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Theoretical Model and Experimental Research on Friction and torque Characteristics of Hydro-viscous Drive in Mixed Friction Stage

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Chinese Journal of Mechanical Engineering 2019年第5期32卷 59-69页

作者： Hongwei Cui Qiliang Wang Zisheng Lian Long Li College of Mechanical and Vehicle Engineering Taiyuan University of TechnologyTaiyuan 030024China Shanxi Key Laboratory of Fully Mechanized Coal Mining Equipment Taiyuan University of TechnologyTaiyuan 030024China

The hydro-viscous drive(HVD)has been widely used in fan transmission in vehicles,fans,and scraper conveyors for step-less speed regulation or soft starting.In the mixed friction stage,the contact,friction,and torque characteristics of friction pairs are very complex and change at any time.The characteristics of the frictional and hydrodynamic lubrication states were studied in order to calculate and predict the friction and torque characteristics of the friction pairs in the mixed friction stage.The fluid torque was calculated by applying the average shear stress model and the load-carrying capacity of asperity was determined on the basis of the fractal contact theory.In addition,the contact friction coefficient of the friction pairs was taken into consideration and measured by using the MM1000-Ⅲfriction and wear testing machine.The asperity friction torque and total torque in the mixed friction stage were obtained and finally,the test rig for the torque characteristics was set up.The results show that the contribution to the total torque is shared by the oil film and the asperity friction.The friction coefficient decreases sharply at first and then increases with a change in the relative rotational speed,following the Stribeck curve closely,and the contact frictional coefficient slowly decreases with increase in the pressure between the friction pairs.The torque between the friction pairs is provided by the asperity friction,and the torque due to the oil film reduces to zero.When the thickness of the oil film is small,a major contribution to the total torque is due to the asperity friction.The total torque also increases with the decrease in the film thickness ratio.Therefore,by theoretical analysis and experimental verification,the torque of the friction pairs in the mixed friction stage can be accurately calculated using the average shear stress model and asperity friction torque model.

关键词： Hydro-viscous drive(HVD) Mixed friction stage torque characteristics Contact friction coefficient

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Research on Influence of Motor Parameters on the Negative-Salient Permanent Magnet Synchronous Motor

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CES Transactions on Electrical Machines and Systems 2022年第1期6卷 77-86页

作者： Fei Guo Qiu Chu Chunyan Li Tao Meng Department of Mechanical and Electrical Engineering Heilongjiang University IEEE

The d-axis inductance(Ld)of the negative-salient permanent magnet synchronous motor(NSPMSM)is larger than the q-axis inductance(Lq).Compared with the traditional motor,the NSPMSM has the characteristics of a high overload capacity,wide speed range,and preventing permanent magnet demagnetization.Positive d-axis current(id)is applied to control positive reluctance torque when running at base speed.When the motor is running at high speed,a relatively small id can achieve speed expansion and effectively expand the motor flux-weakening range.The use of a magnetic bridge to increase the Ld and a W-type permanent magnet to reduce the Lq is proposed in this article as a novel NSPMSM rotor structure.Firstly,the working principle of the NSPMSM was determined according to the equivalent magnetic circuit.Secondly,using the finite element method,the influence of motor structure on torque and speed performance of NSPMSM was analyzed,and the motor structure was optimized.Thirdly,the effect of the internal power factor angle on the performance of the two motors is analyzed.Finally,the short circuit simulation and analysis verified that the NSPMSM has a stronger short circuit current suppression ability without sacrificing overload ability.

关键词： Speed range inner power factor angle flux weakening torque short-circuit current

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Analysis of Permanent Magnet-assisted Synchronous Reluctance Motor Based on Equivalent Reluctance Network Model

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CES Transactions on Electrical Machines and Systems 2022年第2期6卷 135-144页

作者： Changbin Li Xiuhe Wang Feng Liu Jie Ren Zezhi Xing Xinwei Gu School of Electrical Engineering Shandong UniversityJinan 250061China

In this paper,the equivalent reluctance network model(ERNM)is used to calculate the magnetic circuit of a permanent magnet-assisted synchronous reluctance motor(PMASynRM)and calculate no-load air-gap magnetic field and electromagnetic torque.Iteration method is used to solve the relative permeability of iron core.A novel reluctance network model based on actual distribution of the magnetic flux inside the motor is established.The magnetomotive force(MMF)generated by armature winding affects the relative permeability of iron core,which is considered in the calculation of ERNM to improve the accuracy when the motor is under load.ERNM can be used to measure air-gap flux density,no-load back electromotive force(EMF),the average value of motor torque,the armature winding voltage under load,and power factor.The method of calculating the motor performance is proposed.The results of calculation are consistent with finite element method(FEM)and the computational complexity is much less than that of the FEM.The results of ERNM has been verified,which will provide a simple method for motor design and analysis.

关键词： Permanent magnet-assisted synchronous reluctance motor(PMASynRM) Equivalent reluctance network model(ERNM) Air-gap flux density No-load back electromotive force(EMF) torque

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Accuracy improvement of the traditional rolling force and torque model powered by an industrial data platform

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Baosteel Technical Research 2022年第2期16卷 1-9页

作者： WANG Quansheng JIAO Sihai Research Institute Baoshan Iron&Steel Co.Ltd.Shanghai 200940 China

The calculation results of the rolling force and torque model based on Orowan's differential equation numerical solution method do not fit with the industrial measurements very well.In particular,a quite large deviation on the torque model was found.On the basis of analyzing the shortcomings of the existing method,an improved rolling force and torque model algorithm aided by the Process Integrated Data Application System platform is proposed.Accordingly,the calculation accuracy of the rolling torque model is improved.The improved models are verified by 1711136 records of a data platform.The improved models are also based on Orowan's differential equation.Two coefficients,namely,friction factor and forward slip,are recognized as the crucial factors to be determined from industrial measurements to improve the accuracy.Therefore,the proposed method is a hybrid method that can be used to deeply understand the rolling process and improve the model's accuracy by combining traditional plastic mechanics and data-driving global optimization algorithms.This paper proposes a new approach to studying theoretical rolling deformation models powered by the industrial data platform.

关键词： data platform rolling force torque numerical method hybrid strategy

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Modal analysis of the torque converter in different prestress

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High Technology Letters 2020年第1期26卷 61-67页

作者：张泽宇 Hui Jizhuang Shi Ze Suo Xuefeng Zhang Xuhui Fan Hongwei Key Laboratory of Road Construction Technology and Equipment Ministry of EducationChang'an UniversityXi'an 710064P.R.China Shaanxi Key Laboratory of Mine Electromechanical Equipment Intelligent Monitoring Xi'an University of Science and TechnologyXi'an 710054P.R.China Research Center Tibet Tianlu Co.LtdLhasa 850000P.R.China

In order to study the mechanical properties and the dynamic performance of torque converter,to reduce the vibration and noise during the operation and to improve the stability,a 215 mm hydraulic torque converter is taken as the research object,and modal analyses are performed based on the finite element method.The weak parts of the impeller structure are obtained after calculating the models of the impeller and turbine without prestress.The variation of the modal frequency of the turbine and impeller are obtained under different prestress conditions by calculating different rotational speeds of the transmission shaft.The fundamental frequencies of the impeller and the turbine increase by 0.43%and 4.82%respectively when the rotational speed ranges from 100 rpm to 4500 rpm.The results of the present research indicate that the modal frequencies at different speeds are similar to the fundamental frequencies of the structure.Therefore,it is possible to estimate the vibration characteristics of the structure and optimize the structural design by numerical modal analysis in the static state instead of the dynamic state.

关键词： hydraulic torque converter modal analysis prestress finite element analysis

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Strain transfer mechanism of passive wireless surface acoustic wave torque sensors using shear lag theory

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Journal of Beijing Institute of Technology 2011年第2期20卷 221-226页

作者：张运涛徐春广潘勤学刘婧李喜朋 Key Laboratory of Fundamental Science for Advanced Machining Beijing Institute of Technology

A shear-lag theory was developed to investigate the strain transfer from the metal substrate to the surface acoustic wave （SAW） resonator through a bonding layer. A three-layer model of host structure-adhesive layer-resonator layer was established. The strain transfer was theoretically analyzed, and the main factors impacting the SAW sensor measurement were studied. The relationship between the sensor response and the individual effect of all these factors under static loads was discussed. Results showed that better accuracy could be achieved with increase in the adhesive stiffness or resonator length, or decrease in the adhesive thickness. The values of the strain transfer rate calculated from the analytical model agreed well with that from the available experiment data.

关键词： passive wireless surface acoustic wave （SAW） torque strain transfer shear lag

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BALANCING torque OF SINGLES COTTON ROTOR YARNS

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Journal of China Textile University(English Edition) 1997年第3期14卷 41-46页

作者：陶肖明刘燕媚卢伟杰 Hongkong Polytechnic Univ Hongkong Hong Kong

This paper reports a recent development of a yarn modification process to produce torque balanced singles spun yarns. Taking advantages of the core-sheath structure of unconventional spun yarns, we have developed a yarn modification process and applied it to singles yarns spun by rotor spinning. torque free singles yarns have been produced from 100% cotton fibers. The spirality of resultant single jersey knit fabrics has been greatly reduced or, in some cases, completely eliminated. Properties and performance characteristics of both parent and modified yarns as well as their resultant fabrics have been evaluated including the yarn tensile properties, surface properties, handle, air permeability, burst strength, and pilling resistance of the fabrics.

关键词： yarn production rotor spinning torque balancing

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Fluid-solid interaction analysis of torque converters

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High Technology Letters 2019年第3期25卷 239-244页

作者：张泽宇 Hui Jizhuang Suo Xuefeng Zhang Fuqiang Lei Jingyuan National Engineering Laboratory for Highway Maintenance Equipment Chang’an University

In order to extend the service life of torque converters, it is essential to predict the pressure condition and improve its weak areas. According to computational fluid dynamics and structural statics, a model of torque converter is constructed using software ANSYS. Then, a fluid-solid interaction(FSI) analysis method is proposed to obtain its stress distribution, in which the fluid pressure is applied to the coupling surface to calculate the interaction between fluid and solid. The results show that the fluid pressure at the inlet of the impeller is maximum and decreases along the flow direction, the pressure at the inlet of the turbine blade is minimum and the outlet pressure is the largest, increasing along the flow direction gradually;the pressure distribution of the impeller is concentrated mainly at the corner, especially between the inner ring and the impeller blades;the pressure of the turbine is concentrated mainly on the connection between turbine and the outer edge of the blade.

关键词： torque converter fluid-solid interaction(FSI) stress distribution pressure analysis simulation

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torque Calculation of Five-Phase Synchronous Reluctance Motors With Shifted-Asymmetrical-Salient-Poles Under Saturation Condition

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CES Transactions on Electrical Machines and Systems 2020年第2期4卷 105-113页

作者： Qian Chen Xuping Shi Gaohong Xu Wenxiang Zhao School of Electrical and Information Engineering Jiangsu UniversityZhenjiang212013China

In traditional analytical method(AM),the magnetic saturation is always ignored to simplify the calculation process.However,synchronous reluctance motors(SynRMs)often operate around saturation point to achieve higher torque density.Therefore,a new AM is proposed,in which the saturation of stator iron has been considered.The key of the proposed method includes a saturation factor,and an iterative method is adopted to compute the saturation factor in the SynRM by increasing the air-gap length.Especially,the proposed AM can be applied to a SynRM even with shifted-asymmetrical-salient-poles.In the process of AM,the expression of stator magnetomotive force(MMF)is built firstly.Additionally,the air-gap density including slotting effect and salient-poles is calculated.Then,the rotor MMF under saturation of the stator iron is obtained.Therefore,the precision of the instantaneous torque can be improved significantly.Eventually,by the verification of finite elements method(FEM)and experiments,the torque performance of SynRMs with shifted asymmetrical rotor can be predicted accurately by the proposed AM.

关键词： Synchronous reluctance motors torque shifted asymmetrical salient pole analytical method,saturation.

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Uncertainty analysis of atmospheric friction torque on the solid Earth

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Geodesy and Geodynamics 2016年第3期7卷 165-170页

作者： Haoming Yan Yong Huang State Key Laboratory of Geodesy and Earth's Dynamics Institute of Geodesy and Geophysics Chinese Academy of Sciences Physics Department School of Science Wuhan University of Technology College of Earth Sciences University of Chinese Academy of Sciences

The wind stress acquired from European Centre for Medium-Range Weather Forecasts （ECMWF）, National Centers for Environmental Prediction （NCEP） climate models and QSCAT satellite observations are analyzed by using frequency-wavenumber spectrum method. The spectrum of two climate models, i.e., ECMWF and NCEP, is similar for both 10 m wind data and model output wind stress data, which indicates that both the climate models capture the key feature of wind stress. While the QSCAT wind stress data shows the similar characteristics with the two climate models in both spectrum domain and the spatial distribution, but with a factor of approximately 1.25 times larger than that of climate models in energy. These differences show the uncertainty in the different wind stress products, which inevitably cause the atmospheric faction torque uncertainties on solid Earth with a 60% departure in annual amplitude, and furtherly affect the precise estimation of the Earth＇s rotation.

关键词： Uncertainty Wind stress Friction torque Earth＇s rotation Annual amplitude Spectrum

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