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Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 873-890页

作者： Jinghu TANG Chaofeng LI Jin ZHOU Zhiwei WU School of Mechanical Engineering&Automation Northeastern UniversityShenyang 110819China key laboratory of vibration and control of aero-propulsion systems of ministry of education of china Northeastern UniversityShenyang 110819China School of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

The modeling and self-excited vibration mechanism in the magnetic levitation-collision interface coupling system are investigated.The effects of the control and interface parameters on the system's stability are analyzed.The frequency range of self-excited vibrations is investigated from the energy point of view.The phenomenon of self-excited vibrations is elaborated with the phase trajectory.The corresponding control strategies are briefly analyzed with respect to the vibration mechanism.The results show that when the levitation objects collide with the mechanical interface,the system's vibration frequency becomes larger with the decrease in the collision gap;when the vibration frequency exceeds the critical frequency,the electromagnetic system continues to provide energy to the system,and the collision interface continuously dissipates energy so that the system enters the self-excited vibration state.

关键词： magnetic levitation coupling system self-excited vibration mechanical interface vibration frequency

Comparison of nonlinear modeling methods for the composite rubber clamp

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Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 763-778页

作者： Yiming CAO Hui MA Xumin GUO Bingfeng ZHAO Hui LI Xin WANG Bing WANG School of Mechanical Engineering and Automation Northeastern UniversityShenyang 110819China key laboratory of vibration and control of aero-propulsion systems of ministry of education of china Northeastern UniversityShenyang 110819China AVIC Shenyang Engine Design Institute Shenyang 110013China Dalian Mengyu Machinery Co. Ltd.Dalian 116317Liaoning ProvinceChina

The cubic stiffness force model(CSFM)and Bouc-Wen model(BWM)are introduced and compared innovatively.The unknown coefficients of the nonlinear models are identified by the genetic algorithm combined with experiments.By fitting the identified nonlinear coefficients under different excitation amplitudes,the nonlinear vibration responses of the system are predicted.The results show that the accuracy of the BWM is higher than that of the CSFM,especially in the non-resonant region.However,the optimization time of the BWM is longer than that of the CSFM.

关键词： pipeline system nonlinear clamp model composite rubber clamp amplitude-dependent characteristic vibration response experiment

A toroidal SAW gyroscope with focused IDTs for sensitivity enhancement

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Microsystems & Nanoengineering 2024年第2期10卷 47-56页

作者： Lu Tian Haitao Zhao Qiang Shen Honglong Chang ministry of education key laboratory of Micro and Nano systems for aerospace School of Mechanical EngineeringNorthwestern Polytechnical UniversityXi’an710072China

A surface acoustic wave(SAW)gyroscope measures the rate of rotational angular velocity by exploiting a phenomenon known as the SAW gyroscope effect.Such a gyroscope is a great candidate for application in harsh environments because of the simplification of the suspension vibration mechanism necessary for traditional microelectromechanical system(MEMS)gyroscopes.Here,for the first time,we propose a novel toroidal standing-wave-mode SAW gyroscope using focused interdigitated transducers(FIDTs).Unlike traditional SAW gyroscopes that use linear IDTs to generate surface acoustic waves,which cause beam deflection and result in energy dissipation,this study uses FIDTs to concentrate the SAW energy based on structural features,resulting in better focusing performance and increased SAW amplitude.The experimental results reveal that the sensitivity of the structure is 1.51µV/(°/s),and the bias instability is 0.77°/s,which are improved by an order of magnitude compared to those of a traditional SAW gyroscope.Thus,the FIDT component can enhance the performance of the SAW gyroscope,demonstrating its superiority for angular velocity measurements.This work provides new insights into improving the sensitivity and performance of SAW gyroscopes.

关键词： angular deflection gyroscope

含外圈剥落和不对中的齿轮-转子-轴承系统振动分析

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Journal of Central South University 2024年第2期31卷 511-525页

作者：徐宏阳赵翔马辉罗忠韩清凯闻邦椿 School of Mechanical Engineering and Automation Northeastern UniversityShenyang 110819China key laboratory of vibration and control of aero-propulsion System(ministry of education) Northeastern UniversityShenyang 110819China

轴承套圈的不对中和剥落是影响齿轮-转子-轴承系统振动特性的典型误差和故障。为了研究外圈不对中和剥落对系统的耦合影响,有必要对含不对中和剥落的齿轮-转子-轴承系统振动特性进行分析。首先,考虑外圈不对中和剥落,计算了轴承的五自... 详细信息

轴承套圈的不对中和剥落是影响齿轮-转子-轴承系统振动特性的典型误差和故障。为了研究外圈不对中和剥落对系统的耦合影响,有必要对含不对中和剥落的齿轮-转子-轴承系统振动特性进行分析。首先,考虑外圈不对中和剥落,计算了轴承的五自由度非线性恢复力。然后,基于轮齿承载接触分析(LTCA)方法,计算了啮合刚度并且建立了直齿轮副的动力学模型。在此基础上,基于切片法建立了花键的等效刚度模型。最后,通过将轴承的恢复力模型、直齿轮副的动力学模型和花键的等效刚度模型与转子系统的有限元模型耦合,建立了齿轮-转子-轴承系统的动力学模型。分析表明,只有剥落位于承载区时,才会对轴承接触力、接触角和系统振动特性产生影响。外圈的不对中导致轴承的承载区范围增大,并使得剥落对系统产生影响的概率增加。

关键词：球轴承不对中剥落振动特性齿轮-转子-轴承系统

Energy-based Directional Pilot Protection for Distribution Networks with IBDGs Considering Unmeasured Load Switching

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CSEE Journal of Power and Energy systems 2024年第1期10卷 139-150页

作者： Chenghan Zhou Guibin Zou Shuo Zhang Xuhui Wen key laboratory of Power System Intelligent Dispatch and control of ministry of education Shandong UniversityJinan 250061China

Inverter-based distributed generations(IBDGs)are the main approach to utilizing clean energy in distribution networks(DNs).Compared with synchronous source,fault response of IBDG is very different.As a result,in DNs with high penetration of IBDGs,legacy protection schemes will no longer be applicable.In this paper,an energy-based directional pilot protection scheme suitabie for DNs with IBDGs is proposed.This scheme considers the large range of phase angle caused by IBDG integration and uses improved energy polarity criterion to determine fault direction.In addition,magnitude of energy is used to distinguish between faults and load switching to overcome maloperation of directional pilot protection caused by internal unmeasured load switching.The proposed scheme first uses local measured information to determine fault direction sign and then exchanges the direction sign with the remote terminal.This scheme does not require high-bandwidth communication and strict data synchronization,so it can be implemented at a low cost.Finally,simulation studies verify effectiveness of the proposed scheme.

关键词： Distribution network energy polarity inverterbased distributed generation pilot protection unmeasured load

Reduced-order modeling and vibration transfer analysis of a fluid-delivering branch pipeline that consider fluid–solid interactions

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Frontiers of Mechanical Engineering 2024年第2期19卷 75-97页

作者： Wenhao JI Hongwei MA Wei SUN Yinhang CAO School of Mechanical Engineering and Automation Northeastern UniversityShenyang 110819China key laboratory of vibration and control of aero-propulsion systems(ministry of education) Northeastern UniversityShenyang 110819China College of Power and Energy Engineering Harbin Engineering UniversityHarbin 150001China

The efficient dynamic modeling and vibration transfer analysis of a fluid-delivering branch pipeline(FDBP)are essential for analyzing vibration coupling effects and implementing vibration reduction optimization.Therefore,this study proposes a reduced-order dynamic modeling method suitable for FDBPs and then analyzes the vibration transfer characteristics.For the modeling method,the finite element method and absorbing transfer matrix method(ATMM)are integrated,considering the fluid–structure coupling effect and fluid disturbances.The dual-domain dynamic substructure method is developed to perform the reduced-order modeling of FDBP,and ATMM is adopted to reduce the matrix order when solving fluid disturbances.Furthermore,the modeling method is validated by experiments on an H-shaped branch pipeline.Finally,transient and steady-state vibration transfer analyses of FDBP are performed,and the effects of branch locations on natural characteristics and vibration transfer behavior are analyzed.Results show that transient vibration transfer represents the transfer and conversion of the kinematic,strain,and damping energies,while steady-state vibration transfer characteristics are related to the vibration mode.In addition,multiple-order mode exchanges are triggered when branch locations vary in frequency-shift regions,and the mode-exchange regions are also the transformation ones for vibration transfer patterns.

关键词： fluid-delivering branch pipeline vibration transfer analysis reduced-order modeling fluid-solid interactions finite element method absorbing transfer matrix method

Disturbance Observer-based Pointing control of Leighton Chajnantor Telescope

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Research in Astronomy and Astrophysics 2024年第1期24卷 135-150页

作者： Weirui Chen Zheng Wang School of Automation Southeast UniversityNanjing 210096China key laboratory of Measurement and control of Complex systems of Engineering Ministry of EducationSoutheast UniversityNanjing 210096China

Leighton Chajnantor Telescope(LCT), i.e., the former Caltech Submillimeter Observatory telescope, will be refurbished at the new site in Chajnantor Plateau, Chile in 2023. The environment of LCT will change significantly after its relocation, and the telescope will be exposed to large wind disturbances directly because its enclosure will be completely open during observation. The wind disturbance is expected to be a challenge for LCT's pointing control since the existing control method cannot reject this disturbance very well. Therefore, it is very necessary to develop a new pointing control method with good capability of disturbance rejection. In this research, a disturbance observer—based composite position controller(DOB-CPC) is designed, in which an H∞feedback controller is employed to compress the disturbance, and a feedforward linear quadratic regulator is employed to compensate the disturbance precisely based on the estimated disturbance signal. Moreover, a controller switching policy is adopted, which applies the proportional controller to the transient process to achieve a quick response and applies the DOB-CPC to the steady state to achieve a small position error. Numerical experiments are conducted to verify the good performance of the proposed pointing controller(i.e., DOB-CPC) for rejecting the disturbance acting on LCT.

关键词： instrumentation:miscellaneous methods:analytical methods:numerical telescopes

Supercritical CO_(2) Cycles for Nuclear-Powered Marine propulsion:Preliminary Conceptual Design and Off-Design Performance Assessment

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Journal of Thermal Science 2024年第1期33卷 328-347页

作者： LI Zhaozhi SHI Mingzhu SHAO Yingjuan ZHONG Wenqi key laboratory of Energy Thermal Conversion and control of ministry of education School of Energy and EnvironmentSoutheast UniversityNanjing 210096China

Using the efficient,space-saving,and flexible supercritical carbon dioxide(sCO_(2)) Brayton cycle is a promising approach for improving the performance of nuclear-powered ships.The purpose of this paper is to design and compare sCO_(2) cycle power systems suitable for nuclear-powered ships.Considering the characteristics of nuclear-powered ships,this paper uses different indicators to comprehensively evaluate the efficiency,cost,volume,and partial load performance of several nuclear-powered sCO_(2) cycles.Four load-following strategies are also designed and compared.The results show that the partial cooling cycle is most suitable for nuclear-powered ships because it offers both high thermal efficiency and low volume and cost,and can maintain relatively high thermal efficiency at partial loads.Additionally,the new load-following strategy that adjusts the turbine speed can keep the compressor away from the surge line,making the cycle more flexible and efficient compared to traditional inventory and turbine bypass strategies.

关键词： supercritical CO_(2)cycle nuclear marine propulsion off-design performance

High Dynamic Bounding and Jumping Motion of Quadruped Robot Based on Stable Optimization control

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Journal of Bionic Engineering 2024年第1期21卷 101-111页

作者： Sai Gu Fei Meng Botao Liu Junyao Gao Qiang Huang School of Mechatronical Engineering Beijing Institute of Technology100081 BeijingChina key laboratory of Biomimetic Robots and systems Ministry of EducationBeijing 100081China

Aiming at the environment such as ravines and obstacles that may be encountered in the actual movement,this paper proposes a method for optimizing the bounding and jumping motion based on the ground touching force trajectory and the air motion trajectory of the quadruped robot.The method of optimizing the ground reaction force according to the speed of the demand and the height of the jump,and adjusting the stance and swing time according to the relationship of dynamics and momentum conservation.At the same time,under the constraints of dynamics and energy consumption of the robot system,considering the jumping distance and height,a method for optimizing the air trajectory of bounding and jumping is proposed.State switching and landing stability control are also added.Finally,the experimental results show that the quadruped robot has strong bounding and jumping ability,and has achieved stable bounding movement and forward jump movement of 0.8 m.

关键词： Quadruped robot High dynamic motion control-Periodic limit cycle Trajectory optimization

含呼吸裂纹的旋转扭型变截面叶片的动态接触特性

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Journal of Central South University 2024年第3期31卷 858-877页

作者：汪伟伟马辉赵晨光吴志渊王洪基 School of Mechanical Engineering and Automation Northeastern UniversityShenyang 110819China key laboratory of vibration and control of aero-propulsion systems Ministry of EducationNortheastern UniversityShenyang 110819China Wuhan Lotus Cars Co. Ltd.Wuhan 430024China State key laboratory of Mechanical System and vibration Shanghai Jiao Tong UniversityShanghai 200240China

航空发动机叶片经常发生裂纹故障失效,从而引发一系列事故。以往的研究主要集中在裂纹引起的非线性振动上,而裂纹呼吸过程中裂纹表面的接触状态往往被忽略。然而,考虑裂纹表面的接触行为是非常重要的,因为它会导致裂纹叶片的非线性振动... 详细信息

航空发动机叶片经常发生裂纹故障失效,从而引发一系列事故。以往的研究主要集中在裂纹引起的非线性振动上,而裂纹呼吸过程中裂纹表面的接触状态往往被忽略。然而,考虑裂纹表面的接触行为是非常重要的,因为它会导致裂纹叶片的非线性振动。为了进一步研究裂纹诱发非线性振动的机理,本文提出了一种基于自编非协调六面体单元(SNCHE)的旋转叶片动态接触呼吸裂纹模型,并使用弹簧单元模拟呼吸效应。通过接触有限元模型验证了模型的有效性。此外,还研究了裂纹参数(裂纹深度和裂纹位置)及载荷参数(气动振幅和气动频率)对裂纹叶片动态接触特性的影响。在此基础上,提出了一个呼吸裂纹量化指标(BCQI)来表征呼吸裂纹的非线性水平。结果表明,在裂纹呼吸过程中,裂纹面从叶片侧面向裂纹尖端中心方向闭合。并且BCQI随裂纹深度、气动幅值和转速的增加而增大,随裂纹位置越靠近叶尖而减小。

关键词：呼吸裂纹动态接触特性旋转叶片非线性动力学非协调六面体单元