Search Results (72)

Marine-related activities contribute significantly to plastic pollution in oceans worldwide, particularly in regions located along international maritime routes such as Türkiye. The Dardanelles serves as a major maritime gateway connecting the Aegean Sea with both the Sea of Marmara and the Black Sea, enabling heavy vessel traffic that subsequently disperses plastic pollutants across large areas of the Mediterranean and beyond. Therefore, for the first time, this study applied material flow analysis to estimate potential sources and pathways of macro- and microplastics from 12 vessel categories, including fishing fleets, merchant ships, cruise liners, and military vessels in the Northern Aegean Sea. This approach provides insight into the range of sources and pathways, highlights priority areas for mitigation, and identifies additional knowledge gaps. Through material flow analysis–based estimations, general macro- and microplastic waste is found to be the largest contributor to marine plastic pollution, with an average of 14,965 tons/year, followed by antifouling particles at 5848.5 tons/year. Overall, this study presents a comprehensive evaluation of vessel-derived plastic pollution in a strategically significant maritime corridor and emphasizes its potential implications for the broader marine eco-system. Full article

Dredged reservoir sediments (DRS), generated in large volumes during dam desilting operations, pose significant stockpiling and land-use challenges in Mediterranean regions. Owing to their high fines content and moderate plasticity, these sediments present potential for reuse as compacted hydraulic barrier materials. This study evaluates the feasibility of using DRS as a liner material and, for the first time, provides a direct comparative assessment of natural (wheat straw fibers, WSF) and synthetic (polypropylene fibers, PPF) reinforcement within the same sediment matrix under liner-relevant conditions. Fiber contents of 0–0.9% (by dry mass) were investigated. Mechanical and consolidation behaviors were assessed using direct shear and oedometer tests. Fiber inclusion significantly improved shear strength, with an optimal response at 0.6%. At this dosage, PPF reduced the compression index by ~50%, while WSF provided moderate but consistent improvement. Estimated hydraulic conductivity increased slightly with fiber addition but remained within the range typically reported for compacted barrier materials. FTIR analysis indicated distinct reinforcement mechanisms, with lignocellulosic interactions for WSF and mechanical bridging for PPF. These results demonstrate that DRS can be effectively valorized as liner materials, while highlighting the contrasting performance of biodegradable and synthetic fibers, with 0.6% identified as a balance between mechanical efficiency and material sustainability. Full article

This study evaluated the geotechnical, mineralogical, chemical, and physico-mechanical properties of natural clays from two Portuguese regions, Aveiro and Taveiro, for their potential use as compacted landfill liners. A comprehensive set of tests was conducted, including particle size distribution, Atterberg limits, specific surface area (SSA), cation exchange capacity (CEC), swelling potential, and hydraulic conductivity (K), complemented by X-ray diffraction (XRD) and chemical composition (XRF) analyses. Results showed that Aveiro clays were predominantly fine-grained, with clay fractions exceeding 65% and high Σphyllosilicates content, particularly illite and smectite. These samples exhibited low hydraulic conductivity (K < 1 × 10⁻⁹ m/s), moderate to high plasticity, and good sealing behavior. In contrast, Taveiro clays showed greater textural variability, with higher sand content and a wider range of mineral composition, from kaolinitic to smectitic units. Selected Taveiro samples also achieved acceptable permeability values, particularly those with higher smectite content, but may require strict compaction control or blending with finer materials. The CEC and SSA measurements further distinguished the sealing potential between clay types, correlating with mineralogy and swelling capacity. The use of local clays offers potential cost savings and environmental benefits, including reduced transportation emissions and support for circular economy principles. These findings highlighted the technical viability of Portuguese clays for landfill barrier systems and underscore the importance of localized characterization for optimized liner design. Full article

This study evaluated the feasibility of culturing Seriola lalandi in a low-cost recirculating aquaculture system (RAS) in an arid region of northern Chile, aiming to establish strategies for broodstock farming and diversify national aquaculture. The system was designed as a low-cost recirculating aquaculture system (RAS) built with locally available materials, such as galvanized corrugated steel panels and flexible plastic liners, instead of specialized aquaculture tanks. Its modular configuration, based on gravity-fed filtration using sedimentation, sand, and disc filters, allows efficient water reuse with minimal energy consumption and a daily water turnover of 12 times the total volume. This design significantly reduced construction and operational costs, making it a feasible option for aquaculture development in arid regions with limited water resources. Over an 8-month period, 46 S. lalandi individuals were used, and the results showed successful physiological adaptation of the specimens to confinement, as evidenced by low mortality, progressive acceptance of formulated feed, and sustained growth. Individual weights progressively increased, with averages ranging from 675 to 1435 g, and the specific growth rate (SGR) fluctuated between 0.14 and 0.43% per day. Fulton’s condition factor (K) remained in an adequate range between 2.4 and 2.8, suggesting good physical condition of the sampled individuals. Water quality within the RAS system was maintained within acceptable parameters, although a strong negative correlation between temperature and dissolved oxygen was recorded (Spearman coefficient = −0.71, p < 0.001), highlighting the importance of monitoring these factors in warm environments. The lack of adequate protocols for the adaptation of marine species in arid areas, such as northern Chile, has limited aquaculture development in these regions. This study addresses this problem by assessing the feasibility of a low-cost recirculating system (RAS) for the cultivation of S. lalandi under conditions of water scarcity, with the aim of diversifying the national aquaculture in arid zones. Full article

This article is based on ABAQUS 2022 finite element software to establish a finite element model of the hydraulic forming process of bimetallic composite pipes. The results show that the larger the bulging pressure, the earlier the circumferential elastic deformation of the outer wall of the lining pipe is fully restored during unloading. Under the action of the base pipe, the compression elastic deformation of the lining pipe is greater, and the bonding strength between the base pipe and the lining pipe is higher; as the bulging pressure increases, the rebound amount of the outer wall of the liner slightly decreases, while the rebound amount of the inner wall of the base pipe gradually increases, and the difference in rebound amount between the inner wall of the base pipe and the outer wall of the liner pipe gradually increases; before plastic deformation occurs on the inner wall of the base pipe, its circumferential rebound increases rapidly with the increase in bulging pressure. When plastic deformation occurs on the inner wall of the base pipe, the rate of increase in circumferential rebound decreases; the residual contact stress between the base pipe and the liner increases linearly with the increase in bulging pressure. Full article

In addition to the minerals naturally present in grapes, wine can acquire additional minerals during its production and storage from materials that come into contact with it, including bottling materials. This study aimed to evaluate the concentration of a wide range of elements in white wine samples packaged in 0.75 L green glass bottles sealed with two different closure systems: natural cork stoppers and metal screw caps with a plastic liner. No statistically significant differences were observed between the two closure types for most elements (Li, Be, Fe, Co, Ni, Zn, Se, Rb, Sr, Mo, Sb, Cs, Ba, and Tl). For V, Cr, Mn, Cu, As, Cd, and Pb, some differences were observed, but without a clear pattern. However, the concentration of Sn was significantly higher in wines packaged in bottles sealed with metal screw caps plus plastic liner. Elemental analysis of the original, unused liners showed negligible content of Sn and other studied elements, suggesting that the Sn in the wine comes from the Sn-plated steel screw cap, despite the presence of the plastic liner. Although the changes in the natural elemental composition under these bottling conditions are not very high and unlikely to pose a health risk to consumers, they may still influence wine stability and sensory attributes. Understanding these effects is important for both wine producers and consumers to ensure optimal wine quality and preservation. 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

Composite pressure vessels have attracted significant attention in recent years owing to their lightweight characteristics and superior mechanical performance. However, analyzing composite layers remains challenging due to complex filament-winding (FW) pattern structures and the associated high computational costs. This study introduces a homogenization method to achieve cross-scale modeling of carbon fiber-reinforced plastic (CFRP) layers, accounting for both lay-up sequence and in-plane FW diamond-shaped form. The stacking sequence in an FW Type IV composite pressure vessel is numerically investigated through ply modeling and cross-scale homogenization. The composite tank structure, featuring a polyamide PA66 liner, is designed for a working pressure of 70 MPa and comprises 12 helical winding layers and 17 hoop winding layers. An FW cross-undulation representative volume element (RVE) is developed based on actual in-plane mesostructures, suggesting an equivalent laminate RVE effective elastic modulus. Furthermore, six different lay-up sequences are numerically compared using ply models and fully and partially homogenized models. The structural displacements in both radial and axial directions are validated across all modeling approaches. The partial homogenization method successfully captures the detailed fiber-direction stress distribution in the innermost two hoop or helical layers. By applying the Hashin tensile failure criterion, the burst pressure of the composite tank is evaluated, revealing 7.56% deviation between the partial homogenization model and the ply model. Fatigue life analysis of the Type IV composite pressure vessel is conducted using ABAQUS^® coupled with FE-SAFE, incorporating an S-N curve for polyamide PA66. The results indicate that the fatigue cycles of the liner exhibit only 0.28% variation across different stacking sequences, demonstrating that homogenization has a negligible impact on liner lifecycle predictions. The proposed cross-scale modeling framework offers an effective approach for multiscale simulation of FW composite pressure vessels, balancing computational efficiency with accuracy. Full article

Composite overwrapped pressure vessels (COPVs) have become the core unit for high-pressure hydrogen storage and transportation. However, excessive autofrettage pressure could induce unilateral buckling damage of the metal liner because of large rebound compressive stress induced by large plastic deformation in the depressurization stage. When the liner contains initial defects, its critical unilateral buckling pressure would be further reduced. In this paper, a critical buckling pressure calculation formula was established by finite element analysis and theoretical derivation. Firstly, the classical theoretical calculation models and research methods were analyzed and discussed. Then, by discussing the key influencing parameters, a semi-empirical calculation formula of nonlinear confined buckling pressure of a metal liner with ovality defects was established. Finally, the proposed semi-empirical formula was used to predict the critical internal pressure of a Type-III COPV, and the predicted value was compared with the experimental result. The predicted result was higher than the experimental result and the error range was −2.8%~−23%. The proposed semi-empirical formula of nonlinear confined buckling could provide theoretical support for designing the autofrettage pressure of Type-III COPVs and help to reduce the uncertainty and repeated test cost in the design process. Full article

As hydrogen fuel cell vehicles gain momentum as crucial zero-emission transportation solutions, the urgency to address hydrogen permeability through the polymer liner becomes paramount for ensuring the safety, efficiency, and longevity of Type IV hydrogen storage tanks. This paper synthesizes existing research findings, analyzes the influence of different materials and structures on gas permeability, elucidates the dissolution and diffusion mechanisms of hydrogen in plastic liners, and discusses their engineering applications. We focus on measurement methods, influencing factors, and improvement strategies for liner gas permeability. Additionally, we explore the prospects of Type IV hydrogen storage tanks in fields such as automotive, aerospace, and energy storage industries. Through this comprehensive review of liner gas permeability, critical insights are provided to guide the development of efficient and safe hydrogen storage and transportation systems. These insights are vital for advancing the widespread application of hydrogen energy technology and fostering sustainable energy development, significantly contributing to efforts aimed at enhancing the performance and safety of Type IV hydrogen storage tanks. Full article

The metallic shaped charge liner (SCL) is widely utilized in the defense industry, oil perforation, cutting, and other industrial fields due to the powerful penetration performance. However, quantitative law and underlying mechanisms of material properties affecting SCL penetration performance are unclear. Based on the real and virtual material properties, by combining numerical simulation with machine learning, the influence of material properties on SCL penetration performance was systematically studied. The findings in the present work provided new insights into the penetration mechanism and corresponding influencing factors of the metal jet. It indicated that penetration depth was dominated by the melting point, specific heat, and density of the SCL materials rather than the conventionally perceived plasticity and sound velocity. Average perforation diameter was dominated by the density and plasticity of the SCL materials. Particularly, the temperature rise and thermal softening effect of the SCL controlled by the melting point and specific heat have a significant effect on the “self-consumption” of the metal jet and further on the penetration ability. Additionally, the density of the SCL influences the penetration depth deeply via dynamic pressure of the jet, but the influence of density on penetration depth decreases with the increase in density. The correlation between the key properties and penetration performance was obtained according to a quadratic polynomial regression algorithm, by which the penetration potential of SCL materials can be quantitatively evaluated. Overall, the present study provides a new SCL material evaluation and design method, which can help to expand the traditional penetration regime of the SCL in terms of the penetration depth and perforation and is expected to be used for overcoming the pierced and lateral enhancement trade-off. Full article

Desiccation-induced cracking in clay soils significantly affects the structural performance and durability of geotechnical systems. This study presents a data-driven approach to predict the Crack and Shrinkage Intensity Factor (CSIF), a comprehensive index quantifying both crack formation and shrinkage behavior in drying soils. A database of 100 controlled desiccation tests was developed using five clay mixtures with varying plasticity indices, which were subjected to a range of drying rates, soil thicknesses and initial conditions. Four predictive models—Multiple Linear Regression (MLR), Classification and Regression Random Forest (CRRF), Artificial Neural Network (ANN) and Genetic Programming (GP)—were evaluated. The ANN model using Bayesian Regularization demonstrated superior performance (R = 0.99, MAE = 5.44), followed by CRRF and symbolic GP equations. Sensitivity analysis identified drying rate and soil thickness as the most influential parameters, while initial moisture content and ambient conditions were found to be redundant when the drying rate was included. This study not only advances the predictive modeling of desiccation cracking but also introduces interpretable equations for practical engineering uses. The developed models offer valuable tools for crack risk assessment in clay liners, soil covers and expansive soil foundations. Full article

This article presents, in detail, design considerations for a thin-walled glass fiber reinforced plastic (GFRP) liner on a fluid-cooled stator lamination of an electric motor. In addition to structural requirements due to the cooling fluid pressure, the GFRP liner needs to guarantee impermeability. Analytical considerations deriving from different coefficients of thermal expansion (CTEs) determine the two-layered laminate design. Empirical investigations show two innovative, simple, and, therefore, efficient test setups for the leakage of liquid media through a GFRP liner. The weeping investigations employ two different GFRP systems with four different configurations of interfiber failure (IFF) and, therefore, crack densities. The weeping investigations show that at least one ply in the laminate needs to be flawless regarding IFF cracks in order to guarantee the sealing function. Alternatively, a third sealing layer can be used. Full article

Hydrogen is a promising alternative to fossil fuels, but its efficient storage presents significant challenges. Polymer composite vessels, especially those made from carbon fiber-reinforced plastic (CFRP), are gaining attention, due to their high strength-to-weight ratio for storing compressed or cryogenic hydrogen. The latest Type V tanks, which lack internal liners, rely solely on fiber composites for both structural integrity and gas containment, enhancing the storage volume-to-weight ratio and supporting recycling. However, this linerless design faces the challenge of preventing gas permeation. Epoxy resins, widely used in aerospace carbon fiber-reinforced composites (CFRCs), offer excellent processability and load-bearing capabilities. The addition of high-aspect-ratio nanofillers can enhance the gas barrier properties, which are essential for preventing hydrogen leakage, while also improving the mechanical, electrical, and thermal properties of the nanocomposites. This study focuses on epoxy-based composites with expanded graphite, aiming to optimize their physical properties and processing for Type V tanks, using a rheological framework to evaluate their processability and multifunctionality in transport applications. Full article

In recent years, W-Cu composite systems have become very interesting subjects due to good electrical and thermal conductivity, high-temperature strength, certain plasticity, and excellent radiation resistance. W-Cu composites are a very important class of materials in applications like PFM (plasma facing materials), functional graded materials (FGM), electronic packaging materials, high-voltage electrical contacts, sweating materials, shaped charge liners, electromagnetic gun-rail materials, kinetic energy penetrators, and radiation shielding/protection. There is no possibility of forming a crystalline structure between these two materials. However, due to the unique properties these materials possess, they can be used by preparing them as a composite. Generally, W-Cu composites are prepared via the conventional powder metallurgy routes, i.e., sintering, hot pressing, hot isostatic pressing, isostatic cold pressing, sintering and infiltration, and microwave sintering. However, these processes have certain limitations, like the inability to produce bulk material, they are expensive, and their adoptability is limited. Here, in this review, we will discuss in detail the fabrication routes of additive manufacturing, and its current progress, challenges, trends, and associated properties obtained. We will also explain the challenges for the additive manufacturing of the composite. We will also compare W-Cu composites to other materials that can challenge them in terms of specific applications or service conditions. The solidification mechanism will be explained for W-Cu composites in additive manufacturing. Finally, we will conclude the progress of additive manufacturing of W-Cu composites to date and suggest future recommendations based on the current challenges in additive manufacturing. Full article