Reaction bonded SiC (RB-SiC) possesses advantages such as high hardness, temperature resistance, and corrosion resistance; however, these advantages also result in significant challenges in the machining of RB-SiC. Considering its high efficiency and low cost in the processing of difficult-to-cut materials, blasting erosion arc machining (BEAM) demonstrates considerable potential for the efficient machining of RB-SiC. However, research on BEAM has primarily focused on highly conductive materials, and application to low-conductivity, hard, and brittle ceramic materials has received limited attention. Thus, this study proposed the application of BEAM to RB-SiC and investigated its machining characteristics. Firstly, as the heat source in BEAM, the arc plasma behavior during RB-SiC machining was investigated via single-discharge experiments and compared with that observed for AISI 304 stainless steel. The results showed that the arc plasma generated during RB-SiC machining exhibited a higher development speed, stability, and maintaining voltage. Therefore, to ensure timely extinction of the arc plasma and protect the workpiece surface from thermal damage, a shorter pulse duration is more suitable for machining RB-SiC as it forcibly terminates energy input. Then, to analyze the machining effect of BEAM, the behavior of the molten pool and morphology of craters were investigated. The results indicate that RB-SiC is difficult to melt and expel efficiently, owing to its high thermal conductivity, high melting temperature, and large specific heat capacity. Therefore, high-speed flushing is essential to ensure effective material removal. Based on the research of arc discharge characteristics of RB-SiC, the machining performance was evaluated through machining experiments. The material removal rate (MRR) in RB-SiC machining reached 539.6 mm3/min, which was five times higher than that achieved using electrical discharge machining (EDM). The surface roughness was 25.31 µm, which was only 67.39
Carbon fiber-reinforced silicon carbide (C/SiC) composites are extensively employed in aerospace applications owing to their high-temperature strength, low density, and thermal stability. However, conventional machining of these hard and brittle materials is hindered by severe tool wear, low processing efficiency, and high operational costs. As a non-contact and tool-wear-free technique, abrasive waterjet (AWJ) machining enables efficient bulk material removal and can function as a roughing process that complements conventional finishing operations to ensure dimensional accuracy. In this study, AWJ milling was systematically investigated to elucidate how fiber orientation and jet parameters influenced material-removal behavior and surface integrity. Experiments were conducted on a five-axis AWJ system at traverse speeds ranging from 2 000 mm/min to 4 000 mm/min and standoff distances between 6 mm and 18 mm. Scanning electron microscopy (SEM), white-light interferometry, and depth-profilometry identified three orientation-dependent fiber-damage modes—splitting and pull-out in warp yarns, circumferential fracture in weft yarns, and protrusion-bending in needled fibers—originating from crack deflection and fiber-matrix interfacial debonding under localized jet loading. An increase in standoff distance broadened the kerf width while reducing the maximum removal depth by approximately 50
Time-varying tooth flank loaded contact pressure provides significant access to load capability, contact strength, and fatigue life forecasting for face-hobbed spiral bevel gears. Considering the reliability and time-varying meshing characteristics, an innovative assessment and identification model is developed using the discrete convolution and fast Fourier transformation (DC-FFT)-based conjugate gradient method (CGM). The reliability assessment mainly includes the edge impact, time-varying meshing characteristics, and the maximum loaded contact pressure, in addition to conventional assessment items. Firstly, an advanced face-hobbed cutting process involving a continuous indexing method is simulated for tooth flank modeling. Subsequently, contact initialization, time-varying edge contact solution, and numerical loaded tooth contact analysis (NLTCA) approximation and operation are developed for the loaded contact pressure reliability analysis and assessment. In particular, the time-varying edge impact provides an accurate parametric computation for reliability and assessment. Moreover, a DC-FFT-based CGM is used to establish time-varying loaded flank identification considering reliability assessment. Finally, a spiral bevel gear set from a helicopter transmission system is used to verify the impact of the proposed model on the loaded flank pressure distribution.
To address issues in traditional double-sided lapping machines, such as machining accuracy drift, structural thermal deformation, and insufficient intelligence, this study designed a high-precision double-sided lapping machine structure system oriented toward intelligent control systems, providing a physical carrier platform for subsequent system implementation. Based on the structural stability and dynamic adjustment requirements during machining, the machine adopted a swing-type structure and modular assembly architecture to construct a mechanical system with dynamic compensation characteristics. Finite-element-method-based static simulation and modal analysis ensured the rational design of critical components and structures while maintaining favorable dynamic stability. To resolve the lapping plate thermal deformation challenges, a low coefficient of thermal expansion (CTE) Invar alloy 4J36 was selected as the base material with embedded cooling channels designed to enhance temperature control. Fluid structure thermal interaction (FSTI) analysis shows that, under identical operating conditions, the thermal deformation of this material is reduced by nearly an order of magnitude compared with conventional alternative substrates. The machine integrates dual-airbag lever-pressurized mechanisms, high-rigidity lower-plate support structure, and dressing units. Simultaneously, a multi-source sensor network was embedded to provide the hardware foundations for data acquisition in intelligent control systems. Preliminary glass substrate machining experiments were conducted to verify the fundamental mechanical and structural performance. The results indicate that the total thickness variation (TTV) of the post-processed substrate is below 3 μm, validating the rationality and feasibility of the proposed design as a deployment and verification platform for subsequent intelligent control frameworks.
Regenerative chatter and strong cutting vibrations frequently occur during the milling of flexible parts. Auxiliary fixtures have been employed to improve the stiffness of flexible workpieces, thereby suppressing chatter and vibrations. However, the influence of fixture parameters such as supporting forces on milling dynamics remain insufficiently understood, particularly for hydraulic fixtures. This study developed a hydraulic fixture with precisely controllable forces for thin-walled flexible workpieces. The milling process of flexible workpieces equipped with a hydraulic fixture was modelled by incorporating the effects of runout and vibrations. The dynamic responses were calculated employing a time-domain simulation algorithm, and stability characteristics were evaluated via stroboscopic sampling. The modal parameters of the flexible workpiece were obtained by varying the supporting forces of the hydraulic fixture, and the proposed model was used to predict chatter stability and cutting vibrations. A series of cutting experiments was conducted to validate the predicted stability diagrams and vibration displacements. Both the theoretical and experimental results demonstrate that the hydraulic fixture can significantly suppress regenerative chatter and cutting vibrations in flexible workpieces. Increasing the supporting forces enhances the dynamic stiffness of the flexible workpiece; however, this improvement gradually reaches saturation. Consequently, the suppression effectiveness of the regenerative chatter and cutting vibrations also reaches saturation. These findings provide quantitative guidance for the optimal fixture design and control of hydraulic fixtures in milling applications involving flexible components.
Laser powder bed fusion (LPBF) is widely used for fabricating complex parts; however, a significant portion of the Ti6Al4V powder remains unused during the process. The efficient recycling of this powder is essential for sustainable development and cost reduction. This paper proposes an optimal mixing ratio of recycled and virgin Ti6Al4V powders to obtain a blend that meets the initial quality requirements for LPBF. Mechanical testing, microscopic characterization, and thermomechanical simulations were conducted to evaluate the effect of the mixed powder on the properties of the as-built parts. The results indicate that volumetric energy density (VED) is a critical parameter governing the mechanical properties and unfused-region-induced defects of parts fabricated from mixed powder feedstocks. Although the optimal VED of the mixed powder was 28.01
The busbar, one of the electrical connectors in electric-vehicle battery packs, undergoes a process to form a terminal at its end (i.e., a termination). In this study, laser edge welding was performed on two types of busbars (round and square) for busbar termination, and the weld formation mechanisms and joint properties were analyzed. In the round busbar, the curved shape of the edge forms a groove, resulting in different welding characteristics compared with the square-type busbar, which has a flat edge. In round-type welding, the groove structure increased thermal interaction at the laser-material interface, producing a total weld depth 0.24 mm greater than that of the square type; it also caused the grain growth direction to branch into two distinct paths. Additionally, cracks of approximately 100 m size were sporadically observed in round-type welds; this effect was attributed to the constraint on shrinkage deformation imposed by the groove structure. The mean hardness of the square-type weld remained uniform at 63.74 HV, whereas the hardness in the round-type weld decreased to 28.8 HV in cracked regions. For both edge types, the electrical resistance of the joints decreased with increasing weld depth. However, the round-type joint exhibited the electrical resistance 2.4 Ω higher than that of the square type, as a result of differences in dislocation density of the base metal. This study also provides in-depth insights into the heat transfer mechanism of laser edge welding based on the geometric shape of the busbar, which is a decisive factor influencing welding characteristics.
Thermal errors have a significant impact on the precision of computer numerical control (CNC) machine tools, particularly in high-speed spindle systems such as the BL20-HSY. This study presents a novel and data-efficient framework for thermal error modeling and compensation, designed to enhance machining accuracy under thermal load conditions. An experimental platform was developed to collect comprehensive thermal data from critical locations on the spindle structure. To improve the selection for temperature-sensitive points, fuzzy C-means (FCM) clustering, optimized through ant colony optimization (ACO), was employed. Additionally, a multivariable grey correlation analysis (MGCA) was conducted to further refine sensor selection by identifying critical points that exhibited a high correlation with thermal deviations. To overcome the challenges associated with small datasets, a robust model-agnostic meta-learning (MAML) approach was integrated with the grey wolf optimizer (GWO), resulting in an adaptive model capable of generalizing across various operating conditions. Experimental validation conducted on the T65 CNC lathe demonstrated that the proposed MAML-GWO model achieved a reduction of over 90
The machining accuracy control of honing 9310 steel thin-walled components (e.g., helicopter tail drive shafts) remains challenging owing to complex abrasive-workpiece interactions. This paper proposes a modeling approach that integrates abrasive machining theory with kinematic analysis. A novel honing-stone machining simulation model was developed based on the abrasive machining theory, enabling the accurate prediction of key parameters, including the number of effective abrasive grains, depth of cut, and tangential force under varying normal forces. By incorporating the honing stone trajectories, a diameter increment distribution model was established, achieving a prediction error of 9.74
Additive manufacturing (AM) has enabled the fabrication of complex lattice structures with unique mechanical properties, making them valuable for applications in biomedical and aerospace industries. However, the inherent surface roughness of as-built AM parts can adversely affect mechanical performance and corrosion resistance, particularly in complex structures like lattices. This study investigates the effectiveness of electrochemical polishing (ECP) strategies using an eco-friendly electrolyte, consisting of 1 mol/L NaCl in ethylene glycol with 20
Composites produced using the centrifugal gelcasting (CGC) method have an axially symmetrical shape with a hole in the axis. The top layer of the composite is rich in metallic components, while the inner layer is made entirely of ceramics. Between the outer and inner zones of such a pipe element, there is a gradual change in the share of the metallic phase. It was found that the local properties, measured along the structural gradient, depended on the content of Ni particles and changed accordingly in individual zones. The Ni content leads to reduced hardness and improved fracture toughness. The hardness of the external surface exceeds 10 GPa, with a crack resistance of 6.2 MPa·m0.5, and in the inner layer, it is 19.6 GPa, with a crack resistance of 3.9 MPa·m0.5. The samples have a comprehensive strength of 99.06 MPa.
Conventional remelting-based methods are widely used for recycling aluminium alloys scraps; however, these approaches come with significant drawbacks, including high energy consumption, permanent material losses, reduced purity, and low mechanical properties. To address these issues, solid state techniques have emerged over the last years as environmentally friendly recycling processes. Among them, friction stir extrusion (FSE) has proved to be a promising technique for producing wires/rods directly from metallic chips. In order to cover the market demand of semifinished product shapes, this study explores the possibility to produce aluminium alloys tube directly from chips without intermediate steps. This would save energy and resources, strengthening the environmental sustainability performance of FSE based recycling processes. An experimental and numerical approach is here proposed and the impacts of the main process parameters on the microstructural and mechanical properties of extruded aluminium tubes are analyzed. Results revealed that FSE could be used as sole process step to produce tubes from chips, and mechanical and microstructural analysis showed a substantial increase in hardness in correspondence to very fine and equiaxed grain structure. Moreover, numerical simulations were used to explain the small variations observed in grain size. Lastly, the electrical energy demand of this single-step approach was compared with that of conventional multi-step routes, demonstrating its superior energy efficiency.
A group of heat-treatment-free Al-7Si-0.3Mg-xFe (x = 0.15, 0.3, 0.45, 0.6 wt
Polytetrafluoroethylene (PTFE)-bolted joints are commonly used in equipment, apparatuses, and devices in various industries, including the semiconductors, chemical, biomedicine, food, and pharmaceutical industries. However, owing to their significant viscoelasticity, these joints are prone to preload attenuation during service, which significantly compromises the joint reliability. This study aimed to elucidate the preload attenuation behavior of PTFE bolts and the effects of environmental temperature, initial tightening torque, and bolt geometry on this attenuation. A thermo-viscoelastic constitutive model for PTFE was developed based on material relaxation test data, followed by the construction of a finite element model for the PTFE bolted joints. The simulation and experimental results over 24 h indicated that approximately 90
Shape reconstruction and force measurement of surgical diagnostic tools are crucial to ensure surgical safety. This study focuses on the strain transfer of an overall flexible fiber Bragg grating (FBG) shape sensor. A theoretical equation of strain transfer was established, with the fiber and bonding layers as the core structures. The response characteristics of the fibers under axial and radial forces were investigated. Through finite element simulations, the strain values of the bonding and fiber layers were analyzed and compared with the theoretical values to determine the influence of the bonding layer thickness, elastic modulus, encapsulation length, and Poisson’s ratio on the strain transfer. A 260-mm-long, 2-mm-diameter, substrate-free FBG shape sensor was encapsulated, and axial/radial force sensing experiments were conducted to verify the theoretical force-wavelength change model. Additionally, shape reconstruction experiments were performed on a flat surface, achieving a 3.68
In the aerospace and defense industries, flow forming is a critical process for the integral fabrication of large-scale tubular components. Simulating this process using the finite element method (FEM) requires an excessively fine mesh to accurately capture the contact interactions, resulting in an infeasibly high computational cost. To address this challenge, a modified multimesh method is proposed to accelerate the simulation by reducing the overall mesh scale while preserving local refinement. This method employs a customized three-mesh system that enables the rapid and automatic construction of locally refined meshes using hierarchical 4- and 9-refined templates. Additionally, radial basis function interpolation (RBFI) combined with the restricted additive Schwarz method (RASM) to efficiently transfer state variables among meshes via localized subregion sampling. The complete multi-mesh framework was implemented in Python and integrated into ABAQUS/Explicit. Validation across multiple flow-forming cases demonstrated that both the final geometry and state variable distributions aligned closely with those obtained from traditional fine-mesh simulations. In the studied forward flow-forming examples, the proposed method reduced the computational time by up to 59.09
To address the problem of low efficiency in the machining of double-sided gradient-structured (GS) metallic sheets, a novel severe plastic deformation (SPD) technology, plastic flow machining with arrayed arc-sawtooth (PFM-AA), is proposed in this study. The PFM-AA process achieves significant grain refinement and forms a double-sided GS through single-step processing, as opposed to those that require multiple passes, such as surface mechanical attrition treatment (SMAT). Compared with conventional plastic flow machining (PFM) methods, the minimal deformation experienced by the core region preserves the coarse-grained structure and maintains excellent plasticity. Furthermore, by adjusting the arc-sawtooth parameters (arc angle and tooth pitch), the coarse-grained layer ratio can be regulated to achieve gradient controllability and a strength-ductility trade-off. In this study, the formation mechanism, microstructure, grain refinement mechanism, and mechanical properties of double-sided GS aluminum alloy AA1060 sheets with different arc angles and tooth pitches were investigated using experimental and simulation techniques. The results indicated that the established coupled Eulerian-Lagrangian finite element model based on a dislocation density-based model accurately reflected the evolution trends of the microstructure and mechanical properties. According to the electron backscatter diffraction (EBSD) results, both sides of the sheet were refined. The formed sheet showed a clear double-sided GS in hardness and the ultimate tensile strength (UTS) of the sheet reached 125.9 MPa while maintaining reasonable ductility (elongation to fracture: 27.66
The sizing process is a critical intermediate forming procedure in multipass rolling-brazing for producing double-wall brazed tubes (DWBTs). In the sizing process, the mandrel plays an essential role in accurately forming DWBTs and ensuring tight fitting of the inner and outer layers, which is of great importance for the success of the subsequent brazing operation, as well as the quality of the final product. However, achieving control over precise dimensions and uniform stress distribution in the formed tube remains a challenge. This study aims to obtain the optimal design parameters of an olive-shaped mandrel by investigating the effect of its key parameters, specifically the length and diameter of the mandrel head, on the forming quality of DWBTs during the sizing process. The results of experimental and numerical studies show that, with the increasing length and diameter of the mandrel head, the cross-section of the formed double-wall tube gets closer to an ideal roundness. An increase in the mandrel head length results in a more uniform stress distribution but a decreased uniformity in the wall thickness. In contrast, an increase in the mandrel head diameter improves the geometrical accuracy of the formed double-walled tube; however, the uniformity of the stress distribution decreases owing to the higher sizing force. Through a comprehensive analysis of multiple forming indices such as roundness, wall thickness distribution, and stress distribution, the optimal design parameters of the sizing mandrel are determined, offering practical guidance for achieving high-quality DWBT manufacturing.
Part sedimentation in volumetric additive manufacturing (VAM) technology is a well-known detrimental effect that can significantly deteriorate printing resolution and shape fidelity. This study reveals the underlying mechanism by which process parameters and material properties affect the sedimentation properties of parts fabricated by VAM, considering the intrinsic thermal process and its interaction with polymerization kinetics. It was found that thermally induced changes in material viscosity and polymerization parameters played an essential role in regulating sedimentation behavior. Lowering the ambient and initial printing temperatures can increase viscosity resistance and thus weaken the sedimentation phenomenon, whereas a longer printing time adversely influences part sinking. Optimal thermal conditions that simultaneously ensure low sedimentation and a relatively short printing time should be determined during printing, particularly for thermally thinned materials. Importantly, using the wall-end effect, the model revealed that settlement could be effectively mitigated by solidifying the part near the bottom of the container. The experiments confirmed a reduction of approximately 39.4
This study investigates the mechanical properties and thermal conductivity of metal parts produced using metal fused filament fabrication (Metal FFF), focusing on three distinct printing profiles (Fast, Strong, and Quality) provided by the material manufacturer. The correlation between thermal conductivity and mechanical strength is explored, aiming to optimize part performance by understanding the impact of printing parameters. Results demonstrate that the “Quality” profile delivers superior mechanical strength and thermal conductivity due to enhanced inter-layer bonding and reduced porosity, as confirmed by SEM analysis. Conversely, the “Fast” profile offers the lowest performance but maximizes productivity and cost-efficiency. The “Strong” profile represents a balanced compromise among mechanical performance, thermal properties, and manufacturing cost. This work highlights the potential of using thermal conductivity tests as a faster and more resource-efficient proxy for mechanical testing in initial assessments. Such tests are particularly valuable in applications where thermal conductivity is a critical requirement (e.g., battery thermal management systems, heat exchangers, cooling systems in electronic, etc.). Future research should focus on developing predictive models to further streamline the characterization and optimization of Metal FFF processes for industrial applications.
