Fiber-reinforced Composite Materials Research Articles

Broadband Response Diaphragm Materials for Human Acoustics Engineering.

High-performance fiber-reinforced composite materials demonstrate great potential for manufacturing diaphragms in human-engineered acoustic loudspeakers. However, the notable scarcity of high-quality fibers and the uncontrollable nature of the diaphragm structure limit the production of high-quality sound that conforms to human hearing. In this study, a novel composite diaphragm material is devloped by integrating the swelling carboxymethyl cellulose microfiber (CMF) with the hot-melted sheath-core fiber (SCF) based on the "interpenetrating polymeric network" ("IPN") strategy. Simulation methods and Flory-Huggins theory are applied to explain the mechanism of fiber-structure-property interaction in composite diaphragm materials. Owing to the distinct microstructure, this bio-based diaphragm material shows superior mechanical characteristics, including low density (≈0.92gcm- 3), high tensile strength (≈235MPa), and high modulus (≈9.73GPa). Moreover, the loudspeaker mounted with bio-based diaphragm material exhibits enhanced sensitivity (≈82.6dB) and stable performance across a broad frequency spectrum. This study not only elucidates the multiphysics working principles of loudspeakers but also establishes a crucial connection between the physical properties of diaphragms and loudspeaker performance. It opens up new avenues for the design of high-performance bio-based loudspeaker diaphragms in high-fidelity (Hi-Fi) acoustic devices.

Combined hybrid machining of laser ablation-drilling small holes in Cf/SiC composites

Carbon fiber-reinforced silicon carbide composite material (Cf/SiC) serves as a typical advanced material for fabricating hot-end components of aircraft engines. Its unique properties, including high hardness and anisotropy, pose significant challenges in processing. Nevertheless, a crucial structural element of hot-end components, specifically the cooling and heat dissipation holes, necessitates hole machining within the Cf/SiC composites. The intricate nature of machining this material often leads to compromised surface quality and severe wear on cutting tools during the hole machining process. This study delves into the feasibility of combined hybrid machining of laser ablation-drilling(L-DCM) for fabricating small holes in woven Cf/SiC composites, along with elucidating the underlying material removal mechanisms. The findings reveal approach significantly enhances the cutting performance of hard alloys tools when dealing with ceramic matrix composites. Notably, the wear mechanisms of the cutting tools primarily involve abrasive wear and adhesive wear. The primary processing defects observed in the small holes include fiber pullout at the entrance and exit, as well as material delamination at the exit, which are primarily attributed to debonding at the layer interface and brittle fracture of the matrix. The subsequent drilling process, conducted based on laser drilling, effectively eliminates thermal defects such as the heat-affected zone and recast layer, as well as morphological defects like taper. Additionally, this approach mitigates the tool wear process, minimizes the impact of compression effects on material removal, and enhances the shear action of the tool. Consequently, the layer interface remains securely bonded and intact after processing, thereby preserving the material's strength.

Study of mechanical properties of composite materials reinforced with aluminum fibers

This study investigates the mechanical properties of composite materials reinforced with aluminum fibers of varying lengths and concentrations. The research aims to evaluate the effects of fiber reinforcement on both flexural and compressive strengths, using fibers of three distinct lengths (2×20 mm, 2×30 mm, and 2×40 mm) and four different concentrations (0.5%, 1%, 1.5%, and 2%) by weight within the composite matrix. Mechanical tests were performed after 28 and 56 days of curing to assess the influence of fiber reinforcement over time. The results demonstrate that increasing fiber length and concentration generally improves the flexural and compressive strengths, with the most notable gains observed at moderate fiber content. However, the study also finds that excessively high fiber percentages may lead to diminishing returns in strength performance, possibly due to fiber agglomeration or stress concentration effects. These findings provide valuable insights into optimizing the design of fiber-reinforced composite materials for various structural applications, enhancing both performance and material efficiency.

Multi-objective topological design considering functionally graded materials and coated fiber reinforcement

This study presents a multi-objective topology optimization method tailored to structures fabricated from functionally graded materials (FGMs), coated FGMs, and coated fiber-reinforced composite materials (FRCMs) with fixed fiber thickness. The design objective is the simultaneous minimization of elastic and thermal compliance. The material properties of these composite materials were derived to generate datasets using the representative volume element method under periodic boundary conditions. Subsequently, machine learning modules were developed based on the datasets to combine with the design process. The multi-objective optimization problem was addressed using the weighted sum method ensuring the generation of the Pareto front. The adaptive weighting strategy is employed to avoid biased results toward a single objective function. To define the coated boundaries within the design domain, image post-processing techniques such as convolution filters, interpolation schemes, and erosion methods were employed on the material layout information of the optimized FGM structures. Through numerical examples, optimized material layouts for coated assemblies incorporating FGMs and FRCMs are presented, with the performance verified through objective function values.

Experimental study of rotational friction damper for seismic response control: friction material comparison and configuration optimization

Rotational friction dampers (RFDs) can be incorporated into structures flexibly as energy-dissipation devices for seismic response control. However, the basic primary form of RFD has three main challenges and objectives in enhancing its performance: (1) avoiding strength fluctuation and jittering, namely, improving the stability of the performance, (2) enhancing the strength, and (3) relieving the basic assumption that the clamping pressure is uniformly distributed on the friction pads and ensuring the accuracy of the theoretical equation. To address these issues, this study proposes four potential approaches: (1) selecting a friction material with a stable performance, (2) increasing the friction coefficient, (3) increasing the clamping force, and (4) optimizing key configurations. Based on these concepts, two sets of experimental studies, including 27 friction pad material comparison tests and 17 lug plate and clamping bolt configuration optimization tests, were conducted. According to the test results, the fiber-reinforced resin-based composite (FRRC) material was found to be better than H62 brass and 7075 aluminum alloy in realizing a high friction coefficient and stable performance, as well as achieving uniformly distributed pressure. The four-bolt lug plate and six-bolt lug plate with stiffening ribs were found to be effective in realizing a high clamping force and, thus, a high RFD strength, as well as in achieving a uniformly distributed pressure. In contrast, the single-bolt lug plate could not realize a high clamping force because of the tightening torque limit. A six-bolt lug plate can cause pressure concentration and edge damage to the friction pad.

Fabrication and mechanical performance investigation of jute/glass fiber hybridized polymer composites: Effect of stacking sequences

The green, biodegradable, and cost-effective properties of natural fiber-reinforced polymer composite materials have attracted significant interest when compared to synthetic polymer composites. Jute is a naturally occurring bast fiber that is inexpensive, durable, and often utilized. In contrast, glass is a composite material that is frequently used in various applications, despite its high cost and potential environmental risks. Owing to jute's superior mechanical properties, there is a great deal of potential for combining it with glass, which would lower the amount of glass used and the composite's overall cost. This study employed bleached jute fabric and non-woven glass fabric to develop neat jute, neat glass, and hybrid composites by using different stacking sequences. The composites were fabricated utilizing a thermoset polymer matrix by following the hand layup process. Subsequently, an investigation was carried out to examine the mechanical, physical, thermal, and morphological properties of these composites. Out of the developed samples, the neat jute presents the least tensile and bending strength at 31.35 MPa and 41.138 MPa respectively, whereas the neat glass composite demonstrates exceptional tensile and bending strengths at 132.03 MPa and 184.86 MPa respectively. In the case of hybrid samples, they exhibited mechanical capabilities that fell between neat jute and neat glass, which was attributed to the combination of glass with jute fabric and the placement of glass as the outer layer. Apart from that, we observed that the moisture take-up% and thermal conductivity of hybrids composite were within 4–4.3% and 0.28–0.32 Wm−1 K-1 respectively. Moreover, thermogravimetric analysis and morphological behavior were also assessed. However, this study suggested that jute and nonwoven glass fabric with different stacking sequences may be combined to create a reinforced hybrid composite that may have potential use in furniture, interior design, and inner sections of cars.

Investigation of the Effect of Hexagonal Boron Nitride Addition on the Mechanical Properties of Flax Fiber-Reinforced Composite Materials

Hexagonal boron nitride (h-BN) has recently been utilized as a reinforcement in composite materials due to its properties such as hardness, thermal conductivity, electrical insulation, and strong chemical stability. The aim of this study is to investigate the effect of nano-sized hexagonal boron nitride (h-BN) on the mechanical properties of flax fiber-reinforced composite material. For this purpose, initially, hexagonal boron nitride was added to epoxy resin in different weight ratios and homogenized without agglomeration using ultrasonic treatment. Then, by employing the hand lay-up method, the mixture was applied to flax fiber fabrics and the flax fiber-epoxy composites were produced using the vacuum bagging method. Mechanical performance of the composites, produced with 0.5%, 1%, and 1.5% by weight of hexagonal boron nitride, was determined through tensile, flexural, shear, and compression tests. Experimental results indicated that the addition of hexagonal boron nitride to flax fiber epoxy composite material increased the flexural strength and modulus compared to the unreinforced flax fiber epoxy composite material. The highest flexural strength and modulus were observed in the samples with 1.5% by weight of hexagonal boron nitride (h-BN). Consequently, it can be considered that flax fiber-epoxy composite material with hexagonal boron nitride (h-BN) addition holds potential, especially for applications subjected to bending moments.

Effect of Cutting Conditions on the Size of Dust Particles Generated during Milling of Carbon Fibre-Reinforced Composite Materials.

Conventional dry machining (without process media) of carbon fibre composite materials (CFRP) produces tiny chips/dust particles that float in the air and cause health hazards to the machining operator. The present study investigates the effect of cutting conditions (cutting speed, feed per tooth and depth of cut) during CFRP milling on the size, shape and amount of harmful dust particles. For the present study, one type of cutting tool (CVD diamond-coated carbide) was used directly for machining CFRP. The analysis of harmful dust particles was carried out on a Tescan Mira 3 (Tescan, Brno, Czech Republic) scanning electron microscope and a Keyence VK-X 1000 (Keyence, Itasca, IL, USA) confocal microscope. The results show that with the combination of higher feed per tooth (mm) and lower cutting speed, for specific CFRP materials, the size and shape of harmful dust particles is reduced. Particles ranging in size from 2.2 to 99 μm were deposited on the filters. Smaller particles were retained on the tool body (1.7 to 40 μm). Similar particle sizes were deposited on the machine and in the work area.

Damage detection and classification of carbon fiber-reinforced polymer composite materials based on acoustic emission and convolutional recurrent neural network

Carbon fiber-reinforced polymer (CFRP) composite laminates generate acoustic emission signals during the tensile process, which can be used to identify the type of acoustic emission (AE) signal at a given moment and determine the current damage condition. However, due to the large number and complexity of AE signals generated during the tensile process of carbon fiber composite laminates, it is challenging to manually identify and annotate them. To address this issue, we propose a low-complexity classification and detection network model based on the convolutional recurrent neural network (CRNN) architecture. First, we construct a dataset of composite damage signals for a single damage category and use log-mel spectrogram features to train the model for that specific category of damage signals. Then, we utilize the trained model to recognize the AE signals of CFRP composite laminates. The proposed method achieves an accuracy of 99.02% in classifying single damage modes in the test set and effectively distinguishes the types of AE signals generated during the damage process of CFRP composite laminates. Compared with the classic classification model using AE signals, the number of parameters in our proposed low-complexity CRNN model is reduced by 94.42%. It also demonstrates that 19.4% of the AE signals during the damage process are in a superimposed state, indicating the simultaneous occurrence of multiple damage modes in CFRP composite laminates.

Dodging reality, striking the virtual: An undulating strategy for effectively enhancing CF/PEEK interfacial adhesion!

The design of carbon fiber (CF)-reinforced polyetheretherketone (PEEK) composite materials with suitable interfaces has consistently been challenging. In this study, we sulfonated poly (phthalazinone ether sulfone ketone) (PPESK) and PEEK to prepare water-soluble SPPESK and SPEEK. Subsequently, we prepared a water-soluble sizing agent (SPPESK/SPEEK) via a straightforward blending process. This sizing agent tended to accumulate randomly on the surfaces of CFs, forming a thin film with a heterogeneous structure in the nanoscale. At the molding temperature of the composite material, the two components on the fiber surface exhibited different rheological behaviors, with PEEK preferentially infiltrating the SPEEK region, forming strong molecular entanglements. Meanwhile, the SPPESK region provided a rigid supportive structure, offering the potential for the mechanical interlocking of PEEK in the interface layer. The performance of the prepared composite materials was significantly enhanced, with their interlaminar shear strength and flexural strength reaching 87.1 MPa and 975.8 MPa, respectively. With respect to those of commercial fiber-reinforced PEEK composites, an 89.8 % increase in interlaminar shear strength and a 79.39 % increase in flexural strength were observed. This interface reinforcement mechanism presents a universally applicable strategy for the future development of fiber-reinforced composite materials.

Enhancement of Additively Manufactured Bagasse Fiber-Reinforced Composite Material Properties Utilizing a Novel Fiber Extraction Process Used for 3D SLA Printing

Enhancement of Additively Manufactured Bagasse Fiber-Reinforced Composite Material Properties Utilizing a Novel Fiber Extraction Process Used for 3D SLA Printing

Fibre misalignments in the split-disk test represented by random fields

Fibre misalignment is a major type of manufacturing defect in fibre-reinforced composite materials which has an adverse effect on the mechanical performance of composites. The present paper utilises stochastic models based on the random fields of fibre misalignment in the finite element analysis (FEA) of the split-disk test for filament wound composites. Local fibre misalignment characteristics are determined experimentally using X-ray micro-computed tomography (μ-CT) and then used to generate spatially correlated anisotropic random fields further mapped to finite element mechanical properties. The model predicts pronounced stress and strain non-homogeneity, an expected reduction in the overall modulus and pre-mature damage initiation. This leads to the evaluation of effect-of-defects and allowable for manufacturing tolerances in hoop layers of composite pressure vessels.

Investigating the solid particle erosion behavior of H3BO3 / B2O3 / SiO2 / Al2O3 reinforced glass fibre/epoxy composites and parametric evaluation using artificial intelligence

In this experimental study, the erosion wear behavior of glass fibre-reinforced (GF) composite materials was examined according to ASTM G76–95. Pure/GF reinforced epoxy composite (EP) materials were chosen as the main test sample. Boric Acid (H3BO3), Borax (B2O3), Silicon Dioxide (SiO2), and Aluminium Oxide (Al2O3) were added to the resin as reinforcement at a rate of 15% by weight. The erosion wear rate was investigated with various impingement angles (30°, 60°, and 90°), impact velocities (≈23, 34, and 53 m/s), alumina abrasive particle sizes (≈200 and 400 μm), and fibre directions (0° and 45°). Neural network models were employed effectively to predict the influence of the reinforcements on erosive wear rate. The erosive wear rate indicated that Al2O3 added GF/EP exhibited the most anti-erosive characteristics followed by silicon dioxide GF/EP and pure GF/EP however, the anti-erosive nature of GF/EP deteriorated with the addition of Borax and Boric Acid.

Vibration analysis of Ti-SiC composite airfoil blade based on machine learning

In this study, machine learning (ML) methods are integrated with Rayleigh-Ritz method and first-order shear deformation theory (FSDT) to predict the vibration properties of Ti-SiC fiber-reinforced composite airfoil blade. The natural vibration characteristics of airfoil blade are largely determined by various geometric and material parameters, which leads to the high computational cost of numerical methods. Therefore, the low-cost ML models in conjunction with Ti-SiC fiber-reinforced composite material is developed to replace traditional numerical methods in order to predict the vibration characteristics of airfoil blade. Random Forest (RF), Gradient Boosting Decision Tree (GBDT) and Back Propagation (BP) neural network models are utilized to compare the predicted results with existing data. Among these models, the BP neural network demonstrates superior performance. Additionally, the SHapley Additive exPlanation (SHAP) method is utilized to elucidate BP neural network model, facilitating the prioritization of input features. This approach offers a feasible auxiliary solution for investigating the vibration characteristics of airfoil blade.

Characterisation of basalt/glass/kevlar-29 hybrid fibre-reinforced plastic composite material through Nd: YAG laser drilling and optimisation using stochastic methods

Characterisation of basalt/glass/kevlar-29 hybrid fibre-reinforced plastic composite material through Nd: YAG laser drilling and optimisation using stochastic methods

The influence of the hot-pressing process on the mechanical properties of continuous aramid fiber-reinforced PA12 composites

Abstract Hot-pressing post-treatment can effectively improve the mechanical properties of composite specimens. In order to improve the impact resistance of continuous aramid fiber-reinforced nylon 12 (CAF/PA12) composites, the effect of hot-pressing parameters on the interlaminar shear strength of the composite was studied. The effects of hot-pressing temperature, hot-pressing time, and hot-pressing pressure on the interlaminar shear strength of composite formed specimens were studied by single factor test. Based on the optimized parameters of hot-pressing, the influence of hot-pressing on low-speed impact performance was analyzed. The results shown that the interlaminar shear strength first increased and then decreased with the increase of hot-pressing temperature and pressure. With the extension of hot-pressing time, the interlaminar shear strength continued to increase. When the hot-pressing parameters were 170°C, 30 min, and 600 kPa, the shear strength and specimen quality were the best. Under this hot-pressing process, the low-speed impact performance was increased by 36.0%. In this paper, the research content of the hot-pressing process of composite materials was expanded, which provided a reference for the research of impact resistance of continuous aramid fiber-reinforced PA12 composite materials.

Investigation of Drilling Performances, Tribological and Mechanical Behaviors of GFRC Filled with B4C and Gr

AbstractIn this study, the effects of Gr and B4C filler materials on drilling performance, mechanical, and tribological behaviors of glass fiber-reinforced epoxy composites were experimentally investigated. Glass fiber-reinforced composite materials filled with B4C and Gr at different weight ratios (5%, 10%, and 15%) were manufactured using hand lay-up method. The produced composite materials underwent various tests, including mechanical tests (tensile and flexural tests), tribological tests (wear behavior), and drilling tests under different parameters. Additionally, SEM images of the worn and fractured surfaces were examined. The addition of both B4C and Gr fillers adversely affected the mechanical properties of glass fiber-reinforced composites. It was observed that tensile and flexural strengths decreased with increasing filler ratios. However, the addition of B4C and Gr fillers enhanced the wear resistance of glass fiber-reinforced composites. It was revealed that in drilling operations, as the feed rate increased, the thrust forces increased, while the cutting speed increased, the thrust forces decreased. It was determined that delamination values in glass fiber reinforced composites decreased as the feed rate increase, while delamination values increased as the cutting speed increased. Generally, the thrust forces, vibration, delamination, and moment values obtained during the drilling of B4C-filled glass fiber composites were found to be higher compared to Gr-filled glass fiber composites.

Cumulative energy demand and environmental impact analysis in the manufacture of recycled fiber reinforced composites panels for use in truck bodies

ABSTRACT The reuse of fiber-reinforced composite materials has become increasingly important with the tremendous waste produced by aerospace, wind turbine blades, and automobile components. Recycling fiber-reinforced composites from parts at their end-of-life provides the benefit of reinforcing strength and integrity. The life cycle assessment (LCA) method has been widely used to examine the embodied energy (EE) and the environmental impact of the manufacturing process. Two different types of composite panels made via hand layup and compression molding are considered for a comparative LCA investigation using SimaPro software. Some panels are made with a mixture of 50% virgin glass fiber (GF) and 50% polyester resin. Others are produced with a mixture of 25% virgin GF, 25% shredded recyclates from wind turbine blade, and 50% of polyester resin. Panels from the recyclates termed Recycled Glass Fiber Reinforced Polyester (rGFRP) had 2.44% lower EE as compared to their counterparts vGFRP. Ozone depletion proved to be the greatest impact on the environment as regard to the manufacturing of rGFRP (4.38E–6 kg CFC-11eq). rGFRP panels manufacture generated 3.8% less greenhouse gas emissions than the vGFRP. LCA analysis suggests that the manufacture of panels for truck body/floor using recyclates from shredded wind turbine blades involves less energy use and has less environmental impact.

The Quick Determination of a Fibrous Composite’s Axial Young’s Modulus via the FEM

Knowing the mechanical properties of fiber-reinforced composite materials, which are currently widely used in various industrial branches, represents a major objective for designers. This happens when new materials are used that are not yet in production or for which the manufacturer cannot give values. Given the practical importance of this problem, several methods of determining these properties have been proposed, but most of them are laborious and require a long calculation time. And, some of the proposed calculation methods are very approximate, providing only upper and lower limits for these values. Experimental measurements are obviously the optimal solution for solving this problem, but it must be taken into account that this type of method consumes time and material resources. This paper proposes a sufficiently accurate and fast estimation method for determining Young’s modulus for a homogenized fibrous material. Thus, the FEM is used to determine the natural frequencies of a standard bar, for which there are sufficiently precise classical methods to express the engineering constants according to the mechanical properties of the component phases of the homogenized material. In this paper, Young’s modulus is determined for such a material using the relationships that provide the eigenfrequencies for the longitudinal vibrations. With the adopted model, transverse and torsional vibrations are eliminated by blocking the nodes on the surfaces of the bars. In this way, more longitudinal eigenfrequencies can be obtained, so the precision in calculating Young’s modulus is increased.

The Effect of Carbon Nanofibers on the Mechanical Performance of Epoxy-Based Composites: A Review.

This review is a fundamental tool for researchers and engineers involved in the design and optimization of fiber-reinforced composite materials. The aim is to provide a comprehensive analysis of the mechanical performance of composites with epoxy matrices reinforced with carbon nanofibers (CNFs). The review includes studies investigating the static mechanical response through three-point bending (3PB) tests, tensile tests, and viscoelastic behavior tests. In addition, the properties of the composites' resistance to interlaminar shear strength (ILSS), mode I and mode II interlaminar fracture toughness (ILFT), and low-velocity impact (LVI) are analyzed. The incorporation of small amounts of CNFs, mostly between 0.25 and 1% by weight was shown to have a notable impact on the static and viscoelastic properties of the composites, leading to greater resistance to time-dependent deformation and better resistance to creep. ILSS and ILFT modes I and II of fiber-reinforced composites are critical parameters in assessing structural integrity through interfacial bonding and were positively affected by the introduction of CNFs. The response of composites to LVI demonstrates the potential of CNFs to increase impact strength by reducing the energy absorbed and the size of the damage introduced. Epoxy matrices reinforced with CNFs showed an average increase in stiffness of 15% and 20% for bending and tensile, respectively. The laminates, on the other hand, showed an increase in bending stiffness of 20% and 15% for tensile and modulus, respectively. In the case of ILSS and ILFT modes I and II, the addition of CNFs promoted average increases in the order of 50%, 100%, and 50%, respectively.