-based construction material, this study investigates the influence of different diameters, lengths, and dosages of polyvinyl alcohol (abbreviated as PVA) fibers on the workability and mechanical properties of phosphogypsum-based construction material. The results show that as the length and dosage of PVA fibers increase, the flowability of the slurry gradually decreases, and the setting time also shortens. With an increase in the diameter of PVA fibers, the rate of decrease in flowability slows down, and the rate of shortening of setting time also gradually slows down. Moreover, the inclusion of PVA fibers significantly improves the mechanical strength of the specimens. When PVA fibers with a diameter of 15 μm, length of 12 mm, and dosage of 1.6% are used, the phosphogypsum-based construction material reinforced with PVA fibers exhibits optimal performance. Under this mixing ratio, the strength values of the specimens for flexural strength, bending strength, compressive strength, and tensile strength are 10.07 MPa, 10.73 MPa, 13.25 MPa, and 2.89 MPa, respectively. Compared to the control group, the strength enhancements are 273.00%, 164.29%, 15.32%, and 99.31%, respectively. SEM scanning of the microstructure provides a preliminary explanation for the mechanism of how PVA fibers affect the workability and mechanical properties of phosphogypsum-based construction material. The findings of this study can provide a reference for the research and application of fiber-reinforced phosphogypsum-based construction material.

The Microstructural and Hardness Changes of Tungsten Fiber after Au2+ Irradiation

Tungsten fiber-reinforced tungsten composite (Wf/W) material is considered a plasma-facing material (PFM) with good application prospects. Commercial tungsten wire (fiber) prepared through forging and drawing processes has excellent mechanical properties, as well as a very high recrystallization temperature due to the unique texture of it grain structure. Commercial tungsten fiber is the most proper reinforcement for Wf/W. The change in the properties of tungsten fiber because of neutron irradiation makes it inevitable for Wf/W to be used as PFMs. However, there is very little research on the change in the properties of tungsten fiber caused by neutron irradiation. In this work, we used heavy ion irradiation to simulate the displacement damage generated by neutron irradiation to explore the alteration of the properties of a commercial tungsten fiber caused by neutron irradiation. The investigated subject was tungsten fiber with a diameter of 300 μm. The irradiation source was 7.5 MeV Au2+, which generated a maximum displacement damage of 60 dpa at a depth of 400 nm, and the irradiation influenced depth was 1000 nm. Because of the irradiation, significant lattice distortion occurred within the tungsten fiber, resulting in the transition from (110) texture to (100) texture at the fiber’s cross-section. The results of the Schmidt factor and Taylor factor analysis indicate a decrease in the plasticity of the tungsten fiber after irradiation, but it did not completely lose its plasticity. The results of the nanoindentation test confirmed the radiation hardening. After irradiation, the hardness of the tungsten fiber increased by approximately 0.33 GPa, but this increase was relatively small compared to other tungsten-based materials. This indicates that commercial tungsten fiber is a low-cost and highly reliable reinforcement material for Wf/W composite materials.

Development of an AI system for characterization of fiber-reinforced polymer composite materials

Development of an AI system for characterization of fiber-reinforced polymer composite materials

A generalised deep learning-based surrogate model for homogenisation utilising material property encoding and physics-based bounds

The use of surrogate models based on Convolutional Neural Networks (CNN) is increasing significantly in microstructure analysis and property predictions. One of the shortcomings of the existing models is their limitation in feeding the material information. In this context, a simple method is developed for encoding material properties into the microstructure image so that the model learns material information in addition to the structure-property relationship. These ideas are demonstrated by developing a CNN model that can be used for fibre-reinforced composite materials with a ratio of elastic moduli of the fibre to the matrix between 5 and 250 and fibre volume fractions between 25 and 75%, which span end-to-end practical range. The learning convergence curves, with mean absolute percentage error as the metric of interest, are used to find the optimal number of training samples and demonstrate the model performance. The generality of the trained model is showcased through its predictions on completely unseen microstructures whose samples are drawn from the extrapolated domain of the fibre volume fractions and elastic moduli contrasts. Also, in order to make the predictions physically admissible, models are trained by enforcing Hashin–Shtrikman bounds which led to enhanced model performance in the extrapolated domain.

Physics-informed neural networks for data-free surrogate modelling and engineering optimization – An example from composite manufacturing

Engineering components require an optimization of design and manufacturing parameters to achieve maximum performance – usually involving numerous physics-based simulations. Optimizing these parameters is a resource-intensive endeavor, though, especially in high-dimensional scenarios or for complex materials like fiber reinforced plastics. Surrogate models are able to reduce the computational effort, however, data generation still proves to be resource-intensive. Additionally, their data-driven nature may lead to physically implausible results in limit cases. As a remedy, physics-informed neural networks (PINNs) include known physics into the training for enhanced surrogate reliability. This allows to cast a physically consistent, data- and mesh-free manufacturing surrogate for variable process conditions and material parameters. The paper demonstrates how PINNs can be embedded in a design-framework to enhance process understanding, to devise engineering-interpretable processing windows and to support time-efficient process optimization at the example of a thermochemical manufacturing process with fiber-reinforced composite materials. In this work, an over 500-fold speed up of the process optimization is achieved compared to conventional approaches.

Tension controlled hollow-fiber winding machine for blood oxygenator prototypes

Blood oxygenators involve a complex network of hollow fibers for efficient gas exchange with blood. The optimal microstructural arrangement of these fibers is an ongoing research interest. While the fiber systems of commercial oxygenators are manufactured to address mass production, the research oxygenator prototypes demand more flexibility so that different design parameters can be tested. Here a hollow-fiber assembly system is designed and built for winding research grade extracorporeal blood oxygenator mandrels at different layout dimensions so that these different configurations can be evaluated for mass transfer capacity and blood damage. The hardware design and manufacturing details of this system presented together with its impact on the prototype oxygenator device assembly process. This in-house built system can wind thin fibers, having outer diameters ranging from 100 μm to 1 mm, at any specified winding angle continuously. A control system for fiber stress is also incorporated to eliminate fiber damage. Our system consists of three main units: (1) unwinding, (2) accumulator, and (3) winding systems, integrated together via the control software. The unwinding unit has a PID controller to maintain the position of the accumulator motor on the reference point by tuning the velocity of feeding fibers to the accumulator unit. Another PID controller preserves the desired tension value of the fibers by adjusting the position of the accumulator motor. Desired tension value is defined by the user and typically obtained through uniaxial testing of fibers. The control unit employs a “cascaded” PID controller since the PID controller in the accumulator unit maintains the tension and the PID controller in the unwinding unit controls the position of the accumulator motor. Finally, the winding unit utilizes two motors to wind the fibers over the outer diameter of a mandrel at the desired winding angle. The first motor drives the translational movement, and the second one provides mandrel rotation. The desired angles are achieved by tuning the synchronous movement of the winding motors. While the system is designed to produce assembled blood oxygenator mandrel prototypes, this concept is also applicable for producing cylindrical fiber-reinforced composite materials with specified fiber angles and stents winded on jigs.

Nonlinear progressive damage model for woven patch-repaired laminate composites

Laminated fiber-reinforced composite materials are vulnerable to damages arising due to impact events like accidental tool drops, bird strikes, etc., which significantly reduce the structural integrity of these materials. Therefore, one of the popular adhesively bonded repair techniques, i.e. patch repair is employed in this work. The present work focuses on developing a three-dimensional energy-based gradual degradation model for patch-repaired laminates, including the effects of shear non-linearity under tensile load. The model utilizes modified Hashin failure criteria for plain woven laminate and maximum shear stress criteria for the adhesive. Using the nonlinear model, the failure strengths for different pristine, drilled and repaired specimens with double-sided patches of [0]2 and [45]2 are studied. Tensile experiments in accordance with ASTM-D3039/D3039M are performed using Digital Image Correlation (DIC) and Acoustic Emission (AE) to validate numerical results. The simulated results based on the proposed model and experimental observations are used to compare the damage mechanisms of pristine, drilled, and patch-repaired laminates. It is observed that matrix cracking is majorly responsible for damage initiation. Subsequently, fiber–matrix debonding and fiber breakage account for the ultimate failure of pristine, drilled and repaired specimens. The developed model is used for studying the effect of different patch sizes of repaired specimens under tensile load.

Experimental and Numerical Analysis of the Progressive Damage and Failure of SiCf/TC4 Composite Shafts

Long fibre-reinforced metal matrix composite materials, which are widely used in industry, have complex and diverse damage modes due to their structural characteristics. In this study, the progressive damage process and failure mode analysis of the SiCf/TC4 composite shafts were thoroughly investigated under single torsional loads. A bearing performance test was carried out, the damage process was monitored using acoustic emissions, and the fracture specimens were analysed using a scanning electron microscope (SME). More specifically, under reverse torque loading, the damage process was slow-varying, the interface was subjected to tensile force, and fracture occurred mostly in the form of interface cracking; further, the breaking load of the specimen was 11,812 Nm. Under forward loading, the damage process was fast-varying. The fibres were subjected to tensile forces, and the fracture form was mostly fibre fracture; the breaking load of the specimen was 10,418 Nm. Under torque loading, the first damage to the specimens appeared in the outermost layer of the composite material’s reinforced section, and the initial cracking position was at the interface, expanding from the outside to the inside. Based on the principles of macro-mechanics and micro-mechanics theory, the cross-scale models were proposed, which contain the shaft with the same dimensions as the specimen and a micro-mechanics representative volume element (RVE) model. The initial interface damage load was 6552 Nm under reverse torque loading. Under forward loading, the initial interface damage load was 9108 Nm. In comparison to the acoustic emission test results, the main goal was to calculate the progressive damage process under the same conditions as the experiment, verifying the effectiveness of the cross-scale models.

Rayleigh wave in a piezoelectric micro-mechanical bi-material system with mechanically and dielectrically imperfect interfaces

The present work investigates the propagation behavior of Rayleigh waves in a piezoelectric fiber-reinforced composite (PFRC) material stratum lying over a PFRC substrate with mechanically and dielectrically imperfect interfaces. The PFRC material structure is micro-mechanically modeled using the analytical techniques of the Strength of Materials (SM) and Rule of Mixtures (RM). Dispersion equations are obtained by employing suitable boundary conditions for electrically open and short conditions. The data of CdSe-epoxy and PZT-5A-epoxy materials as PFRC materials have been taken into account for fiber volume fraction to investigate the latent characteristics of Rayleigh wave propagation. Numerical calculations have been carried out to study the influence of mechanically compliant and dielectrically weakly (MCDW)/highly (MCDH) conducting imperfect interfaces on Rayleigh wave propagation in the considered structure. A comparative study has also been carried out to exhibit the concealed characteristics of Rayleigh wave propagation for various distinct cases in both the electrical conditions and manifested graphically for the fundamental mode of Rayleigh wave.

VIBRATION ANALYSIS OF BIO-DEGRADABLE COMPOSITE WITH A NUMBER OF LAYERS

—Modern scientists are now focusing their research on materials that are naturally biodegradable and kind to the environment. Bio-composite materials formed of natural/regular fiber materials and resins, or a mixture of both, are regarded as one of the key accomplishments in the diverse field of experimental work as we are aware that concerns about natural protections are growing worldwide. The two stages of the composited make up the majority of its constituents: 1) Matrix, and 2) Binder. Natural fiber composites have received a lot of attention from scientists throughout the world due to the availability of the necessary characteristic fiber and the ease of assembly. The Mechanical APDL Analysis tool is used to create the desired model, which has different layers (3, 4, 6, and 8 accordingly). To compare the results, the natural frequencies of each individual layer are taken into consideration and documented in a tabular data format. Both eigen buckling analysis and modal analysis are successfully performed on the desired model. The reference research paper demonstrates the buckling loads for glass fiber with various layers made up of various orientations. The main objective of the project is to create a biocomposite with Bamboo fiber and Rice Husk as filler and to perform the vibration analysis with different layers and Eigen buckling analysis. Natural frequencies are obtained from vibration analysis and buckling loads are obtained from Eigen buckling analysis thus for a better understanding of the dynamic behavior of components made from fiber-reinforced composite materials, specifically for the case of plates. This study contributes to a better& more realistic understanding of the dynamical behavior of plates formed of fiber-reinforced composite materials in order to prevent structural damage imposed on or induced by undesirable vibrations.

Review of the effects of low-velocity impact events on advanced fiber-reinforced polymer composite structures

Most typical polymer composite materials have the weakest impact characteristics observed in Low-Velocity Impact (LVI) events. As a result, typical polymer composite materials are reinforced to improve their proper application attributes. The Fiber-Reinforced Polymer Composite (FRPC) materials must be converted to enhanced polymer composite structures, such as incorporating nanoparticles and selecting appropriate lamination techniques to improve the composite structure impact strength of the polymer materials. The matrix layer was created using a variety of lamination processes. The hybridization techniques with the inclusion of filler material into polymer composite structures were used to produce better results in impact kinetics for the composite structures. The quasi-static mechanical sequence approach was used to improve the LVI properties of FRPC. The inclusion ofnano-fillerparticles in polymer composites to reduce obvious low-velocity impact damage during low-velocity accidents or events is the subject of this review. This investigation aims to explore if conventional fiber materials with obvious low-velocity impact damage might be enhanced to overcome the effects of advanced FRPCs.

Effect of reinforcement of Alkaline-treated sugar palm/bamboo/kenaf and fibreglass/ Kevlar with polyester hybrid biocomposites: mechanical, morphological, and water absorption properties

In this age of globalisation, decreasing synthetic resources have exhilarated global communities to apply natural fibres as substitute materials for green technology development. The growth of products from lignocellulose fibre-reinforced composites has been a wide topic among material scientists and engineers due to their abundance, sustainability in nature, biodegradability, and availability at low cost. A series of natural/synthetic hybrid fibre-reinforced composites are prepared by reinforcing polyester resin as the matrix. Natural fibres such as sugar palm/kenaf/bamboo with fibreglass/Kevlar hybrid composite materials were used in this research to determine the mechanical and water absorption properties. The difference between the weight content of natural fibres which were 0 (control sample), 15, 45, and 60 wt% influenced their strength of mechanical properties. The Charpy impact and tensile test were performed following the ASTM D6110-10 and ASTM D3039, respectively. A water absorption test in accordance with ASTM D570-98 was also performed on three different natural fibre-reinforced hybrid composite materials to determine which composite had the best water resistance property. The results showed that hybrid fibre-reinforced composite for 45 wt% kenaf fibre possessed better tensile properties and 60 wt % sugar palm fibre performed better during the Charpy impact strength test compared to other natural/synthetic hybrid fibre-reinforced composites. It was concluded that sugar palm fibres demonstrated the best water resistance in this study.

Influence of interphase characteristics on the elastic modulus of unidirectional glass-reinforced epoxy composites: a computational micromechanics study

Abstract This article briefly discusses the role of interphase in the elastic moduli of unidirectional fiber-reinforced polymer composite materials. For this unidirectional glass fiber was chosen as reinforcement, and epoxy was selected as the matrix. A hexagonally packed representative volume element is used for the micromechanical analysis. Experimental validation was initially used to verify the accuracy of the established equations of the rule of mixing, Composite Cylinder Assemblage, Chamis, Halpin and Tsai, and Puck. The Chamis equation was found to be the most reasonable. Then the finite element approach in which interphase has been included was used to estimate the elastic moduli. The finite element model without interphase and the experimental result were taken as a reference. The influence of interface ratio and property of interphase on the homogenised elastic properties of the unidirectional fiber-reinforced polymer composites is analysed. A micromechanics plugin in Abaqus software was used to estimate the density and Young’s modulus of the unidirectional fiber-reinforced polymer composites. The interphase properties are varied, having 6.25%, 12.5%, 25% and 50% influence of the fiber phase and the remaining influence of the matrix phase with interface ratios of 0.1, 0.2 and 0.3. The interface ratio of 0.3, having 6.25% fiber phase influence, gave the most reasonable moduli values (with an error <10%) compared to the mean experimental moduli. The study showed interface ratio and interphase properties to critically influence the overall elastic property of the unidirectional fiber-reinforced polymer composites.

Biomimetic Design and Topology Optimization of Discontinuous Carbon Fiber-Reinforced Composite Lattice Structures

The ever-increasing requirements for structural performance drive the research and development of lighter, stronger, tougher, and multifunctional composite materials, especially, the lattice structures, heterogeneities, or hybrid compositions have attracted great interest from the materials research community. If it is pushed to the extreme, these concepts can consist of highly controlled lattice structures subject to biomimetic material design and topology optimization (TO). However, the strong coupling among the composition and the topology of the porous microstructure hinders the conventional trial-and-error approaches. In this work, discontinuous carbon fiber-reinforced polymer matrix composite materials were adopted for structural design. A three-dimensional (3D) periodic lattice block inspired by cuttlefish bone combined with computer modeling-based topology optimization was proposed. Through computer modeling, complex 3D periodic lattice blocks with various porosities were topologically optimized and realized, and the mechanical properties of the topology-optimized lattice structures were characterized by computer modeling. The results of this work were compared with other similar designs and experiments to validate the effectiveness of the proposed method. The proposed approach provides a design tool for more affordable and higher-performance structural materials.

Exploration of mechanical properties of hemp fiber/flax fiber reinforced composites based on biopolymer and epoxy resin

Recently natural fiber-reinforced polymer composite materials are highly growing both in the relationship of their manufacturing industries applications such as automobile, lightweight biosensor chips, and microfluid and fundamental research as they are renewable, low, eco-friendly, biodegradable and completely recyclable. The hemp and flax solutions have not only met the technical requirements of prepared composite but also reduced environmental impacts. The present study involves the investigation on mechanical behavior such as flexural strength, flexural modulus along with moisture absorption performance of flax and hemp fiber composite is reinforced with the natural resin and epoxy resin. The biodegradable composite by the help of synthesis of natural acids such as citric acid (CA) and maleic anhydride (MA). In additional acrylic acid (AA) and glycerol (GL) were used for synthesis of natural resin to be more reactive by condensation method. The laminate has been prepared by flax and hemp fiber reinforced with the epoxy resin. The prepared laminate has been used study the flexural and tensile studies by ASTM standard procedure. The mechanical properties of flexural test and tensile test has been studied by hemp fiber/flax fiber reinforced composites. The obtain results were compared with the natural fiber reinforced by natural resin and epoxy resin. Hence, this kind of light weight biocomposite materials has been utilized for many industrial applications.