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3-DOF decoupled magnetic platform for optical low-frequency vibration isolation

International Journal of Mechanical Sciences 2025年 300卷

作者： Wen-Hao Qi Tian-Yu Zhao Qiu-Hua Gao Jia-Jia Lu Long-Qi Cai Yang Li Ge Yan Wen-Ming Zhang State Key Laboratory of Mechanical System and Vibration School of Mechanical Engineering Shanghai Jiao Tong University 800 Dongchuan Road Shanghai 200240 China National Key Laboratory of Nuclear Reactor Technology Nuclear Power Institute of China Chengdu 610213 China

Optical instruments, such as atomic force microscopes (AFM), are susceptible to interference from external vibrations, which can diminish imaging clarity and hinder optimal performance. A three-degree-of-freedom (3-DOF) decoupled magnetic platform (DMP) is proposed for optical low-frequency vibration isolation. The specially developed platform attains vibration decoupling through an orthogonal structural design and utilizes six identical vibration isolation units that are specially configured to achieve low dynamic stiffness and significantly low-frequency vibration isolation performance in both horizontal and vertical directions simultaneously. Different from the traditional realization of positive and negative stiffness combination, the novel isolation unit is designed using the constant magnetic force, which is generated from the magnetic field distortion. This implementation is revealed through magnetic field analysis and verified via static calibration. The dynamic model is established by considering viscous damping and dry friction, and the Runge-Kutta Method is applied to calculate the vibration response. Theoretical analyses are conducted to guide the design of the DMP and predict dynamic responses under different structural parameters, damping settings, and excitation conditions. Experiments are implemented to demonstrate the vibration isolation performance of the prototype. The result reveals the different effects of viscous damping and dry friction and demonstrates that the developed DMP has a broad frequency decoupled vibration isolation capability. The magnetic platform achieved by reusing the newly designed quasi-zero stiffness (QZS) unit provides a new option for optical vibration isolation, with the advantages of a large stroke and strong vibration decoupling.

关键词： constant magnetic force decoupled platform large stroke Nonlinear dynamics optical vibration isolation quasi-zero stiffness

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Prediction of electrical contact endurance subject to micro-slip wear using friction energy dissipation approach

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Friction 2019年第6期7卷 537-550页

作者： Xiangjun JIANG Fengqun PAN Guoqiang SHAO Jin HUANG Jun HONG Aicheng ZHOU Key Laboratory of Electronic Equipment Structural Design Xidian UniversityXi'an 710071China State Key Laboratory for Manufacturing System Xi’an Jiaotong UniversityXi'an 710049China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian 116024China Guilin University of Aerospace Technology Guilin 541004China

Fretting wear is a common cause of failure of an electrical contact(EC). In this study, we analyzed in detail the failure of EC induced especially by sliding using the representative electrical terminals. Furthermore, combining the friction energy dissipation theory, we proposed a prediction model to evaluate the electrical connector endurance(ECE) based on the contact stress and geometrical changes during the wear process obtained from a numerical model. The study helps establish that the friction energy dissipation theory is a powerful tool to analyze a contact failure due to wear. The proposed model proves to be effective in predicting the ECE for all considered cases such as micro-slip amplitude, contact force, overturning angle, superficial layer thickness, and friction/wear coefficients.

关键词： electrical connector endurance fretting wear friction energy dissipation finite element analysis

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A Review on Binderless Tungsten Carbide: Development and Application

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Nano-Micro Letters 2020年第1期12卷 158-194页

作者： Jialin Sun Jun Zhao Zhifu Huang Ke Yan Xuehui Shen Jiandong Xing Yimin Gao Yongxin Jian Hejie Yang Bo Li State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi’an Jiaotong UniversityXi’an 710049People’s Republic of China Key Laboratory of High Efficiency and Clean Mechanical Manufacture of MOE School of Mechanical EngineeringShandong UniversityJinan 250061People’s Republic of China Key Laboratory of Education Ministry for Modern Design and Rotor‑Bearing System Xi’an Jiaotong UniversityXi’an 710049People’s Republic of China School of Mechanical and Automotive Engineering Qilu University of TechnologyJinan 250353People’s Republic of China

WC-Co alloys have enjoyed great practical significance owing to their excellent properties during the past *** the advantages,however,recently there have been concerns about the challenges associated with the use of Co,*** instability,toxicity and properties degeneration,which necessitates the fabrication of binderless tungsten carbide(BTC).On the other hand,BTC or BTC composites,none of them,to date has been commercialized and produced on an industrial scale,but only used to a limited extent for specialized applications,such as mechanical seals undergoing high burthen as well as high temperature electrical *** are two challenges in developing BTC:fully densifying the sintered body together with achieving a high ***,this review applies towards comprehensively summarize the current knowledge of sintering behavior,microstructure,and mechanical properties of BTC,highlighting the densification improving strategies as well as toughening methods,so as to provide reference for those who would like to enhance the performance of BTC with better reliability advancing them to further wide applications and prepare the material in a way that is environment friendly,harmless to human health and low in production *** paper shows that the fabrication of highly dense and high-performance BTC is economically and technically *** properties of BTC can be tailored by judiciously selecting the chemical composition coupled with taking into careful account the effects of processing techniques and parameters.

关键词： Binderless tungsten carbide Sintering Densification Toughening Mechanical properties

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Characterization of molten 2LiF–BeF_2 salt impregnated into graphite matrix of fuel elements for thorium molten salt reactor

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Nuclear Science and Techniques 2019年第5期30卷 32-39页

作者： Hong-Xia Xu Jun Lin Ya-Juan Zhong Zhi-Yong Zhu Yu Chen Jian-Dang Liu Bang-Jiao Ye Center for Thorium Molten Salt Reactor System Shanghai Institute of Applied PhysicsChinese Academy of Sciences State Key Laboratory of Particle Detection and Electronics University of Science and Technology of China USTC

The impregnation behavior of molten 2LiF–BeF_2(FLiBe) salt into a graphite matrix of fuel elements for a solid fuel thorium molten salt reactor(TMSR-SF) at pressures varying from 0.4 to 1.0 MPa was studied by mercury intrusion, molten salt impregnation, X-ray diffraction, and scanning electron microscopy *** was found that the entrance pore diameter of the graphite matrix is less than 1.0 μm and the contact angle is about 135°. The threshold impregnation pressure was found to be around 0.6 MPa experimentally, consistent with the predicted value of 0.57 MPa by the Washburn equation. With the increase of pressure from 0.6 to 1.0 MPa, the average weight gain of the matrix increased from 3.05 to 10.48%,corresponding to an impregnation volume increase from 2.74 to 9.40%. The diffraction patterns of FLiBe are found in matrices with high impregnation pressures(0.8 MPa and1.0 MPa). The FLiBe with sizes varying from tens of nanometers to a micrometer mainly occupies the open pores in the graphite matrix. The graphite matrix could inhibit the impregnation of the molten salt in the TMSR-SF with a maximum operation pressure of less than 0.5 MPa.

关键词： keywords Molten salt reactor FLiBe Impregnation Graphite matrix

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Ballistic performance of CFRP under normal and oblique impacts by square fragments: Experimental, numerical, and theoretical investigations

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Thin-Walled Structures 2025年 215卷

作者： Feng, Bo Dong, Yongxiang Min, Qiang Liu, Jian Shi, Xinping Tian, Yumo An, Fengjiang State Key Laboratory of Explosion Science and Safety Protection Beijing Institute of Technology Beijing 100081 China National Key Laboratory of Digital and Agile Aircraft Design Chengdu Aircraft Design & Research Institute Chengdu610091 China Beijing Institute of Electronic System Engineering Beijing 1000854 China

High-performance carbon fibre-reinforced polymer (CFRP) composites are commonly used as external protective structures in military and aerospace applications and are frequently subjected to impact from fragments or projectiles. This study investigated the damage mechanisms of CFRP laminates under normal and oblique impacts from square fragments. Impact tests were conducted on 3–9 mm CFRP laminates using 4 g and 7 g square fragments at velocities ranging from 100 to 1300 m/s and impact angles from 0° to 60° Finite element simulations based on yarn-scale models were also performed. The results revealed that under oblique penetration conditions, the fragment edge initially contacting the target plate caused deeper shear damage. An analytical model was developed to predict the residual velocity of the fragments and the ballistic limit velocity (BLV) of the CFRP laminates. The average error between the model predictions and experimental results was 8.42 %, whereas that between the predictions and simulation results was 3.69 %. Interestingly, the analysis revealed a non-zero minimum resistance angle for the laminate under square fragment impact, at which the BLV of the target plate was minimised. The predicted distribution range of the minimum resistance angle in this study was 23–28° The developed predictive model and identified "minimum resistance angle" provide theoretical foundations for protective engineering design, bridging laboratory research to real-world high-risk applications such as military and aerospace. © 2025 Elsevier Ltd

关键词： Military applications

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Data-driven Topology Optimization (DDTO) for Three-dimensional Continuum Structures

arXiv

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arXiv 2022年

作者： Guo, Yunhang Du, Zongliang Wang, Lubin Meng, Wen Zhang, Tien Su, Ruiyi Yang, Dongsheng Tang, Shan Guo, Xu State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering Mechanics Dalian University of Technology Dalian116023 China Ningbo Institute of Dalian University of Technology Ningbo315016 China Beijing System Design Institute of Electro-Mechanic Engineering Beijing100854 China China Academy of Launch Vehicle Technology Beijing100076 China

Developing appropriate analytic-function-based constitutive models for new materials with nonlinear mechanical behavior is demanding. For such kinds of materials, it is more challenging to realize the integrated design from the collection of the material experiment under the classical topology optimization framework based on constitutive models. The present work proposes a mechanistic-based data-driven topology optimization (DDTO) framework for three-dimensional continuum structures under finite deformation. In the DDTO framework, with the help of neural networks and explicit topology optimization method, the optimal design of the three-dimensional continuum structures under finite deformation is implemented only using the uniaxial and equibiaxial experimental data. Numerical examples illustrate the effectiveness of the data-driven topology optimization approach, which paves the way for the optimal design of continuum structures composed of novel materials without available constitutive relations. Copyright © 2022, The Authors. All rights reserved.

关键词： Constitutive models

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Rational design of Robust Flower-Like Sharp-Edge Acoustic Micromixers Towards Efficient Engineering of Functional 3d Zno Nanorod Array

SSRN

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SSRN 2022年

作者： Zhao, Xiong Chen, Hongqiang Xiao, Yaxuan Zhang, Jinhua Hao, Nanjing School of Chemical Engineering and Technology Xi'an JiaoTong University 28 Xianning West Road Shaanxi Xi’an710049 China State Key Laboratory of Transducer Technology Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences 865 Changning Road Shanghai200050 China Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System Xi’an Jiaotong University 28 Xianning West Road Shaanxi Xi’an710049 China

Sharp-edge acoustofluidic micromixers have attracted considerable attention in recent years due to their unique features in terms of flexible control, contactless operation, and short mixing distance. However, optimizing sharp-edge structures to achieve robust mixing performance towards efficient practical applications is still a great challenge. Herein, we first propose flower-like sharp-edge acoustic micromixers for developing functional 3D ZnO nanorod array. Numerical simulation and experimental validation are conducted to investigate the effect of petal numbers, spreading angles, and tip angles on the mixing performance. Generally, more petals need a larger spreading angle to achieve better mixing while a large spreading angle is unfavorable, and the mixing performance decreases with the increase of tip angles. Compared to single sharp-edge devices, flower-like sharp-edge ones always perform better mixing efficiency. The optimized device is utilized to synthesize well-defined 3D ZnO nanorod array inside a glass capillary and the excellent capabilities of photodegradation of dye and enrichment of heavy metal ions are examined. The photodegradation and enrichment efficiencies can be well regulated by adjusting the flow rates, and superior reusability of the engineered ZnO nanorod array is validated. These results not only shed new light on the rational design of acoustic micromixers, but also open up new possibilities for developing advanced lab-on-a-chip functional technologies. © 2022, The Authors. All rights reserved.

关键词： II-VI semiconductors

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Evaluation of surface wind speed over East Asia and the adjacent ocean in three reanalyses using satellite and in-situ observations

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Atmospheric and Oceanic Science Letters 2025年

作者： Li, Siyuan Wang, Kai Miao, Hao Zhu, Xuedan Liu, Yanjie Li, Jinxiao Wang, Wei Zheng, Xiao Feng, Juan Wang, Xiaocong Shanghai Investigation Design and Research Institute Co. Ltd. Shanghai China College of Atmospheric Science Nanjing University of Information Science and Technology Nanjing China China Meteorological Administration Transportation Meteorology Key Laboratory Nanjing Joint Institute for Atmospheric Sciences Nanjing China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Center for Monsoon System Research Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China

Surface wind speed (SWS) not only plays a crucial role in regulating the Earth's energy and hydrological cycle, but also is an important source of sustainable renewable energy. This study assesses the credibility of SWSs in three reanalyses (ERA5, MERRA2, and JRA-55) in East Asia using both satellite and in-situ observations. Results show all three reanalyses can capture the spatial pattern of SWS as in observations, yet there are notable differences in magnitude. On land, ERA5 and MERRA2 overestimate the SWS by about 0.6 and 1.5 m s⁻¹, respectively, whereas JRA-55 underestimates it. The biases over the oceans are opposite to those on land and are relatively small due to the assimilation of observations of oceanic surface winds. Overall, JRA-55 and ERA5 offer better estimates of seasonal means and variances of SWS than MERRA2. The observed SWS shows a negative trend of −0.08 m s⁻¹/10 yr on land and a positive trend of 0.09 m s⁻¹/10 yr in the western North Pacific. Only JRA-55 shows similar trends to observations over both land and ocean, while ERA5 and MERRA2 show varying degrees of deviation from the observations. Further investigation shows that there is a strong link between the trend of SWS and that of the large-scale circulation, and that a large part of the SWS trend can be attributed to changes in large-scale circulations. 摘要利用卫星和地面站点观测数据, 本文对再分析产品中的地表风速 (SWS) 进行了可信度评估. 研究结果表明, 再分析产品能够较好地再现SWS的观测分布特征, 但在风速的量级上则存在显著差异. 具体而言, 在陆地区域, ERA5和MERRA2分别高估了约0.6 m s⁻¹和1.5 m s⁻¹, 而JRA-55则存在低估现象;而在海洋区域, 偏差情况与陆地相反. 总体来看, JRA-55和ERA5在模拟SWS的气候态及其变率方面, 更加接近观测数据. 其中, JRA-55中SWS的年代际趋势与观测数据最为一致. © 2024

关键词： ASCAT East Asia Reanalysis Surface wind speed Trend analysis

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Coupled fluid-thermal investigation on non-ablative thermal protection system with spiked body and opposing jet combined configuration

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Chinese Journal of Aeronautics 2019年第6期32卷 1390-1402页

作者： Jie HUANG Weixing YAO Xianyang SHAN State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China Key Laboratory of Fundamental Science for National Defense-Advanced Design Technology of Flight Vehicle Nanjing University of Aeronautics and AstronauticsNanjing 210016China System Design Institute Hubei Aerospace Technology AcademyWuhan 430040China

In this paper, a Non-Ablative Thermal Protection system(NATPS) with the spiked body and the opposing jet combined configuration is proposed to reduce the aerodynamic heating of the hypersonic vehicle, and the coupled fluid-thermal numerical analysis is performed to study the thermal control performance of the NATPS. The results show that the spiked body pushes the bow shock away from the protected structure and thus reduces the shock intensity and the wall heat flux. In addition, the low temperature gas of the opposing jet separates the high temperature gas behind the shock from the nose cone of the spiked body, ensuring the non-ablative property of the spiked body. Therefore, the NATPS reduces the aerodynamic heating by the reconfiguration of the flow field, and the thermal control efficiency of the system is better than the Thermal Protection system(TPS) with the single spiked body and the single opposing jet. The influencing factors of the NATPS are analyzed. Both increasing the length of the spiked body and reducing the total temperature of the opposing jet can improve the thermal control performance of the NATPS and the nonablative property of the spiked body. However, increasing the heat conductivity coefficient of the spiked body can enhance benefit the non-ablative property of the spiked body, but has little influence on the thermal control performance of the NATPS.

关键词： Coupled method Non-ablative Opposing jet Spiked body Thermal protection system

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Structural design and strength analysis of multi-ring packed flywheel with heavy metal alloy segments 2

Structural design and strength analysis of multi-ring packed...

引用

2nd International Conference on Numerical Modelling in Engineering, NME 2019

作者： Jiang, L. Zhang, W. Wu, C.W. Zhang, L.P. Zhang, Y.X. Liu, Z.Y. National Key Laboratory of Science and Technology on Reactor System Design Technology Nuclear Power Institute of China Chengdu610041 China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian116024 China

Flywheel, as a kinetic energy storage and conversion device, has promising applications due to its high efficiency, no pollution and long lifetime. In particular, with a three-layer structure packed with heavy metal alloy middle layer, a flywheel can achieve both a large rotational inertia and a high energy density. To guarantee structural strength safety of this type of multi-ring packed flywheel operating at high temperature, structural and thermal stress analysis for a flywheel with a tungsten alloy layer sandwiched between two stainless steel layers is carried out using finite element method (FEM). Based on plane stress assumption, flywheel stress characteristic along radius under assembly force, centrifugal force and thermal loading is demonstrated. The results show that, the rise of temperature causes inconsistent thermal expansion between neighbouring layers and results in a large thermal stress. Particularly, a high circumferential tensile stress occurs in the middle layer. It is also found that, the segments of the middle tungsten alloy layer can efficiently relieve the inconsistent thermal expansion and lower the thermal stress. Moreover, the number of segments significantly influences the efficiency of thermal stress releasing and the reserved gap between adjacent segments significantly improves the contact pressure between inner hub and tungsten alloy layer. This work may provide reference for structural design of the multi-ring packed flywheels under thermal loading. © Published under licence by IOP Publishing Ltd.

关键词： Kinetics

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