Kevlar Fibers Research Articles

Preparation and the influence of twist factor on cut resistance performance of Kevlar short fiber covered yarn fabric

This research utilized Kevlar short fibre yarn to cover Kevlar and UHMWPE filaments, resulting in six different types of covered yarns and their associated fabrics. The aim of the research was to examine the impact of the twist factor of Kevlar short fibre yarn and the type of covered yarn on the mechanical properties of the yarns and their corresponding fabrics. The results indicated that the KPf covered yarn with a twist factor of 305 exhibited the highest breaking strength at 13.06cN/dtex, approximately 24% higher than the KKf covered yarn. The 225-KPf covered yarn fabric demonstrated peak breaking strength at 1772.01 N. Under similar conditions, KPf coated yarn outperformed KKf coated yarn in terms of tensile strength. However, KKf covered fabrics exhibited superior cutting resistance compared to KPf covered fabrics, with the 385-KKf fabric having the highest resistance at 1117.29 N. The study concluded that increased twist factor factors lead to varied outcomes in tensile performance and cutting resistance due to changes in inter-fiber spacing and cohesion pressure on the short fiber yarn, as well as the influence of material molecular structure.

Tensile properties and constitutive modeling of Kevlar29 fibers: from filaments to bundles

This paper experimentally investigates the tensile properties of Kevlar29 filaments and fiber bundles, revealing the size and strain rate effects on the mechanical properties of fiber bundles. The fracture modes and mechanisms of the fibers were analyzed, and viscoelastic constitutive models at the fiber bundle scale and constitutive models for filaments-bundles based on the Weibull distribution were established. The results show that Kevlar29 fiber bundles exhibit significant strain rate effects: as the strain rate increases, tensile strength and modulus increase, while fracture strain and toughness decrease. Under quasi-static loading, the fracture modes of the fibers are mainly fibrillation or shear flow, but as the strain rate increases, the failure modes shift towards brittle fracture. Both constitutive models can accurately predict the tensile properties of fiber bundles at different strain rates. The accuracy and applicability of the filament-to-bundle constitutive model were verified through numerical simulations, demonstrating that the model better describes the size effect of fibers and quantifies the damage to the fiber bundles.

Enhancements of Creep Compliance of Kevlar and Carbon Fibers Reinforced Sika Epoxy Composites

Enhancements of Creep Compliance of Kevlar and Carbon Fibers Reinforced Sika Epoxy Composites

Simulation and experimental verification of the orthogonal friction continuous wear of PTFE-Kevlar fabric liner

Woven fabric liners, which are customizable and maintenance-free, have extensive applications in self-lubricating spherical bearings. However, owing to the orthogonal anisotropy and non-homogeneous characteristics, their frictional and wear behaviors are complex. Currently, average performance testing is primarily based on long-term macroscopic wear experiments. However, unobservable parameters such as mesoscopic stress and pressure distribution in liners are bottlenecks in the experimental exploration of wear sources and mechanisms. Therefore, an innovative strategy for modeling orthogonal friction and continuous wear in non-homogeneous liners is presented. This approach has the potential to overcome experimental limitations and significantly expedite liner design and cost-effective validation. The initial step involves establishing a mesoscopic voxel-based planar model of the liner that maintains the topological relationship during wear processes. This is achieved by introducing a circular voxel mesh and spatial transformation methods. Based on orthogonal friction and wear assumptions, separate constitutive models for orthogonal friction and wear are developed. Using the CETR UMT-3 friction and wear testing machine, GCr15 is selected as the counterface material, the pin disc wear method is adopted to conduct sliding test on PTFE and Kevlar fibers, and the required wear constitutive parameters are fitted. Furthermore, incremental equations for the total wear are derived. An element wear fusion strategy is introduced. This approach leads to the development of a continuous wear algorithm for liners and subsequently to the establishment of a voxel-based finite element model with continuous wear capability in the form of a circular voxel grid. This method transcends experimental methods and allows for the determination of the mesoscopic contact pressure, stress distribution, and variations in the contact material composition patterns of liner. The accuracy of the average macroscopic wear prediction is validated experimentally. This method has the potential for practical applications in bearing design.

Mechanical characterization and performance evaluation of twisted Jute-Kevlar hybrid composites with varied fiber orientations

Abstract Composite materials play a vital role in developing new materials in engineering and technology. Composites show how the properties of the matrix and reinforcement work together to create more robust, more rigid materials than would be possible from the individual components working alone. They consist of two or more component materials combined with notably dissimilar physical or chemical characteristics. Two categories of composite coupons have been developed in this research work: the first category (C1) is made up of jute twisted-Kevlar twisted jute fiber (0/90 degree), and the second category (C2) is made up of jute twisted-Kevlar twisted jute fiber (0/45 degree). The nano-silica is reinforced with the matrix with a weight percentage of 0%,5%,10% and 15%. The necessary interfacial adhesion and bonding between fiber layers have been accomplished using a 10:1 mixture of epoxy resin (LY556) and hardener (HY951). According to ASTM guidelines, the tensile, flexural, impact, double shear, wear, and hardness tests were carried out. This study uses two natural and synthetic fibers—twisted Jute and Kevlar fibers—as reinforcement. The Jute fibers have a high strength since they are high in cellulose. Efforts have been made to create a composite material with completely different twisted fiber orientations and to assess the mechanical properties of the composites. This involved various mechanical tests, analysis of wear surfaces, as well as DMA, DSC, FEA testing, and ultimately, the machining of the composites studied. The machining parameters used in waterjet machining have been carefully analyzed.

Assessing PET composite prosthetic solutions: A step towards inclusive healthcare

The demand for affordable prostheses is particularly high in Low Middle-Income Countries (LMICs). Currently, sockets are predominantly manufactured using monolithic thermoplastic polymers, which lack durability and strength, or consumptive thermoset resin reinforcing with expensive composite fillers like carbon, glass, or Kevlar fibers. However, there exist unmet and demanding needs among amputees for procuring low-cost, high-strength, and faster socket manufacturing methods. We evaluate a socket made from a novel manufacturing technique utilizing an affordable and sustainable composite material called commingled PET (polyethylene terephthalate) yarn, along with a reusable vacuum bag, to produce custom-made sockets in a purpose-built curing oven. Our innovative fabrication methodology enables the production of complex-shaped patient sockets in under 4 h. To evaluate the efficacy and performance of the PET sockets, we conducted trials with both unilateral and bilateral amputees over a six-month period, in collaboration with Bhagwan Mahaveer Viklang Sahayata Samiti (BMVSS) in India. Utilizing a 6-min walking test, we measured various gait parameters, including ground reaction forces and flexion angle, for both unilateral and bilateral amputees.The gait analysis conducted on amputees using our PET-based sockets demonstrated their ability to engage in daily activities without interruptions, reaffirming the functional efficacy of our approach. By combining self-reinforced PET with our novel fabrication technique, we offer a unique and accessible solution that benefits clinicians and patients alike. This study represents significant progress towards achieving affordable and personalized prostheses that cater to the needs of LMICs.

The effect of short Kevlar fibers interfacial toughening on impact properties of carbon fiber/aluminum honeycomb sandwich panels

Due to the susceptibility of carbon fiber/aluminum honeycomb sandwich structures to interface damage under impact loading, their overall mechanical performance can be compromised, potentially leading to structural failure. This poses a severe risk to the safety of such structures in engineering applications. This study initially conducted low-velocity impact tests and post-impact compression tests on carbon fiber/aluminum honeycomb sandwich panels with both untoughened and short Kevlar fibers toughened interfaces, using four different impact energy levels (10 J, 20 J, 30 J, and 50 J). The experimental results indicated that the toughening with short Kevlar fibers significantly enhanced the impact resistance and residual compression performance of the sandwich panels. Subsequently, the impact test on the toughened specimen was simulated numerically and the experimental results were in good agreement with the numerical simulations. Finally, based on the numerical model, the study explored the influence of varying face sheet parameters on the impact resistance of short Kevlar fibers toughened carbon fiber/aluminum honeycomb sandwich panels. Layup quantity and layup angle have significant influence on the impact resistance of sandwich panels. With the increase of layup quantity, the impact resistance improves. In several layup angles, [0/45/90/-45/0/45] layering method shows the best impact resistance.

Investigation of Gnetum Gnemon and Ramie Natural Fiber on the Mechanical Properties of Composites with the Combination of Aramid and Carbon Fiber as Reinforcement for Military Personnel Applications

Every equipment infrastructure in a TNI unit will be needed to support an operation in the defence system to maintain the integrity of the Unitary State of the Republic of Indonesia. Personal protective equipment is needed for a war operation’s safety or continuity. Protective components made from composite fibers have the advantage of being resistant to corrosion caused by the environment. The natural and carbon fibers will be mixed/reinforced with epoxy resin to become composite materials. This study aims to identify Gnetum Gnemon fiber composites with carbon fiber and aramid fiber to determine the mechanical properties of the composite material resulting from a collision. Natural fiber Gnetum gnemon has not been widely studied as a reinforcing material for polymer composites. Gnetum gnemon fiber chemical composition is hemicellulose approx. 25%, 40% alpha cellulose, 10% lignin and 3-5% benzene extractive. Its density is quite light, 1.2087 g/cm³ - 1.8069 g/cm³. Because this fiber has a continuous fiber structure and a strong natural weave, its use is still minimal. Special treatment such as alkali treatment on Gnetum gnemon, can increase the strength of natural fibers. Due to its exceptional mechanical properties, Kevlar or aramid fibre are extensively used in industrial and military applications. The aramid fiber exhibited a transversely anisotropic nature in a small strain range, with its stress-strain behavior as linear and elastic. The anisotropic nature of the aramid fiber was due to its high tensile-to-shear modulus ratio. The high strength and modulus were also found to be scattered due to the larger distribution of defects in the longer fiber. Epoxy resin is a type of polymer characterized often by one or more epoxide functional groups, with at least one of the epoxide functional groups acting as a monomer and terminal unit of the polymer within the structural chain.

Functionally‐Graded Serrated Fangs Allow Spiders to Mechanically Cut Silk, Carbon and Kevlar Fibers

Functionally‐Graded Serrated Fangs Allow Spiders to Mechanically Cut Silk, Carbon and Kevlar Fibers

Flexural and interlaminar shear response of novel methylmethacrylate composites reinforced with high-performance fibres

This experimental work presents a comparative study on the mechanical behaviour of novel infusible methylmethacrylate matrix (Elium®) composites reinforced with different types of high-performance fibres. A vacuum-assisted resin infusion process was employed to fabricate the laminates using carbon, basalt, Kevlar®, and high molecular weight polyethene (UHMWPE) fibres. Flexural and interlaminar shear properties of the composites were evaluated. Test results revealed that carbon fibre composites had superior flexural strength, stiffness and interlaminar shear stress as compared to the other composites tested. Further, composites containing Kevlar and UHMWPE fibres demonstrated significantly higher flexural strains to failure. Post-testing, specimens were examined using scanning electron microscopy (SEM). Microscopy revealed possible interfacial interaction differences based on the reinforcement fibre type, which was further confirmed by an analytical approach for analysing the flexural behaviour of various types of composites. The sequence of damage progression in specimens was also analysed.

Hybridization effect of Kevlar and glass fiber on carbon/epoxy composites to enhance the damage strength under low velocity impact. Part II: Numerical simulations

The research outlined in this paper extends the authors previous work to explore the impact resistance enhancement of CFRP composites through numerical simulations, focusing on the incorporation of a hybrid combination of Kevlar and glass fibers. Experimental drop weight low velocity impact and advanced NDT tests on CFRP and hybrid laminates were carried out in previous work. The current work focuses on the analysis of the dynamic behavior of hybrid composite subjected to LVI by numerical simulation methods. The numerical simulations have been validated with experiments and the damage area of numerical and experimental tests were compared. CFRP and hybrid laminates were modeled using Abaqus/Explicit FEA software to investigate the damage modes and mechanisms. The history curves of simulation results such as load/displacement-time etc. compared with experimental. Results show that incorporating 25% Kevlar fibers on the outer layer of the CFRP, denoted as [01K/06C/01K] resulted in a reduction of laminate deflection by 63.64%. Additionally, the stress distribution expanded over a larger area. A good concurrence between the simulation and experimental findings has been established, indicating that the modeling approach is suitable for conducting further parametric investigations.

Bioinspired Flexible Kevlar/Hydrogel Composites with Antipuncture and Strain-Sensing Properties for Personal Protective Equipment.

Currently, multifunction has become an essential direction of personal protective equipment (PPE), but achieving the protective effect, flexibility, physiological comfort, and intelligent application of PPE simultaneously is still a challenge. Herein, inspired by the meso-structure of rhinoceros skin, a novel strategy is proposed by compounding an ammonium sulfate ((NH4)2SO4) solution soaked gelatin hydrogel with the high weight fraction and vertically interwoven Kevlar fibers to manufacture a flexible and wearable composite with enhanced puncture resistance and strain-sensing properties. After (NH4)2SO4 solution immersion, the hydrogel's tensile strength, toughness, and fracture strain were up to 3.77 MPa, 4.26 MJ/m3, and 305.19%, respectively, indicating superior mechanical properties. The Kevlar/hydrogel composites revealed excellent puncture resistance (quasi-static of 132.06 N and dynamic of 295.05 N), flexibility (138.13 mN/cm), and air and moisture permeability (17.83 mm/s and 2092.73 g m-2 day-1), demonstrating a favorable balance between the protective effect and wearing comfort even after 7 days of environmental exposure. Meanwhile, salt solution immersion endowed the composite with excellent strain-sensing properties at various bending angles (30-90°) and frequencies (0.25-1 Hz) and allowed it to monitor different human motions directly in real-time. The rhinoceros-skin-inspired Kevlar/hydrogel composites provide a simple and economical solution for antipuncture materials that combine high protective effects, a comfortable wearing experience, and good strain-sensing properties, promising multifunctional PPE in the future.

Investigation of Kevlar and Basalt fiber hybridization on vibrational characteristics of composite plates

The study of vibrational characteristics of plates, specifically composite plates, has gained significant importance in contemporary and cutting-edge industries involved in industrial plate manufacturing. This paper investigates the vibrational behavior of composite plates made of Kevlar, basalt, and a hybrid combination of Kevlar and basalt fibers embedded in an epoxy matrix. The investigation was carried out through experimental methods utilizing the D3560 analyzer device. Furthermore, in order to ensure the reliability of the findings, the experimental data were simulated and compared with finite element modeling using the ABAQUS software. The results demonstrate that hybridizing the fibers in the first and second modes leads to an increase in the natural frequency compared to pure Kevlar, while the hybridization effect compared to pure basalt has a negative impact. However, in the third to fifth modes, the layered arrangement shows an increase in the natural frequency compared to pure Kevlar and pure basalt. The experimental results obtained and the simulated ones in the finite element software exhibit a consistent trend.

Development and mechanical properties evaluation of environmentally sustainable composite material using various reinforcements with epoxy

In this study, the mechanical properties of advanced composites fabricated by the hand lay-up process were investigated. The mechanical properties evaluated in this study included tensile strength, flexural strength, and impact strength. Tensile tests were performed to measure the resistance of the composites to pulling forces, while flexural tests assessed their resistance to bending. Impact tests, on the other hand, determine the material's ability to absorb sudden forces or shocks. Results showed that all the composite materials exhibited high tensile strength, with the Carbon fiber epoxy composite displaying the highest value due to the exceptional strength of carbon fibers. In terms of flexural strength, the Glass-Fiber Polymer Matrix composite demonstrated the highest resistance to bending, while the Kevlar-Epoxy composite exhibited the highest impact strength, owing to the unique properties of Kevlar fibers, which offer excellent energy absorption capabilities. In the hardness test, the Kevlar composite to epoxy matrix showed hardness from HRB 105 to HRB 125 an increase of 19.04 %, while fiberglass increased hardness by 14.2 % and carbon fiber by 16.3 %. The Impact test shows that the Kevlar composite to epoxy matrix showed hardness from HRB 105 to HRB 125 an increase of 19.04 %, while fiberglass increased hardness by 14.2 % and carbon fiber by 16.3 %. Kevlar reinforcing composite produced the highest flexural strength, compared to neat epoxy by 91.7 %. Carbon fibre composites were 52.5 % higher, whereas glass fibre composites were 15.6 % higher. SEM imaging results from the cross-sections show that the best bonding between the base material and the fibers was observed for Kevlar reinforced with epoxy. All mechanical test showed that Kevlar (Aramid fiber) provides excellent mechanical properties when compared to carbon fibre and glass fibre. Hence, Kevlar (aramid fiber) can be an option for preparing light weight helmets, automobiles, aeronautics, safety equipments etc.

Microstructural characteristics and mechanical properties of 3D printed Kevlar fibre reinforced Onyx composite

Abstract The main objective of this study is to develop the Kevlar fibre reinforced Onyx composite (KFRO) material by employing the 3D printing technology and examine the effect of Kevlar fibre reinforcement percentage on microstructural characteristics and mechanical properties of developed composite material. The methodology of continuous fibre reinforced composites (CFRC) was followed and the Kevlar fibre reinforcement % was varied as 10 %, 20 % and 30 % in the composite material fabrication. Results disclosed that the KFRO composite 3D printed using 30 % Kevlar fibre reinforcement in Onyx matrix yielded greater tensile strength of 124 MPa, flexural strength of 105 MPa, impact toughness of 2.4 J and shore hardness of 76 D. The mechanical properties of KFRO composite were significantly improved at 20 % of Kevlar fibre reinforcement compared to 10 % of Kevlar fibre reinforcement. Further increase in Kevlar fibre reinforcement up to 30 % showed slight enhancement in mechanical properties of KFRO composite when compared to 20 % of Kevlar fibre reinforcement. The overall strength improvement is a result of the increased reinforcement, precise alignment of fibres in the loading direction, and the uniform distribution of fibres within the onyx.

Multi-scale moisture diffusion modeling and analysis of carbon/Kevlar-fiber hybrid composite laminates under the hygrothermal aging environment

Hybrid fiber reinforced polymer (HFRP) can have more complex micro moisture diffusion process than single fiber composite, owing to diverse hygroscopic properties of dissimilar fibers. Thus, elucidating the multi-scale moisture diffusion mechanism of HFRP through experimental method becomes a challenging endeavor. To this end, a multi-scale moisture diffusion modeling approach is proposed to investigate the moisture diffusion behavior of carbon/Kevlar HFRP under the hygrothermal aging environment. Leveraging Fick's law as a foundation, a combination of multi-scale moisture diffusion model and finite element method is employed. To validate the effectiveness of model, accelerated aging experiments are conducted on HFRP samples with various stacking sequences. By SEM characterization, the surface aging on aged Kevlar fibers and the debonding of aged fiber/matrix interface are conspicuously observed. Based on this model, the moisture diffusion behaviors in different HFRP configurations are simulated and analyzed to reveal the micro-, meso‑ and macro-scale moisture diffusion and resistance mechanisms. Our findings highlight the profound influence of factors such as fiber type, fiber content, fiber placement, hygroscopic properties of constituents, and their synergistic effects on moisture absorption and saturated moisture absorption rates. Finally, the hygroscopic properties of HFRP laminate with different stacking sequences are predicted by multi-scale model. This work endeavor furnishes valuable insights and guidelines for the design and analysis of moisture-resistant HFRP.

SEM of Erosive Wear Mechanisms of Kevlar Fiber Reinforced Composites

SEM of Erosive Wear Mechanisms of Kevlar Fiber Reinforced Composites

The tensile properties of adhesively bonded single lap joints with short kevlar fiber

In this paper, short Kevlar fiber was added to epoxy resin adhesive to form a short fiber toughened adhesive, and its effect on the static strength and elongation at break of Carbon fiber laminate adhesively bonded single lap joints was investigated. 1 wt%, 2 wt%, 3 wt% and 4 wt% short Kevlar fibers were added to make short fiber toughened adhesive joints to investigate the effects of different contents of short Kevlar fibers on the connecting properties of the test pieces of Carbon fiber laminate single lap adhesively bonded joints; In addition, microscopic toughening mechanism of short Kevlar fiber in adhesives revealed by combining DIC technique and SEM technique. The test results showed that the addition of appropriate amount of short Kevlar fiber could slow down the crack extension compared with the without toughening specimens, but the toughening effect was weakened by excessive content. 2 wt% short Kevlar fiber toughened specimens achieved the best toughening effect, with 30.52 % increase in peak load and 25.78 % increase in elongation in tensile test. The combination of DIC and SEM further showed that short Kevlar fiber toughened joints absorb crack strain energy through fiber-bridging thus increasing adhesive properties.

Validation of DOE Factorial/Taguchi/Surface Response Models of Mechanical Properties of Synthetic and Natural Fiber Reinforced Epoxy Matrix Hybrid Material.

A validation of the factorial, Taguchi and response surface methodology (RSM) statistical models is developed for the analysis of mechanical tests of hybrid materials, with an epoxy matrix reinforced with natural Chambira fiber and synthetic fibers of glass, carbon and Kevlar. These materials present variability in their properties, so for the validation of the models a research methodology with a quantitative approach based on the statistical process of the design of experiments (DOE) was adopted; for which the sampling is in relation to the design matrix using 90 treatments with three replicates for each of the study variables. The analysis of the models reveals that the greatest pressure is obtained by considering only the source elements that are significant; this is reflected in the increase in the coefficient of determination and in the predictive capacity. The modified factorial model is best suited for the research, since it has an R2 higher than 90% in almost all the evaluated mechanical properties of the material; with respect to the combined optimization of the variables, the model showed an overall contribution of 99.73% and global desirability of 0.7537. These results highlight the effectiveness of the modified factorial model in the analysis of hybrid materials.

Machine learning approach to evaluating impact behavior in fabric-laminated composite materials

Fabric-layered composites play a crucial role in safety and surveillance applications, making it imperative to accurately predict their impact behavior. This research focuses on creating a machine-learning model to predict the impact behavior of fabric-stacked composites, specifically carbon and Kevlar fabrics. Low-velocity impact tests were performed with varying parameters, and the impact energy and laminate thickness information were used to train machine-learning models to predict impact properties such as impact force, displacement, and absorbed energy. It was observed that the impact force increased by 118.5 % in carbon-laminated fibers and 175.8 % in Kevlar-laminated fibers, while the hybrid layer showed a 101.4 % increase upon impact from 16J. Displacement can affect the stability of the layered structure; thus, a similar stacking sequence is less stable than the hybrid laminated structure. In terms of absorbed energy, as the laminated layers increase, carbon fiber laminate absorbs 4.8 times more energy, and Kevlar fiber and hybrid laminated structures absorb 3 times more energy at higher impact energy. Furthermore, four machine learning models were used to investigate the impact behavior of identical and mixed-layered laminated composites. The impact force and displacement were predicted with higher accuracy using the polynomial regression model, achieving 80 % and 89 % accuracy, respectively. The support vector machine predicted the absorbed energy with approximately 96 % accuracy. In continuing, the experimental results closely matched the predictions made by the other machine learning models utilized in this study. Additionally, the importance of distinctive features and their influence on the performance of the machine learning-based model were interpreted using transposed features of importance and dependency plots. Various failure modes in fabric laminated composites were also identified, providing insights to enhance the performance of stacked fiber materials.