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Wear analysis of revolute joints with clearance in multibody systems

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Science China(Physics,Mechanics & Astronomy) 2013年第8期56卷 1581-1590页

作者： bai zhengfeng ZHAO Yang WANG XingGui Department of Mechanical Engineering Harbin Institute of Technology (Weihai) Department of Astronautic Engineering Harbin Institute of Technology

In this work, the prediction of wear for revolute joint with clearance in multibody systems is investigated using a computational methodology. The contact model in clearance joint is established using a new hybrid nonlinear contact force model and the friction effect is considered by using a modified Coulomb friction model. The dynamics model of multibody system with clearance is established using dynamic segmentation modeling method and the computational process for wear analysis of clearance joint in multibody systems is presented. The main computational process for wear analysis of clearance joint includes two steps, which are dynamics analysis and wear analysis. The dynamics simulation of multibody system with revolute clearance joint is carried out and the contact forces are drawn and used to calculate the wear amount of revolute clearance joint based on the Archard's wear model. Finally, a four-bar multibody mechanical system with revolute clearance joint is used as numerical example application to perform the simulation and show the dynamics responses and wear characteristics of multibody systems with revolute clearance joint. The main results of this work indicate that the contact between the joint elements is wider and more frequent in some specific regions and the wear phenomenon is not regular around the joint surface, which causes the clearance size increase non-regularly after clearance joint wear. This work presents an effective method to predict wear of revolute joint with clearance in multibody systems.

关键词： clearance joint contact model friction force wear multibody system

Numerical and experimental study on dynamics of the planar mechanical system considering two revolute clearance joints

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International Journal of Mechanical System Dynamics 2021年第2期1卷 256-266页

作者： zhengfeng bai Fusong Xu Jijun Zhao Department of Mechanical Engineering Harbin Institute of TechnologyWeihaiChina

Due to assembly,wear and manufacturing errors and clearance in the joints are *** the clearance is introduced into a mechanical system,the impact force in the clearance joint will cause undesirable vibration of the *** this paper,the dynamic responses of the mechanical system with two revolute clearance joints are studied using computational and experimental *** clearance joint is considered as force *** normal contact force and tangential friction force between the journal and bearing in a clearance joint are modeled using a nonlinear contact force model considering energy loss and a modified Coulomb friction model considering a dynamic friction coefficient,respectively.A planar slider-crank mechanism with two revolute clearance joints is used to implement the *** dynamic responses obtained from numerical simulation are compared with the experimental *** simulations and experimental tests for different clearance sizes and crank speeds are presented and discussed,*** simulation results agree quite well with those of the experiment for different cases,which proves the accuracy and efficiency of the computational method for dynamics analysis of the mechanical system with two revolute clearance joints in this *** investigation indicates that the clearances in revolute joints significantly affect the dynamic characteristics of mechanical systems,which must be considered in the precision analysis,design,and control of multibody systems,especially for high-speed machinery.

关键词： clearance joint dynamic characteristics experimental tests mechanical system modeling and simulation

Knowledge and data jointly driven aeroengine gas path performance assessment method

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Chinese Journal of Aeronautics 2024年第5期37卷 533-557页

作者： Zhe WANG Xuyun FU Rui ZHANG zhengfeng bai Xiangzhao XIA Wei JIANG Department of Mechanical Engineering Harbin Institute of TechnologyWeihai 264209China Weihai Key Laboratory of Intelligent Operation and Maintenance Harbin Institute of TechnologyWeihai 264209China Control System Design Laboratory AECC ShenYang Engine Research InstituteShenyang 110015China

Aeroengines,as the sole power source for aircraft,play a vital role in ensuring flight *** gas path,which represents the fundamental pathway for airflow within an aeroengine,directly impacts the aeroengine's performance,fuel efficiency,and ***,timely and accurate evaluation of gas path performance is of paramount *** paper proposes a knowledge and data jointly driven aeroengine gas path performance assessment method,combining Fingerprint and gas path parameter deviation ***,Fingerprint is used to correct gas path parameter deviation values,eliminating parameter shifts caused by non-component performance ***,coarse errors are removed using the Romanovsky criterion for short-term data divided by an equal-length overlapping sliding ***,an Ensemble Empirical Mode Decomposition and Non-Local Means(EEMD-NLM)filtering method is designed to“clean”data noise,completing the preprocessing for gas path parameter deviation ***,based on the characteristics of gas path parameter deviation values,a Dynamic Temporary Blended Network(DTBN)model is built to extract its temporal features,cascaded with Multi-Layer Perceptron(MLP),and combined with Fingerprint to construct a Dynamic Temporary Blended AutoEncoder(DTB-AutoEncoder).Eventually,by training this improved autoencoder,the aeroengine gas path multi-component performance assessment model is formed,which can sufficiently decouple the nonlinear mapping relationship between aeroengine gas path multi-component performance degradation and gas path parameter deviation values,thereby achieving the performance assessment of engine gas path *** practical application cases,the effectiveness of this model in assessing the aeroengine gas path multi-component performance is verified.

关键词： Performance assessment Aeroengine Fingerprint Gas path parameter deviation values Jointly drive

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软体连续机械臂动力学建模与仿真

力学学报 2022年第1期54卷 184-195页

作者：白争锋孔清峰赵起哈尔滨工业大学(威海)机械工程系山东威海264209

由于软体机械臂的质量是沿臂的长度连续分布,因此采用拉格朗日方法建立软体机械臂的动力学模型时,涉及计算复杂的积分运算,采用离散化的集中质量模型降低了计算的复杂性,但准确性不足.为了提高软体机械臂动力学建模与仿真的准确度和计... 详细信息

由于软体机械臂的质量是沿臂的长度连续分布,因此采用拉格朗日方法建立软体机械臂的动力学模型时,涉及计算复杂的积分运算,采用离散化的集中质量模型降低了计算的复杂性,但准确性不足.为了提高软体机械臂动力学建模与仿真的准确度和计算效率,本文采用模态方法对软体机械臂进行运动学描述,并从能量的角度分析软体机械臂动力学特性,研究发现,角速度产生的转动动能计算复杂,影响动力学方程的求解效率.在给定条件下,占总动能的百分比不超过3%,对动力学结果影响很小,可以忽略.在此基础上,提出一种基于质心集中质量描述的软体机械臂动力学模型,该模型将软体机械臂的连续分布质量模型等效为位于质心的集中质量模型,利用统计的方法计算出动能等效系数,通过动能等效系数实现两种模型的动能匹配.仿真结果表明,与通常将集中质量放置在任意位置(例如,软体机械臂的中点或末端)的集中质量模型相比,该模型兼顾了连续分布质量模型的准确性,以及集中质量模型的计算高效性,能够准确、高效地获得软体机械臂的动力学特性,并且数值计算稳定.

关键词：软体机械臂模态方法能量集中质量动力学

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磨损与动力学耦合的行星传动齿轮动力学研究

力学学报 2022年第4期54卷 1125-1135,I0006页

作者：宁志远白争锋蒋鑫王思宇哈尔滨工业大学航天工程系哈尔滨150001 哈尔滨工业大学(威海)机械工程系山东威海264209

行星齿轮磨损会导致齿轮齿侧间隙非线性增大、传动精度下降、齿面冲击力增大,进而会导致齿轮传动系统振动加剧,因此需要对行星齿轮的齿面磨损与动力学耦合特性进行研究.本文构建了齿轮非线性磨损与考虑齿轮齿侧间隙的非线性动力学耦合... 详细信息

行星齿轮磨损会导致齿轮齿侧间隙非线性增大、传动精度下降、齿面冲击力增大,进而会导致齿轮传动系统振动加剧,因此需要对行星齿轮的齿面磨损与动力学耦合特性进行研究.本文构建了齿轮非线性磨损与考虑齿轮齿侧间隙的非线性动力学耦合计算模型,对行星传动齿轮磨损动力学特性进行了研究.首先建立齿轮啮合非线性动力学模型,获得齿轮运行过程中的非线性啮合力;进一步将非线性啮合力与齿轮齿面磨损模型相结合,研究齿轮齿面磨损分布规律;并根据齿轮磨损后的齿侧间隙对齿面重构,同时对齿轮动力学模型进行更新;进而得到行星齿轮传动中动态啮合力和磨损特性的变化趋势,并获得齿轮传动系统齿轮齿向振动响应.数值计算结果表明,行星齿轮磨损导致齿轮在单-双齿交替啮合时产生的冲击增大,同时太阳轮-行星轮啮合齿对对磨损较为敏感,齿面啮合条件剧烈恶化,是造成行星齿轮传动性能退化的主要原因,本文研究结果为行星齿轮传动系统运行状态评估与可靠性预测提供了理论基础.

关键词：齿轮磨损磨损预测齿轮啮合力振动响应动力学分析

基于信号分解和切比雪夫多项式的多体系统区间不确定性分析方法

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力学学报 2022年第6期54卷 1694-1705,I0004页

作者：蒋鑫白争锋宁志远王思宇哈尔滨工业大学航天工程系哈尔滨150001 哈尔滨工业大学(威海)机械工程系山东威海264209

参数的不确定性会对多体系统动力学响应产生显著影响,区间分析方法只需根据不确定性参数的边界信息,便可实现在多体系统动力学分析中考虑参数的不确定性.考虑区间参数不确定性,采用切比雪夫区间方法(Chebyshev interval method,CIM)在... 详细信息

参数的不确定性会对多体系统动力学响应产生显著影响,区间分析方法只需根据不确定性参数的边界信息,便可实现在多体系统动力学分析中考虑参数的不确定性.考虑区间参数不确定性,采用切比雪夫区间方法(Chebyshev interval method,CIM)在分析多体系统动力学响应时,随着时间的增大,响应边界精度会越来越低.为解决CIM的这一问题,本文将信号分解技术与切比雪夫多项式结合,采用切比雪夫多项式分别对HHT变换(Hilbert-Huang transform,HHT)和局域均值分解(local mean decomposition,LMD)得到的瞬时幅值和瞬时相位近似,提出CIM-HHT方法和CIM-LMD方法,以获得含区间参数的长周期动力学响应边界.HHT和LMD分解能够将多体系统的多分量响应分解为多个单分量和一个趋势分量(残余分量)之和,CIM-HHT和CIM-LMD对每个分量的瞬时幅值和瞬时相位、和趋势分量采用切比雪夫多项式近似,进而建立系统响应的耦合模型,可以得到系统的动力学响应边界.最后,考虑单摆和曲柄滑块机构中的参数不确定性,验证了CIMHHT和CIM-LMD方法的有效性.结果表明,相比CIM,在长周期区间动力学响应分析中CIM-HHT和CIMLMD能够获得较准确的结果.此外,相比CIM-HHT,CIM-LMD具有更弱的末端效应,计算精度更高.

关键词：区间不确定多体系统动力学信号分解切比雪夫多项式

Boosting bidirectional sulfur conversion enabled by introducing boron-doped atoms and phosphorus vacancies in Ni2P for lithium-sulfur batteries

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Journal of Energy Chemistry 2025年第1期100卷 760-769页

作者： Lin Peng Yu bai Hang Li Meixiu Qu Zhenhua Wang Kening Sun Advanced Research Institute of Multidisciplinary Science Beijing Institute of Technology Beijing Key Laboratory of Chemical Power Source and Green Catalysis School of Chemistry and Chemical Engineering Beijing Institute of Technology

Lithium-sulfur （Li-S） batteries have gained great attention due to the high theoretical energy density and low cost,yet their further commercialization has been obstructed by the notorious shuttle effect and sluggish redox ***,we supply a strategy to optimize the electron structure of Ni2P by concurrently introducing B-doped atoms and P vacancies in Ni2P （Vp-B-Ni2P）,thereby enhancing the bidirectional sulfur *** study indicates that the simultaneous introduction of B-doped atoms and P vacancies in Ni2P causes the redistribution of electron around Ni atoms,bringing about the upward shift of d-band center of Ni atoms and effective d-p orbital hybridization between Ni atoms and sulfur species,thus strengthening the chemical anchoring for lithium polysulfides （LiPSs） as well as expediting the bidirectional conversion kinetics of sulfur ***,theoretical calculations reveal that the incorporation of B-doped atoms and P vacancies in Ni2P selectively promotes Li2S dissolution and nucleation ***,the Li-S batteries with Vp-B-Ni2P-separators present outstanding rate ability of 777 m A h g-1at 5 C and high areal capacity of 8.03 mA h cm-2under E/S of 5μL mg-1and sulfur loading of 7.20 mg *** work elucidates that introducing heteroatom and vacancy in metal phosphide collaboratively regulates the electron structure to accelerate bidirectional sulfur conversion.

关键词： Lithium sulfur batteries

Synergistic effect of bonding heterogeneity and phonon localization in introducing excellent thermoelectric properties in layered heteroanionic NdZnSbO material

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Journal of Energy Chemistry 2025年第1期100卷 259-272页

作者： Da Wan Shuwei Tang Shulin bai Xiaodong Li Peng Ai Wanrong Guo Tuo Zheng College of Materials Science and Engineering Liaoning Technical University Faculty of Chemistry Northeast Normal University

Layered rare-earth metal oxides, harnessing the dual properties of oxides and two-dimensional layered materials, exhibit remarkable thermal stability and quantum confinement effects. Therefore, this work adopts the first-principles calculation combined with the Boltzmann transport theory to predict the thermoelectric properties of NdZnSbO compound. The coexistence of weak interlayer van der Waals interactions, robust intralayer ionic bonding, and partial covalent bonding leads to remarkable bonding heterogeneity, which engenders pronounced phonon scattering and imposes constraints on thermal transport along the out-of-plane direction. The weakened chemical bonds induced by the antibonding states, together with the rattling-like behavior of the Zn atom, culminate in the profound anharmonicity in the layered NdZnSbO compound. The weakening bond and heavy element contribute to the softness of phonon modes, which significantly diminishes the phonon group velocity. The redistribution-dominated four-phonon scattering process spans a large optical gap, which effectively reduces the lattice thermal conductivity. The NdZnSbO compound exhibits direct semiconductor characteristic with a bandgap of 0.73 e V by adopting the Heyd-Scuseria-Ernzerhof(HSE06) functional in combination with spin–orbit coupling(SOC) effect. The multi-valley feature of NdZnSbO compound augur favorably for band degeneracy, thus amplifying the power factor. Consequently, an optimal figure-of-merit(ZT) of 3.40 at 900 K is achieved for the n-type NdZnSbO compound. The present study delves deeply insights into the origins for the low thermal conductivity of NdZnSbO compound and proposes an optimization scheme to enhance overall thermoelectric performance.

关键词： Bond strength (chemical)

New exploration on pathogenesis and early diagnosis of gestational diabetes

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World Journal of Clinical Cases 2025年第1期13卷 1-5页

作者： Hua bai Department of Neurology The Third Affiliated Hospital of Guizhou Medical UniversityDuyun 558099Guizhou ProvinceChina

Gestational diabetes mellitus(GDM)refers to varying degrees of abnormal glucose metabolism that occur during pregnancy and excludes patients pre-viously diagnosed with *** is a unique among the four subtypes of diabetes classified by the international World Health Organization *** GDM patients constitute a small proportion of the total number of diabetes cases,the incidence of GDM has risen significantly over the past decade,posing substantial risk to pregnant women and ***,it warrants considerable *** pathogenesis of GDM is generally considered to resemble that of type II diabetes,though it may have distinct *** blood biochemical proteins in the context of GDM can help elucidate its pathogenesis,thereby facilitating more effective prevention and management *** article reviews this critical clinical issue to enhance the medical community's sufficient understanding of GDM.

关键词： Gestational diabetes mellitus Pathogenesis Proteomics RBP4 ANGPTL8