Abstract Although hypereutectic A390 (Al–Si–Cu) alloys are widely used in engine liners due to their superior wear resistance, conventional casting methods fail to provide the functional gradient required by internal combustion engines – specifically, high hardness at the inner surface and toughness at the outer surface – in a single processing step. The aim of this study is to produce in-situ formed Functionally Graded Materials (FGMs) from A390 alloy by optimizing centrifugal casting parameters and to elucidate the underlying microstructural segregation mechanisms. In this study, the effects of casting temperature (700 °C and 750 °C) and mold rotational speed (1,000, 1,250, and 1,500 rpm) on radial solidification behavior and phase distribution were systematically investigated. The selected range of rotational speeds was intended to establish a balance between the centrifugal force required to segregate Si particles and the structural disturbances induced by excessive turbulence. Microstructural characterization was carried out using SEM and EDS analyses, while mechanical properties were evaluated by Brinell hardness measurements taken along the radial cross-section. Results showed that the casting parameters play a critical role in governing the migration behavior of primary Si particles. The highest inner-surface hardness (92 HB) was achieved at a casting temperature of 700 °C and a rotational speed of 1,000 rpm. At higher rotational speeds, such as 1,500 rpm, increased turbulence and vibration effects were found to reduce segregation efficiency, leading to a decrease in hardness values (88 HB). The lower casting temperature of 700 °C increased the solidification rate, thereby suppressing the growth of Si particles leading to a grain refinement. The results also showed that, by optimally controlling the centrifugal casting parameters, a functionally graded (FG) structure was achieved in the A390 alloy, which can potentially be used in the manufacturing of monolithic engine liners without the need for any additional joining process.
Abstract The deformation is used to improve the mechanical properties of aluminum matrix composites. The effect of deformation on the aluminum powder morphology is analyzed. The influence of the flaked aluminum powders on oxygen content is discussed. The mechanical properties of Al 2 O 3 /Al composite are studied. The results show that when subjected to compression deformation during cold pressing and hot forging, the initial spherical aluminum powders can be flaked with the layered structure in meridian section. Ball milling can flake the initial spherical aluminum powders and promote the oxidation degree of aluminum powder. The flaked aluminum powders are stacked with the direction approximate perpendicular to the loading direction in meridian section. The increased broken alumina film can be considered as reinforcement, improving the strength of the Al 2 O 3 /Al composite. Shear deformation can significantly improve the hardness and tensile strength of the Al 2 O 3 /Al composite. The hardness and tensile strengths of the Al 2 O 3 /Al composite prepared by shear deformation with flaked aluminum powders are 92.7 HV and 207.7 MPa, respectively.
Abstract Hard milling has emerged as an alternative to conventional grinding for finishing hardened steels because of its productivity and cost advantages. However, achieving high surface quality and stable machining performance under sustainable lubrication conditions remains challenging. In this study, the machining performance of hardened AISI 4140 steel was experimentally evaluated during face milling under three lubrication conditions: dry cutting, minimum quantity lubrication (MQL), and multi-walled carbon nanotube (MWCNT)-reinforced nanofluid-assisted MQL using biodegradable peanut oil as the base fluid. The effects of cutting speed ( V ) and feed rate ( f ) on surface roughness (Ra), vibration, sound intensity, cutting temperature, power consumption, and energy consumption were analyzed. Chip morphology and tool wear mechanisms were also examined. The results showed that increasing V and f deteriorated surface quality and increased vibration, temperature, and power demand. Among the tested strategies, Nanofluid-MQL provided the best overall performance. The lowest Ra value (0.090 µm) was obtained with Nanofluid-MQL, whereas the highest value (0.423 µm) was obtained under dry cutting. Compared with dry machining, Nanofluid-MQL reduced cutting temperature and power consumption by up to 12.62 % and 7.03 %, respectively. SWARA–CoCoSo optimization identified 90 m min −1 and 0.05 mm tooth −1 under Nanofluid-MQL as the optimum condition.
Abstract The incorporation of Aluminium Borate whisker (ABOw) as a reinforcing element in the AM60 magnesium matrix is investigated in this study. The characteristic XRD patterns of the prepared ABOw revealed their orthorhombic crystalline structure. The composite materials with varying proportions of ABOw are prepared using the vacuum stir casting method. Mechanical testing revealed that the addition of ABOw led to a notable enhancement in mechanical properties, up to 15 % proportion. The composite with 15 % ABOw exhibited superior corrosion resistance compared to the AM60 alloy.
Abstract Critical parameters needed for geotechnical design are frequently estimated using empirical correlations derived from laboratory classification and strength tests. These tests are essential techniques for assessing the engineering behaviour of cohesive soils. Since undrained shear strength and consistency limits are important engineering characteristics that describe soil behaviour, it is crucial to evaluate the reliability of these parameters obtained from different testing techniques. In this study, the physical and index properties of 40 cohesive soils with varying characteristics were determined in the laboratory. For each soil, five samples with different water contents were prepared and subjected to Casagrande, fall cone, and laboratory vane shear tests. The undrained shear strength values obtained from vane shear tests were used as reference to evaluate the variation of the fall cone factor for each soil. Based on the liquid limit values obtained from the fall cone and Casagrande tests, undrained shear strength was estimated using liquidity index and water content ratio parameters. The undrained shear strength predicted from fall cone data exhibited a high level of accuracy, achieving R 2 ≈ 0.89. Additionally, similarities and differences between the models were analysed by comparing the single-variable equations created in this study with empirical correlations found in the literature. ANN, RF, SVM, XGB, and stacking machine learning models were used in addition to traditional statistical methods to forecast the undrained shear strength. Overall, the machine learning framework demonstrated superior predictive performance, and the top-performing model, RF, demonstrated reliable estimation capability for undrained shear strength, with R 2 ≈ 0.97.
Abstract This paper introduces the Modified Stellar Oscillation Optimizer (MSOA) for constrained industrial design problems. The base optimizer, which models the pulsation and oscillatory behavior of stars, is hybridized with chaotic maps. MSOA is tested on five constrained engineering problems: a speed reducer, a cantilever beam, a step-cone pulley, a rolling element bearing, and a vehicle structural component. On the cantilever beam, MSOA reaches the global feasible optimum f = 1.33996, tying with CSA, FOX, GWO, AVOA, and SMA. On the speed reducer and step-cone pulley, MSOA reaches the global feasible optima of 2,996.348 and 16.0899, matching SFOA and BBO and improving on the other tested algorithms by 0.1–4 %. For the rolling element bearing and the automobile component, MSOA produces better objective function than several other recent metaheuristics. The chaotic hybridization helps MSOA remain in the feasible region on problems where most rivals converge to penalty-corrected local minima.
Abstract This study presents a comprehensive structural characterization of medieval glazed ceramics from Toprakkale and Osmaniye regions in Upper Plain Cilicia, Türkiye. Utilizing advanced non-destructive techniques, the research investigates ceramic body, slip, and glaze phases to elucidate production technologies and raw material selections. Results reveal that Toprakkale sherds possess relatively homogeneous aluminosilicate matrices with moderate silica and low flux oxide contents, indicative of controlled raw material preparation and firing protocols. Conversely, Osmaniye sherds display broader compositional variability, characterized by higher silica, calcareous, and alkali oxide contents, reflecting the incorporation of diverse temper materials and less standardized manufacturing processes. Mineralogical analyses show that Toprakkale sherds experienced higher firing temperatures, promoting the formation of diopside phases, while Osmaniye ceramics exhibit incomplete calcite decomposition, suggesting moderate firing conditions. Glaze compositions demonstrate significant variations in lead oxide content highlighting differing fluxing strategies and technological choices. The study underscores regional technological diversity and adaptation to local resources, contributing valuable insights into medieval ceramic production and cultural interactions within the northeastern Mediterranean basin.
Abstract This study investigates the mechanical performance of nanoclay-filled pineapple leaf fibre (PALF) reinforced polyester composites prepared using the hand lay-up technique followed by compression moulding. The influence of PALF content (5–25 wt.%), nanoclay loading (0–4 wt.%), and NaOH surface treatment (0–8 %) on hardness, impact strength, tensile strength, flexural strength, and shear strength was evaluated using the Taguchi optimization method. Signal-to-noise ratio analysis and analysis of variance (ANOVA) were employed to determine the significance and contribution of each parameter affecting the mechanical behaviour of the composites. The results revealed that PALF content was the most influential factor governing the overall mechanical performance, followed by nanoclay addition and NaOH treatment. Mechanical properties improved significantly with increasing PALF content up to 20 wt.% and moderate nanoclay addition of about 1–2 wt.%, while higher fibre loading resulted in slight property reduction due to fibre agglomeration and reduced matrix continuity. Alkali treatment further enhanced fibre–matrix adhesion, leading to improved stress transfer efficiency. SEM analysis confirmed improved interfacial bonding in the optimized composite specimen. The optimized parameter combination demonstrated enhanced mechanical characteristics, indicating that the developed composites are suitable for lightweight structural and semi-structural engineering applications.
Lithium-ion batteries in transport and vibration-rich environments experience simultaneous thermal and mechanical stress, yet the combined influence of temperature and vibration on short-term ageing remains insufficiently characterised. This study quantifies coupled degradation by evaluating capacity and internal resistance of cylindrical cells cycled between -20 and 60 degrees C under vibrational and static conditions. In-situ discharge capacity was recorded over nine cycles, and internal resistance was measured at room temperature before and after exposure to enable direct comparison across conditions. Capacity loss was strongly temperature dependent, peaking at -20 degrees C where the vibrated cell showed a 2.97 % loss, while the minimum loss of 0.20 % occurred at 20 degrees C. Across all temperatures, vibration accelerated degradation and increased average capacity loss by approximately 1.8 times relative to static operation. Internal resistance increased by 0.05-0.28 % and followed the same temperature trend as capacity. A two-variable polynomial model represented capacity as a function of temperature and cycle number and reproduced the measured trends with good accuracy. These results demonstrate non-additive thermo-mechanical interactions and support vibration-aware state-of-health assessment for batteries in service.
Abstract This study investigates the design, fabrication, and comprehensive characterization of epoxy-based nanocomposites reinforced with cobalt oxide (Co 3 O 4 ) nanoparticles using stereolithography (SLA), a prominent vat photopolymerization additive manufacturing technique. Composite formulations containing 0.05 to 0.25 wt.% Co 3 O 4 were prepared via sequential probe sonication, and ultrasonic bath treatment to ensure homogeneous nanoparticle dispersion within the photosensitive epoxy resin. Both solid specimens and architected structures based on triply periodic minimal surface (TPMS) topologies, specifically gyroid and Kelvin lattices, were fabricated to assess the synergistic influence of reinforcement content and lattice geometry on multifunctional performance. Mechanical tests including tensile, flexural, compressive, and Shore D hardness evaluations were conducted alongside thermogravimetric analysis and thermal conductivity measurements. The results revealed that 0.10 wt.% Co 3 O 4 yielded optimal enhancements in mechanical strength and thermal conductivity without causing detrimental agglomeration. Gyroid lattices exhibited superior compressive strength and extended plateau behavior compared to Kelvin counterparts, owing to smoother load redistribution and delayed densification. Fractographic analysis further corroborated these findings, showing improved crack deflection and interfacial adhesion at the optimal filler level. This work demonstrates the efficacy of integrating nanoscale reinforcement with topological optimization in SLA-based photopolymer composites, offering a promising route toward lightweight, mechanically robust, and thermally functional materials for structural applications.
In the present study, welding processes used in the manufacturing of agricultural machinery were investigated with the aim of reducing manufacturing energy consumption, thermal deformation, and the carbon footprint associated with production. A comparative analysis was performed between manual gas metal arc welding (GMAW) and an automated twin-wire welding process (TWIN MIG PMC) for the fabrication of long cutterbars used in disc mowers. Experimental investigations included weld geometry characterization, microhardness measurements, finite element analysis of structural loads, and 3D scanning of technological deformations. The results show that the automated TWIN welding process significantly improves manufacturing efficiency and structural quality. Compared with manual welding, the TWIN process reduced welding time by approximately 61 %, electrical energy consumption by 32 %, and shielding gas consumption by 61 %. The lower heat input (approximate to 31 % reduction) resulted in a smaller heat-affected zone and reduced technological deformation of the cutterbars by approximately 20 %, improving dimensional accuracy and eliminating the need for post-weld straightening operations. These results demonstrate that automated TWIN welding provides a more energy-efficient and dimensionally stable manufacturing solution for long welded structures used in agricultural machinery.
The long-term reliability of structural components operating under high-temperature and stress conditions is critically influenced by creep deformation and rupture. To address this, a wide array of computational creep life assessment models has emerged over the past decade, incorporating empirical, phenomenological, and artificial intelligence (AI)-assisted approaches. This study presents a quantitative bibliometric analysis of global research output from 2012 to 2025, with a focus on the development, performance, and adoption of computational creep models. Using data from Scopus, ScienceDirect, and Google Scholar, and analytical tools such as VOS viewer, this work maps publication trends, influential authors, institutional affiliations, and research clusters. The analysis categorizes key modeling approaches, ranging from classical constitutive laws to advanced continuum damage mechanics and hybrid AI-physics models, while highlighting their industrial relevance in sectors such as power generation, aerospace, and petrochemicals. Furthermore, it identifies underexplored areas, regional disparities, and evolving research frontiers. This study offers critical insights into the trajectory of creep modeling research and provides guidance for future development of more robust, predictive, and computationally efficient creep assessment frameworks.
This study investigates the microstructural, mechanical, and corrosion properties of Inconel 625 alloy joints produced by fiber laser welding, both autogenously and with ERNiCrMo-3 filler metal. Macrostructural analysis confirmed defect-free welds with increased weld metal volume in filler-added joints. Autogenous welding yielded finer grain structure, but higher concentrations of brittle Laves phase precipitates, leading to increased hardness yet reduced ductility and early crack initiation. Conversely, filler metal welds exhibited coarser grains, lower Laves phase formation, and superior tensile strength and elongation. Corrosion testing revealed the base material possessed the highest corrosion resistance, while filler metal welds demonstrated increased corrosion rates attributed to grain coarsening. These findings highlight the critical influence of welding metallurgy on joint performance, indicating that filler metal use enhances mechanical properties at a moderate compromise in corrosion resistance, guiding optimal welding strategies for Inconel 625 applications.
The impact of welding polarity on thermal distribution, micro-structure development and mechanical performance of AA8011 aluminum alloy joints that were prepared using Gas Tungsten Arc Welding (GTAW) was carefully researched. Direct current electrode negative (DCEN-TIG) and variable polarity TIG (VP-TIG) were used to do the welding with the same process conditions. The DCEN-TIG joints presented more penetrative dendritic microstructures, refined, and smaller pores, which lead to high ultimate tensile strength (135 MPa) and hardness (81 VHN). Conversely, VP-TIG welding had larger weld beads with concentrated porosity and coarsened grain because of increased heat input, resulting into lower strengths (112 MPa) and higher ductile (7.1 %) one. Analysis of fractographic showed that DCEN-TIG joints mostly exhibited ductile fracture, whereas VP-TIG joints exhibited mixed-mode fracture. The findings prove that the welding current polarity is a major determinant of heat input, solidification characteristics, and mechanical behavior of AA8011 weldments and offer useful information to the use of polarity in strength or ductility-critical conditions.
Abstract Vehicle components need to be lightweight in order to reduce fuel consumption, lower emissions, and maintain structural integrity. This study proposes a glider snake optimizer enhanced with the dynamic random walk (DRW) technique to improve convergence performance and solution quality in engineering design optimization. The proposed algorithm incorporates periodic learning mechanisms and quasi-oppositional population initialization to achieve a better balance between exploration and exploitation while avoiding premature convergence. The developed optimization approach was applied to the lower control arm of an automotive suspension system with the objective of minimizing structural mass while satisfying stress constraints. The optimization framework integrates parametric design variables with finite element analysis. The results demonstrate that the dynamic random walk-based glider snake optimizer achieved a minimum mass of 3.311 kg while maintaining the maximum stress at 144.5 MPa. Compared with the initial design, the proposed method provided a mass reduction of 21.00 %. The findings indicate that the proposed DRW-based glider snake optimizer converges efficiently and can be considered an effective tool for lightweight automotive component design and emission reduction-oriented engineering optimization problems.
Abstract In this study, the effects of atmospheric pressure cold plasma treatment on surface contact angles and adhesive joint performance of aluminum 7075-T6 alloy and carbon fiber reinforced polymer composites were investigated using experimental, numerical, and statistical methods. A full factorial experimental design was applied to evaluate three plasma parameters: application distance, number of passes, and application speed. Contact angle measurements were conducted to assess surface activation, and single lap adhesive joints were fabricated and tested to determine lap shear strength. The results were analyzed using analysis of variance to identify significant parameters and their contribution ratios. Process–output relationships were modeled using response surface methodology. Finite element analyses with LS-DYNA were performed to investigate stress distributions and mechanical behavior of the adhesive joints. Multi-objective optimization was carried out using the non-dominated sorting genetic algorithm II to minimize contact angles and maximize lap shear strength. Application distance was found to be the most influential parameter. The lowest contact angles and highest lap shear strength were achieved at high number of passes and low application distance and speed. Numerical results showed good agreement with experiments, and a Random Forest model was used to improve prediction accuracy within the optimization framework.
Abstract Pinless friction stir spot welding (PFSSW) is a promising solid-state joining technique for high-strength aluminum alloys, in which joint performance is primarily governed by shoulder-induced material flow and process parameters. In this study, the combined effects of shoulder groove geometry, rotational speed, and dwell time on the mechanical and microstructural characteristics of 3-mm-thick AA7075-T6 aluminum alloy joints were systematically investigated. Two pinless tools with identical dimensions but different shoulder groove geometries (gamma and spiral) were employed to isolate the influence of groove-induced material flow. Welding was conducted at rotational speeds of 2,500–3,500 rpm and dwell times of 6–14 s. Joint performance was evaluated through lap-shear tensile testing, energy absorption capacity derived from load–displacement curves, effective weld width (Weff) measurements, macrostructural analysis, microhardness profiling, and fractographic observations. The results demonstrated that increasing rotational speed and dwell time generally enhanced Weff for both tools due to improved material plasticization and consolidation at the lap interface. However, the spiral tool consistently produced larger Weff values (419–852 µm) than the gamma tool (340–711 µm) under comparable conditions. A strong positive correlation was observed between effective weld width and energy absorption capacity, as confirmed by regression analysis. Microhardness profiles revealed a hardened region near the weld center (≈201–215 HV) and a softened heat-affected zone (≈150–162 HV), where dwell time primarily governed the extent of HAZ softening, while rotational speed influenced the peak hardness. Overall, the spiral groove geometry promoted more distributed material flow and superior energy absorption performance compared to the gamma geometry.
