Search Results (190)

This study addresses the fundamental problem of representing the rheological properties of heterostructured materials composed of metals that differ significantly in their crystal structure, stacking fault energy, and related characteristics. The necessity of accounting for essential strengthening mechanisms is highlighted. The study is based on experimental results related to the fabrication of a multilayer, heterogeneous system via multistage wire drawing, supported by microstructural analysis, microhardness measurements, and numerical simulations employing various flow-stress models. A discussion is presented regarding the effectiveness of these models in representing the deformation behavior of the investigated materials. The primary materials examined were a multilayer system composed of microalloyed steel and titanium. The obtained results indicate that, in addition to incorporating strengthening mechanisms, it is necessary to consider significant microstructural changes affecting microstructure evolution—particularly grain refinement induced by continuous recrystallization and the effects of strain hardening. Moreover, the findings point to the potential intensification of strengthening associated with pile-up mechanisms, linked to the development of dislocation substructures and the possible fragmentation of the hard phase in the vicinity of the more ductile microalloyed steel phase. In conclusion, the discussion integrates measurements of rheological properties obtained through tensile tests, supported by microstructural analysis, digital image correlation (DIC), and microhardness measurements, which collectively demonstrate the effectiveness of the adopted analytical approach. Full article

Engineering programmes have been giving more weight to experiential learning, largely because many students still find it difficult to see how classroom theory connects to the work that engineers handle on the ground. With this in mind, a robotics-centred Project-based Learning (PBL) module was introduced to first-year general engineering students as part of the faculty’s engineering spine. The module asks students to design, build, and program small autonomous robots capable of navigating and competing in a set arena. Even a simple task of this kind draws together multiple strands of engineering. Students shift between sketching mechanical layouts, wiring basic circuits, writing code, testing prototypes, and negotiating the usual challenges that arise when several people share responsibility for the same piece of hardware. To explore how students learned through the module, a mixed-methods evaluation was carried out using survey responses alongside reflective pieces written by the students themselves. Certain patterns appeared repeatedly. Many students felt that their technical skills had grown, particularly in breaking down a messy problem into smaller, more workable components. Teamwork also surfaced as a prominent theme. Groups often had to sort out issues such as a robot veering off course due to a misaligned sensor or a block of code producing unpredictable behaviour. These issues were undoubtedly challenging for the students, but they also had a certain pedagogical flavour, with many students describing them as a source of frustration as well as a learning opportunity. Later iterations of the module may benefit from more targeted support at key stages. Despite the many challenges, robotics has been shown to be an attractive way for students to step into engineering practice. The project helped them build technical capability, but it also encouraged habits that matter just as much in real work, such as planning, communicating clearly, and returning to a problem until it behaves as expected. Taken together, the experience offers useful guidance for curriculum designers seeking to create early learning environments that feel authentic and manageable and for motivating students who are just beginning their engineering journey. Full article

With the rapid development of the new energy vehicle industry, the quality control of battery pack glue application processes has become a critical factor in ensuring the sealing, insulation, and structural stability of the battery. However, existing detection methods face numerous challenges in complex industrial environments, such as metal reflections, interference from heating film grids, inconsistent orientations of glue strips, and the difficulty of accurately segmenting elongated targets, leading to insufficient precision and robustness in glue dimension measurement and glue break detection. To address these challenges, this paper proposes a battery pack glue application detection method that integrates the YOLOv11 deep learning model with pixel-level geometric analysis. The method first uses YOLOv11 to precisely extract the glue region and identify and block the heating film interference area. Glue strips orientation correction and image normalization are performed through adaptive binarization and Hough transformation. Next, high-precision pixel-level measurement of glue strip width and length is achieved by combining connected component analysis and multi-line statistical strategies. Finally, glue break and wire drawing defects are reliably detected based on image slicing and pixel ratio analysis. Experimental results show that the average measurement errors in glue strip width and length are only 1.5% and 2.3%, respectively, with a 100% accuracy rate in glue break detection, significantly outperforming traditional vision methods and mainstream instance segmentation models. Ablation experiments further validate the effectiveness and synergy of the modules. This study provides a high-precision and robust automated detection solution for glue application processes in complex industrial scenarios, with significant engineering application value. Full article

The transverse grain boundaries in pure copper wires increase resistivity, generating capacitance and inductance effects, leading to a decrease in the electrical conductivity of pure copper wires. Directional heat treatment technology can eliminate transverse grain boundaries in pure copper conductors, which is of great significance for improving electrical conductivity. Directional heat treatment is essentially a secondary recrystallization process, with influencing factors involving microstructure, texture, etc. This study systematically investigated the effects of cold-drawing deformation rate and heat treatment processes on secondary recrystallization microstructure, grain boundary structure, and crystallographic texture in pure copper wires. The results demonstrate that higher deformation levels (≥89%) facilitate secondary recrystallization and enhance <100> texture development. Moreover, the heat treatment temperature exerts a more significant influence on secondary recrystallization than the heat treatment duration. The grain coarsening temperature for pure copper wires with a deformation degree of 89% was determined to be 400 °C. These findings provide a fundamental basis for formulating directed heat treatment processes for pure copper wires. Full article

This study examines Phase B of the GREENERGY project focusing on the seismic performance and structural health monitoring of a renovated single-story RC frame with brick masonry infills that received significant strategic structural interventions. The columns were confined with basalt fiber ropes (FR, 4 mm thickness, two layers) in critical regions, the vertical interfaces between infill and concrete were filled with polyurethane PM forming PUFJ (PolyUrethane Flexible Joints), and glass fiber mesh embedded in polyurethane PS was applied as FRPU (Fiber Reinforced PolyUrethane) jacket on the infills. Further, greenery renovations included the attachment of five double-stack concrete planters (each weighing 153 kg) with different support-anchoring configurations and of eight steel frame constructions (40 kg/m²) simulating vertical living walls (VLW) with eight different connection methods. The specimen was subjected to progressively increasing earthquake excitation based on the Thessaloniki 1978 earthquake record with peak ground acceleration ranging from EQ0.07 g to EQ1.40 g. Comprehensive instrumentation included twelve accelerometers, eight draw wire sensors, twenty-two strain gauges, and a network of sixty-one PZTs utilizing the EMI (Electromechanical Impedance) technique. Results demonstrated that the structure sustained extremely high displacement drift levels of 2.62% at EQ1.40 g while maintaining structural integrity and avoiding collapse. The PUFJ and FRPU systems maintained their integrity throughout all excitations, with limited FRPU fracture only locally at extreme crushing zones of two opposite bottom bricks. Columns’ longitudinal reinforcement entered yielding and strain hardening at top and bottom critical regions provided the FR confinement. VLW frames exhibited equally remarkably resilient performance, avoiding collapse despite local anchor degradation in some investigated cases. The planter performance varied significantly, yet avoiding overturning in all cases. Steel rod anchored planter demonstrated superior performance while simply supported configurations on polyurethane pads exhibited significant rocking and base sliding displacement of ±4 cm at maximum intensity. PZT structural health monitoring (SHM) sensors successfully tracked damage progression. RMSD indices of PZT recordings provided quantifiable damage assessment. Elevated RMSD values corresponded well to visually observed local damages while lower RMSD values in columns 1 and 2 compared with columns 3 and 4 suggested that basalt rope wrapping together with PUFJ and FRPU jacketed infills in two directions could restrict concrete core disintegration more effectively. The experiments validate the advanced structural interventions and vertical forest renovations, ensuring human life protection during successive extreme EQ excitations of deficient existing building stock. Full article

The wire drawing process, used for both ferrous and non-ferrous metals, employs different machines depending on the material and wire diameter: breakdown, single- or multi-wire machines for non-ferrous, and bull block machines for ferrous and non-ferrous alloy wires. In all cases, wire is drawn through dies by tensile forces, with die design, material, and lubrication crucial for reducing friction, dissipating heat, and ensuring quality. Die type and geometry, lubricant, drawing speed, and machine configuration are the main process variables. The present work evaluates the effects of die type, lubricant, and drawing speed on Zn–Al alloy wire drawing (Ø2.18 to Ø2.00 mm) using a Taguchi L9 (3³) design of experiments. Three lubricants (Multidraw oil/water, Multipress oil and water/oil emulsion), three dies (conventional, carbide 19.38-grade pressure die, carbide H3F-grade pressure die), and three drawing speeds (0.16 to 0.28 m/s) were tested. Results have shown that lubricant and die geometry dominate process performance. Pressure dies reduced drawing force by up to 8% versus the conventional die, and emulsion increased force by 14% compared to oils. Output wire temperatures increased with speed, peaking at 46.5 °C with water emulsion oil and pressure die with H3F carbide, while Multidraw oil kept values ~20% lower. However, emulsions lowered the die output temperatures by 15–25% compared to oils. The coefficient of friction averaged μ = 0.104, with pressure dies yielding the lowest values (0.091–0.096, ~20% below conventional). Surface quality was governed mainly by lubricant effectiveness, with pressure-drawing dies ensuring dimensional accuracy and surface cleanliness. The study identifies lubricant selection as the most influential factor, followed by die type, providing a basis for optimizing efficiency and product quality in the wire drawing of ZnAl15% alloy. Full article

In this investigation, Ni_50.9Ti_49.1 wires cold rolled to 40% and straight annealed at 480 °C, 510 °C, and 550 °C, respectively, were heat treated to shape set these wires as helical springs and enhance their SME for use as electro-mechanical actuators. These spring actuators were heat treated at 350 °C, 400 °C, and 450 °C for 30, 60, and 90 min. The wires’ performance as actuators was assessed on a custom-built testing rig, which measured both the stroke and actuation time for each wire. Additionally, the wires were characterised experimentally by DSC, XRD, and nanoindentation. The final resulting properties of the R-phase transformation helical spring actuator are controlled by the competing mechanisms of dislocation annihilation, and precipitation of Ni₄Ti₃, as well as the prior thermomechanical treatment. The optimum conditions for actuator response in Ni_50.9Ti_49.1 40% cold-worked wires were a straight annealing temperature of 480 °C and shape-setting aging conditions of 450 °C for 60 min. These parameters result in the optimum combination of defect annihilation and density of precipitates, resulting in a high-stroke (56 mm), low-hysteresis (2.68 °C) actuator with an actuation time of 6 s. Full article

The implementation of K–12 engineering education presents significant challenges for current teachers. To strengthen the instructional readiness of elementary school teachers in Taiwan for engineering education, this study developed a STEM-oriented engineering design activity. It draws on international K–12 engineering education models and incorporates the computational thinking competencies prioritized by Taiwan’s national technology curriculum. The activity involves employing the micro:bit microcontroller to design an educational buzz wire game machine themed on energy education, integrating the engineering design process with knowledge from science, mathematics, and technology. The activity was implemented in an elementary teacher education course through a one-group pretest–posttest quasi-experimental design. The results indicate that participants completed engaging buzz wire game machines that incorporated energy concepts. Significant improvements were observed in participants’ engineering concepts, engineering design self-efficacy, computational thinking, and programming self-efficacy, with a considerable effect size noted in programming self-efficacy (N = 27, Cohen’s d = 1.84, p < 0.05). Most participants expressed highly positive attitudes toward the activity. The findings suggest that the engineering design activity developed in this study shows promising evidence of enhancing professional growth across multiple dimensions of engineering education for pre-service elementary teachers. The study serves as a valuable reference for future curriculum design in teacher education programs. Full article

As a high-frequency and essential type of special electromechanical equipment, a vertical elevator has a significant societal implication for their safe operation. The load-weighing module, serving as the core component for overload warning, is susceptible to precision degradation due to the nonlinear deformation of rubber buffers installed at the base of the elevator car. This deformation arises from the coupled effects of environmental factors such as temperature, humidity, and material aging, leading to potential safety risks including missed overload alarms and false empty status detections. To address the issue of accuracy deterioration in elevator load-weighing systems, this study proposes an online self-calibration method based on multimodal information fusion. A reference detection model is first constructed to map the relationship between applied load and the corresponding relative compression of the rubber buffers. Subsequently, displacement data from a draw-wire sensor are integrated with target detection model outputs, enabling real-time extraction of dynamic rubber buffers’ deformation characteristics under empty conditions. Based on the above, a displacement-based compensation term is derived to enhance the accuracy of load estimation. This is further supported by a dynamic error compensation mechanism and an online computation framework, allowing the system to self-calibrate without manual intervention. The proposed approach eliminates the dependency on manual tuning inherent in traditional methods and forms a highly robust solution for load monitoring. Field experiments demonstrate the effectiveness of the proposed method and the stability of the prototype system. The results confirm that the synergistic integration of multimodal perception and adaptive calibration technologies effectively resolves the challenge of load-weighing precision degradation under complex operating conditions, offering a novel technical paradigm for elevator safety monitoring. Full article

In this paper, high-strength W-1%La₂O₃ alloy wire was obtained by solid-state doping using tungsten powder and lanthanum oxide, large deformation rotary forging and wire drawing, which solved the disadvantages of traditional tungsten alloy wire processing such as the uneven distribution of rare earth oxides. The effects of rotary forging and annealing on the microstructure and properties of tungsten alloy were studied, which provided some basis for preparing high-strength tungsten alloy wire. The results indicate that tungsten alloy undergoes recovery at relative high temperatures (1480–1380 °C) during the rotary forging process. After large deformation, subgrains and uneven microstructures appear, so annealing is required before tungsten alloys wire drawing processing. With increasing annealing temperature, the recrystallization degree gradually increases and the hardness of tungsten alloy gradually decreases. When the deformation is less than 81.2%, tungsten alloy wire exhibits brittle fracture. When the deformation increases to 88.4% (ø0.8 mm), the fracture surface of the wire exhibits a plastic–brittle mixed fracture mechanism. Full article

Soft sensors are designed to be flexible, making them ideal for wearable devices as they can conform to the human body during motion, capturing pertinent information effectively. However, once these wearable sensors are constructed, modifying them is not straightforward without undergoing a re-prototyping process. In this study, we introduced a novel design for a modular soft sensor unit (M2SU) that incorporates a short, wire-shaped sensory structure made of eutectogel, with magnetic blocks at both ends. This design facilitates the easy assembly and reversible integration of the sensor directly onto a wearable device in situ. Leveraging the piezoresistive properties of eutectogel and the dual conductive and magnetic characteristics of neodymium magnets, our sensor unit acts as both a sensing element and a modular component. To explore the practical application of M2SUs in wearable sensing, we equipped a glove with 8 M2SUs. We evaluated its performance across three common gesture recognition tasks: numeric keypad typing (Task 1), symbol drawing (Task 2), and uppercase letter writing (Task 3). Employing a 1D convolutional neural network to analyze the collected data, we achieved task-specific accuracies of 80.43% (Top 3: 97.68%) for Task 1, 88.58% (Top 3: 96.13%) for Task 2, and 79.87% (Top 3: 91.59%) for Task 3. These results confirm that our modular soft sensor design can facilitate high-accuracy gesture recognition on wearable devices through straightforward, in situ assembly. Full article

A solid/liquid continuous composite casting technology was developed to produce brass-clad copper stranded wire billets efficiently with continuous casting speeds ranging from 200 mm/min to 1000 mm/min. As the casting speed increased, the microstructure of the brass cladding transformed at an angle to the radial direction. The wire billet prepared at a casting speed of 600 mm/min was then subjected to drawing. As the percentage reduction in area of the billet increased from 11.9 to 81.5% during the drawing process, the tensile strength improved from 336 MPa to 534 MPa, while the elongation after fracture decreased from 30.1 to 4.7%. Meanwhile, dislocation, dislocation cells, and microbands successively formed in the pure copper strand wires, while twins, shear bands, dislocation pile-ups, and secondary twins gradually formed in the brass cladding. During the drawing process, the interface between copper and brass remained metallurgically bonded, exhibiting coordinated deformation behavior. This paper clarified the evolution of microstructure and mechanical properties of brass-clad copper stranded wires in high-speed solid/liquid continuous composite casting and drawing, which could provide important reference for industrial production. Full article

The development of microelectronics results in higher demand for copper microwires and thin foils. Higher demand requires conducting research to obtain knowledge on the influence of extreme plastic deformation on materials’ susceptibility to plastic processing without the loss of coherence. One of the key factors contributing to rupture during the plastic deformation of copper is the presence of micrometer-sized, eutectic Cu₂O oxides, which are weakly bound to the copper matrix. These oxides are formed during the metallurgical stage of wire rod copper manufacturing. Copper wire rod of the ETP (electrolytic tough pitch) grade was subjected to wire drawing followed by cold-rolling. Applying different states of stress during plastic deformation (wire drawing, cold-rolling, and upsetting) made it possible to specify the conditions required for Cu₂O oxides’ fragmentation due to the extreme total deformation. Qualitative and quantitative analyses of the Cu₂O oxides’ evolution and fragmentation as the plastic deformation progressed were the main focus of this paper. It was determined that major fragmentation occurred during the initial stages of plastic deformation. Applying further extreme deformation or changing the state of stress during plastic deformation did not facilitate the continuation of fragmentation. It was only their shape that was becoming elongated. Full article

This paper focuses on the study of the tensile fracture behaviour of prismatic notched specimens of cold drawn pearlitic steel, providing a macro- and micro-approach. Two types of notched samples with very different notch radius (sharp and blunt notches, PAA and PCC) and the same notch depth were studied, thereby allowing a study of the fracture behaviour under different levels of stress triaxiality (constraint) in the experimental specimen. The studied samples are machined from pearlitic steel wires taken from a real cold drawing chain, analysing the entire drawing process, from the initial base material (hot rolled bar; not cold drawn at all) to the final commercial product (prestressing steel wires; heavily cold drawn), including two intermediate stages in the manufacture chain. The aforesaid specimens were subjected to tensile fracture tests and analysed at macroscopic and microscopical level using the scanning electron microscope (SEM), thereby obtaining micrographs of the different areas appearing in the specimens under study and assembling full micro-fracture maps (MFMs) of the fractured area. The aim of the research is to analyse the macro- and microscopic changes produced by the variation in stress triaxiality state (constraint), along with the different fracture processes. The first relevant finding is the increase in fracture path deflection for higher drawing degrees, and for greater triaxiality levels associated with sharp notches. Another finding is the variation in area of the different fracture zones, i.e., outer crown (OC), fracture process zone (FPZ) and intermediate zone (Z_INT), which are characterised by their specific micro-mechanisms, micro-void coalescence (MVC), cleavage (C) and special (large) micro-void coalescence (MVC*). The higher the stress triaxiality level, the larger the area occupied by the Z_INT in the fracture process. The fracture behaviour tends to unify along with the degree of drawing, with less dependence on the state of triaxiality imposed on heavily drawn wires. Results have been obtained in which the increase in triaxiality, imposed by the smaller radius of curvature of the notch (sharp notch), as well as the greater degree of drawing of the wires, cause the fracture process to place the FPZ at the notch tip. It is demonstrated that the variation in stress triaxiality and the drawing degree can generate different locations of the fracture initiation zone (FPZ). Full article