Search Results (2,131)

This study evaluated the effects of low-dose electron beam irradiation (0, 1, 2, and 3 kGy) on storage stability and quality properties of chicken and duck breast meat. Five foodborne pathogens (Salmonella typhimurium, Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, and Escherichia coli) were inoculated into the samples and subjected to irradiation under vacuum packaging. The irradiated samples were vacuum-packed and stored at 4 °C. Microbial recovery, lipid and protein oxidation, physicochemical characteristics, and meat color were analyzed over 0, 1, and 2 weeks. A completely randomized design was used with five biological replicates (n = 5) per treatment, and each measurement was performed in triplicate (technical replicates). Electron beam treatment effectively reduced microbial counts, achieving complete inactivation of all pathogens except Bacillus cereus at 3 kGy. Irradiation resulted in significant reductions in pH and water-holding capacity (p < 0.05) while increasing thiobarbituric acid-reactive substances (TBARS) and volatile basic nitrogen (VBN) values, particularly in duck and chicken, respectively. Color parameters such as L* and b* decreased, while a*, chroma, and redness increased, with hue angle showing a decreasing trend. These changes were associated with myoglobin transformation and protein oxidation caused by irradiation-induced reactive oxygen species. Despite minor variations, proximate composition remained unaffected by irradiation. Overall, electron beam irradiation at doses up to 3 kGy effectively enhanced microbial safety without compromising nutritional quality, indicating its potential as a non-thermal preservation method for raw poultry meat products. Full article

The objective of this study was to investigate electron beam hardening (EBH) technology and compare its performance with laser beam hardening (LBH) in the context of manufacturing components such as gears, which increasingly employ submicron bainitic steels. Given the stringent demands for durability and fatigue resistance of gear teeth, identifying an optimal surface hardening method is essential for extending service life. Comprehensive analyses, including light and electron microscopy, hardness testing, tribocorrosion testing, and X-ray diffraction for phase composition, were conducted. The EBH-treated layer exhibited a slightly higher hardness (by 26 HV) compared to the LBH-treated layer (average 654 HV), while the base material measured 393 HV. The EBH process produced a uniform hardness distribution with a subsurface zone of reduced hardness. In contrast, LBH resulted in a surface oxide layer absent in EBH due to its vacuum environment. Both techniques reduced the residual austenite content in the surface layer from 22.5% to approximately 1.3%–1.4%. Notably, EBH achieved comparable hardening effects with nearly half the energy input of LBH, demonstrating superior energy efficiency and industrial feasibility. Application of the developed EBH process to an actual gear component confirmed its practical potential for modern gear manufacturing. Full article

Fiber-reinforced polymer (FRP) composites, particularly glass fiber-reinforced polymer (GFRP), are increasingly utilized in civil engineering due to their high strength-to-weight ratio, corrosion resistance, and environmental sustainability compared to steel. Shear connectors in FRP–concrete hybrid beams are critical for effective load transfer, yet their behavior under static loads remains underexplored. This study aims to investigate the shear strength, stiffness, and failure modes of GFRP, CFRP, AFRP, and stainless-steel shear connectors in FRP–concrete hybrid beams through a comprehensive parametric analysis, addressing gaps in material optimization, bolt configuration, and design guidelines. A validated finite element model in Abaqus was employed to simulate push-out tests based on experimental data. The parameters analyzed included shear connector material (GFRP, CFRP, AFRP, and stainless steel), bolt diameter (16–30 mm), number of bolts (1–6), longitudinal spacing (60–120 mm), embedment length (40–70 mm), and concrete compressive strength (30–70 MPa). Shear load–slip (P-S) curves, ultimate shear load (P), secant stiffness (K₁), and failure modes were evaluated. CFRP bolts exhibited the highest shear capacity, 26.50% greater than stainless steel, with failure dominated by flange bearing, like AFRP and stainless steel, while GFRP bolts failed by shear failure of bolt shanks. Shear capacity increased by 90.60%, with bolt diameter from 16 mm to 30 mm, shifting failure from bolt shank to concrete splitting. Multi-bolt configurations reduced per-bolt shear capacity by up to 15.00% due to uneven load distribution. Larger bolt spacing improved per-bolt shear capacity by 9.48% from 60 mm (3d) to 120 mm (6d). However, in beams, larger spacing reduced the total number of bolts, decreasing overall shear resistance and the degree of shear connection. Higher embedment lengths (he/d ≥ 3.0) mitigated pry-out failure, with shear capacity increasing by 33.59% from 40 mm to 70 mm embedment. Increasing concrete strength from 30 MPa to 70 MPa enhanced shear capacity by 22.07%, shifting the failure mode from concrete splitting to bolt shank shear. The study highlights the critical influence of bolt material, diameter, number, spacing, embedment length, and concrete strength on shear behavior. These findings support the development of FRP-specific design models, enhancing the reliability and sustainability of FRP–concrete hybrid systems. Full article

To address the problem of corrosion, glass fiber-reinforced polymer (GFRP) bars have been introduced as a viable alternative to conventional steel reinforcement in concrete structures. While extensive research has been conducted on the flexural behavior of RC beams reinforced with steel and GFRP bars over both normal-term and long-term periods, studies focusing on fresh concrete beams are almost non-existent. Consequently, this research investigates the impact of steel and GFRP longitudinal reinforcement, as well as the influence of varying concrete compressive strengths, on the flexural behavior of RC beams. The study employs 3-point bending experiments and machine learning (ML) predictive analyses. Specifically, the short-term (fresh) concrete reinforcement compatibility and the effects of steel and GFRP bar reinforcements on beam flexural behavior were examined across three concrete compressive strength categories: low (C25), moderate (C35), and high (C50). A notable contribution of this research is the application of different ML regression models, utilizing Python’s library, for deflection prediction of RC beams. The failure mechanisms of the beams under static loading conditions were analyzed, revealing that composite bar RC beams failed through flexural cracking and demonstrated ductile behavior, whereas steel bar RC beams exhibited brittle failure characterized by shear cracks and sudden failure modes. The ML regression models successfully predicted the deflection values of RC beams under ultimate loads, achieving an average accuracy of 91.3%, which was deemed highly satisfactory. Among the 18 beams tested, the highest ultimate load was obtained for the SC50-1 beam at 87.46 kN. In contrast, while the steel-reinforced beams exhibited higher load-bearing capacities, it was observed that the GFRP-reinforced beams showed greater deflection and ductility, particularly in beams with low and medium concrete strengths. Based on these findings, it is recommended that the Gradient Boosting Regressor, an AI regression model, be utilized to guide researchers in evaluating the load-carrying and bending capacity of structural beam elements. Full article

The use of aluminum alloys in aerospace is limited by their poor weldability, making many incompatible with additive manufacturing (AM) processes like powder bed fusion—laser beam metal (PBF-LB/M), known as well as laser powder bed fusion. This incompatibility hinders the fabrication of complex, lightweight components. To overcome this, Aluminum Metal Matrix Composites (AMMCs) are formed by mechanically alloying the non-processable Al6082 base alloy with ceramic reinforcements; subsequently, Titanium Carbide (TiC) and Silicon Carbide (SiC) particles are developed. This approach induces microstructural changes necessary for AM compatibility. The influence of varying reinforcement contents (1–5 wt.%) on powder homogeneity, microstructural evolution (via Energy Dispersive X-ray Spectroscopy and Electron Backscatter Diffraction), processability, and mechanical properties is systematically studied. The key finding is that metallurgical modification is a robust solution. TiC addition at 2 wt.% and 5 wt.% completely eliminated solidification cracking, achieving high processability. SiC substantially reduced cracking compared to the base alloy. These results demonstrate the potential of AMMCs to successfully translate conventional, non-weldable aluminum alloys into the realm of advanced additive manufacturing. Full article

Recycling rubber and steel fibers from end-of-life tires for use in structural concrete presents a sustainable pathway to improve resource efficiency and reduce environmental impact. This study assesses the shear performance of reinforced concrete beams in which shredded tire rubber substitutes 20 vol.% of both fine and coarse natural aggregates. The effect of including recycled tire steel fibers (RSF) and industrial steel fibers (ISF), each at a dosage of 20 kg/m³, is also examined. The experimental program involved testing twenty-four cylindrical specimens and seven reinforced concrete beams to evaluate the mechanical and structural behavior of the proposed mixtures. A novel layered concrete configuration is also evaluated, in which rubberized (RU) concrete or steel fiber reinforced rubberized (RUSF) concrete is placed in the tensile zone, and plain (P) concrete is placed in the compressive zone. The results indicate that rubber incorporation alone reduces shear strength by 30.9% compared to P concrete. However, the inclusion of steel fibers not only compensates for this reduction but significantly improves strength and ductility. Beams fully cast with RUSF concrete exhibit a 31.9% increase in shear strength compared to P concrete. In contrast, layered beams with RUSF concrete in the bottom and P concrete in the top show a comparable performance. These findings highlight the potential of integrating steel fiber reinforced rubberized concrete and functional layering to enable the use of substantial quantities of recycled tire materials without compromising structural performance, offering a promising solution for eco-efficient construction. Full article

This paper presents a novel Ripple Evolution Optimizer (REO) that incorporates adaptive and diversified movement—a population-based metaheuristic that turns a coastal-dynamics metaphor into principled search operators. REO augments a JADE-style current-to-p-best/1 core with jDE self-adaptation and three complementary motions: (i) a rank-aware that pulls candidates toward the best, (ii) a time-increasing that aligns agents with an elite mean, and (iii) a scale-aware sinusoidal that lead solutions with a decaying envelope; rare Lévy-flight kicks enable long escapes. A reflection/clamp rule preserves step direction while enforcing bound feasibility. On the CEC2022 single-objective suite (12 functions spanning unimodal, rotated multimodal, hybrid, and composition categories), REO attains 10 wins and 2 ties, never ranking below first among 34 state-of-the-art compared optimizers, with rapid early descent and stable late refinement. Population-size studies reveal predictable robustness gains for larger N. On constrained engineering designs, REO achieves outperforming results on Welded Beam, Spring Design, Three-Bar Truss, Cantilever Stepped Beam, and 10-Bar Planar Truss. Altogether, REO couples adaptive guidance with diversified perturbations in a compact, transparent optimizer that is competitive on rugged benchmarks and transfers effectively to real engineering problems. Full article

This paper explores the application of the generalized beam theory (GBT) in analyzing the buckling behavior of isotropic and composite thin-walled beams with open cross-sections, both with and without branching. The composite beams are composed of orthotropic laminate layers arranged in arbitrary symmetrical orientations. By integrating GBT with the Ritz method and solving the associated generalized eigenvalue problem (GEP), an efficient and robust semi-analytical framework is developed to assess the stability of such isotropic and orthotropic members. The novelty of this work is not the GBT cross-sectional formulation itself, but its implementation at the beam level using a Ritz formulation leading to a generalized eigenvalue problem for the critical buckling loads and mode shapes that capture coupled global, local, and distortional modes in isotropic and orthotropic composite members. This makes the method suitable for early-stage design studies and parametric investigations, where many design variants (geometry, laminate lay-up, and aspect ratios) must be screened quickly without building large-scale high-fidelity finite element (FE) models for each case. The preliminary outcomes, when compared with those obtained using FE, confirm the approach’s effectiveness in evaluating buckling responses, particularly for open-section composite beams. Ultimately, the combined use of GBT and the Ritz method delivers both physical insight and computational efficiency, allowing engineers and researchers to address complex stability issues that were previously difficult to solve. In summary, the methodology can be correctly used for stability assessment of thin-walled composite members prone to interacting global–local–distortional buckling, especially when rapid, mechanistically transparent predictions are required rather than purely numerical FE output. Full article

This paper presents the investigation of the effect of electron radiation or the combined action of this radiation and triallyl isocyanurate (TAIC) on the structural, thermal, and mechanical properties of epoxy resin filled with a fraction of dust fibers (DFs) from recycled wind turbine blades. The resin containing 20 wt% of DF was irradiated with doses of 40, 80, 120, and 160 kGy. The results showed that electron radiation had only a slight effect on the properties of the studied composite, mainly on its glass transition temperature. More significant changes were observed with the combined action of radiation and TAIC. The main effect that occurred after the TAIC addition was the plasticization of the polymer matrix. With its participation, the glass transition temperature, thermal stability, and the hardness of the material and its flexural modulus were significantly reduced. The degree of change in these properties was regulated by the radiation dose. Furthermore, no significant changes in the composite structure were observed after radiation treatment, while the introduction of TAIC into the polymer matrix caused the formation of gas cells, probably due to the partial decomposition of TAIC. Full article

Composite steel–concrete beams have gained significant attention in modern construction due to their superior structural efficiency, economic viability, and adaptability to diverse applications. This paper presents a comprehensive review of research developments related to both conventional and post-tensioned composite beam systems. Emphasis is placed on the structural behavior, design considerations, and performance improvements achieved through external post-tensioning using high-strength tendons. Such systems enhance ultimate load capacity, extend the elastic range before yielding, and reduce the required amount of structural steel, thereby improving material efficiency and reducing construction costs. The review also examines the influence of tendon application timing, connection type, and load conditions in both positive and negative bending regions. By synthesizing experimental and analytical findings, this study identifies key advantages, limitations, and research needs in optimizing the design and performance of steel–concrete composite beams. The insights presented herein aim to guide engineers, researchers, and practitioners in advancing the application of composite beam strengthening techniques in modern infrastructure. Full article

High-density polyethylene (HDPE) is a valuable material, but its application under certain operational conditions is limited by oxidation resistance. To mitigate this, rice husk ash (RHA), a silica-rich (~95%) byproduct, was incorporated as a reinforcing filler. This study evaluates the effect of electron beam (EB) irradiation, at doses up to 100 kGy, on the properties of HDPE/RHA composites, focusing on mechanical performance and the polymer–filler interface. The results demonstrate that EB irradiation induces crosslinking and enhances interfacial interaction between the HDPE matrix and RHA filler. While the overall tensile strength of neat HDPE tended to decrease with irradiation dose (from 28.5 ± 1.2 MPa to 24.1 ± 1.5 MPa at 100 kGy), the optimization of dose and filler contents produced notable results: A maximum tensile strength of 29.0 ± 1.1 MPa was achieved in the composite containing 5 wt% RHA at 75 kGy. Furthermore, irradiation stabilized the material’s behavior, resolving the heterogeneous dispersion observed in non-irradiated samples with low RHA content. Regarding toughness, Izod’s impact resistance increased from 3.2 ± 0.2 kJ/m² to 3.7 ± 0.3 kJ/m² for the 10 wt% RHA composites irradiated at 50 kGy. Statistical analysis (ANOVA, p < 0.05) confirmed the significance of these changes. In conclusion, electron beam irradiation is an effective tool for optimizing the mechanical properties and performance uniformity of HDPE/RHA composites, making them promising candidates for applications requiring enhanced durability and consistency, such as food packaging. Full article

This study reveals the Vierendeel mechanism of hybrid high-strength steel composite cellular beams (HHS-CCBs) through experimental investigation and finite element analysis (FEA). The forces acting on the openings of composite cellular beams (CCBs) are further analyzed. A calculation method is developed to evaluate the load-carrying capacity of HHS-CCBs under the combined action of bending moment and shear force, which takes into account the shear contributions of the concrete slab and beam flange at circular openings. The accuracy of the proposed formula and the influence of key parameters on load-carrying capacity are thoroughly examined through FEA. The results indicate that within the range of D = 0.6h_s − 0.7h_s and L = 0.7h_s − 1.0h_s (D and L represent the hole diameter and edge distance, respectively; h_s is the height of the steel beam), stress concentration at the beam-end welds could be avoided, the formation of Vierendeel mechanism at the beam-end opening could be ensured, and excessive reduction in load-carrying capacity could be prevented. Furthermore, the high-strength steel (HSS) flange strength and location had a minimal effect on the failure mode of HHS-CCBs. As the flange strength increased, full plasticity was not achieved in the cross-section, and the load-carrying capacity increased nonlinearly. Asymmetric specimens with HSS in the lower flange only and symmetric specimens with HSS in both the upper and lower flanges exhibited comparable load-carrying capacities. The load-carrying capacity calculation formula is applicable to HHS-CCBs with different section types, provided that circular holes are present in the beam web and Vierendeel mechanism damage occurs. However, the flange width–thickness ratio must not significantly exceed the specified limit. Full article

This study systematically evaluates the mode-I (opening) and mode-II (shearing) interlaminar strength and fracture toughness of four co-cured fiber–metal laminates (FMLs): AL–CF (aluminum–carbon fiber fabric), AL–GF (aluminum–glass fiber fabric), AL–HC (aluminum–carbon/glass hybrid fabric), and AL–HG (aluminum–glass/carbon hybrid fabric). Epoxy adhesive films were interleaved between metal and composite plies to enhance interfacial bonding. Mode-I interlaminar tensile strength (ILTS) and mode-II interlaminar shear strength (ILSS) were measured using curved beam and short beam tests, respectively, while mode-I and mode-II fracture toughness ($G_{Ic}$ and $G_{IIc}$) were obtained from double cantilever beam (DCB) and end-notched flexure (ENF) tests. Across laminates, interlaminar tensile strength (ILTS) values lie in a narrow band of 31.6–31.8 MPa and interlaminar shear strength (ILSS) values in 41.0–41.9 MPa. The mode-I initiation ($G_{Ic,init}$) and propagation ($G_{Ic, prop}$) toughnesses are 0.44–0.56 kJ/m² and 0.54–0.64 kJ/m², respectively, and the mode-II toughness ($G_{IIc}$) is 0.65–0.79 kJ/m². Scanning electron microscopy reveals that interlaminar failure localizes predominantly at the metal–adhesive interface, displaying river-line features under mode-I and hackle patterns under mode-II, whereas the adhesive–composite interface remains intact. Collectively, the results indicate that, under the present processing and test conditions, interlaminar strength and toughness are governed by the metal–adhesive interface rather than the composite reinforcement type, providing a consistent strength–toughness baseline for model calibration and interfacial design. Full article

The current study investigates the influence of timber-to-concrete connection types on the behaviour of timber–concrete composite (TCC) structures employing metal web timber joists. Two groups of laboratory specimens were prepared, each comprising four samples with push-joisted beams joined by oriented strand board (OSB) and cast with a concrete layer. One group utilised compliant timber-to-concrete connections via perforated steel tape angles, while the other employed rigid connections through epoxy adhesive and granite chips. The specimens, consisting of two 1390 mm long beams of grade PS10 timber, were tested under three-point bending. Experimental results and finite element analyses demonstrated that specimens with compliant connections exhibited 14–16% greater maximum vertical displacements but only a marginal 1.79% reduction in load-carrying capacity compared to those with rigid connections. Findings indicate that connection compliance markedly affects stiffness and deflection but has a minor impact on ultimate strength. These insights can guide optimisation of TCC members with metal web joists, balancing structural performance and design requirements in sustainable timber construction. Full article

A3B5 nanowires are usually grown via the vapor-liquid-solid mechanism. Species from the vapor are incorporated into the nanowires using a catalyst droplet. Typically, the droplet is a low-melting-point eutectic alloy of catalyst and group III metal. This growth imposes a set of limitations on the heterostructure formation and doping. Axial A3B5 heterostructure nanowires obtained via an interchange of group III metals suffer from blurring and kinking. Amphoteric dopants such as Si could act as donors and acceptors, leading to electron-to-hole ratio oscillations along the nanowire. To overcome these limits, the growth with a catalyst, which could dissolve both components of the nanowire, is studied. Tin has a eutectic with both components, As and Ga. This makes the growth of GaAs nanowires with a tin catalyst different from that with standard catalysts. Nanowire growth occurs with at least two types of catalysts, Ga-rich and Ga-poor (As-rich). This article aims to study the nanowire growth with an Sn catalyst. For the first time, the growth of GaAs nanowires using a tin catalyst by molecular beam epitaxy is shown. Tin can serve as a catalyst not only for the chemical growth of GaAs nanowires but also as a nucleation site for their growth. Both compositions of the catalyst are observed. The annealing of a thin film of tin on a Si and GaAs substrate has also been studied. At temperatures below 450 °C, small metal droplets form, while tin dissolves into the substrate at higher temperatures. Full article