Search Results (331)

The increasing threat posed by micrometeoroids and orbital debris to in-orbit spacecraft necessitates the development of lightweight and deformable shielding systems capable of withstanding hypervelocity impacts. Ultra-high-molecular-weight polyethylene (UHMWPE) films, owing to their high specific strength and energy-absorption capacity, present a promising candidate for such applications. However, the hypervelocity impact response of thin, highly oriented UHMWPE films—distinct from bulk plates or composites—remains poorly understood, particularly for micron-scale particles at velocities relevant to space debris (≥8 km/s). In this study, we systematically investigate the impact resistance of 0.1 mm UHMWPE films using a plasma-driven microparticle accelerator and a hypervelocity dust gun to simulate impacts by micron-sized Al₂O₃ and Fe particles at velocities up to ~8.5 km/s. Through detailed analysis of crater morphology via scanning electron microscopy, we identify three distinct damage modes: plastic-dominated craters (Type I), fracture-melting craters (Type II), and perforations (Type III). These modes are correlated with impact energy and particle size, revealing the material’s transition from large-scale plastic deformation to localized thermal softening and eventual penetration. Crucially, we provide quantitative penetration thresholds (e.g., 2.25 μm Al₂O₃ at 8.5 km/s) and establish a microstructure-informed damage classification that advances the fundamental understanding of UHMWPE film behavior under extreme strain rates. Our findings not only elucidate the energy-dissipation mechanisms in oriented polymer films but also offer practical guidelines for the design of next-generation, flexible spacecraft shielding systems. Full article

The structural dependence of self-propelled motion in micro/nanomotors is essential for effectively predicting and controlling their dynamic behaviors. In this study, platinum–silica (Pt-SiO₂) micromotors, with structures ranging from spherical Janus to dimer configurations, are fabricated through conventional template-assisted deposition, followed by annealing. These structures are used to investigate how geometry influences motion. Our results demonstrate that the architecture of the Pt-SiO₂ micromotor strongly affects its propulsion mode and trajectory in solution. When immersed in a hydrogen peroxide (H₂O₂) solution, spherical Janus Pt-SiO₂ micromotors exhibit quasi-linear motion, driven by the Pt side (Pt pushing). In contrast, dimeric structures and intermediate forms varied from Janus to dimer display quasi-circular trajectories with continuously changing directions, characteristic of Pt-dragging motion. We reveal that these distinct propulsion behaviors stem from differences in the spatial distribution of Pt on the SiO₂ sphere surface. Variations in Pt distribution alter the exposed silica surface area—rich in hydroxyl groups—which modulates the driving force and causes the resultant force acting on the micromotor to deviate from its mass center axis (or the axis connecting the mass centers of the Pt component and silica sphere), thereby inducing circular motion. This study offers a versatile strategy for fabricating Pt-SiO₂ micromotors with tailored structures and advances the fundamental understanding of structure-dependent self-propulsion mechanisms. Full article

The present article relates to the description of phenomenological relations of amorphous material behavior within the framework of viscoelasticity and elastic-viscoplasticity theory, as well as to the creation of its digital analog. Ultra-high-molecular-weight polyethylene (UHMWPE) is considered in the study. The model is based on the results of a series of experimental studies. Free compression of cylindrical specimens in a wide range of temperatures [−40; +80] °C and strain rates [0.1; 4] mm/min was performed. Cylindrical specimens were also used to determine the thermal expansion coefficient of the material. Dynamic mechanical analysis (DMA) was performed on rectangular specimens using a three-point bending configuration. Maxwell and Anand models were used to describe the material behavior. In the framework of the study, the temperature dependence of a number of parameters was established. This influenced the mathematical formulation of the Anand model, which was adapted by introducing the temperature dependence of the activation energy, the initial deformation resistance, and the strain rate sensitivity coefficient. Testing of the material models was carried out in the process of analyzing the deformation of a spherical bridge bearing with a multi-cycle periodic load. The load corresponded to the movement of a train on a bridge structure, without taking into account vibrations. It is shown that the viscoelastic model does not describe the behavior of the material accurately enough for a quantitative analysis of the stress–strain state of the structure. It is necessary to move on to more complex models of material behavior to minimize the discrepancy between the digital analog and the real structure; it has been established that taking into account plastic deformation while describing UHMWPE would allow this to be performed. Full article

The continuous advancement of modern weaponry has intensified the pursuit of next-generation ballistic protection systems that integrate lightweight architectures, superior flexibility, and high energy absorption efficiency. This review provides a technological overview of current trends in the design, processing, and performance optimization of metallic, ceramic, polymeric, and composite materials for ballistic applications. Particular emphasis is placed on the role of advanced surface coatings and nanostructured interfaces as enabling technologies for improved impact resistance and multifunctionality. Conventional materials such as high-strength steels, alumina, silicon carbide, boron carbide, Kevlar^®, and ultra-high-molecular-weight polyethylene (UHMWPE) continue to dominate the field due to their outstanding mechanical properties; however, their intrinsic limitations have prompted a transition toward nanotechnology-assisted solutions. Functional coatings incorporating nanosilica, graphene and graphene oxide, carbon nanotubes (CNTs), and zinc oxide nanowires (ZnO NWs) have demonstrated significant enhancement in interfacial adhesion, inter-yarn friction, and energy dissipation. Moreover, multifunctional coatings such as CNT- and laser-induced graphene (LIG)-based layers integrate sensing capability, electromagnetic interference (EMI) shielding, and thermal stability, supporting the development of smart and adaptive protection platforms. By combining experimental evidence with computational modeling and materials informatics, this review highlights the technological impact of coating-assisted strategies in the evolution of lightweight, high-performance, and multifunctional ballistic armor systems for defense and civil protection. Full article

Escalating global explosive threats pose persistent challenges to building security. To address this issue, a novel Ultra-High-Molecular-Weight Polyethylene (UHMWPE) cavity protection structure is proposed to enhance the blast resistance of reinforced concrete (RC) walls. In this study, numerical simulation was conducted to investigate the blast resistance and protective mechanisms of the UHMWPE cavity protection structure. The results reveal that the protection mechanism involves two synergistic processes: dissipating energy through plastic deformation of the high-toughness panel and attenuating the shock wave via cavity wave modulation. This configuration achieves a peak overpressure attenuation exceeding 88% within the cavity zone, thereby effectively mitigating blast effects. Compared to an unprotected wall, the UHMWPE cavity protection system achieves a peak overpressure attenuation rate exceeding 86.3% on the blast-facing surface and decreases the peak displacement at the wall center by 60%, effectively suppressing localized damage. Parametric research further indicates that adding stiffeners to the cavities and making the panels thicker can greatly increase the ability to dissipate energy and overall stability of the UHMWPE cavity protection panel. The findings of this study offer valuable guidance for the design of high-performance blast-resistant structures. Full article

This paper presents the design and experimental investigation of a multifunctional friction test bench, aiming to characterize the frictional and transmission efficiency of rope–drum systems in high-altitude wind power generation. The study addresses a critical gap in the experimental validation of key components for this demanding application. The test bench, comprising loading, power, test, and data acquisition modules, was designed to measure the equivalent friction coefficient (a comprehensive macro-parameter, not the traditional material friction coefficient) between an ultra-high-molecular-weight polyethylene (UHMWPE) fiber rope and a drum, as well as the transmission efficiency of pulleys. Key parameters, including contact angle, gasket material (steel vs. polyamide (PA)), groove type (U vs. V), and rotational speed, were systematically tested using tension and speed and torque sensors for data acquisition. Experimental results show that the equivalent friction coefficient initially increased and then decreased with the contact angle, reaching a maximum of approximately 0.15 at 100°. The coefficient was positively correlated with rotational speed, increasing by about 40% for steel and 10% for PA linings as speed rose from 25 to 100 rpm. Steel linings exhibited a significantly higher equivalent friction coefficient (0.14–0.17) than PA linings (0.10–0.13). Similarly, in transmission tests, steel pulleys demonstrated superior efficiency compared to PA pulleys, while V-grooves slightly reduced efficiency compared to U-grooves. Furthermore, pulley misalignment was found to decrease transmission efficiency. This work provides essential experimental data and a robust testing platform, laying a foundation for optimizing the efficiency and reliability of high-altitude wind energy systems. Full article

This study investigates the ballistic performance and energy-absorption behavior of advanced multilayer ceramic composite armor systems composed of silicon carbide (SiC) ceramics, composite metal foam (CMF), rolled homogeneous armor (RHA), ultra-high-molecular-weight polyethylene (UHMWPE), aluminum, and rubber interlayers. The objective is to enhance impact resistance and optimize energy dissipation efficiency against armor-piercing (AP) projectiles. Ballistic tests were performed following the NIJ Standard 0101.06 Level IV specifications using .30” caliber AP M2 rounds with an impact velocity of 784–844 m/s. Experimental results revealed that the SiC front layer effectively fragmented the projectile and dispersed its kinetic energy, while the CMF and UHMWPE layers were the primary energy absorbers, dissipating approximately 70% of the total impact energy (≈3660 J). The aluminum and RHA layers provided additional reinforcement, and the rubber interlayer significantly reduced stress-wave propagation and suppressed crack growth in the ceramic. The most efficient configuration 0.5 mm RHA + 7 mm SiC + 7 mm EPDM + 7 mm CMF + 5 mm UHMWPE achieved an areal density absorption of 77.2 J·m²/kg and a unit thickness absorption of 190.6 J/mm. These findings establish a quantitative layer-wise energy dissipation framework, highlighting the synergistic interaction between brittle, porous, and ductile layers. This work provides practical design principles for developing lightweight, high-efficiency composite armor systems applicable to defense, aerospace, and personal protection fields. Moreover, this study not only validates the NIJ Standard 0101.06 ballistic performance experimentally but also establishes a reproducible methodology for quantitative, layer-wise energy analysis of hybrid ceramic-CMF-fiber armor systems, offering a scientific framework for future model calibration and optimization. Full article

To enhance the effectiveness and precision of design and to produce more low-carbon and high-performance Engineered Cementitious Composites (ECCs), novel hybrid fiber-reinforced high-ductility cementitious composites developed by incorporating a combination of ultra-high-molecular-weight polyethylene fibers (UHMWPE) and basalt fibers (BFs) into the cementitious matrix. Building upon the Box–Behnken design model from Response Surface Methodology (RSM), this study investigates the effects of different water-to-binder ratios and fiber contents on the mechanical properties of hybrid fiber-reinforced ECC. Analysis of variance (ANOVA) was used to validate the regression models. Furthermore, multi-objective optimization of the ECC mix proportion was achieved by employing the NSGA-II algorithm in conjunction with the TOPSIS comprehensive evaluation method. The results indicate that UHMWPE and BFs exhibited a significant positive hybrid effect. The order of factor significance was as follows: The content of ultra-high-molecular-weight polyethylene is greater than that of basalt fiber, and the content of basalt fiber is greater than that of the water–binder ratio. The results of variance analysis show that the regression model has high fitting accuracy. Furthermore, the algorithmic optimization yielded an optimal mix proportion: a water-to-binder ratio of 0.21, UHMWPE fiber content of 1.51%, and BF content of 0.85%. This study provides a valuable reference for the multi-objective optimization design of ECC mix proportions targeting diverse strength and toughness requirements. Full article

Flexible pipes have significant application potential in deep-sea mineral resource exploitation. As the innermost barrier of flexible pipes, the liner directly withstands abrasive wear from mineral particles. The extrusion quality of the liner is a decisive factor for the service life of the pipe and requires optimization of process parameters for improvement. However, the extrusion process of wear-resistant liners made of ultra-high molecular weight polyethylene (UHMWPE) involves complex thermo-mechanical coupling behavior, which creates major challenges in developing accurate numerical models that represent the entire process. To precisely simulate the extrusion process and guide process parameter optimization, this paper establishes a numerical simulation model for flexible pipe liner extrusion based on the Eulerian–Lagrangian coupling method. Simulations under various outlet temperature and screw speed conditions were carried out to reveal the evolution of mechanical behavior during extrusion and clarify the influence of key process parameters. The main conclusions can be summarized as follows. An increase in extrusion temperature reduces the maximum stress and promotes better molecular orientation and crystallinity in UHMWPE material, while the maximum heat flux remains essentially unchanged. An increase in screw speed has little effect on maximum material stress but leads to a significant increase in maximum heat flux. In addition, significant stress appears in the UHMWPE material at the extrusion die exit and is mainly concentrated in the unextruded material section. The numerical model effectively addresses the challenges of simulating material phase transition, large deformation and long-distance flow, which are difficult to capture with traditional methods. The findings offer a theoretical basis and technical guidance for optimizing extrusion process parameters and strengthening quality control in flexible pipe liner extrusion. Full article

Traditional single-layer water-lubricated rubber or plastic bearings suffer from water film rupture, excessive frictional losses, and insufficient load-carrying capacity, which limit performance and service life in marine propulsion and ocean engineering. To address these issues, this study introduces an innovative laminated bearing consisting of a rubber composite layer and an ultra-high-molecular-weight polyethylene (UHMWPE) layer. A three-dimensional dynamic model based on fluid–structure interaction theory is developed to evaluate the effects of eccentricity, rotational speed, and liner thickness on lubrication pressure, load capacity, deformation, stress–strain behavior, and frictional power consumption. The model also reveals how thickness matching governs load transfer and energy dissipation. Results indicate that eccentricity, speed, and thickness are key determinants of lubrication and structural response. Hydrodynamic pressure and load capacity rise with eccentricity above 0.8 or higher speeds, but frictional losses also intensify. The rubber layer performs optimally at a thickness of 5 mm, while excessive or insufficient thickness leads to stress concentration or reduced buffering. The UHMWPE layer exhibits optimal performance at 5–7 mm, with greater deviations resulting in increased stress and deformation. Proper thickness matching improves pressure distribution, reduces local stresses, and enhances energy dissipation, thereby strengthening bearing stability and durability. Full article

The development of radiation-protective materials with high resistance under reactor irradiation conditions is one of the urgent tasks in modern nuclear technologies. Ultra-high molecular weight polyethylene (UHMWPE) is considered a promising matrix material due to its high hydrogen content, low density, and strong chemical resistance. Composite samples were fabricated by flame formation and irradiated in the IVG-1M research reactor of the National Nuclear Center of the Republic of Kazakhstan. Their neutron absorption capacity, bending strength, and chemical resistance were measured before and after irradiation. The results show that H₃BO₃ provides the strongest contribution to the increase in the neutron absorption coefficient, with the maximum effect observed at 30% filler content. Reactor irradiation caused only a moderate reduction in the composites’ bending strength. Chemical resistance tests confirmed that UHMWPE-based composites with WC and PbO retain stability in aggressive environments, even after reactor exposure. Overall, UHMWPE-based composites containing boron and heavy-element fillers demonstrate strong potential as radiation-protective materials. Their design should account not only for neutron absorption efficiency but also for mechanical strength and chemical resistance under reactor operating conditions. Full article

Ultra-high molecular weight polyethylene (UHMWPE) is widely used in orthopedic and prosthetic applications due to its excellent wear resistance and biocompatibility. However, its high molecular weight presents significant challenges in terms of processing and formability, particularly at the micro scale. This study investigates the flowability characteristics of a new melt-processable UHMWPE in micro-disc geometries to evaluate its suitability for advanced prosthetic applications. Micro-injection molding experiments assessed the material’s behavior under various thermal conditions. The influence of parameters such as temperature, pressure, and disc dimensions has direct effects on the flow behavior of UHMWPE and was analyzed by simulation and experiments. Results indicate that while UHMWPE exhibits limited flow under conventional conditions, optimized processing parameters can enhance discs’ formability without compromising the material’s structural integrity, avoiding defects. These findings provide critical insights for the microfabrication of UHMWPE thin components in next-generation prosthetic devices, enabling improved design precision and functional performance. Full article

The complexity of the processes occurring in both natural and artificial joints necessitates carrying out the analysis on a 3D model based on already existing mathematical models. All the presented numerical calculations define qualitative conclusions about the influence of certain parameters of endoprostheses on the values of stresses and strains arising in polyethylene parts of hip and knee endoprostheses. The obtained results make it possible to reveal “weak points” in the studied models and thus counteract the later effects resulting from premature wear of the endoprosthesis components. The study included a numerical analysis of the stress and strain distribution of polyethylene components of hip and knee endoprostheses working with the most commonly used material associations in this type of solution. The most common are metal alloys and ceramics. The analyses were carried out using ADINA and Autodesk Simulation Mechanical software. Geometric models were designed based on current solutions used by leading endoprosthesis manufacturers. The load models adopted are based on models commonly used in musculoskeletal biomechanics. Particular attention was paid to modeling the resistance due to friction at the hip endoprosthesis node. To build the hip endoprosthesis model, eight-node 3D solid elements were used. Due to the axisymmetric geometry of the model, the resulting discrete model consisted of 10,000 cubic elements described by 10,292 nodes. In the case of the knee endoprosthesis, a finite element mesh was adopted for the calculations, which was built with 3600 3D solid cubic elements and 4312 nodes. The accuracy of the adopted numerical model did not differ from the generally used solutions in this field. Full article

The thermal, thermomechanical, and viscoelastic properties of continuous unidirectional (UD) glass fiber/high-density polyethylene (GF/HDPE) and ultra-high-molecular-weight polyethylene/high-density polyethylene (UHMWPE/HDPE) tapes are characterized in this paper in order to support their use in extreme environments. Unlike prior studies that focus on short-fiber composites or limited thermal conditions, this work examines continuous fiber architectures under five operational environments derived from Army Regulation 70-38, reflecting realistic defense-relevant extremes. Differential scanning calorimetry (DSC) was used to identify melting transitions for GF/HDPE and UHMWPE/HDPE, which guided the selection of test conditions for thermomechanical analysis (TMA) and dynamic mechanical analysis (DMA). TMA revealed anisotropic thermal expansion consistent with fiber orientation, while DMA, via strain sweep, temperature ramp, frequency sweep, and stress relaxation, quantified their temperature- and time-dependent viscoelastic behavior. The frequency-dependent storage modulus highlighted multiple resonant modes, and stress relaxation data were fitted with high accuracy (R² > 0.99) to viscoelastic models, yielding model parameters that can be used for predictive simulations of time-dependent material behavior. A comparative analysis between the two material systems showed that UHMWPE/HDPE offers enhanced unidirectional stiffness and better low-temperature performance. At the same time, GF/HDPE exhibits lower thermal expansion, better transverse stiffness, and greater stability at elevated temperatures. These differences highlight the impact of fiber type on thermal and mechanical responses, informing material selection for applications that require directional load-bearing or dimensional control under thermal cycling. By integrating thermal and viscoelastic characterization across realistic operational profiles, this study provides a foundational dataset for the application of continuous fiber thermoplastic tapes in structural components exposed to harsh thermal and mechanical conditions. Full article

A recently proposed method called “controlled swelling of monolithic films” was implemented to prepare ultra-high-molecular-weight polyethylene (UHMWPE) ultrafiltration membranes. For the first time, the effect of UHMWPE molecular weight (MW) on the structure and properties of the membranes prepared via this special case of thermally induced phase separation was studied in detail. The morphology and properties of the membranes were studied using SEM, DSC, liquid–liquid displacement porometry, and standard methods for the evaluation of mechanical properties, permeance, rejection, and abrasion resistance. High-quality membranes with a tensile strength of 5.0–17.8 MPa, a mean pore size of 25–50 nm, permeance of 17–107 L m⁻² h⁻¹ bar⁻¹, rejection of model contaminant (blue dextran) of 72–98%, and great abrasion resistance can be prepared only if the MW of the polymer in the initial monolithic film is sufficiently high. The properties of the membranes can effectively be controlled by changing the MW of the polymer and the mass fraction of the latter in the swollen film. Shrinkage is responsible for the variation in the membrane properties. The membranes prepared from a higher-MW polymer are more prone to shrinking after the removal of the solvent. Shrinkage decreases before rising again and minimizes with an increase in the polymer content in the swollen film. Full article