Search Results (12,834)

The present article considers the feasibility of using 3D-printed patterns for sand casting applications. The patterns have been produced by FDM/FFF technology, and the casting process has been simulated in the specialized CAE software product ProCAST. A prototype series of castings has been produced for the purpose of experimentally validating the applicability of 3D-printed patterns in the sand casting process. The results obtained demonstrate the significant potential of 3D-printed patterns to streamline the technological process in the manufacture of foundry tooling equipment. The use of additive-manufactured patterns reduces the time required for their design and production and increases flexibility in the manufacture of prototypes or small series products. The result is more efficient production planning and a reduction in the overall time required to produce sand castings. Full article

This study addresses the influence of process conditions on the dimensional accuracy, geometric deviations, and surface quality of PLA parts manufactured using high-dynamics material extrusion (MEX) technology. The aim was to identify the dominant sources of variability and to assess within-condition manufacturing consistency and inter-machine consistency. The investigation considered two 3D printers, nine build locations on the working platform, two printing strategies (layer-by-layer and model-by-model), and model face orientation. Additionally, an exploratory comparison of aligned and random seam configurations and an analysis of local temperature variations within the build chamber were performed. Regular dodecahedron geometries were manufactured using a Bambu Lab P1S system and processed under identical high-quality printing parameters. Dimensional measurements were performed using a Linear 100 universal length measuring machine, while full-field geometric deviations were acquired using a GOM Scan 1 structured-light 3D scanner. Surface roughness (Ra) was measured with a MarSurf XR 20 profilometer. Part orientation is the dominant source of dimensional variability, representing the largest relative contribution to linear deviation in the mixed-effects model (ΔR² = 0.776), while local temperature variations near the printing zone were associated with location-dependent dimensional deviations. Within the supplementary temperature dataset, the regression model including temperature and printers explained 66% of the variability in mean linear dimension. This association provides indirect evidence of a thermal contribution but does not establish direct causality. The layer-by-layer strategy provided better dimensional stability than the model-by-model approach. In the exploratory seam comparison, seam configuration did not explain the orientation-dependent LD pattern. Surface roughness variability was primarily geometry-driven (ΔR² = 0.852). Variability between independent manufacturing series and specimens for linear deviation and Ra was low after accounting for the investigated factors, indicating consistent process performance under constant settings; however, the present design did not allow measurement repeatability and reproducibility to be separated. In conclusion, dimensional accuracy in high-dynamics MEX is strongly associated with part orientation, while thermal variations may represent an additional contributing factor; however, the observed correlation between thermal conditions and dimensional variability does not establish direct causality. Full article

Al-Li alloys present significant challenges for conventional fusion-based additive manufacturing (AM) due to their low evaporation temperature and high reactivity with oxygen. As a solid-state process, friction stir additive manufacturing (FSAM) is expected to eliminate melting and solidification during processing, thereby overcoming these limitations. This study investigates the FSAM of 2195 Al-Li alloy through temperature measurements and numerical simulations. The research focuses on the temperature at the center of the deposited region and the phase evolution before and after FSAM. The results indicate that during FSAM, the temperature at the center of the deposited zone ranges from 458 to 497 °C. In terms of phase constitution, the T3-tempered alloy primarily consists of an α-Al matrix and the δ’ (Al₃Li) phase. The T8-tempered alloy contains α-Al, θ’ (Al₂Cu), and T₁ (Al₂CuLi) phases. In the nugget zone (NZ), the peak temperature exceeds 450 °C. As a result, the T₁ and θ’ phases dissolve, leaving only a small amount of δ’/β’ precipitates. This study presents a preliminary investigation based on a single-layer FSAM process. These findings provide a foundation for optimizing FSAM process parameters for Al-Li alloys. Full article

To advance the goals of carbon peaking and carbon neutrality alongside the global energy transition, energy conservation and carbon reduction in refrigeration and air-conditioning systems have garnered widespread attention. Dew-point evaporative cooling (DPEC) represents a promising energy-efficient cooling technology, whose performance is strongly governed by the water supply strategy. This study presents a systematic comparison of falling-film and atomization water supply modes on a counter-flow DPEC test bench featuring 3D-printed palm fiber filament walls. Experiments were conducted over inlet air temperatures of 32–50 °C, velocities of 1.3–4.0 m/s, and a range of water supply temperatures. The results demonstrate that the falling-film mode yields 15–25% higher dew-point efficiency than the atomization mode under baseline operating conditions. Water supply temperature (15–30 °C) exerts a negligible influence on falling-film cooling performance. The hybrid falling-film–atomization mode achieves the highest cooling capacity in the medium-to-low air velocity range, with a maximum wet-bulb efficiency of 1.15, while the falling-film mode yields the highest COP of up to 2.2. These findings offer experimental guidance for optimizing water supply strategies in fiber-wall DPEC systems. Full article

Ulluco (Ullucus tuberosus), the second most economically important Andean tuber after potato, has been cultivated for over 5500 years. Despite its resistance to frost, drought, and high altitudes, as well as its biochemically complex profile, ulluco remains underrepresented in the scientific literature and absent from international markets. This comparative review synthesises the evidence available up to November 2025 regarding its biology, nutritional profile, phytochemistry, and food industry applications relative to four other Andean tubers: oca (Oxalis tuberosa), mashua (Tropaeolum tuberosum), native potato (Solanum tuberosum L.), and yacon (Smallanthus sonchifolius). The main comparative findings are as follows: First, ulluco is the only Andean tuber that biosynthesises betalains instead of anthocyanins, producing up to 32 distinct compounds that are stable across a pH range of 3–7, a chromatic stability advantage over anthocyanin-based pigments from mashua, oca, and native potato, which suggests its potential as a source for the development of clean-label natural colourants. Second, among the five species evaluated, ulluco protein content across different morphotypes ranges from 5.60 to 15.7 g/100 g dry weight, ranking within the upper range of values reported for mashua and oca, and comparable to or higher than the upper ranges reported for native potato and yacon. This variability reflects the genotypic and ecogeographical diversity of the evaluated accessions and is not a methodological inconsistency, with 20% of varieties exceeding 10 g/100 g and providing six essential amino acids, supporting genetic improvement programmes aimed at nutritional security. Third, ulluco starch exhibits a low gelatinisation temperature (56–60 °C), a high amylose content (24–36%), and pseudoplastic behaviour, properties comparable or superior to potato starch for specific applications, with technical viability validated at a laboratory scale in applications including biodegradable films, food 3D printing inks, and dehydrated snacks. Unlike yacon, which accumulates fructooligosaccharides and lacks starch, ulluco aligns with oca, mashua, and potato as a starch-accumulating species. Critical gaps identified include the absence of clinical evidence on betalain bioavailability, the lack of a complete nuclear genome assembly, and the non-existence of standardised processing methods for industrial scaling. A coordinated agenda that integrates clean seed programmes, pilot-scale validation, and genomic breeding is essential for the bioeconomy of the 21st century to transform ulluco into a high-value ingredient. Full article

Recently, flexible electronics have attracted widespread attention in personalized health monitoring, soft robotics, and smart human-machine interactions due to intrinsic high stretchability. Among them, constructing buckled structures in flexible devices is one of the most effective strategies to achieve flexibility and stretchability. Flexible electronic devices based on buckled structure (FEDB) have gained significant research progress, owing to their outstanding advantages such as simple fabrication processes, excellent structural stability, and broad applicability. Furthermore, its application areas are expanding to emerging scenarios, including the human body, underwater environments, the oceans, and space. However, there are few systematic reviews concerning their progresses, although researchers show increasing interest in the emerging applications of FEDB. This review summarizes recent research progress in FEDB. First, this review explains the buckled instability mechanism, listing the common conductive and substrate materials. The polymeric substrates discussed mainly include PDMS, TPU, SBS, PC, and hydrogel, which provide the flexibility and deformability required for FEDB. In addition, this review summarizes several methods for constructing buckled structures, including prestretch-release, solvent swelling, thermal, mold, and 3D printing as well as techniques for controlling morphology. Second, this review summarizes the applications of FEDB, such as flexible electrodes, strain and pressure sensors, and energy devices. Particularly, it provides a detailed introduction to the expansion of emerging scenarios, involving underwater monitoring, in vitro and in vivo physiological signal detection, human-machine interactions, and portable capsule devices. Finally, this review points out the current challenges of FEDB, including long-term service stability, adaptability to extreme environments, conformal attachment to complex curved surfaces, and large-scale manufacturing. Full article

Additive manufacturing enables rapid prototyping, the production of complex geometries, and a reduction in production costs, which contributes to its widespread use in engineering. Despite the numerous advantages of additive technologies, limitations still exist regarding the dimensional and geometric accuracy of manufactured parts, particularly in MEX technology. The aim of this study was to investigate the possibility of using subtractive machining as a post-processing method to improve the accuracy of 3D-printed parts. Cylindrical samples were manufactured using the MEX method with specified process parameters and then subjected to turning. As part of the research, an analysis of the diameter and roundness deviations was conducted before and after the machining process. The results showed a clear reduction in geometric deviations and an improvement in dimensional accuracy after turning. The findings indicate that subtractive machining can effectively compensate for inaccuracies resulting from the nature of the additive manufacturing process. The turning process reduced the sample diameter by up to 7.04%, as intended, while improving geometric accuracy by reducing the roundness error by up to 95.76%, depending on the printing orientation and cutting parameters. As a result, turning can serve as a method for the final machining of components manufactured using MEX technology. Full article

This study developed 3D-printable cement mortar (3DPCM) incorporating modified basic oxygen furnace slag (MBOFS) sand and waste printed circuit board powder (WPCBP). Five WPCBP-to-cement ratios, namely 0, 10, 20, 30, and 40 wt.%, were adopted, and the printability of each mixture was first evaluated. Subsequently, the compressive, flexural, and splitting tensile behaviors of mold-cast and 3D-printed specimens were compared, and the structural response of 3D-printed truss members was assessed through four-point bending tests and finite element analysis. The results showed that all mixtures could be printed stably. For the standard 3D-printed specimens, WPCBP/C = 20 wt.% provided the highest quasi-static mechanical performance, and the mechanical response exhibited clear anisotropic behavior. In contrast, the mechanical performance of the mold-cast specimens decreased with increasing WPCBP content. In the 3D-printed truss members, the average peak load increased from 8.041 to 20.710 kN, the displacement corresponding to the peak load increased from 0.201 to 0.683 mm, and the finite element analysis reasonably captured the overall load–displacement response. Overall, MBOFS sand and WPCBP can be effectively incorporated into 3DPCM and show potential for sustainable structural material applications. Full article

The use of recycled polymers in additive manufacturing has emerged as a promising strategy for reducing the environmental impact of polymer processing. However, the influence of recycling on monotonic and fatigue properties of polymeric materials manufactured by fused deposition modelling (FDM) is not yet completely understood. This paper compares the monotonic and fatigue properties of virgin PET–G and recycled PET–G (rPET–G) specimens manufactured via FDM using commercial filaments supplied by the same manufacturer. Monotonic tensile tests were conducted under uniaxial quasi-static loading conditions, while fatigue tests were performed under rotating bending with constant amplitude and load-controlled conditions. Fatigue fracture surfaces were analysed using scanning electron microscopy to identify the main failure micromechanisms. The results revealed a reduction in the tensile strength of rPET–G compared with the virgin PET–G, which agrees with the trends reported in the literature. However, only a relatively small difference was observed in the fatigue strength. For a fatigue life of 10⁵ cycles, the recycled material exhibited reductions of 6.5% at a 50% probability failure and 1.9% at a 5% probability failure relative to the virgin material. This behaviour was associated with the presence of voids, which were more numerous in the rPET–G. Full article

Heritage museums increasingly seek to support visitors as active meaning-makers during the visit and to extend that experience beyond the museum through personally meaningful takeaways. Generative AI (GenAI) may support this goal by helping visitors transform museum source material into personalized artifacts, but open-ended generation may weaken heritage linkage and obscure curatorial responsibility. This paper proposes two paired design principles for heritage GenAI: bounded creativity, which defines what visitors may change, and curatorial accountability, which defines how cultural limits are set, explained, and revised. We implemented these principles at the Lanting Calligraphy Museum in Shaoxing, China, through a visit-linked co-creation system. Visitors collected source images during the museum tour and later created a personalized 3D-printed takeaway through either a rule-based editor with predefined templates and options or a GenAI-mediated dialogue interface. A between-subjects field study with adult visitors (N = 60; 20 per condition) compared conventional consumption (a standard tour and souvenir), rule-based co-creation, and GenAI-mediated co-creation. Both co-creation pathways improved cultural engagement, perceived connection to heritage sources, personal meaning and self-expression, and psychological ownership compared with conventional consumption. The GenAI-mediated pathway produced further gains in cultural engagement, personal meaning, self-expression, and psychological ownership. Still, it did not reliably increase perceived connection to heritage sources beyond that of the rule-based pathway. These findings suggest that the GenAI pathway added value mainly on personal authenticity and psychological ownership, by helping visitors articulate and revise intentions within accountable cultural boundaries; its incremental effect on heritage-linked authenticity remains undetermined at this sample size. Full article

To address the collaborative optimization problem caused by the strong coupling between 2D sheet metal nesting and flexible shop floor scheduling in the sheet metal manufacturing process for color-separation ovens of satellite-type flexographic printing presses, this paper proposes a collaborative optimization method for nesting and scheduling based on a dual-flow graph attention network and proximal policy optimization. This problem involves inherent structural and resource symmetry in manufacturing operations and is further complicated by process precedence constraints, multi-resource competition, human–machine collaboration, assembly dependencies, and the dynamic coupling between nesting decisions and downstream production takt. Based on the composition of oven components and actual production methods, a collaborative optimization model integrating nesting and scheduling was constructed; a discrete-event simulation-driven joint scheduling environment was established to uniformly model the nesting, cutting, flexible machining, and assembly processes. On this basis, the collaborative nesting–scheduling process was formalized as a Markov decision process, clearly defining the state space, action space, reward function, and state transition mechanism. To enhance the state representation capabilities of the reinforcement learning agent in a high-dimensional discrete action space and under strongly constrained dynamic scheduling scenarios, this paper embeds a dual-stream graph attention network into the PPO framework to develop the DS-GAT-PPO algorithm. This algorithm simultaneously captures spatial nesting relationships among parts as well as temporal dynamic features such as equipment load, worker fatigue, and production takt time, thereby generating feasible and efficient joint scheduling plans. Experimental results show that the proposed method can reduce completion time by approximately 10.9–33.8% while maintaining a high sheet utilization rate; in a comparison of reinforcement learning algorithms, the proposed method achieved better completion times in most test cases and reduced the number of convergence steps by approximately 6.67–66.67%, validating its effectiveness in improving solution quality, convergence efficiency, and scheduling stability. These findings provide a foundation for further research and practical applications of collaborative nesting–scheduling optimization in dynamic manufacturing environments. Full article

The increasing availability of recycled carbon fibres (rCFs) from manufacturing waste and end-of-life composite structures offers new opportunities for sustainable, high-performance composites. However, the discontinuous nature of recycled fibres requires efficient alignment and consolidation. In this study, highly aligned discontinuous carbon fibre tapes were manufactured from recycled carbon staple fibres and bio-based polyamide 11 (PA11) fibres using a textile-based processing route and compression moulding. Two material systems containing nominal fibre mass fractions of 50 wt.% and 70 wt.% rCF were investigated. The resulting laminates were characterised in terms of fibre volume content (FVC), fibre orientation distribution, and mechanical performance. FVC of up to 56.72 vol.% were achieved for the 70 wt.% rCF material. Tensile testing revealed a significant increase in stiffness and strength with increasing fibre content, reaching values of 48.1 GPa and 866 MPa. The longitudinal compression modulus and the in-plane shear modulus showed similar trends, while the transverse tensile strength and compressive strength remained strongly influenced by local defects and fibre–matrix interactions. A 2D mesoscopic image analysis demonstrated a pronounced preferential fibre orientation, with approximately 69% of the analysed fibre regions aligned within ±10° of the dominant fibre direction. The derived alignment coefficient η₀ correlated well with the tensile modulus, confirming the strong influence of mesoscopic fibre architecture on mechanical performance. The results demonstrate that the combination of bio-based PA11 and oriented rCF, enabled through textile-based alignment technologies, provides a promising pathway towards sustainable lightweight composite structures. Full article

The nanoscale surface topography and microhardness of additive and subtractive dental polymers were evaluated following exposure to environmental challenges. The study examined two 3D-printed resins (Saremco and Voco) and two milled CAD/CAM blocks (Vita Enamic and Tetric). Specimens were allocated to control or experimental groups and subjected to hydrothermal ageing (thermocycling), in vitro mechanical wear, or a combined protocol involving wear followed by thermal ageing. Surface microtopography was analysed both quantitatively and qualitatively using atomic force microscopy (AFM), while structural stability was assessed through surface microhardness testing. Statistical significance was determined using matrix comparisons (p < 0.05). Milled monolithic blocks demonstrated a dense, uniform baseline topography, whereas 3D-printed resins exhibited structural heterogeneity attributed to their layer-by-layer photocuring process. Saremco maintained polymer network stability under thermal stress (p = 0.1878), while Voco was highly susceptible to hydrothermal swelling and early matrix plasticization (p = 0.0084). The combined protocol of wear and thermal ageing resulted in advanced structural breakdown in all groups (p < 0.001). Industrial subtractive blocks exhibited greater resistance to oral environmental stresses. The ceramic framework of Vita Enamic limited polymer domain collapse, whereas Tetric experienced accelerated inter-layer delamination and embrittlement. The combined protocol of wear followed by thermal ageing resulted in significant and uniform degradation of surface microhardness and topographic roughness in all tested groups. Nevertheless, the additively manufactured resins demonstrated substantial structural integrity and exhibited low volumetric wear rates. Full article

This paper is dedicated to the determination of the electrical properties of a wire arc additively manufactured (WAAM) aluminum alloy component. Statistical processing of the electrical properties and hollow micro-interlayer zones of the WAAM sample made of ER4043 aluminum alloy is performed. The eddy current electrical conductivity measurement method is employed for WAAM 3D-printed sample surface properties mapping. Measured data on electrical conductivity are estimated depending on the 3D printing axis directions and the lift-off distance from the sample surface. The 3D standard deviation is calculated for property anisotropy correlation. These data can be used for improved additive manufacturing control for enhanced electrical conductivity of aluminum WAAM samples as well as for numerical modeling of the properties of such samples. Full article

This study evaluated the effects of thermocycling and staining on the optical behavior, chemical stability, and surface morphology of three commercial dental composites manufactured using different polymerization protocols: a light-cured composite (Omnichroma, OMNI) and two digital light-processed (DLP) 3D-printed composites intended for permanent (SprintRay CROWN, SPRINT) and temporary (GC Temp PRINT, TEMP) clinical applications. Disc-shaped specimens were subjected to thermocycling (0, 5000, 10,000, and 30,000 cycles) and immersion in coffee, Coca-Cola, or red wine for 1 and 7 days. Color change (ΔE₀₀) and translucency parameter (TP) were determined spectrophotometrically, while Fourier-transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) were employed to assess the polymerization efficiency (expressed as the relative conversion index) and surface morphology, respectively. Thermocycling induced material-dependent changes in color stability and translucency. After 30,000 cycles, ΔE₀₀ values reached 2.77 ± 0.89 for OMNI, 0.74 ± 0.34 for SPRINT, and 3.30 ± 0.89 for TEMP. SPRINT maintained the highest TP values throughout the aging protocol, ranging from 26.09 ± 0.33 to 23.81 ± 1.93, whereas OMNI and TEMP exhibited lower TP values. The most favorable optical performance and the highest resistance to beverage-induced coloration were detected for SPRINT, whereas TEMP showed the greatest susceptibility to aging- and staining-induced optical degradation. Red wine and coffee produced substantially greater color changes and reductions in translucency than Coca-Cola. AFM analysis demonstrated progressive surface degradation and increased roughness following prolonged thermocycling, highlighting the significant influence of material composition and manufacturing protocol on the long-term optical stability of the investigated dental composites. Full article