A novel shallow oil chamber hybrid journal bearing with adjustable oil chamber depth was designed based on piezoelectric ceramics, inspired by conventional shallow oil chamber bearing structures. The computational fluid dynamics method is used to analyze the bearing characteristics of shallow oil chamber bearings, including the volume flow, the seal oil pressure, load capacity and stiffness. An experimental platform equipped with signal acquisition device and piezoelectric ceramic control device was developed. The eddy current sensors collected the displacement signal at the shaft end. The required voltage was calculated by the displacement signal. The piezoelectric ceramics elongated or shortened, causing a displacement of the same magnitude in the depth of the oil chamber, thereby controlling the radial displacement of the shaft. The adjustment effect of this bearing was verified by experiment for no-load and 500 N load at 200-1000 rpm, with a baseline initial oil chamber depth of 20 and an oil supply pressure of 2 MPa. The results showed that compared with the case without adjustment, the accuracy in Y direction has increased from 8.9 mu m to 1.9 mu m (max. 78.4%) after adjustment. Under the above load conditions, the displacement can be controlled below 2 mu m, indicating a significant improvement in shaft vibration resistance.

The porous aerostatic spindle, a key component in wafer grinding machines, exhibits time-varying dynamic behaviors–including vibration, dynamic stiffness, and damping–that critically affect wafer surface roughness during self-rotational grinding. To address the limited understanding of these dynamics under grinding conditions, this study proposes a bidirectional fluid–structure interaction cross-scale modeling approach. A transient dynamic framework is established by coupling compressible gas flow within the aerostatic bearing with the nonlinear dynamic response of the rotor, enabling comprehensive analysis of the time-dependent evolution of bearing performance and rotor vibrations under the combined effects of gas film forces, grinding forces, and gravity. To validate the proposed model's accuracy and the influence of coupling on grinding, a kinematic-based wafer surface roughness prediction model was developed, incorporating time-varying grinding wheel vibrations and abrasive particle removal mechanisms. The model predictions show a close match with experimental results, with a deviation of only 5.09

The regulation system for the radial error motion of aerostatic-bearing spindles faces challenges such as poor integration, large volume, and complex control mechanisms. This study proposes a time-dependent electromagnetic regulation method (TERM) based on opto-electromagnetic integrated technology. A fluid-solid-magnetic coupling rotor model with five degrees of freedom is developed. The effects of various factors, including supply pressure, rotational speed, mean clearance, and radial mass unbalance distance on the regulation model are investigated. A regulation system is constructed using the optical measurement, non-contact electromagnetic force application, and force measurement devices. The system significantly reduces the volume of the control system and simplifies the control model while maintaining a minimal number of control parameters. Both simulation and experimental results demonstrate that the proposed TERM can substantially reduce radial error motion and improve spindle rotation accuracy, offering a novel theoretical framework and practical approach for the regulation of radial error motion of aerostatic-bearing spindles.

The subaperture stitching method based on computer-generated holograms(CGH)is a common approach for measuring the surface profile of cylindrical mirrors.However,the stitching result suffers from distortion of low-frequency surface shape information.This is primarily caused by the cumulative amplifica-tion of errors and the inability of conventional aberration fitting methods(based on orthogonal polynomials)to effectively separate errors from the true surface figure.To address this issue,this paper proposes a novel method to compensate for and correct the low-frequency information of cylindrical mirror surface profiles.First,an initial stitching is performed using a successive subaperture stitching method based on Chebyshev polynomials.Next,the profile along the mirror's stitching direction(i.e.,the generatrix direction)is meas-ured independently to extract its low-frequency component.Finally,this low-frequency information is used to further fuse and correct the initial stitching result.Experimental validation was conducted on a cylindrical mirror with a clear aperture of 150 mm×210 mm and a radius of curvature of 790.23 mm.The results demonstrate that the proposed method effectively corrects the generatrix direction profile of the cylindrical mirror.Compared to the full-aperture reference surface obtained via full-aperture CGH measurement,the root mean square(RMS)of the residual error for the stitching result is approximately 0.010 3λ.This represents a reduction of about 37%in the RMS value compared to the pre-correction result,indicating a significant im-provement in measurement accuracy.The proposed method offers advantages including ease of implementa-tion,low hardware requirements,and reliable measurement accuracy.

This study investigates the use of a nanosecond ultraviolet laser for micromachining molybdenum to address challenges in processing this hard, brittle refractory metal. Using a 355 nm laser system, microgrooves were fabricated on molybdenum surfaces to examine how scanning speed (50–250 mm/s), repetition frequency (20–60 kHz), and processing times (2−10) affect groove geometry, material removal rate, and heat-affected zone (HAZ). The research combines experimental work with multi-field numerical simulation and microscopic characterization. Results reveal that scanning speed has a non-monotonic effect on groove width: Marangoni convection causes width to expand (from ~110 μm to ~135 μm) at moderate speeds (50–200 mm/s), whereas excessive speed (250 mm/s) reduces width to 115 μm due to insufficient energy input. The repetition frequency shows an optimal value of 40 kHz, where single-pulse energy and plasma shielding balance to maximize ablation depth, achieving ~32 μm per pass at 50 mm/s. Increasing processing times linearly enhances removal depth without significantly broadening the HAZ, owing to molybdenum's excellent thermal conductivity, thereby making the process suitable for high-aspect-ratio structures. The corresponding material removal rate under optimized conditions reaches ~0.13 mm3/min. The material removal mechanism comprises four stages: surface melting, vaporization, plasma shielding, and recast-layer solidification. These findings establish process-structure relationships for UV ns-laser processing of molybdenum, providing guidance for manufacturing applications in aerospace and semiconductor industries where precision micro-features are required.

Cylindrical surfaces play a critical role in advancing the performance of next-generation optical systems. However, conventional null interferometry based on computer-generated holograms (CGHs) is limited by the fabrication errors of CGH and the surface error of the reference mirror. Thus, it is difficult to meet the demand for higher-precision measurement. To address this, we propose a shift-rotation absolute measurement for the cylindrical optics. Since a cylinder curves in only one direction, the proposed method decomposes the surface into rotationally symmetric and asymmetric components. First, an optimized iterative algorithm is employed to achieve high-precision reconstruction of the rotationally asymmetric component. Subsequently, the rotationally symmetric part is recovered via pseudo shearing interferometry by shifting the cylinder in two orthogonal directions. The two components are then combined to obtain the absolute result of cylindrical surfaces. Experimental results confirm that the method effectively reduces systematic errors from the CGH and reference surface, leading to substantially improved accuracy. It thus enables high-precision absolute measurement of cylindrical optics in a feasible and reliable way.

In the field of high-speed rotating machinery, it is a common phenomenon that the rotor is liable to lose stability when rotating at high speeds. Installing a layer of damping structure between the bearing and the housing is a potential means to restrain the vibration of the rotor. In this article, it is useful to improve the stability of the rotor in the way of increasing the damping of the bearing by installing several O-rings on the porous air journal bearing (PAJB). The rotor-bearing test rig is set up to study the vibration of the rigid rotor supported by PAJBs with three types of O-rings mounted for different supply pressures. Moreover, a nonlinear numerical model is established to predict the rotor responses. The accuracy of the numerical model is verified by comparing the calculated results with the data tested by the above experiment. Based on the experimental and simulation results, the effects of the supply pressures, stiffness and damping of O-rings on the stability of the rotor-PAJB system are investigated. The influence of the stiffness and damping of O-rings on the nonlinear dynamic characteristics of the systems is further studied by expanding the parameter range of the numerical simulation, and the relevant laws are summarized. The results demonstrate that both the stiffness and damping of O-rings have significant influence on the stability of the rotor-PAJB system. When the stiffness of O-rings is in the unstable stiffness interval, the stability of the rotor at high speeds will decrease. Meanwhile, larger damping produces better stability. By both the experimental and theoretical studies, the investigation is expected to promote the development of turbomachinery towards higher speeds and better stability.

As a critical component in the transition of production processes, the support stability of the transport system in the high-end grinding machines significantly impacts the surface quality of the wafer. To guarantee the stability of the transposition system under heavy loads and large floating volumes, an air cushion structure supported by aerostatic pressure with slender holes is proposed. Based on Computational Fluid Dynamics (CFD), the effects of traditional orifices, slender orifices, cylindrical cavity, and square cavity throttling on the air cushion pressure distribution and flow field characteristics were analyzed, determining the superior performance of the slender orifice structure. Furthermore, the influence of structural factors, including throttling hole diameter, number and length-diameter ratio, on air cushion performance and floating displacement is discussed. The findings indicate that, at a film thickness of 34 mu m, the slender hole exhibits a bearing capacity 7.28 times higher than that of the small hole, accompanied by a stiffness that is 3.28 times increased. Moreover, for slender holes, a positive correlation is observed between the load capacity and both the diameter and the number of throttling holes, while stiffness is negatively correlated with these parameters. The length-diameter ratio has a negligible influence on both load capacity and stiffness. Building on the above findings, a ceramic-supported air cushion with an orifice diameter of 1 mm was fabricated, and floating displacement measurements were conducted. Under a load of approximately 1000 kg, the air cushion lift exceeded 20 mu m, thereby validating its supporting performance. The maximum error compared to the calculated results was less than 5.96 %. The results of the research offer both theoretical underpinning and data evidence for designing air cushions with high bearing capacity and stiffness under conditions of large floating volumes.

The utilization of nanoimprint technology has become widespread in various industries. Nanocoining, a new type of nanoimprinting technology, is essentially graphic copying. Ensuring the indenter's accuracy and the transfer's integrity is crucial. Structured tool (ST)-metal workpiece interface commonly exists in adherence phenomenon during the nanoimprint. To reduce the adherence of workpieces in ST, it is remarkable to illustrate the adhesion mechanism. The molecular dynamic simulation model for indenting aluminum with a diamond ST indenter was established, and the influence of critical process parameters on adhesion, including the indenter geometry, indenter temperature, and indenter speed, was investigated. The results demonstrate that various factors significantly influence adhesion, including the van der Waals force, surface energy, temperature, mechanical embedding, diffusion, and holding stage. The mechanism of adhesion can be composed of three parts: the mechanical embedding caused by the large range of cavity filling of the indenter, the slow thermal diffusion and thermal migration of aluminum atoms along the indenter and the combined effect of thermal-tensile stress in the demolding process. The intensity of adhesion is affected by several factors, namely the degree of plastic deformation during loading and unloading, atomic thermal migration caused by system temperature, and the magnitude of tensile stress during the demolding stage. The geometry of the indenter exerts the most significant influence on the van der Waals force, surface energy, imprinting force, and unloading force. Additionally, the omission of the holding stage during processing contributes to a reduction in adhesion. This study provides atomic-level insights into the adhesive properties of metallic materials in the nanocoining process.

In the realm of ultra-precision machining, the radial error motion of the aerostatic-bearing spindle directly impacts the quality of the workpiece. However, there remains a gap in understanding the underlying mechanisms governing the radial error motion. In this study, a numerical solution method for radial error motion of 5-DOF aerostatic-bearing spindles under the unbalanced electromagnetic force is proposed. The physical model is presented globally considering the governing equation of air film, balance equation of airflow, and motion equation of rotor. The effects of the amplitude of unbalanced electromagnetic force, number of motor pole pairs, supply pressure, and rotational speed on the radial error motion under the unbalanced electromagnetic force are characterized. Additionally, a measurement system is devised to assess the radial error motion of aerostatic-bearing spindles. The congruence between the experimental and simulated outcomes validates the proposed method. The radial error motion can be diminished by minimizing the amplitude of unbalanced electromagnetic force, the number of motor pole pairs, and rotational speed or increasing the supply pressure. Besides, it is found that the number of motor poles is mapped to that of lobes of radial error motion. This study provides practical guidance for the design of aerostatic-bearing spindles with desired radial error motion.

Black phosphorus (BP) stands out among vdW materials for chemical sensing, with its edge sites offering the potential to enhance performance. While the nanocutting method shows promise for BP edge fabrication, the underlying mechanism remains unclear, lacking guidance for the process. In this study, molecular dynamics (MD) simulations were conducted to investigate the material removal behavior during nanocutting of BP while considering the influence of cutting thickness, tool edge radius, and tool angle. These findings indicate that the plastic removal of BP is primarily governed by interlayer slip when using a cutting tool with a relatively large rake angle. In contrast, at a small rake angle, a brittle removal state occurs due to the formation and expansion of a shear band spanning across the BP layers, leading to crack propagation. Additionally, as the cutting thickness approaches the tool edge radius, a "size effect" is observed in the BP. This phenomenon results in both decreased plastic deformation and a singular decrease in cutting force, ultimately causing an increase in chip thickness deviation. The research findings offer a comprehensive theoretical foundation for the removal behavior of BP and serve as a technical reference for the fabrication of nanostructures for chemical sensing via nanocutting.

High-speed aerostatic spindles have found widespread application in precision machining instruments. During the machining process, these spindles are constantly subjected to external excitations, which are crucial factors influencing spindle stability. However, current research on the specific impact of coupled external excitations on the vibration characteristics of spindles is still insufficient. A dynamic characteristic computational model for high-speed aerostatic spindles with multiple degrees of freedom has been established, which incorporates the effects of multi-excitation coupling. This model accounts for the interactions and parametric transfers between the different spindle components and is grounded in the principles of fluid mechanics and rotor dynamics. The impact of factors such as external load excitations, rotational speeds, air supply pressures, and air film thicknesses on the nonlinear dynamic behavior of aerostatic spindles has been explored. Additionally, an experimental setup has been developed to monitor the nonlinear dynamic characteristics of high-speed aerostatic spindles. Through comparisons of dynamic responses, the accuracy of the computational model has been validated. The results of this study offer valuable theoretical insights that can support the advancement and application of high-speed aerostatic spindles in the realm of high-precision machining.

The silicon carbide particle-reinforced aluminum matrix composite (SiCp/Al) exhibits remarkable properties, such as low density and coefficient of thermal expansion, as well as high specific strength. Structures machined from SiCp/Al, such as thin-walled components, have found extensive applications in the aerospace and automotive industries due to their superior mechanical properties and lightweight characteristics. However, the inherent hardness of SiC particles introduces significant challenges during the processing of SiCp/Al composites. Consequently, the fabrication of thin-walled structures in SiCp/Al remains a critical and ongoing challenge. This study investigates the formation of top burrs, surface roughness, and thin-wall deformation during the micro-milling process. A three-dimensional cutting model for micro-milling SiCp/Al is established through finite element simulation to analyze material removal mechanisms and surface damage characteristics. Based on the simulation results, an optimal range of micro-milling parameters is determined. Subsequent experiments reveal that increasing the feed per tooth (fz) effectively reduces burr size. Furthermore, the interactive effects of key parameters—spindle speed (n), feed per tooth (fz), radial cutting depth (ae), and axial cutting depth (ap) —on surface roughness and thin-wall deformation are systematically investigated using the response surface methodology (RSM). The findings indicate that reducing ap and ae while increasing n and fz significantly minimizes surface roughness. Specifically, the surface roughness is reduced by 17.2

Inorganic semiconductors play a pivotal role in various technological applications; however, their inherent brittleness limits their utilization in flexible electronics. Thinning materials such as glass fibers and silicon enhances flexibility while preserving mechanical properties. The focus of this research lies in strain engineering within indium selenide (InSe), a representative type of inorganic semiconductor renowned for its exceptional electron mobility and adjustable bandgap. By means of nanoskiving, ultrathin vertically aligned InSe ribbons were fabricated and subsequently transferred onto flexible polyethylene terephthalate (PET) substrates. The photoluminescence (PL) spectra revealed the tunability of the bandgap induced by strain, and the molecular dynamics (MD) simulations emphasized the influence of thickness on the mechanical properties. The vertically aligned InSe ribbons demonstrated an enhanced photoresponse under tensile strain in photodetectors, thereby demonstrating their potential for use in flexible optoelectronic devices. The nanocutting method results in novel mechanical and electronic properties, offering an alternative means to adjust the bandgap and facilitating the efficient fabrication of flexible optoelectronic devices with potential applications.

Silicon carbide (SiC) ceramics are extensively utilized in aerospace, national defense, and petrochemical industries due to their superior physical and chemical properties. The processing of bulk SiC ceramics necessitates precise and efficient grinding techniques to produce components with satisfactory functionality. However, the inherent high hardness and brittleness of SiC ceramics present significant challenges during grinding, leading to severe brittle fracture and tool wear that compromise both surface integrity and production efficiency. Although ductile-regime grinding of SiC ceramics can be achieved by enhancing machine tool accuracy and stiffness while optimizing wheel performance alongside appropriate selection of process parameters, a comprehensive summary of the mechanisms underlying damage evolution during grinding is lacking, and a mature grinding process for SiC ceramics has yet to be developed. To bridge this gap, the sintering technologies, mechanical properties, and microstructures of SiC ceramics were briefly covered. The grinding-induced damage mechanism and low-damage grinding technologies of SiC ceramics were summarized. The fundamental science underlying the ductile deformation and removal mechanisms of brittle solids was emphasized. Additionally, attention was directed towards the critical role of hybrid energy field grinding in minimizing brittle damages and promoting removal efficiency. This review not only elucidates the intrinsic interactions between the work material and abrasives, but also offers valuable insights for optimizing the grinding processes of brittle solids.

With the increasing demand for extreme performance in laser and imaging systems, optics manufacturing now requires the collaborative convergence of errors across the full spatial frequency domain. As a critical step in the optics manufacturing process chain, gadget tool polishing and its impact on mid-spatial-frequency (MSF) errors have attracted considerable interest. To reduce the need for lengthy subsequent smoothing iterations caused by residual MSF errors, the imprinting effect of gadget tools, which significantly contributing to these errors, was investigated and a vibration-excitation polishing method was then proposed to suppress the formation of imprinting scratches. Modeling, analysis, and experimental investigations of tool surface topography and removal functions reveal that material removal gradients caused by heterogeneous microstructure distributions on the tool surface, are a primary cause of periodic scratch formation. Furthermore, introducing vibration with optimized parameters to disrupt tool motion trajectories effectively suppresses scratch formation by homogenizing the removal gradient. In general, this work could provide a valuable reference for improving optics polishing quality.

Porous aerostatic bearings, which employ porous media for gas throttling, offer outstanding pressure equalization characteristics and are extensively utilized in high-precision measurement and machining systems. The performance of porous aerostatic bearings is intrinsically linked to the physical and mechanical properties of the porous materials used. Consequently, comprehensive theoretical investigation, precise design, meticulous fabrication, and rigorous testing are imperative for performance enhancement and evaluation. This review systematically examines the structural characteristics and functional applications of five prevalent configurations of porous aerostatic bearings: radial, thrust, spherical, localized, and tilting-pad types. It further consolidates current theoretical modeling approaches and solution methodologies, with a particular emphasis on the interplay between microstructural pore characteristics and their influence on overall bearing performance. The performance requirements for porous materials, including permeability, porosity, Young's modulus, and roughness, are discussed. The research progress on four main types of porous materials—metals, ceramics, graphite, and new materials—is compared, along with their design and preparation processes. Additionally, methods and devices for testing bearing performance, such as load capacity, stiffness, vibration, and slewing accuracy, are thoroughly reviewed. Finally, the review consolidates current advances and future directions, highlighting the essential role of micro–macro synergy in advancing porous aerostatic bearings technology. This review provides critical theoretical support and practical guidance for the design, optimization, and application of porous aerostatic bearings, contributing to the advancement of ultra-precision machinery and fluid dynamics technologies.

Due to its exceptional electronic and optical properties, single crystal gallium arsenide (GaAs) has garnered significant attention in recent years. The utilization of nanostructures on GaAs holds significant potential across various applications. Therefore, comprehending the underlying mechanisms governing material removal and plastic deformation during mechanical nanomachining of GaAs is imperative for its widespread implementation. The fabrication of nanochannels on the GaAs surface is achieved through the utilization of an AFM tip-based nanomilling technique in this study. Furthermore, insights into the mechanisms underlying material removal and plastic deformation during the nanomilling process of GaAs are unveiled. The GaAs materials are observed to be removed in the form of chips and pile-ups, resulting from the extrusion by the tip. Transmission electron microscopy (TEM) observation and MD simulation reveal that dislocations, lattice distortions and amorphization are caused by the plastic deformation of GaAs. Additionally, the high-pressure exerted by the tip contributes to phase transformation. The effects of nanomilling parameters such as normal load and feed speed on the machining outcomes are also investigated. Nanochannels with a flat bottom are obtained when a small normal load is applied, which can be attributed to the slight torsional deformation of the tip. The machined width can be controlled by adjusting the driving voltage during nanomilling. These findings provide valuable insights into the mechanisms of material removal and plastic deformation in GaAs during nanomilling, offering guidance for fabricating nanostructures on GaAs samples.

This study presents a comprehensive multi-objective optimization of a diamond-based U-type counter-flow manifold microchannel heat sink (U-type CMMC) for ultra-high heat flux applications. A systematic optimization framework integrating Sobol sensitivity analysis, surrogate modeling, and NSGA-II algorithm was developed to simultaneously optimize thermal resistance, pumping power, and entropy generation. Analysis of five key geometric parameters revealed that fin width dominated thermal resistance (71.49 %), while microchannel width exhibited the strongest influence on entropy generation (75.24 %) and pumping power (52.18 %). The established BP neural network surrogate model achieved prediction accuracy exceeding 99 %. The tri-objective optimization incorporating entropy generation achieved 46.7 % reduction in thermal resistance and 25.2 % decrease in entropy generation compared to the initial design, while the bi-objective optimization scheme reduced thermal resistance by 44.1 % with only 13.3 % increase in pumping power. Temperature uniformity analysis showed that the optimized design significantly improved temperature distribution, with non-uniformity reduced by 34.82 %. This study provides valuable insights into the design optimization of high-performance microchannel heat sinks and establishes a robust methodology for multi-objective thermal management optimization.

Ultra-high-strength steel is primarily used in aerospace transmission gears, where the quality of the ground surface and surface wear resistance significantly influence gear performance. The quality of the ground surface significantly impacts friction, wear behavior, and overall wear efficiency. Ultrasonic vibration composite machining technology effectively enhances the quality of machined surfaces. Therefore, this study conducted ultrasonic vibration-assisted grinding tests on ultra-high-strength steel to investigate the friction and wear properties of the ground surface. Both ultrasonic vibration-assisted grinding (UVAG) and conventional grinding (CG) were applied to the carburized surface of ultra-high-strength steel, comparing temperature and surface hardness under various grinding parameters. The results indicate that compared to CG, UVAG’s separation characteristics allow better penetration of grinding fluid into the grinding arc, reducing the grinding temperature by over 33