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This study presents a novel hybrid‐sandwich composite structure, customized for nose radomes applications, incorporating a foam core and distinct opposite face sheets composed of Kevlar and S‐Glass materials. Addressing in‐phase electromagnetic properties, UV protection and low velocity impact responses in our previously published work, this paper empirically and numerically investigates the damage tolerance response of the proposed structures through compression after impact (CAI) testing. The low velocity impacts (LVIs) on S‐Glass face sheets exhibited unique energy dispersion and absorption mechanisms, resulting in variations in indent damage depths and widths across all impact energy levels as compared with LVIs on Kevlar face sheets. After experimentally assessing the CAI behavior, a FE model is developed to predict CAI behavior, which closely aligned with experimental findings. This study, unprecedented in existing literature, proposes hybrid sandwich structures for nose radome aerospace applications, with superior specific impact and residual strength compared to various composite sandwich structures documented in the published literature expanding its utility beyond radomes. Highlights: Innovative composites with superior low velocity impact response, tested for compression after impact performance.Designed for nose radomes found suitable for other impact prone applications.Experimental and numerical modeling showed comparable results.Major differences observed in damage mechanics, resistance, and tolerances. [ABSTRACT FROM AUTHOR]

This paper presents the effect of varying the type of Z‐pin on the delamination bridging performance of unidirectional composite laminates. Carbon and Kevlar Z‐pins were inserted in thick composite laminates using the pre‐hole insertion Z‐pinning process and their bridging performance characterized across the different mode‐mixity range. The bridging response indicated that Kevlar Z‐pin experienced load reduction driven by interfacial friction (Stage III), which was absent in the Carbon Z‐pin. When Mode II dominated the bridging crack, Kevlar Z‐pin showed partial pullout and fiber shear cracking, while the Carbon Z‐pin exhibited clean transverse fracture. Although the bridging load obtained by the Carbon Z‐pin was twice that of Kevlar Z‐pin, the Kevlar Z‐pin provided a higher interlaminar fracture energy. The superior bridging performance of Kevlar Z‐pin is correlated with the enhanced ductility. Moreover, the resin‐rich area was involved in deformation and provided the extra axial load of Z‐pin. Highlights: The comparison of mixed‐mode bridging mechanism between Kevlar Z‐pin and Carbon Z‐pin.Reveal the variation of multi‐directional load and energy consumption with mixed‐mode angle in thick laminates.Detailed scanning electron microscope observation to understand failure characteristics of ductile Z‐pin.Evidence that the extra axial load of Z‐pin provided by resin‐rich area. [ABSTRACT FROM AUTHOR]

This research aimed to augment the properties of interfibre interfaces through surface treatment with ZnO nanorods while simultaneously modifying the matrix with graphene nanoplatelets. The strategic approach of this research focused on synergizing these interventions to enhance the mesomechanical, and macromechanical properties, which are specifically targeted at improving the performance of aircrew helmets. This study investigated the effectiveness of these enhancements in improving the mechanical performance of aircrew helmets. The synergy of integrating ZnO nanorods and doped GNPs into Kevlar fabric resulted in a 29% increase in impact energy absorption compared to that of the standard Kevlar composite. Furthermore, the composite samples underwent thorough analysis through techniques such as thermogravimetric analysis (TGA), Raman spectroscopy, Fourier‐transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM) imaging. The findings indicate that incorporating 1% graphene nanofillers into Kevlar during the fourth seed cycle of ZnO treatment yields favorable mechanical performance characteristics. SEM at 50 KX magnification provided detailed visualization of the ZnO nanorods grafted onto the fabric substrates, with subsequent evaluation of the morphological damage and fractography of the impacted composites. The findings of this research hold significance for advancing the understanding of composite material behavior under impact loads and contribute to ongoing efforts to enhance the durability and performance of structural composites in diverse applications. Highlights: Synergistic treatment with ZnO nanorods and graphene nanoplatelets boosted Kevlar composite properties for aircrew helmets.Adding 1% graphene during ZnO treatment increased impact energy absorption by 29%.Comprehensive analysis validated treatment efficacy, showing substantial mechanical improvements.The research advances composite understanding, paving the way for durable, high‐performance materials for applications like aircrew helmets. [ABSTRACT FROM AUTHOR]

This study deals with the development of interlayer hybrid composites with improved low-velocity impact response. In the composites produced using the hand lay-up technique, glass, carbon, and Kevlar woven fabrics were used as reinforcement materials and epoxy resin was used as the matrix material. Shear thickening fluid (STF) was impregnated into the fabric for enhancing their performance. The effect of hybridization with different stacking sequences and the impregnation of STF on the peak load, deflection at peak load, energy absorption, impact strength, and damage degree were investigated. All samples were subjected to 3.12 m/s and 4.42 m/s impact velocities using a drop-weight impact tester applying 200J and 400J impact energy levels, respectively. The results revealed that in samples containing neat fabrics, the performances of the pure Kevlar samples were much better in comparison to hybrid samples, especially under high impact energy. However, STF significantly improved the impact strength and energy absorption (up to 30 times) of all samples, including hybrid ones. On the other hand, as the impact energy increased, the use of a Kevlar reinforced plate on the impact surface was crucial, providing higher energy absorption, and no perforation was observed since most of the energy was required to initiate the damage. In the samples with Kevlar in the intermediate layer, however, the majority of the impact energy caused propagation and expansion of the damage. According to the findings, up to 50% cost savings were achieved in STF-impregnated hybrid samples containing Kevlar. [ABSTRACT FROM AUTHOR]

This study investigates the influence of nano clay reinforcement on the mechanical behavior of Kevlar/epoxy composite laminates and sandwich structures subjected to quasi‐static punch shear loading. Three types of composite face sheets were fabricated using hand lay‐up technique: Kevlar/epoxy neat, 0.5, and 1 wt. % of nano clay. The mechanical properties of these composites were characterized through compression, shear, and tensile tests. Sandwich structures were then constructed using the fabricated face sheets and an aluminum honeycomb core. Quasi‐static punch shear tests were performed on the composite laminates and sandwich specimens using hemispherical impactors. Numerical simulations of the punch shear tests were conducted in LS‐Dyna, employing appropriate material models and contact definitions for the constituent materials. Furthermore, to further investigate the failure mechanisms, scanning electron microscopy (SEM) analysis was conducted on the fractured Kevlar/epoxy composite plate specimens. The comparison between the experimental outcomes and numerical data demonstrated a strong correspondence, indicating consistency between the two methodologies. In conclusion, the incorporation of 0.5 wt. % nano clay into the Kevlar/epoxy composite resulted in a 5.09% increase in shear strength and an 11.29% increase in maximum reaction force. The study provides insights into the effect of nano clay reinforcement on the punch shear resistance and energy absorption capabilities of Kevlar/epoxy composites and sandwich structures. Highlights: Proper alignment of the nano clay within the epoxy was achieved.The most efficient rate of nano clay was observed to be 0.5% by weight.The mechanical properties of nano clay‐containing composites were improved.Quasi‐static punch shear tests were performed numerically and experimentally.Numerical results were in close agreement with experimental results. [ABSTRACT FROM AUTHOR]

This article discusses the mechanical evaluation of recycled PETG filament for 3D printing. The authors emphasize the importance of plastic recycling and the potential of 3D printing in manufacturing. They focus on PETG as a leading material for 3D printing and examine the feasibility of recycling PETG for additive manufacturing. The study demonstrates that PETG 3D printing waste can be effectively recycled into new filament with promising mechanical properties. The research aims to contribute to the understanding of sustainable usage of PETG in 3D printing and inform future efforts in optimizing recycling processes. Another document provides information on the mechanical properties and testing of a specific material used in 3D printing. The material is tested in two different forms, filament and pellets, to compare their characteristics. The testing includes tensile, compression, and impact tests, with results showing slight differences between the two forms of the material. The document also describes the equipment used for the testing process. Additionally, another document presents the results of a study on the behavior of PETG filament in 3D printing when comparing specimens printed from new material versus recycled material. The study conducted compression, tensile, and impact tests on the specimens. The findings indicate a marginal difference in stiffness, with recycled material exhibiting slightly higher stiffness and increased brittleness. However, caution is advised in drawing definitive conclusions based on this initial data, as the sample size was small and only one recycling cycle was examined. Further research is needed to understand the effects of recycling on material [Extracted from the article]

Solid–liquid composite materials that confine a functional liquid within a porous solid have appeared in a wealth of emerging applications. However, creating dynamic liquid interfaces for efficient ion capture while stably retaining functional liquid in porous confinements is challenging. Here, an aerogel‐confined liquid‐based composite membrane (ALCM) for dynamic and highly efficient uranium capture is reported. As a proof of concept, Kevlar aerogel membrane is selected as the nanoporous solid, and calix[6]arene/tributyl phosphate (C6/TBP) is used as the guest liquid. The obtained ALCMs possess high stability, optimum adhesion between solid‐liquid interface, and high selectivity for uranyl ions (250–6510 times over other competing ions). Different dynamic interface regulating approaches are explored for ALCMs, and uranium extraction efficiency under alternating pressures can be up to 258.48 mg g−1 h−1, outperforming many reported uranium capture materials. This strategy can be applicable to develop a rich family of solid‐liquid composite materials and may spearhead a new paradigm for uranium capture from sustainable seawater resources. [ABSTRACT FROM AUTHOR]

Owing to their flexibility and high thermal resistance, para-aramid based Kevlar™ fabric substrates are an ideal candidate for obtaining flexible gas sensors for new-generation wearable technologies. The morphology of the surface of the substrate where the target gas comes into contact directly affects the important features of the sensor such as detection limit, selectivity, and response. In this context, a feasible technique is introduced to enhance the efficiency of flexible gas sensors utilizing ZnO/Kevlar™, entailing the modification of ZnO morphology. ZnO based gas sensing layers were deposited on Kevlar™ fabric substrates by a two-stage method. Initially, seed layer was produced on Kevlar™ fabric using the ultrasonic bath method, with five different seed layer processing times ranging from 1 min to 20 min. In the nucleation, all nanostructured layers were deposited by hydrothermal method with constant parameters and under the same conditions. As the seeding time was increased, nanorods (1D) formed on the surface became flakes (2D), leading to considerable improvement in NH3 gas sensing properties. The sensor with a 5-min seeding time showed a sensitivity of 49 % at an optimal operating temperature of 190 °C, while the sensor produced in 20 min showed the best response performance with 169 % at 130 °C for 50 ppm NH3 gas. The increase in seeding time not only reduced the operating temperature of the gas sensor through the conversion from 1D nanostructure to 2D, but also significantly increased the sensor response. Under constant hydrothermal conditions and solution concentration, the density per unit area increases. However, after 10 min of seeding, the length of nanorods shortens and turn into a rod-flake hybrid morphology. A superior sensor performance was demonstrated for the samples examined. The obtained results also showed that flexible Kevlar™ fabric could be a feasible and interesting substrate for nanostructured ZnO-based NH3 gas sensors. [Display omitted] [ABSTRACT FROM AUTHOR]

The fabrication of light-weight, highly impact-resistant, and energy-absorbent materials is urgently demanded in many facets of the society from body armor to aerospace engineering, especially under an extreme environment. Carbon nanotubes (CNTs), one of the strongest and toughest materials ever found, also have good conductivity, chemical stability, and thermal stability, etc, making them a competitive candidate as building blocks to help achieve the above goal. In this work, a kind of CNT network was prepared by using chlorosulfonic acid (CSA) to release the internal stress of super-aligned carbon nanotube films (SA-CNTF) and dendritic polyamide amine (PAMAM) to further introduce multiple hydrogen bonds and interlocking structures. The fabricated bioinspired carbon nanotube network films (PAMAM@C-CNTF) have a high toughness of 45.97 MJ/m3, showing an increase of 420% compared to neat SA-CNTF. More importantly, the anti-impact performance of the films (e.g., with a maximum specific energy absorption of 1.40 MJ/kg under 80–100 m/s projectile impact) is superior to that of conventional protective materials from steel and Kevlar fiber, and also exceeds that of any other reported carbon-based materials. The hierarchical energy dissipation mechanism was further revealed through experiment and simulation. Additional functions including intelligent heating/anti-icing, ultraviolet protection, as well as electromagnetic interference shielding properties make these network films have great potential in practical multi-protection applications, especially under an extreme environment. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous zinc (Zn) ion batteries (AZIBs) using low-cost and safe Zn metal anodes are considered promising candidates for future grid-scale energy storage systems, but the Zn dendrite problem severely hinders the further prospects of AZIBs. Regulating Zn depositing behaviors toward horizontal alignment is highly effective and thus has received huge attention. However, such a strategy is usually based on previous substrate engineering, which requires complex preparation or expensive equipment. Therefore, it is essential to develop a novel solution that can realize horizontally aligned Zn flake deposition via easy operation and low cost. Herein, we report an ultrathin and robust Kevlar membrane as the interlayer to mechanically suppress Zn dendrite growth. Compared to the randomly distributed flaky dendrites in the control group, the deposited Zn sheets would grow into parallel alignment with the existence of such interlayer. As the dendrites are effectively suppressed, Zn∥Cu asymmetric, Zn∥Zn symmetric, and Zn∥MnO2 full batteries using Kevlar interlayer deliver significantly improved cycling stabilities. Furthermore, the Zn∥MnO2 pouch cell using a Kevlar interlayer delivers stable cycling performance and shows stable operation during multi-angle folding. We believe this work provides a new possibility for regulating Zn deposition from a crystallographic perspective. [ABSTRACT FROM AUTHOR]

This study explores the stiffness enhancement in textile composites using four different fiber types: carbon, Kevlar, Vectran, and high-tenacity polyester (HTP). Pretension levels of 0.2, 2, 5, and 10 N were applied. A setup was developed to measure fiber stiffness. Results indicate that carbon fiber consistently demonstrates the highest stiffness across all pretenstionlevels, attributable to its high tensile strength and modulus. Kevlar fiber, although initially less stiff than carbon, exhibits the most substantial increase in stiffness, particularly between 5 and 10 N of pretension, reaching a peak stiffness of 33.8 at 10 N. Vectran fiber shows a gradual increase in stiffness, surpassing HTP but slightly lagging behind carbon and Kevlar. The rates of yarn-specific bending stiffness increase were measured as 0.168 for HTP, 0.054 for carbon fiber, 0.173 for Kevlar fiber, and 0.191 for Vectran fiber. The study highlights the importance of understanding how yarn pretension affects the bending stiffness of yarn-polymer composites, which is crucial for advancements in textile engineering. It was found that variations in the bending stiffness of HTP and carbon fibers significantly impacted the composite bending stiffness more than Vectran and Kevlar fibers under pretension during composite formation. High-stiffness yarns were less influenced by increasing pretension during composite fabrication. The study suggests utilizing yarn pretension to control the stiffness of textile/polymer composites and proposes individually tensioning and pultruding fibers or yarns in the polymer matrix before composite formation. A specialized setup for achieving this during the protrusion process is recommended. [ABSTRACT FROM AUTHOR]

Highlights The present work highlights the benefits of matrix strengthening through the inclusion of hard particles within the resin‐impregnated woven Kevlar mat. Aluminium Oxynitride (ALON) particles are added to epoxy resin by 5, 10, and 15 volume percentages. The test coupons were developed through a hand‐lay‐up technique to estimate the low‐velocity impact resistance. The characterization was performed through EDAX and SEM to ensure the presence of the ALON particles and their homogenous distribution respectively. Low‐velocity testing is preferred to assess the capacity of the materials to rebound the incident energy. The damage assessment was made to estimate the material's stiffness. The compression after impact (CAI) was executed to observe the strength of the material after the impact. The post‐CAI micrographic observation reveals the delamination history. The results manifest that the ALON–rich coupon exhibits higher impact resistance to the scale of 33.33% than that of the ALON‐free coupon. The damage assessment and CAI results annunciate the lesser damage and higher compressive strength of ALON‐rich material respectively. The micrographic study studied after the CAI reveals the delamination and failure behavior. Additionally, explicit numerical assessment was conducted to validate the experimental results. A good agreement is attained between the experimental results and numerical predictions. The enriched stiffness of the synthesized material makes it a perfect candidate for structural application where the frequency of impact loading is high. Development of ALON reinforced Kevlar‐Epoxy composites for low‐velocity impact applications. Evaluating the performance of developed composites under low‐velocity impact loading. Determining the optimal volume percentage of ALON in the composites. Studying the fractography of developed composites. Correlation between experimental and numerical studies. [ABSTRACT FROM AUTHOR]

Increasing demand for high-performance lightweight materials for structural applications poses a challenge to material research and development; subsequently, the expectation of a single lightweight material to sustain itself in a multi-functional environment is also difficult. The present research attempts to address the above-said issue by developing and examining the structural stability of aluminum oxynitride (ALON)-reinforced Kevlar fabric-impregnated epoxy composite. Three different weight percentages 5, 10, and 15 of ALON particles are employed to fabricate the composite sheet through the hand-layup technique. The novel inclusion of ALON particles in the resin-impregnated composite is expected to improve its structural stability. Tensile, flexural, and dynamic mechanical tests are conducted to assess the improved structural stability conforming to standards. The results comprehend the significant improvement of 1.75 times in tensile, 2.59 times in flexural, and 1.28 times in damping characteristics for the higher composition of ALON particles compared to the ALON-free composite. The collective outcome of the study delineates that the novel composite is the right candidate for structural loading. The fracture study conducted through a scanning electron microscope reveals that the failure propagation is followed by collective delamination. [ABSTRACT FROM AUTHOR]

A novel conductive and conjugated composite, comprising Kevlar and p-polyphenylenediamine (Kevlar/PPPD) nanocomposite, was successfully synthesized. These techniques provided valuable insights into the structural and optical properties of the Kevlar composite, affirming its potential for applications in polymer photodetectors. Subsequently, the Kevlar/PPPD nanocomposite underwent rigorous testing to evaluate its performance as a photodetector. During these experiments, the current density generated by the nanocomposite (Jph) was measured under two distinct conditions: in the absence of light (dark) and in the presence of light. The results revealed a notable increase in current, rising from 0.32 mA in the dark to 0.58 mA under illuminated conditions. Additionally, the study assessed two crucial parameters, namely photoresponsivity (R) and specific detectivity (D). The R values displayed a consistent decrease, transitioning from an initial value of 2.7 mA/W to a lower value of 1.65 mA/W. Similarly, the specific detectivity (D) values declined from 6.2×107 to 3.8×107 Jones, corresponding to wavelengths of 340 and 540 nm, respectively. What sets this research apart is the Kevlar/PPPD composite's ability to respond effectively to a range of wavelengths, encompassing ultraviolet (UV), visible (Vis), and near-infrared (IR) regions. This broad-spectrum responsiveness positions the Kevlar composite as a highly promising candidate for various photodetection applications. Consequently, the Kevlar/PPPD composite demonstrates its versatility and potential suitability for deployment as a photodetector in a diverse array of applications. [ABSTRACT FROM AUTHOR]

This investigation aims to figure out the contribution of nanoparticles graphene on the high-velocity impact performance and viscoelastic behavior of luffa cylindrica fiber (LCF)/Kevlar sandwich laminates. The epoxy matrix was altered through a mechanical stirring approach by adding varied wt% of the nanofiller graphene. The graphene-added Kevlar/LCF sandwich epoxy composites were created by hot pressing. The mechanical and viscoelastic performance of the sandwich composites was evaluated. The mechanical characteristics of the 3 wt% filler incorporated sandwich composites exceeded those of the control sample. The mechanical characteristics of the sandwich composites with 3 wt% filler incorporated showed improvements of 27.54%, 25.26%, and 26.05%, respectively, for (tensile, flexural and interlaminar shear strength) in contrast to the control sample. Morphological evaluation was executed on the samples being tested to determine the source of the breakage. The micrograph photographs revealed that the 3 wt% nanoparticles incorporated sandwich laminates had the best interfacial bonding and the least fiber disengagement. Dynamic mechanical analysis (DMA) was employed on the generated sandwich composites. The DMA findings revealed that sandwich laminates with 3 wt% nanoparticles responded with improved viscoelastic performance. The capability of the Kevlar/luffa fiber laminates using nanographene in addition to absorbing energy was assessed through a ballistic impact test. It was revealed that integrating nanographene into Kevlar/luffa sandwich composites enhanced their resistance to impact. It was seen from the ballistic impact tests that the presence of 3 wt% nanofiller resulted in substantial energy absorption. The composite sample with 3 wt% filler excels over the control sample by 68.80% in terms of energy absorption. In addition, the optimal wt% graphene nanofiller composite samples could be used to manufacture helmets for ground personnel due to their good mechanical and energy absorption capabilities. [ABSTRACT FROM AUTHOR]

The use of lightweight natural fiber functional composites in the manufacturing of ballistic protective materials has garnered significant attention in recent years. This is due to their superior mechanical properties, cost-effectiveness, and environmental sustainability. Ballistic panels are constructed using multiple layers of diverse composites, which collectively exhibit excellent mechanical properties. These properties enable them to withstand strong impacts enhancing their capability for different applications in defense, military, and aerospace components. The primary focus of this review is to examine the different influential factors that govern the development of novel polymeric materials for current ballistic applications. It also explores various research approaches, such as experimental, analytical, numerical modeling, and empirical techniques. The review highlights both internal factors, such as material composition, and external factors, such as projectile parameters (e.g., nose angles, projectile shape, and projectile size). These factors are crucial for optimizing the robust ballistic performance of natural fiber-based polymer composites. In addition, various valuable insights to develop more effective and sustainable ballistic protective materials for applications in bulletproof helmets, defense, aerospace, and military sectors have also been elaborated. Consequently, the article presents a comprehensive review of the impact of utilizing various natural fibers as alternative materials to Kevlar for armor structures, offering a state-of-the-art perspective and challenges faced in full-scale implementation. [ABSTRACT FROM AUTHOR]

The purpose of the research discussed in this article is to explore the possibility of creating hybrid soft ballistic panel (BP) package variants by integrating into their composition layers of graphene-modified para-aramid fabrics in combinations with the different ballistic Kevlar textiles to improve the durability of the first layers of the soft ballistic panel. To address this goal, the liquid-phase exfoliation (LPE) method was used for integrating dispersions into composites to solve a number of topical problems in the stages of the technological sequence development of processing methods and optimizing processing parameters in accordance with the processing specifics of aramid textiles to achieve the desired properties of modified ballistic fabric, including the provision of coating adhesion to the surface to be modified. To test the results, ballistic experiments were performed and the back-face signature (BFS) of bullet impact on a backing material was analysed according to standards. Bullet impacts on the first ballistic protective fabric layers were also studied. [ABSTRACT FROM AUTHOR]

Boeing and Airbus developed a special testing procedure to investigate the compressive response of laminates that have been impacted (following standards ASTM D 7137 and DIN 65561). This study focuses on both experimental and numerical analysis of Kevlar plates subjected to compression after impact. To ensure high quality and appropriate mechanical properties, the composite plates were manufactured using autoclaving. The DIN 65561 protocol was followed for all three test systems. Initially, ultrasonic C-scanning was performed on all plates before testing to confirm they were free of any significant defects arising from the manufacturing process. Subsequently, low-energy impact testing was conducted at levels ranging from 0 to 8 Joules. Three specimens were tested at each energy level. After the impact, all specimens underwent ultrasonic C-scanning again to assess the internal delamination damage caused by the impactor. Finally, both pristine and impacted specimens were subjected to compressive testing using the special jig specified in DIN 65561. The compressive impact strength results obtained from these tests were plotted against the delamination area measured by C-scanning. These data were then compared to the results obtained from specimens with artificial damage. Semi-empirical equations were used to fit both sets of curves. The same procedure (impact testing, C-scanning, and data analysis) was repeated to investigate the relationship between impact energy and total delamination area. Lastly, finite element modeling was employed to predict the buckling stresses that develop under compression in the impacted systems studied. These modeling approaches have demonstrated good accuracy in reproducing experimental results for CAI tests. [ABSTRACT FROM AUTHOR]

In this article, carbon/kevlar hybrid composites were prepared using Vacuum Assisted Resin Infusion (VARI). The sandwich structure with plain carbon weave fabric as the core layer and plain kevlar weave fabric as the surface layer was selected as reinforcement and the solution of epoxy resin and curing agent was selected as matrix. The low velocity impact experiment and compression after impact (CAI) experiment were carried out on the samples at different hybrid ratio and different temperatures, and the mechanical response on the impact loads were analyzed respectively. The results show that the specimen can limit the delamination defect expansion of the surface kevlar fiber as the carbon fiber used as the core layer, which reduce the delamination defect area and improve the impact resistance of the sample. The toughness of the sample improves the brittle failure mode, that is, the sample still has a certain bearing capacity after the load exceeds the maximum strength, the sandwiched composites presents a positive hybrid effect. With the increase of temperature, the matrix was obviously softened, the macromolecular movement in the system was intensified, the three‐dimensional network macromolecular structure of the matrix and the fiber/matrix interface properties were damaged, and the mechanical properties showed an obvious downward trend. As far as the influences of hybrid ratio and temperature on impact behavior of composite are concerned, it lay a theoretical foundation for the industrial application of carbon/kevlar hybrid composites. Highlights: The sandwiched structure was used to design the composites, which greatly improves the impact properties of the specimens.The impact properties and compression after impact properties at different hybrid ratios and different temperatures were studied.Based on the hybrid effect and temperature effect, the impact failure mechanism of the sample was analyzed. [ABSTRACT FROM AUTHOR]

The main objective of this study is to enhance the interfacial adhesion between Kevlar fiber‐reinforced epoxy composite for a single lap joint. This has been achieved by performing various chemical treatments on Kevlar fiber. Moreover, the nanofiller‐added epoxy matrices were also used for investigating its potentiality in a single lap joint. A thorough comparison has been made among various chemical treatments based composite and modified epoxy matrix composite. The tensile strength of similar and dissimilar single lap joints was investigated through experiments and was analyzed by SEM, XRD, and Weibull model. It was perceived that the tensile shear strength and Weibull modulus of the treated similar Kevlar lap joint were 21.45% and 40.18% higher than the similar nanocomposite joint; also, it has been found that an increment of about 79.8% and 76.64% with that of untreated similar Kevlar joint. Furthermore, the failure progression of optimized joints was evaluated by acoustic emission (AE) monitoring. Highlights: Interfacial adhesion study of Kevlar fiber with matrix in single lap joint.Kevlar surface modification and epoxy modified by nanocomposites were used.The lap shear strength of similar and dissimilar single lap joint composites.SEM, XRD, and Weibull analysis and AE monitoring were used for this research.Chemical treatments on Kevlar fiber have enhanced the interfacial adhesion. [ABSTRACT FROM AUTHOR]

This research investigates the influence of kevlar and glass fiber reinforcements on the mechanical and thermal properties of epoxy/vinyl ester (hybrid resin) composite. The hybrid resin was synthesized by achieving an interpenetrating network between epoxy and vinyl ester. The composites were characterized using tensile, flexural, impact, and thermo‐gravimetric analysis (TGA). Scanning electron microscopy was employed to analyze surface morphology whereas Fourier‐Transformation Infrared Spectroscopy (FT‐IR) was used to investigate the possible interaction between the constituents of the composites. The findings have shown a notable improvement in the mechanical properties after the hybridization of the resin. For reference, the tensile strength of glass/hybrid resin and kevlar/hybrid resin composites were observed to increase by 8.33% and 23.65%, as compared to glass/epoxy and kevlar epoxy composites respectively, whereas, the bending strength of these composites was improved by 8.36% and 30.61%, respectively. TGA also showed an enhanced thermal stability of the hybrid resin‐based composites. Such improvements are noticed due to multi‐resin incorporation (the oxirane group of epoxy reacts with the hydroxyl group of vinyl ester), confirmed by the FTIR, TGA, and morphological analysis. This study signifies that the proposed hybrid composites are better in terms of strength and modulus relative to conventional metallic materials. Highlights: The paper presents the development of novel hybrid resin, reinforced with synthetic fibers.Hybrid resin is imparted positively and is highly favorable in improving the mechanical properties of composites.The tensile strength of novel composites is increased by 8.33% and 23.65% relative to their base specimens, and a similar trend is observed in flexural and impact analysis.Fractured analysis showed that composite laminates deteriorated more intensely due to cohesive matrix fracture; adhesion failure was not observed at all, as evidenced by the emergence of micro‐cracks in resin.Developed novel composites exhibited maximum thermal stability; residual char in glass/epoxy/vinyl‐ester composite attained 17.81% higher, whereas kevlar/epoxy/vinyl‐ester achieved 3.56% relative to glass/epoxy and kevlar/epoxy base samples. [ABSTRACT FROM AUTHOR]

The impact resistance of layered polymer structures using polyvinyl butyral (PVB) in combination with Kevlar® fabric and ultra-high molecular weight polyethylene (UHMWPE) were fabricated and tested. Methods of wet impregnation and hot-press impregnation and consolidation of fabric with PVB and UHMWPE were used to manufacture multilayer constructs. All sandwich constructs were fixed to the surface of ballistic clay and subject to a free drop-weight test with a conical impactor having a small contact area. All tests were made at the same impact energy of 9.3 J and velocity of 2.85 m/s. The change in the resistance force was recorded using a piezoelectric force sensor at the time intervals of 40 μs. Using experimental force–time history, the change in the impactor's velocity, the depth of impactor penetration, the energy transformation at various stages of impactor interaction with the sample, and other parameters were obtained. Three indicators were considered as the main criteria for the effectiveness of a sample's resistance to impact: (1) minimum deformation, bulging, of the panel backside at the moment of impact, (2) minimum absorption of impact energy per areal density, and (3) minimal or, better yet, no destruction of structural integrity. Under the tested conditions, the rigid Kevlar–PVB–Kevlar sandwich at the frontside and relatively soft but flexible UHMWPE–Kevlar–UHMWPE layers in the middle helped to localize and absorb impact energy, while the backside Kevlar–PVB–Kevlar sandwich minimized local bulging providing the best overall performance. The front layer damage area was very shallow and less than two impactor tip diameters. The backside bulging was also less than in any other tested configurations. [ABSTRACT FROM AUTHOR]

In this study, the effects of hybridizing carbon fibers with Kevlar fibers and incorporating multiwalled carbon nanotube (MWCNT) particles on low‐velocity impact, tensile, and flexural performance were evaluated experimentally. A manual lay‐up procedure followed by vacuum bag molding was used to construct hybrid composites (carbon and Kevlar) with and without MWCNTs, as well as hybrid composites with varying MWCNT weight ratios of carbon and Kevlar fiber reinforcements. When 0.1 wt% of MWCNT was added to the epoxy to enhance absorbed energy and peak load, the maximum improvements observed were 31% and 28%, respectively. The addition of MWCNTs by 0.5 wt% to the epoxy enhanced the flexural strength and flexural modulus by 66% and 41%, and by 5% with 0.1 wt% and 12.3% with 0.5 wt% MWCNT for tensile strength and tensile modulus, respectively. These improvements were observed in both tensile strength and tensile modulus. As for (C5K10C5), the maximum improvements in absorbed energy and peak load were observed to be 11.2% and 31%, respectively, corresponding to a 0.1 wt% MWCNT addition, whereas the maximum improvement in flexural strength and flexural modulus was 12.28% and 44%, respectively, with a 0.1 wt% MWCNT. These improvements in mechanical properties are primarily attributed to the enhanced stress transfer properties from fibers and nanoparticles to the matrix. This enhancement is a result of the strong interfacial interactions between epoxy and MWCNT nanoparticles. Highlights: MWCNT inclusion effects on mechanical properties of carbon/Kevlar hybrid composites.MWCNT inclusion effects on low‐velocity impact properties of Carbon/Kevlar hybrid composites.The effects of Kevlar and carbon stacking sequence with MWCNT incorporation were investigated. [ABSTRACT FROM AUTHOR]

The study aimed to investigate the impact behavior of fabric laminates composed of carbon, Kevlar, and hybrid materials through low‐velocity impact tests. Non‐hybrid and hybrid laminates were created using layup techniques with sandwich stacking sequences. Drop weight impact tests were conducted using varying levels of impact energy to assess the influence of stacking sequence and hybridization on impact properties. The results showed significant improvements in impact properties with increasing stacking sequence, particularly a 108.8% and 137.4% enhancement in C4 and K4 laminates, respectively. Kevlar laminates exhibited higher energy resistance than carbon laminates, and the Kevlar‐carbon‐Kevlar‐carbon hybrid laminate demonstrated superior impact force and energy absorption capabilities. Additionally, the study analyzed penetration depth and identified different failure modes dependent on stacking sequence and impact energy levels. These findings provide valuable insights for optimizing fabric laminated composites. Thus, the research could be implemented in industries requiring materials with enhanced impact resistance, such as aerospace, automotive, sports equipment, and protective gear manufacturing. Highlights: Investigated the impact performance of stacked fabric structures, including carbon, Kevlar, and hybrid laminated composites, through low‐velocity impact tests.Fabricated both non‐hybrid and hybrid laminates using layup techniques with a sandwich stacking sequence to assess the impact properties of the composite laminates.Observed greater penetration depth in the C2 stacked structure, while the KCKC hybrid laminate showcased greater resistance to a depth of penetration (DOP).Various failure modes were investigated, demonstrating their relationship with stacking sequence and impact energy levels. [ABSTRACT FROM AUTHOR]

Developing ultrahigh‐strength fabric‐based triboelectric nanogenerators for harvesting high‐impact energy and sensing biomechanical signals is still a great challenge. Here, the constraints are addressed by design of a multistrand twisted triboelectric Kevlar (MTTK) yarn using conductive and non‐conductive Kevlar fibers. Manufactured using a multistrand twisting process, the MTTK yarn offers superior tensile strength (372 MPa), compared to current triboelectric yarns. In addition, a self‐powered impact sensing fabric patch (SP‐ISFP) comprising signal acquisition, processing, communication circuit, and MTTK yarns is integrated. The SP‐ISFP features withstanding impact (4 GPa) and a sensitivity and response time under the high impact condition (59.68 V GPa−1; 0.4 s). Furthermore, a multi‐channel smart bulletproof vest is developed by the array of 36 SP‐ISFPs, enabling the reconstruction of impact mapping and assessment of body injury location and levels by real‐time data acquisition. Their potential to reduce body injuries, professional security, and construct a multi‐point personal vital signs dynamic monitoring platform holds great promise. [ABSTRACT FROM AUTHOR]

The demand for fiber-reinforced polymers (FRPs) has significantly increased in various industries due to their attributes, including low weight, high strength, corrosion resistance, and cost-efficiency. Nevertheless, FRPs, such as glass and Kevlar fiber composites, exhibit anisotropic properties and relatively low interlaminar strength, rendering them susceptible to undetected damage. The integration of real-time damage detection processes can effectively mitigate this issue. This paper introduces a novel method for fabricating embedded capacitive sensors within FRPs using a coating technique. The study encompasses two types of fibers, namely glass and Kevlar fiber/epoxy composites. The physical vapor deposition (PVD) technique is employed to coat bundle fibers with conductive material, thus creating embedded electrodes. The results demonstrate the uniform distribution of nanoparticles of gold (Au) along the fibers using PVD, resulting in a favorable resistance of approximately ≈100 Ω. Two sensor configurations are explored: axial and lateral embedding of the coated yarn (electrodes) to investigate the influence of load direction on the coating yarn. Axial-sensor configuration specimens undergo tensile testing, showcasing a linear response to axial loads with average sensitivities of 1 for glass and 1.5 for Kevlar fiber/epoxy composites. Additionally, onset damage is detected in both types of fiber composites, occurring before final fracture, with average stress at the turning point measuring 208 MPa for glass and 144 MPa for Kevlar. The lateral-sensor configuration for glass fiber-reinforced polymer (GFRP) exhibits good linearity towards strain until failure, with average gauge factors of 0.25 and −2.44 in the x and y axes, respectively. [ABSTRACT FROM AUTHOR]

In general, the majority of fiber-reinforced polymer composites (FRPs) used in structural applications comprise carbon, glass, and aramid fibers reinforced with epoxy resin, with the occasional utilization of polyester and vinyl ester resins. This study aims to assess the feasibility of utilizing recyclable and sustainable materials to create a resilient composite suitable for structural applications, particularly in scenarios involving low-velocity and high-velocity impact (LVI, HVI) loading. The paper presents a comparative analysis of the performance of E-glass, aramid, and eco-friendly basalt-reinforcing fabrics as reinforcement fibers in both thermosetting (epoxy) and recyclable thermoplastic (Elium©) resins. Given the limited research on Elium composites, especially those incorporating basalt-reinforcing fiber, there is an urgent need to expand the databases of fundamental mechanical properties for these diverse composites. This necessity is exacerbated by the scarcity of the literature regarding their performance under low- and high-velocity impact loadings. The results of this study will demonstrate the potential of basalt-reinforced Elium composite as an effective recyclable and environmentally friendly structural material system for both static and dynamic loading conditions. [ABSTRACT FROM AUTHOR]

Fiber/metal hybrid composites are perceived as superior materials for applications in machine tools because of their enhanced machinability, lightweight nature, and vibration-damping capabilities. The application of AWJM to hybrid composites introduces challenges, including kerf convergence ratio and surface irregularity issues throughout the machining process. This study is all about the AWJM of a Kevlar fiber/SS wire mesh epoxy composite with silicon carbide filler particles and garnet as the abrasive material. The study aims to investigate the effects of varying machining conditions, such as cutting velocity, abrasive performance rate, and nozzle tip distance, and to determine the most effective machining parameters using TOPSIS technique. To achieve this, a total of 27 different experimental trials were conducted, and two key attributes, namely kerf convergence ratio and surface irregularity, were recorded. This approach empowers all-encompassing evaluation and comparison of diverse machining parameter combinations, thus expediting the selection of the most fitting parameters to attain desired machining outcomes. [ABSTRACT FROM AUTHOR]

When Operation Enduring Freedom (OEF) commenced in October 2001, the U.S. Special Forces (SF) were the first U.S. military unit on the ground in Afghanistan, utilising their Unconventional Warfare (UW) capabilities. Despite their significant role at the initial stage of the military campaign, SF began to encounter numerous challenges from as early as 2002 and throughout OEF. Based on an analysis of forty-five master's theses authored by SF officers, this paper discusses the structural-organisational and cultural-conceptual challenges. These obstacles led to the marginalisation of SF's UW efforts. Scholarship on special operations forces (SOF) often regards the period of the so-called global war on terrorism (GWOT) as U.S. SOF's golden age focusing predominantly on the activities of SOF units linked to the U.S. Joint Special Operations Command rather than on SF. By examining the challenges faced by SF, this article aims to contribute to a more nuanced discussion of SOF efforts during GWOT. [ABSTRACT FROM AUTHOR]

Polymer composites with lightweight, ultralow dielectric constant, excellent thermal insulation and mechanical properties are in high demand in aerospace, transport, wireless communications and other fields. In this work, the three‐dimensional woven Kevlar/glass hybrid composites (3DKGC) with lightweight, high strength, excellent dielectric and thermal insulation properties were obtained with the Kevlar fiber and glass fiber as the raw materials. The results showed that the volume content of air in 3DKGC is over 82% and the volume density is as low as 0.29 g·cm−3, while the compression strength is as high as 7.68 MPa. 3DKGC exhibits an ultra‐low dielectric constant of 1.21. The wave transmission performance of 3DKGC was simulated using the CST software. The simulation results showed that 3DKGC has a return loss of 0.036 and a gain of 0.9982. Moreover, the 3DKGC provides superior thermal insulation than three‐dimensional woven Kevlar composites (3DKC) and conventional polystyrene foams. In summary, this work offers an attractive material that holds significant potential for application in aerospace, wireless communications and other fields where lightweight multi‐purpose composites are required. Highlights: 3D woven Kevlar/glass hybrid composites (3DKGC) were proposed and fabricated.3DKGC exhibits low density of 0.29 g·cm−3 but high compression stress (7.68 MPa).3DKGC possesses outstanding dielectric and thermal insulation properties.3DKGC leverages the benefits of cost‐effectiveness and holistic functionality. [ABSTRACT FROM AUTHOR]

Continuous hybrid fiber‐reinforced composites (CHFRCs) have excellent mechanical properties, and strong designability, and are widely used in aerospace and other fields. The development of 3D printing technology offers novel directions in the design and manufacture of complicated CHFRC components in aerospace. For this purpose, this study focused on the design and characterization of hybrid continuous fiber‐reinforced composites prepared by 3D printing. The rapid mold‐free integrated manufacturing of hybrid continuous Kevlar/carbon fiber‐reinforced composites was realized by coaxial hybrid 3D printing technology. The regulation and mechanism of tensile properties of 3D‐printed CHFRCs were elucidated. The tensile strengths of 3D‐printed CHFRCs were enhanced by up to 15.3% and 92.4%, respectively, compared to single continuous carbon and Kevlar fiber composites produced by the same process parameter. A new tensile modulus predicting method for 3D‐printed CHFRCs was proposed. It mitigated the influence of complex interfacial characteristics on mechanical property prediction and achieved precise estimation of the tensile modulus of 3D‐printed CHFRCs. This will provide the theoretical support for the application and development of 3D‐printed CHFRCs. Highlights: Mouldless rapid manufacturing of coaxial hybrid fiber composites achieved.The tensile strength and modulus of the fiber composites are greatly improved.A new prediction method for the tensile modulus of 3D‐printed composites is proposed. [ABSTRACT FROM AUTHOR]

The present research is aimed to understand the influence of graphene-reinforced carbon/Kevlar hybrid fabric epoxy composites. Samples HG0, HG2, HG4, and HG6 are fabricated using four layers of fabric mat and with varying graphene weight percentage as 0, 2, 4, and 6 wt.%, respectively. Mechanical characterizations such as hardness, tensile, and flexural strength were individually assessed. Thermal stability is evaluated through thermos-gravimetric analysis. Composite HG6 with high filler loading showed 71% and 114.4% greater tensile and flexural strength compared to unfilled HG0 specimen. Similarly, HG6 exhibited greater thermal stability. Inclusion of graphene particles in higher concentration improved the interfacial bonding between fibre/matrix/filler system. Fracture surfaces are analysed using scanning electron microscopy to understand the failure mechanisms. [ABSTRACT FROM AUTHOR]

The unique properties of upconversion nanoparticles (UCNPs) are responsible for their diverse applications in photonic materials, medicine, analytics, and energy conversion. In this study, water-soluble rare-earth upconversion nanomaterials emitting green, yellow, and red light under 1550 nm excitation were synthesized. These nanomaterials were then integrated into water-soluble Kevlar nanofibers (KNFs) to fabricate ultra-thin composite films exhibiting favorable mechanical characteristics. The characterization of the products, along with their luminescent, mechanical, and temperature-sensing properties, was examined. The results indicate that the composite material exhibited varying colors based on the doped nanoparticles when subjected to 1550 nm excitation. The composite showed highly sensitive temperature-sensing properties, excellent luminescent characteristics, and superior mechanical strength. This study suggests that KNFs are effective carriers of UCNPs. This study offers a reference for the utilization of rare-earth upconversion in anti-counterfeiting displays, wearable health monitoring, and remote temperature sensing. [ABSTRACT FROM AUTHOR]

Low damage tolerance and residual strength are the main drawbacks of carbon fiber composite laminates that limit their application in many lightweight structures. This study demonstrates the exceptional damage tolerance and high fracture toughness of carbon-Kevlar hybrid laminate, where Kevlar plies are placed between two carbon fiber face sheets. Flexural strength after damage and mode I translaminar fracture toughness of carbon and Kevlar and the hybrid laminates were evaluated using three-point bending and single-edge notched bending tests, respectively. The damage mechanisms in the three configurations were investigated using micro-computed tomography and correlated with their mechanical responses. The results showed that the hybrid laminate could sustain 70% of the laminate strength after fiber damage occurs and can sustain the same strength for large strains, unlike carbon and Kevlar fiber laminates, where they both lose their mechanical integrity after fiber breakage. Moreover, this laminate showed 200% and 170% larger specific absorbed energy than carbon and Kevlar laminates, respectively. The improvement can be justified by the propagation of fiber breakage at three different positions in the Kevlar core and the delamination at the carbon-Kevlar interface that allowed larger energy dissipation during fracture. Additionally, it showed 21% and 42.7% larger absolute and specific fracture toughness, respectively, than the carbon fiber laminate. [ABSTRACT FROM AUTHOR]

In this study, the hybrid usage of Kevlar and steel fiber in concrete pavements was investigated. For this purpose, the concrete was designed using the water/binder ratio (0.40, 0.45, 0.50), silica fume (instead of cement 0, 5, 10%), Kevlar fiber (0 gr/m3, 500 gr/m³, 1000 gr/m³) and steel fiber (0 gr/m³, 500 gr/m³, 1000 gr/m³). Taguchi method was used as the experimental design, and optimum levels of parameters were determined for 28-days compressive strength, flexural strength, and toughness. According to the experiments and observations, the positive effect of Kevlar fiber upon energy absorption capacity (toughness), compressive and flexural strength of concrete was determined. Using only Kevlar fiber increasing up to 5.1% in compressive strength and up to 14.5% in flexural strength were observed. Considering the obtained results, Kevlar was noticed as a possible recycling material to be introduced into the economy by adding concrete. [ABSTRACT FROM AUTHOR]

The rise of the Internet of Things has spurred extensive research on integrating conductive materials into textiles to turn them into sensors, antennas, energy storage devices, and heaters. MXenes, owing to their high electrical conductivity and solution processability, offer an efficient way to add conductivity and electronic functions to textiles through simple dip coating. However, manual development of MXene‐coated textiles restricts their quality, quantity, and variety. Here, a versatile automated yarn dip coater tailored for producing continuously high‐quality MXene‐coated yarns and conducted the most comprehensive MXene‐yarn dip coating study to date is developed. Compared to manual methods, the automated coater provides lower resistance, superior uniformity, faster speed, and reduced MXene consumption. It also enables rapid coating parameter optimization, resulting in a thin Ti3C2 coating uniform over a 1 km length on a braided Kevlar yarn while preserving its excellent mechanical properties (over 800 MPa) and adding Joule heating and damage sensing to composites reinforced by the yarns. By dip‐coating five different yarns of varying materials, diameters, structures, and chemistries, new insights into MXene‐yarn interactions are gained. Thus, the automated dip coating presents ample opportunities for scalable integration of MXenes into a wide range of yarns for diverse functions and applications. [ABSTRACT FROM AUTHOR]

In this work, four varieties of hybrid Fiber-Reinforced Polymer (FRP) panels made of kevlar-29 and natural fibers are studied. All panels have kevlar-29 face sheets and natural fiber core, such as jute, flax, sisal, and hemp. This research focuses on the behavior of these hybrid FRP panels under flexural and impact loading so that the panels can be explored for the structural/semi-structural members of army shelters, portable helipad, and roofing panels in high-altitude areas. Natural fibers are chemically treated with NaOH to improve hydrophobicity. The panels are vacuum bagged, the fiber volume fraction is 0.39, and the thickness is close to 4 mm. Three-point flexural loading using the universal testing machine and low-velocity impact loading up to 24 J under drop weight impact test setup is carried out to characterize the panels. Damage area, delamination, permanent deformation, indentation depth, energy absorbed, flexural strength, and modulus are measured. The hybrid flax/kevlar panel and hemp/kevlar panel, each resist impact with permanent deformation less than 0.5 mm up to 24 J. Without significant face sheet or core fiber breakage, the delamination is spread over a small radial distance of 18.5 and 24.5 mm, respectively. Interface matrix breakage causes delamination. The load vs deflection curve is almost linear under flexural loading, and specimens failed under compression at 240 MPa. The numerical simulation is also done using ANSYS and LS-DYNA for detailed study. [ABSTRACT FROM AUTHOR]

The purpose of this paper was to show how modified benzoxazine resin/ethylene–propylene–diene monomer rubber/Kevlar composites are prepared. The compatibilization of polar benzoxazine resin and non‐polar EPDM was carried out by EPDM‐g‐MAH copolymer synthesized as a compatibilizer, and then, the microwave (MW) irradiation method and conventional thermal cure (CV) were used to cure this composite. The samples cured by both methods were evaluated and compared by differential scanning calorimetry analysis (DSC), dynamic mechanical thermal analysis (DMTA), scanning electron microscope (SEM), and thermo‐gravimetric analysis (TGA). Microwave curing significantly reduced the curing time, and the composites cured with MW irradiation had higher glass transition temperature (Tg), more uniform curing, higher cross‐link density, and more thermal stability than CV‐cured composites. Highlights: Constructing BZ/EPDM/Kevlar thermal composite for use at high temperatures.Using modified resin to reduce curing temperature and improve final properties.Creating compatibility between non‐polar EPDM rubber and polar BZ resin.Investigating and comparing between thermal and MW curing of the composites. [ABSTRACT FROM AUTHOR]

This work aims to explore the effect of side load and rotational speed on the tribological behavior of a novel ceramic–epoxy composite in Kevlar matrix casing lining that is in contact with a rotating drillpipe tool joint (DP-TJ) coated with the same composite. Three rotational speeds (65, 115, and 154 rpm) and three side loads (500, 700, and 1000 N) were considered under water-based mud (WBM) lubrication. Wear depths, volumes, and specific casing wear rates (K) were determined for each combination of speed and load. The wear depth and K were found to increase with an increasing applied side load. However, the specific casing wear rate at the rotational speed of 115 rpm was found to be the lowest among the three speeds. This is mainly due to a probable lubrication regime change from boundary lubrication at 65 rpm to hydrodynamic lubrication with a thick lubricant film at 115 rpm. The digital microscope images were used to determine the wear mechanism, showing that at low speeds, the main mechanism was abrasive wear, but the increase in the speed brought about more adhesive wear. In contrast, the change in the side load does not affect the wear mechanism of the casing. Scanning electron microscopy and energy-dispersive spectroscopy (EDS) were used to analyze the surface and composition of the novel material before and after the wear tests. [ABSTRACT FROM AUTHOR]

Shear thickening fluid (STF), carbon nanotubes (CNTs) are both promising in body protection and anti-impact for the drastic viscosity change of STF and the extremely high tensile strength and elongation of CNTs. The excellent performance of the above two combined with traditional Kevlar fabrics can significantly improve the mechanical properties and reduce the number of layers used for body protection. This work reports a new method to prepare STF/CNTs/Kevlar with excellent tensile properties and anti-impact performance by spraying method with 1 wt% polyvinyl alcohol (PVA) solution as a binder for better integration between CNTs and Kevlar. Surface morphology changes in the preparation process indicate the combined structure of PVA binder, CNTs, and STF, presenting a uniform macroscopic and nonuniform microscopic surface of STF/CNTs/Kevlar composite. The tensile strength and anti-impact properties including punch residual velocity and energy absorbed were studied and results for STF/CNTs/Kevlar composite are 669.8 ± 18.1 MPa, 1.602 ± 0.045 m/s, and 21.683 ± 1.182 J in 12 ms, increased by 46.4%, 23.0%, and 240.2%, respectively, compared with neat Kevlar, owing to the improved tight bonding and friction between fabrics yarns caused by PVA adhesive and tangled CNTs, accompanied with the enhanced viscosity of STF under forces. Highlights • Composites were made by spraying PVA, CNTs, and STF onto Kevlar fabrics; • The tensile strength of the composite was 46.4% higher than Kevlar; • The energy absorbed in 12 ms in anti-impact tests was improved by 240.2%; • Tight bonding and friction between yarns are reasons to improve properties; • The raised viscosity of STF under forces is useful for mechanical properties. [ABSTRACT FROM AUTHOR]

High‐performance fibrous materials urgently desired for fabricating energy storage devices to power wearable textile electronics are expected excellent mechanical properties, improved output capacitance, and rapid charge/discharge capability; nevertheless, their contradictory requirements in material design impose immense challenges. Inspired by the robust structure of higher plants that evolve over millions of years, herein, an interfacial engineering strategy is proposed for synergizing the mechanical strength and electrochemical performance of Ti3C2TX MXene fibers by selecting aramid (Kevlar) nanofibers and borate ions (B) as the enhancers. The intercalation of Kevlar nanofibers endows the nascent wet‐spun MXene gel fibers with a high stretchable ratio through physical interaction (hydrogen bonds), greatly aligning the orientation of MXene nanosheets. B‐cross‐links introduce covalent bonds between MXene nanosheets, which together with hydrogen bonds significantly enhance fiber strength. More importantly, optimal ion transport kinetics is achieved by synergizing the inverse impacts of Kevlar nanofibers and B‐cross‐link on interlayer spacing, guaranteeing excellent electrochemical performances. Benefiting from their excellent mechanical, electrical, and electrochemical performances, borate (B)‐cross‐linked MXene/Kevlar fibers (MKB) are simultaneously adopted as fibrous electrodes and receiving antennae for asymmetric supercapacitors with wireless charging functions. The proposed strategy provides an avenue for designing high‐performance functional fibers for future wearable applications. [ABSTRACT FROM AUTHOR]

The effectiveness of RC panels in terms of explosion resistance was studied. Three field detonation distances and three masses of Gelatin equivalent to that is typically utilized in weapons were employed for the experiments. In the FE investigation, the CONWEP and Jones-Wilkins-Lee (J-W-L) models were applied. Kevlar, E-glass, and carbon fiber reinforced polymer (CFRP) composites were studied for their effects. For the incontact explosion, the panels experienced severe localized damage, debris, and cratering, whereas the most prevalent failure modes for the explosion from 0.5 m were cracking and one-way bending/splitting. Changes in weapon design and internal mechanics can achieve the same result for a highly closed field explosion, thus can help in reducing the need for sensors and lowering weapon development costs. The strain rate raised from 44 to 156 s−1 as the amount of explosive increased but decreased from 156 to 11 s−1 as the explosion distance increased. Simulations using the multi-detonation CONWEP technique correctly anticipated the damage, whereas those using the J-W-L model overestimated it. Peak pressure was significantly influenced by the explosion distance in contrast to the explosive amount. The blast pressure measured on the panel was 479–534 MPa for an incontact explosion and 43.7 MPa when the detonation distance was extended to 0.5 m. In terms of performance against blast loading, CFRP composite outperformed E-glass and Kevlar composite. Compared to when it was employed at the back surface, the CFRP laminate at the panel's front surface was not found to be as successful at reducing splitting damage. [ABSTRACT FROM AUTHOR]

The Kevlar fiber-reinforced polymer (KFRP) is widely used in various fields due to its excellent mechanical and physical properties. However, the material is prone to processing defects such as burring and furry during secondary processing. In this paper, based on the cutting removal mechanism of KFRP, a "pull-shear" material removal principle for the residual fibers was proposed and analyzed. Then, a novel compound structure milling tool was designed. Theoretical and experimental analyses of the milling tests were carried out on the plain-woven KFRP composites. The result indicates that when the fibers are subjected to tension, the cutting surface quality is significantly improved. Therefore, when the "pull-shear" removal principle can be implemented effectively, the fibers can be effectively cut off in time. The "pulling-shearing" effect can be effectively implemented by the novel compound structure milling tool. The milling surface quality of the novel compound structure milling tool is better than the conventional tools. The burr defect factor gradually decreases with the increase of the feed speed. The burr defect factors tend to increase with the increase in cutting speed. [ABSTRACT FROM AUTHOR]

The response of sandwich structures under the synergistic effects of blast wave and fragments is a topic of interest for researchers and designers. Thus, the performance of a sandwich structure used for enhancing the protection of a target structure is numerically investigated because it may experience such complex loading conditions resulting from combined blast and fragment impact. A conventional sandwich structure modelled using aluminium alloy resists a bare blast load imposed on it. Analysis, however, reveals that fragments penetrate through the front facesheet of a conventional sandwich structure, indicating a lower resistance of the front facesheet to combined blast and fragment effects. Thus, the behaviour of conventional aluminium honeycomb sandwich structures is compared with enhanced sandwich configurations consisting of a front facesheet covered with multilayer lightweight composite Kevlar fabric material. The Kevlar fabric arrests the maximum number of fragments, and reduces their momentum, thereby reducing the damage level in the sandwich structure. The effect of the charge weight and shape of the fragments on the damage modes of the sandwich structure is also assessed. With the increase in charge weight, the momentum of the fragments is found to increase, and these penetrate the back facesheet of the sandwich structure. [ABSTRACT FROM AUTHOR]

In this study, five three-dimensional angle-interlock fabrics with different warp and weft densities were fabricated using 1000D Kevlar filaments. The Kevlar/EP composites were prepared by vacuum-assisted molding techniques. The low-velocity impact property of the composite was tested, focusing on the effects of the warp and weft densities, impact energy, impactor shape, and impactor diameter. The damage area, dent depth, and crack lengths in the warp and weft direction were used to evaluate the impact performance, and the specimens were compared with plain-weave composites with similar areal densities. The dominant failure mode of the conical impactor was fiber fracture, while the dominant failure mode of the hemispherical impactor was fiber–resin debonding. The cylindrical impactor showed only minor resin fragmentation. The residual flexural strength of the composite after impact was tested to provide insights into its mechanical properties. The study findings will provide a theoretical basis for the optimization of the design of impact-resistant structures using such materials and facilitate their engineering applications. [ABSTRACT FROM AUTHOR]