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Theoretical and Experimental Study on the Performance of Hermetic Diaphragm Squeeze Film Dampers for Gas-Lubricated Bearings

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Chinese Journal of Mechanical Engineering 2024年第3期37卷 151-169页

作者： Jianwei Wang Haoxi Zhang Shaocun Han Hang Li Peng Wang Kai Feng State key laboratory of advanced Design and manufacturing for Vehicle Body Hunan UniversityChangsha 410082China

Low damping characteristics have always been a key sticking points in the development of gas *** application of squeeze film dampers can significantly improve the damping performance of gas lubricated *** paper proposed a novel hermetic diaphragm squeeze film damper(HDSFD)for oil-free turbomachinery supported by gas lubricated *** types of HDSFDs with symmetrical structure were proposed for good damping *** considering the compressibility of the damper fluid,based on hydraulic fluid mechanics theory,a dynamic model of HDSFDs under medium is proposed,which successfully reflects the frequency dependence of force *** on the dynamic model,the effects of damper fluid viscosity,bulk modulus of damper fluid,thickness of damper fluid film and plunger thickness on the dynamic stiffness and damping of HDSFDs were *** experimental test rig was assembled and series of experimental studies on HDSFDs were *** damper fluid transverse flow is added to the existing HDSFD concept,which aims to make the dynamic force coefficients independent of *** the force coefficient is still frequency dependent,the damping coefficient at high frequency excitation with damper fluid supply twice as that without damper fluid *** results serve as a benchmark for the calibration of analytical tools under development.

关键词： Hermetic diaphragm squeeze film damper Compressibility Dynamic model Experimental studies

Highly efficient optics/microwave beam splitter based on frequency selective surface

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Chinese Optics Letters 2024年第6期22卷 136-141页

作者： Qiao Sun Nianxi Xu Haigui Yang Dongzhi Shan Yang Tang Xin Chen Tongtong Wang Jinsong Gao Yu Cai key laboratory of Optical System advanced manufacturing Technology Changchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China State key laboratory of Applied Optics Changchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China University of Chinese Academy of Sciences Beijing 100049China Jilin Provincial key laboratory of advanced Optoelectronic Equipment and Instrument manufacturing Technology Changchun 130033China Unit 96951 of the People’s Liberation Army Beijing 100039China

The development of hybrid optics/microwave communication systems puts forward a new requirement for beam splitters to efficiently transmit microwave signals and simultaneously reflect optical signals. Owing to mechanical constraints, the physical thickness of beam splitters is of the order of tens of millimeters. The corresponding electrical thickness has the same order of magnitude as microwave wavelengths, and the resulting multi-beam interference effect significantly reduces the microwave transmittance, impacting the beam splitting *** study presents a new optics/microwave beam splitter based on the ability of the frequency selective surface(FSS) to shape the resonant curve. A beam splitter sample,whose physical thickness and substrate material are 20 mm and quartz glass, respectively, is designed, simulated, fabricated, and characterized to validate the feasibility of this strategy. The measured results show that the minimum microwave transmittance between 35 and 36.5 GHz with an incidence angle of 45° under TE polarization is 86.43%, and the mean value of the reflectance spectra from 450 to 900 nm and that from 7.7 to 10.5 μm both exceed 96%. This FSS-based optics/microwave beam splitter is expected to play a key role in hybrid optics/microwave communication systems.

关键词： beam splitter multi-beam interference frequency selective surface high transmission

Optimal Design of the Modular Joint Drive Train for Enhancing Cobot Load Capacity and Dynamic Performance

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Chinese Journal of Mechanical Engineering 2024年第3期37卷 26-40页

作者： Peng Li Zhenguo Nie Zihao Li Xinjun Liu Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China State key laboratory of Tribology in advanced Equipment Tsinghua UniversityBeijing 100084China Beijing key lab of Precision/Ultra-precision manufacturing Equipments and Control Tsinghua UniversityBeijing 100084China

Automation advancements prompts the extensive integration of collaborative robot(cobot)across a range of *** to the commonly used design approach of increasing the payload-to-weight ratio of cobot to enhance load capacity,equal attention should be paid to the dynamic response characteristics of cobot during the design process to make the cobot more *** this paper,a new method for designing the drive train parameters of cobot is ***,based on the analysis of factors influencing the load capacity and dynamic response characteristics,design criteria for both aspects are established for cobot with all optimization design criteria normalized within the design ***,with the cobot in the horizontal pose,the motor design scheme is discretized and it takes the joint motor diameter and gearbox speed ratio as optimization design ***,all the discrete values of the optimization objectives are obtained through the enumeration method and the Pareto front is used to select the optimal solution through multi-objective *** on the cobot design method proposed in this paper,a six-axis cobot is designed and compared with the commercial *** result shows that the load capacity of the designed cobot in this paper reaches 8.4 kg,surpassing the 5 kg load capacity commercial cobot which is used as a *** minimum resonance frequency of the joints is 42.70 Hz.

关键词： Multi-objective optimization Modular joint drive train design Load capacity Dynamic response performance

Microstructure features induced by fatigue crack initiation up to very-high-cycle regime for an additively manufactured aluminium alloy

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Journal of Materials Science & Technology 2024年第6期173卷 247-260页

作者： Xiangnan Pan Leiming Du Guian Qian Youshi Hong State key laboratory of Nonlinear mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China

Fatigue failure can still occur beyond 107 cycles,***-high-cycle fatigue(VHCF),in many metallic materials,such as aluminium alloys and high-strength *** VHCF of high-strength steels,a fine granular area(FGA)surrounding an inclusion is commonly identified as the characteristic region of crack initiation on the fracture ***,no such FGA feature and related crack initiation behaviour were observed in VHCF of conventionally cast or wrought aluminium ***,we first reported the distinct mechanisms of crack initiation and early growth,namely the microstructure feature and the role of FGA in VHCF performance for an additively manufactured(AM)AlSi10Mg *** AM pores play a key role in fatigue crack initiation similar to that of the inclusions in high-strength steels,resulting in almost identical FGA behaviour for different materials under a range of mean stress with a stress ratio at R*** profile microstructure of FGA is identified as a nanograin layer with Si rearrangement and grain boundary *** process consumes a large amount of cyclic plastic energy making FGA undertake a vast majority of VHCF *** results will deepen the understanding of VHCF nature and shed light on crack initiation mechanism of other aluminium and AM alloys.

关键词： Aluminium alloy Additive manufacturing Nanograins Very-high-cycle fatigue(VHCF) Crack initiation Mean stress

Chemoselective epoxidation of electron-deficient olefins with molecular oxygen via conjugated olefins epoxidation and BHT hydroxylation

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Science China Chemistry 2024年第9期67卷 3012-3018页

作者： Jia Nie Huanfeng Jiang Chuanle Zhu School of Chemistry and Chemical Engineering Key Lab of Functional Molecular Engineering of Guangdong ProvinceSouth China University of TechnologyGuangzhou 510640China Guangdong Provincial key laboratory of Technique and Equipment for Macromolecular advanced manufacturing South China University of TechnologyGuangzhou 510640China

The chemoselective epoxidation of electron-deficient olefins in the presence of electron-rich alkene moieties is *** chemoselective epoxidation strategy undergoes a conjugated olefin epoxidation and BHT hydroxylation process to give various useful oxiranes in high yields,especially for the 2-substituted ***,this protocol features mild conditions,is transition-metal free,operationally simple,and gram-scalable,and tolerates diverse functional *** candidate HSD-16 is synthesized smoothly by this *** studies indicate molecular oxygen is the terminal oxidant and the O-source of the oxiranes.

关键词： chemoselective epoxidation alkene fluorine molecular oxygen

Impact Performance Research of Re-Entrant Octagonal Negative Poisson’s Ratio Honeycomb with Gradient Design

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Computer Modeling in Engineering & Sciences 2024年第9期140卷 3105-3119页

作者： Yiyuan Li Yongjing Li Shilin Yan Pin Wen Department of Engineering Structure and mechanics Wuhan University of TechnologyWuhan430070China Hubei key laboratory of Theory and Application of advanced Materials mechanics School of ScienceWuhan University of TechnologyWuhan430070China

Based on the traditional re-entrant honeycomb,a novel re-entrant octagon honeycomb(ROH)is *** deformation mode of the honeycomb under quasi-static compression is analyzed by numerical simulation,and the results are in good agreement with the experimental *** deformation modes,mechanical properties,and energy absorption characteristics of ROH along the impact and perpendicular directions gradient design are investigated under different *** results indicated that the deformation mode of ROH is affected by gradient design along the direction of impact and impact *** addition,gradient design along the direction of impact can increase the initial peak stress of ROH and accelerate its densification *** design perpendicular to the impact direction can enhance the energy absorption performance of ROH,especially for ROH,with wall thickness increasing from the inside *** to ROH with uniform wall thickness at the same relative density,ROH with a gradient design can increase the plateau stress by over *** the elevation of impact velocity,the plateau stress and specific energy absorption exhibit an upward trend,aligning with the dynamic performance pattern observed in conventional *** results can be used as a reference for the design and application of honeycomb and provide a new idea for developing more efficient and reliable energy-absorbing materials.

关键词： Re-entrant honeycomb gradient design finite element analysis additive manufacturing technologies

Hybrid 3D printed three-axis force sensor aided by machine learning decoupling

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International Journal of Smart and Nano Materials 2024年第2期15卷 261-278页

作者： Guotao Liu Peishi Yu Yin Tao Tao Liu Hezun Liu Junhua Zhao Jiangnan key laboratory of advanced Food manufacturing Equipment and Technology School of Mechanical EngineeringJiangnan UniversityWuxiPR China Jiangsu Province Engineering Research Center of Micro-Nano Additive and Subtractive manufacturing Institute of Advanced TechnologyJiangnan UniversityWuxiPR China

Identification of magnitude and orientation for spatially applied loading is highly desired in the fields of not only the machinery components but also human-machine *** the fact that the 3-axis force sensor with different structures has been proposed to measure the spatial force,there are still some common limitations including the multi-step manufacturing-assembly processes and complicated testing of decoupling ***,we propose a rapid fabrication strategy with low-cost to achieve high-precision 3-axis force *** sensor is designed to compose of structural Maltese cross base and sensing *** is directly fabricated within one step by a hybrid 3D printing technology combining deposition modeling(FDM)with direct-ink-writing(DIW).In particular,a machine learning(ML)model is used to convert the strain signal to the force *** of a mount of calibration tests,this ML model is trained by sufficient simulation data based on programmed batch finite element *** sensor is capable of continuously identifying a spatial force with varying magnitude and orientation,which successfully quantify the applied force of traditional Chinese medicine physiotherapy including Gua Sha and *** work provides insight for design and rapid fabrication of multi-axis force sensors,as well as potential applications.

关键词： Hybrid 3D printing 3-axis force sensor machine learning nonlinear decoupling

Wideband chaos generation using a VCSEL with intensity modulation optical injection for random number generation

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Science China(Information Sciences) 2024年第6期67卷 457-458页

作者： Yu HUANG Shuangquan GU Yuhang FENG Yigong YANG Shuiying XIANG Pei ZHOU Nianqiang LI School of Optoelectronic Science and Engineering & Collaborative Innovation Center of Suzhou Nano Science and Technology Soochow University State key laboratory of Integrated Service Networks Xidian University key lab of advanced Optical manufacturing Technologies of Jiangsu Province & key lab of Modern Optical Technologies of Education Ministry of China Soochow University

Physical random numbers have been widely used in modern network society,such as the generation of cryptographic keys for classical and quantum cryptography systems[1].Among the many sources of physical entropy,chaotic semiconductor lasers have attracted wide attention due to their desired characteristics including larger bandwidth,low cost,and monolithic integration[2].

关键词： Optical signal processing

Full-Scale Isogeometric Topology Optimization of Cellular Structures Based on Kirchhoff-Love Shells

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Computer Modeling in Engineering & Sciences 2024年第6期139卷 2479-2505页

作者： Mingzhe Huang Mi Xiao Liang Gao Mian Zhou Wei Sha Jinhao Zhang State key lab of Intelligent manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan430074China

Cellular thin-shell structures are widely applied in ultralightweight designs due to their high bearing capacity and strength-to-weight *** this paper,a full-scale isogeometric topology optimization(ITO)method based on Kirchhoff-Love shells for designing cellular tshin-shell structures with excellent damage tolerance ability is *** method utilizes high-order continuous nonuniform rational B-splines(NURBS)as basis functions for Kirchhoff-Love shell *** geometric and analysis models of thin shells are unified by isogeometric analysis(IGA)to avoid geometric approximation error and improve computational *** topological configurations of thin-shell structures are described by constructing the effective density field on the *** volume constraints are imposed in the proximity of each control point to obtain bone-like cellular *** facilitate numerical implementation,the p-norm function is used to aggregate local volume constraints into an equivalent global *** numerical examples are provided to demonstrate the effectiveness of the proposed *** simulation and comparative analysis,the results indicate that the cellular thin-shell structures optimized by the proposed method exhibit great load-carrying behavior and high damage robustness.

关键词： Cellular thin-shell structures isogeometric analysis full-scale topology optimization Kirchhoff–Love shells