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Influence of Structural Parameters of Turbocharger Floating Bearing on Its Dynamic Characteristic Coefficients 被引量:1
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作者 Junsheng Zhao Yuantong Gu +1 位作者 Shengxian Yi Xuelong Lu 《Journal of Beijing Institute of Technology》 EI CAS 2017年第2期183-190,共8页
The structure parameters in an actual industrial production have a great influence on the coefficient of supercharger floating bearing dynamic characteristics,but there has been little systematic study so far.In this ... The structure parameters in an actual industrial production have a great influence on the coefficient of supercharger floating bearing dynamic characteristics,but there has been little systematic study so far.In this paper,the influence of structural parameters of the turbocharger floating bearing on its dynamic characteristic coefficientsis systematically investigated based on the theories of hydrodynamic lubrication and tribology.The influence of clearance ratio on eccentricity and the influence of internal to external radius ratios,and Sommerfeld number were analyzed.A new formula of responding characteristics of the oil film force caused by the displacement or velocity disturbance was deduced near an equilibrium in the steady state.Applying the newly developed formula,the dynamic characteristic was studied for floating bearings.Regularity for change of oil film stiffness and damping was analyzed with the structural parameters of floating bearing such as radius ratios and eccentricity.It has been found that the clearance ratio increases with eccentricity when the radius ratio is unchanged.The eccentricity decreases with the internal to external radius ratio of floating rings when the clearance ratio is constant.The absolute value of total principal stiffness and total main damping decrease with the clearance ratio and radius ratio of floating rings when the total cross damping is stable.The results and findings in this paper can contribute to nonlinear dynamics designs of turbocharger rotor-bearing systems. 展开更多
关键词 TURBOCHARGER floating bearing structure parameters dynamic characteristic coefficient
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Identification Method of Dynamic Coefficients of Fluid Film Bearings for HDD Spindle Motors 被引量:1
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作者 Masayuki Ochiai Yuta Sunami Hiromu Hashimoto 《Journal of Mechanics Engineering and Automation》 2014年第2期123-129,共7页
Fluid film bearings are widely used as support elements of rotating shaft for HDD (hard disk drive) spindle motors. Recently, the opportunity for the HDD spindle motors exposed to external vibration has been increas... Fluid film bearings are widely used as support elements of rotating shaft for HDD (hard disk drive) spindle motors. Recently, the opportunity for the HDD spindle motors exposed to external vibration has been increasing because the HDDs are used for various information related equipments such as mobile PCs, car navigation systems. Hence, the rotating shaft has a possibility to come in contact with the bearing and it causes wear or seizure to the bearing surface. In order to avoid the problems, it is extremely important to enhance the dynamic characteristics of the fluid film bearings for spindles. However, verification from both theory and experiment of dynamic characteristics such as spring coefficients and damping coefficients is rare and few. In this paper, the bearing vibration characteristics when the HDD spindle is oscillated are investigated theoretically and experimentally. And then the identification method ofoil film coefficients of fluid film bearing spindles is described. 展开更多
关键词 TRIBOLOGY fluid film bearing hard disk drive spindle motor dynamic coefficient VIBRATION identification.
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Application of improved BPNN in image restoration-learning coefficient
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作者 Umar Farooq 沈庭芝 +3 位作者 Muhammad Imran 赵三元 Sadia Murawwat 王清云 《Journal of Beijing Institute of Technology》 EI CAS 2012年第4期543-546,共4页
A new method of artificial intelligence based on a new improved back propagation neural network (BPNN) algorithm is partially applied in the problem of image restoration. In order to over- come the inherited issues ... A new method of artificial intelligence based on a new improved back propagation neural network (BPNN) algorithm is partially applied in the problem of image restoration. In order to over- come the inherited issues in conventional back propagation algorithm i.e. slow convergence rate, longer training time, hard to achieve global minima etc. , different methods have been used including the introduction of dynamic learning rate and dynamic momentum coefficient etc. With the passage of time different techniques has been used to improve the dynamicity of these coefficients. The meth- od applied in this paper improves the effect of learning coefficient η by using a new way to modify the value dynamically during learning process. The experimental results show that this helps in im- proving the efficiency overall both in visual effect and quality analysis. 展开更多
关键词 image restoration image processing INTELLIGENT back propagation neural network(BPNN) dynamic learning coefficient
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DETERMINATION OF STATIC AND DYNAMIC DIFFUSION COEFFICIENTS OF MOISTURE IN PARTICLEBOARDS
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作者 Dai Fangtian Cai LipinNortheast Forestry UniversityZhang ShufenWeihe Forestry Bureau, Heilongjiang Province 《Journal of Northeast Forestry University》 SCIE CAS CSCD 1993年第2期87-92,共6页
The static and dynamic diffusion coefficients are important coefficients to describe the moisture transfer processes in particleboard. In this paper, the formula of culculating the static and dynamic diffusion coeffic... The static and dynamic diffusion coefficients are important coefficients to describe the moisture transfer processes in particleboard. In this paper, the formula of culculating the static and dynamic diffusion coefficients were deduced. At first, the static diffusion coefficients of four kinds of particleboards were determined by using diffusion cup method. The results demonstrated that the static diffusion coefficients parallel to panel surface were 10-20 times as large as that of perpendicular to panel surface for test boards. To determine both dynamic diffusion coefficients and surface emission coefficients of moisture in particleboards in one experimental period, specimens in four different thicknesses of each kind of particleboard were used in the experiment. Then the method of regression was used and the dynamic diffusion coefficients and surface emission coefficients were determined based on the slope and intercept of the regressive line. 展开更多
关键词 Static diffusion coefficient Dynamic diffusion coefficient Moisture transfer
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Resonance analysis of a high-speed railway bridge using a stochastic finite element method 被引量:1
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作者 Xiang Ping Yan Weiran +3 位作者 Jiang Lizhong Zhou Wangbao Wei Biao Liu Xiang 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2023年第4期1015-1030,共16页
There is always some randomness in the material properties of a structure due to several circumstances and ignoring it increases the threat of inadequate structural safety reserves.A numerical approach is used in this... There is always some randomness in the material properties of a structure due to several circumstances and ignoring it increases the threat of inadequate structural safety reserves.A numerical approach is used in this study to consider the spatial variability of structural parameters.Statistical moments of the train and bridge responses were computed using the point estimation method(PEM),and the material characteristics of the bridge were set as random fields following Gaussian random distribution,which were discretized using Karhunen-Loève expansion(KLE).The following steps were carried out and the results are discussed herein.First,using the stochastic finite element method(SFEM),the mean value and standard deviation of dynamic responses of the train-bridge system(TBS)were examined.The effectiveness and accuracy of the computation were then confirmed by comparing the results to the Monte-Carlo simulation(MCS).Next,the influence of the train running speed,bridge vibration frequency,and span of the bridge on dynamic coefficient and dynamic response characteristics of resonance were discussed by using the SFEM.Finally,the lowest limit value of the vibration frequency of the simple supported bridges(SSB)with spans of 24 m,32 m,and 40 m are presented. 展开更多
关键词 train-bridge system material randomness Karhunen-Loève expansion Gauss integral dynamic coefficient natural frequency
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Assessment of Operational Performance in a Power Generation/Selling Integrated Company Using a Dynamic Proportional Adjustment Coefficient
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作者 Jingbin Wu Hongming Yang Sheng Xiang 《Energy Engineering》 EI 2024年第11期3263-3287,共25页
Currently,the operational performance assessment system in the power market primarily focuses on power generation and electricity retail companies,lacking a system tailored to the operational characteristics of power ... Currently,the operational performance assessment system in the power market primarily focuses on power generation and electricity retail companies,lacking a system tailored to the operational characteristics of power generation/selling integrated companies.Therefore,this article proposes an assessment index system for assessing the operational performance of a power generation/selling integrated company,encompassing three dimensions:basic capacity,development potential,and external environment.A dynamic proportional adjustment coefficient is designed,along with a subjective and objective weighting model for assessment indexes based on a combined weightingmethod.Subsequently,the operational performance of an integrated company is assessed using extension theory.The results in the case study demonstrate the feasibility and effectiveness of the proposed dynamic proportional adjustment coefficient. 展开更多
关键词 Power generation/selling integrated company dynamic proportional adjustment coefficient combined weighting extension theory assessment of operational performance
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Dynamic Characteristics of Ultra Thin Liquid Lubricated Head-Disk Assembly in Magnetic Hard Disk Files
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作者 陈敏华 陈云飞 《Journal of Southeast University(English Edition)》 EI CAS 1998年第2期56-60,共5页
The dynamic characteristics of a liquid thin film lubricated head disk system are analyzed. The shear thinning effect is taken into account by introducing modification coefficients into the lubricant rheological mode... The dynamic characteristics of a liquid thin film lubricated head disk system are analyzed. The shear thinning effect is taken into account by introducing modification coefficients into the lubricant rheological model. The perturbation theory is employed to set up the dynamic pressure equation. The Reynolds equation and dynamic pressure equations are solved by finite difference method. The results obtained by the difference methods agree well with that calculated by the close solutions. IBM3370 slider is employed as a physical model. The slider of the system can keep flying at 20 nm height, which promises a potential application on high density recording device. 展开更多
关键词 thin film lubrication dynamic coefficients magnetic head disk system
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Performance analysis of air suspension system of heavy truck with semi-active fuzzy control 被引量:3
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作者 阮文廉 张建润 +2 位作者 黎文琼 焦仁强 廖昕 《Journal of Southeast University(English Edition)》 EI CAS 2017年第2期159-165,共7页
In order to analyze and evaluate the performance of the air suspension system of heavy trucks with semi-active fuzzy control, a three-dimensional nonlinear dynamical model of a typical heavy truck with 16-DOF(degree ... In order to analyze and evaluate the performance of the air suspension system of heavy trucks with semi-active fuzzy control, a three-dimensional nonlinear dynamical model of a typical heavy truck with 16-DOF(degree of freedom) is established based on Matlab/Simulink software. The weighted root-mean-square(RMS) acceleration responses of the vertical driver 's seat, the pitch and roll angle of the cab, and the dynamic load coefficient(DLC) are chosen as objective functions, and the air suspension system is optimized and analyzed by the semi-active fuzzy control algorithm when vehicles operate under different operation conditions. The results show that the influence of the roll angle of the cab on the heavy truck ride comfort is clear when vehicles move on the road surface conditions of the ISO level D and ISO level E at a velocity over 27.5 m/s. The weighted RMS acceleration responses of vertical driver' s seat, the pitch and roll angle of the cab are decreased by 24%, 30% and 25%, respectively,when vehicles move on the road surface condition of the ISO level B at a velocity of 20 m/s. The value of the DLC also significantly decreases when vehicles operate under different operation conditions. Particularly, the DLC value of the tractor driver axle is greatly reduced by 27.4% when the vehicle operates under a vehicle fully-loaded condition on the road surface condition of ISO level B at a velocity of 27.5 m/s. 展开更多
关键词 heavy truck dynamic model air suspension fuzzy logic control dynamic load coefficient
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Nonlinear Dynamic Characteristic Analysis of the Shaft System in Water Turbine Generator Set 被引量:11
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作者 MA Zhenyue SONG Zhiqiang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2009年第1期124-131,共8页
A 3D finite element vibration model of water turbine generator set is constructed considering the coupling with hydropower house foundation. The method of determining guide bearing dynamic characteristic coefficients ... A 3D finite element vibration model of water turbine generator set is constructed considering the coupling with hydropower house foundation. The method of determining guide bearing dynamic characteristic coefficients according to the swing of the shaft is proposed, which can be used for studying the self-vibration characteristic and stability of the water turbine generator set. The method fully considers the complex supporting boundary and loading conditions; especially the nonlinear variation of guide bearing dynamic characteristic coefficients and the coupling effect of the whole power-house foundation. The swing and critical rotating speed of an actual generator set shaft system are calculated. The simulated results of the generator set indicate that the coupling vibration model and calculation method presented in this paper are suitable for stability analysis of the water turbine generator set. 展开更多
关键词 water turbine generator set dynamic characteristic coefficients NONLINEARITY coupling vibration critical speed
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Test and numerical investigations on static and dynamic characteristics of extra-wide concrete self-anchored suspension bridge under vehicle loads 被引量:8
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作者 ZHOU Guang-pan LI Ai-qun +1 位作者 LI Jian-hui DUAN Mao-jun 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第10期2382-2395,共14页
The present work is aimed at studying the mechanic properties of the extra-wide concrete self-anchored suspension bridge under static and dynamic vehicle loads. Based on the field test using 12 heavy trucks and finite... The present work is aimed at studying the mechanic properties of the extra-wide concrete self-anchored suspension bridge under static and dynamic vehicle loads. Based on the field test using 12 heavy trucks and finite element simulations, the static deformations of different components, stress increments and distributions of the girder, as well as the vibration characteristics and damping ratio of the Hunan Road Bridge were analyzed, which is the widest self-anchored suspension bridge in China at present. The dynamic responses were calculated using the Newmark-β integration method assisted by the simulation models of bridge and vehicles, the influences on the dynamic impact coefficient(DIC) brought by the vehicle parameters, girder width, eccentricity travel and deck flatness were also researched. The spatial effect of the girder is obvious due to the extra width, which performs as the stress increments distribute unevenly along the transverse direction, and the girder deflections and stress increments of the upper plate change as a "V" and "M" shape respectively under the symmetrical vehicle loads affected by the shear lag effect, cross slope and local effect of the wheels, the maximum of stress increments are located in the junctions with the inner webs. The obvious girder torsional deformation and the apparent unevenness of the hanger forces between the two cable planes under the eccentric vehicle loads, together with the mode shapes such as the girder transverse bending and torsion which appear relatively earlier, all reflect the weakened torsional rigidity of the extra-wide girder. The transverse displacements of towers are more obvious than the longitudinal ones. As for the influences on the DIC, the static effect of the heavier vehicles plays a major role when pass through with a higher speed and the changes of vehicle suspension stiffness generate greater impacts than the suspension damp. The values of DIC in the vehicle-running side during the eccentric travel, affected by the restricts from the static effects of the eccentric moving trucks, are significantly smaller than the vehicle-free side, the increase in the road roughness is the most sensitive one among the above influential factors. The results could provide references for the design, static and dynamic response analysis of the similar extra-wide suspension bridges. 展开更多
关键词 self-anchored suspension bridge extra-wide girder field test simulation vehicle loads increments distribution damping ratio mode shape dynamic impact coefficient
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Simplified Calculation Methods for All-Vertical-Piled Wharf in Offshore Deep Water 被引量:3
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作者 WANG Yuan-zhan HE Lin-lin 《China Ocean Engineering》 SCIE EI CSCD 2017年第2期182-191,共10页
All-vertical-piled wharf is a kind of high-piled wharf, but it is extremely different from the traditional ones in some aspects, such as the structural property, bearing characteristics, failure mechanism, and static ... All-vertical-piled wharf is a kind of high-piled wharf, but it is extremely different from the traditional ones in some aspects, such as the structural property, bearing characteristics, failure mechanism, and static or dynamic calculation methods. In this paper, the finite element method (FEM) and theoretical analysis method are combined to analyze the structural property, bearing behavior and failure mode of the all-vertical-piled wharf in offshore deep water, and to establish simplified calculation methods determining the horizontal static ultimate bearing capacity and the dynamic response for the all-vertical-piled wharf. Firstly, the bearing capability and failure mechanism for all-vertical-piled wharf are studied by use of FEM, and the failure criterion is put forward for all-vertical-piled wharf based on the 'plastic hinge'. According to the failure criterion and P-Y curve method, the simplified calculation method of the horizontal static ultimate bearing capacity for all-vertical-piled wharf is proposed, and it is verified that the simplified method is reasonable by comparison with the FEM. Secondly, the displacement dynamic magnification factor for the all-vertical-piled wharf under wave cyclic loads and ship impact loads is calculated by the FEM and the theory formula based on the single degree of freedom (SDOF) system. The results obtained by the two methods are in good agreement with each other, and the simplified calculation method of the displacement dynamic magnification factor for all-vertical-piled wharf under dynamic loads is proposed. Then the simplified calculation method determining the dynamic response for the all-vertical-piled wharf is proposed in combination with P-Y curve method. That is, the dynamic response of the structure can be obtained through the static calculation results of P-Y curve method multiplied by the displacement dynamic magnification factor. The feasibility of the simplified dynamic response method is verified by comparison with the FEM under different conditions. 展开更多
关键词 all-vertical-piled wharf failure criterion plastic hinge dynamic amplification coefficient simplified calculation methods
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Numerical analysis of dynamic response of vehicle–bridge coupled system on long-span continuous girder bridge 被引量:4
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作者 Lipeng An Dejian Li +1 位作者 Peng Yu Peng Yuan 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2016年第4期186-194,共9页
To systematically study the vehicle-bridge coupled dynamic response and its change rule with different parameters, a vehicle model with seven degrees of freedom was built and the total potential energy of vehicle spac... To systematically study the vehicle-bridge coupled dynamic response and its change rule with different parameters, a vehicle model with seven degrees of freedom was built and the total potential energy of vehicle space vibration system was deduced. Considering the stimulation of road roughness, the dynamic response equation of vehicle-bridge coupled system was established in accordance with the elastic system principle of total potential energy with stationary value and the "set-in-right-position" rule. On the basis of the self-compiled Fortran program and bridge engineering, the dynamic response of long- span continuous girder bridge under vehicle load was studied. This study also included the calculation of vehicle impact coefficient, evaluation of vibration comfort, and analysis of dynamic response parameters. Results show the impact coefficient changes with lane number and is larger than the value calculated by the "general code for design of highway bridges and culverts (China)". The Dieckmann index of bridge vibration is also related to lane number, and the vibration comfort evaluation is good in normal conditions. The relevant conclusions from parametric analyses have practical significance to dynamic design and daily operation of long-span continuous girder bridges in expressways. Safety and comfort are expected to improve significantly with further control of the vibration of vehicle-bridge system. 展开更多
关键词 Long-span continuous bridge Vehicle-bridge coupled system Dynamic responseVehicle impact coefficient Vibration comfort
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TORSIONAL VIBRATIONS OF A RIGID CIRCULAR PLATE ON SATURATED STRATUM OVERLAYING BEDROCK 被引量:3
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作者 CaiYuanqiang WuDazhi XuChangjie 《Acta Mechanica Solida Sinica》 SCIE EI 2005年第2期142-149,共8页
The torsional vibration of a rigid plate resting on saturated stratum overlaying bedrock has been analysed for the first time. The dynamic governing differential equations for saturated poroelastic medium are solved b... The torsional vibration of a rigid plate resting on saturated stratum overlaying bedrock has been analysed for the first time. The dynamic governing differential equations for saturated poroelastic medium are solved by employing the technology of Hankel transform. By taking into account the boundary conditions, the dual integral equations of torsional vibration of a rigid circular plate are established, which are further converted into a Fredholm integral equation of the second kind. Subsequently, the dynamic compliance coefficients of the foundation on saturated stratum, the contact shear stress under the foundation and the angular amplitude of the foundation are evaluated. Numerical results indicate that, when the dimensionless height is bigger than 5, saturated stratum overlaying bedrock can be treated as saturated half space approximately. When the dimensionless frequency is low, the permeability of the soil must be taken into account. Furthermore, when the vibration frequency is a constant, the height of the saturated stratum has a slight effect on the dimensionless contact shear stress under the foundation. 展开更多
关键词 saturated stratum overlaying bedrock torsional vibration rigid circular plate dynamical compliance coefficients contact shear stress
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Evolution of aggregate surface texture due to tyre-polishing 被引量:2
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作者 陈先华 B.STEINAUER 王大为 《Journal of Central South University》 SCIE EI CAS 2011年第1期259-265,共7页
Three kinds of aggregates were polished by genuine pneumatic rubber tyres.The initial states of surface texture and dynamic friction coefficient were measured and their developments in polishing process were monitored... Three kinds of aggregates were polished by genuine pneumatic rubber tyres.The initial states of surface texture and dynamic friction coefficient were measured and their developments in polishing process were monitored.The characterizations of height distribution and power spectral density of aggregate surface texture were estimated.The changes of micro-texture were also investigated based on a fractal filtering method with sound theoretical backgrounds of rubber friction on rough surfaces.Global height reduction and differential removal of mineral component are observed in polishing process.It is concluded that the tyre-polishing action plays the critical roles in the micro-scale texture,and the evolution of friction of aggregate is governed by the micro-texture changes due to the differential removal of mineral component. 展开更多
关键词 tyre polishing dynamic friction coefficient aggregate surface texture MICRO-TEXTURE
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Wind-induced response analysis of conical membrane structures 被引量:2
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作者 陈波 武岳 沈世钊 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2005年第5期481-487,共7页
Conical membrane structures are a typical form of tensile membrane structures. In the past, most studies focused on the static performance, but few on dynamic performance. In this paper, systematic parameter analysis ... Conical membrane structures are a typical form of tensile membrane structures. In the past, most studies focused on the static performance, but few on dynamic performance. In this paper, systematic parameter analysis of wind-induced response of conical membrane structures has been performed with nonlinear random simulation method in a time domain, by considering some parameters, such as span, rise-span ratio, prestress of membrane, and characteristic of the approaching wind flow. Moreover, formulas of the dynamic coefficient and nonlinear adjustment factor are advised, which can be conveniently used in wind-resistant design of conical membrane structures. 展开更多
关键词 conical membrane structures wind-induced response the dynamic coefficient nonlinear adjustment factor
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Nonlinear coupling analysis of coal seam floor during mining based on FLAC^3D 被引量:2
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作者 YAO Duo-xi XU Ji-ying LU Hai-feng 《Journal of Coal Science & Engineering(China)》 2011年第1期22-27,共6页
Based on the hydro-geological conditions of 1028 mining face in Suntuan Coal Mine, mining seepage strain mechanism of seam floor was simulated by a nonlinear coupling method, which applied fluid-solid coupling analysi... Based on the hydro-geological conditions of 1028 mining face in Suntuan Coal Mine, mining seepage strain mechanism of seam floor was simulated by a nonlinear coupling method, which applied fluid-solid coupling analysis module of FLAC^3D. The results indicate that the permeability coefficient of adjoining rock changes a lot due to mining. The maximum value reaches 1 379.9 times to the original value, where it is at immediate roof of the mined-out area. According to the analysis on the seepage field, mining does not destroy water resistance of the floor aquiclude. The mining fissure does not conduct lime-stone aquifer, and it is less likely to form damage. The plastic zone does not exactly correspond to the seepage area, and the scope of the altered seepage area is much larger than the plastic zone. 展开更多
关键词 FLAC^3D fluid-solid coupling water-inrush dynamic permeability coefficient
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Study on dynamic response of multi-degree-of-freedom explosion vessel system under impact load 被引量:1
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作者 Yun-hao Hu Wen-bin Gu +4 位作者 Jian-qing Liu Jing-lin Xu Xin Liu Yang-ming Han Zhen-xiong Wang 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2020年第4期777-786,共10页
In order to study the dynamic response and calculate the axial dynamic coefficient of the monolayer cylindrical explosion vessel,the wall of vessel is simplified as a multi-degree-of-freedom(MDoF) undamped elastic fou... In order to study the dynamic response and calculate the axial dynamic coefficient of the monolayer cylindrical explosion vessel,the wall of vessel is simplified as a multi-degree-of-freedom(MDoF) undamped elastic foundation beam.Decoupling the coupled motion equation and using Duhamel's integrals,the solutions in generalized coordinates of the equations under exponentially decaying loads,square wave loads and triangular wave loads are calculated.These solutions are consistent in form with the solutions of single-degree-of-freedom(SDoF) undamped forced vibration simplified model.Based on the model,equivalent MDoF design method(also called MDoF dynamic coefficient method) of cylindrical explosion vessel is proposed.The traditional method can only predict the dynamic coefficient of torus portion around the explosion center,but this method can predict that of the vessel wall at any axial n dividing point position.It is verified that the prediction accuracy of this model is greatly improved compared with the SDoF model by comparing the results of this model with SDoF model and numerical simulation in different working conditions.However,the prediction accuracy decreases as the scaled distance decreases and approaches the end of the vessel,which is related to the accuracy of the empirical formula of the implosion load,the simplification of the explosion load direction,the boundary conditions,and the loading time difference. 展开更多
关键词 Explosion vessel Dynamic response Vibration analysis Dynamic coefficient Load feature
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Energy-based dynamic parameter identification for Pasternak foundation model 被引量:1
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作者 Wang-Xi Zhang Wei-Lei Lv +3 位作者 Jin-Yi Zhang Xiong Wang Hyeon-Jong Hwang Wei-Jian Yi 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2021年第3期631-643,共13页
Parameter identification of Pasternak foundation models(PFM)is never satisfactory,which discourages the application and popularization of PFM.In the present study,an energy-based model to predict the dynamic foundatio... Parameter identification of Pasternak foundation models(PFM)is never satisfactory,which discourages the application and popularization of PFM.In the present study,an energy-based model to predict the dynamic foundation coefficients was proposed using the vibration kinetic energy and potential energy of a Pasternak foundation-rigid plate system.On the basis of the Pasternak foundation,the relationship among the natural frequency,dynamic foundation coefficients,rigid plate configuration,and vibrating soil equivalent mass per unit area was considered.To obtain the natural frequencies of the Pasternak foundation-rigid plate system,dynamic tests were performed.Using two or more dynamic test results of various rigid plates on a foundation,a set of equations of dynamic foundation coefficients was set up to directly identify the foundation coefficients and equivalent mass per unit area of vibrating soil.The feasibility of the proposed method was verified by comparing it with the outdoor and indoor test results and finite element analysis results.When the proposed method is used to obtain the dynamic parameters,PFM can be generalized and applied more widely in engineering practice. 展开更多
关键词 Pasternak foundation dynamic tests vibrating soil mass dynamic foundation coefficients dynamic characteristics
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Effect of surface roughness on the surface lubrication performance of galvanized steel sheets with a self-lubricated coating 被引量:1
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作者 YANG Jiayun DONG Hang DAI Yigang 《Baosteel Technical Research》 CAS 2017年第3期43-47,共5页
Four kinds of galvanized steel sheets having different surface roughness values were used to prepare the steel sheets with a self-lubricated coating. The effects of surface roughness on the surface lubrication perform... Four kinds of galvanized steel sheets having different surface roughness values were used to prepare the steel sheets with a self-lubricated coating. The effects of surface roughness on the surface lubrication performance of the steel sheets were examined using a friction coefficient tester. Results revealed large dynamic friction coefficients for the galvanized steel sheets, which increased remarkably with surface roughness. Once the self-lubricated coating was applied, significant drops in the dynamic friction coefficients were measured. After the first stage of the friction test,the coefficients were almost unchanged, which reflected a weak dependence on the surface roughness of the self-lubricated steel sheets. However, the dynamic friction coefficients gradually increased as the test progressed, where these increase clearly correlated with the surface roughness of the self-lubricated steel sheets. 展开更多
关键词 surface roughness self-lubricated coating galvanized steel sheet dynamic friction coefficient
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Laser Surface Textured PTFE Inhibitation for Stick-Slip Phenomenon Under Boundary Lubrication 被引量:1
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作者 LEI Ming WANG Xiaolei HUANG Wei 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2021年第S01期93-101,共9页
When the machine tool is in the start-and stop-stages,the stick-slip phenomenon will be observed and highprecision positioning,machining accuracy and fretting feed will not be guaranteed. The most critical reason is t... When the machine tool is in the start-and stop-stages,the stick-slip phenomenon will be observed and highprecision positioning,machining accuracy and fretting feed will not be guaranteed. The most critical reason is that there is the difference between the dynamic and the static friction coefficients. Textures with different area ratios are fabricated on the surfaces of the upper PTFE-based composite and the friction tests are carried out on a reciprocating tribotester under the boundary lubrication and flat-on-flat contact conditions. The results show that there exists an optimal textured area ratio of 19.6% that can minimize the difference between the dynamic and the static friction coefficients. 展开更多
关键词 machine tool laser surface texturing stick-slip phenomenon difference between the dynamic and static friction coefficients
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