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Discrete element modelling of railway ballast performance considering particle shape and rolling resistance 被引量:6
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作者 Yunlong Guo Chunfa Zhao +3 位作者 Valeri Markine Can Shi Guoqing Jing Wanming Zhai 《Railway Engineering Science》 2020年第4期382-407,共26页
To simulate ballast performance accurately and efficiently,the input in discrete element models should be carefully selected,including the contact model and applied particle shape.To study the effects of the contact m... To simulate ballast performance accurately and efficiently,the input in discrete element models should be carefully selected,including the contact model and applied particle shape.To study the effects of the contact model and applied particle shape on the ballast performance(shear strength and deformation),the direct shear test(DST)model and the large-scale process simulation test(LPST)model were developed on the basis of two types of contact models,namely the rolling resistance linear(RRL)model and the linear contact(LC)model.Particle shapes are differentiated by clumps.A clump is a sphere assembly for one ballast particle.The results show that compared with the typical LC model,the RRL method is more efficient and realistic to predict shear strength results of ballast assemblies in DSTs.In addition,the RRL contact model can also provide accurate vertical and lateral ballast deformation under the cyclic loading in LPSTs. 展开更多
关键词 Discrete element method Ballast performance Boundary condition rolling resistance Direct shear test Lateral displacement
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Computation of rolling resistance caused by rubber hysteresis of truck radial tire 被引量:1
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作者 MA Gai-ling XU Hong CUI Wen-yong 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2007年第5期778-785,共8页
Applying the results of stress and strain calculated by 3D finite element model of truck radial tire 11.00R20, a MATLAB program used to compute rolling resistance of the tire caused by hysteresis rolling resistance (H... Applying the results of stress and strain calculated by 3D finite element model of truck radial tire 11.00R20, a MATLAB program used to compute rolling resistance of the tire caused by hysteresis rolling resistance (HRR) is worked out. The HRR distribution on different part of tire section, and the effects of speed, load, internal pressure and the width of the rim on HRR are analyzed. The analysis results showed that energy loss produced by tread rubber contributes the most part to HRR of the whole tire, and that to decrease the HRR, the hysteresis factor of the tread rubber should be reduced, and the distribution of the stress and strain on the section be optimized. 展开更多
关键词 Truck radial tire Hysteresis rolling resistance (HRR) Finite element analysis (FEA) Hysteresis factor Tire structuredesign
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Influence of Road Wetness on Tire-Pavement Rolling Resistance
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作者 Jerzy Ejsmont Leif Sjogren +1 位作者 Beata Swieczko-Zurek Grzegorz Ronowski 《Journal of Civil Engineering and Architecture》 2015年第11期1302-1310,共9页
Rolling resistance of tires is one of the most important factors influencing energy consumption of road vehicles, especially on rural roads. For practical reasons, most of rolling resistance measurements are usually p... Rolling resistance of tires is one of the most important factors influencing energy consumption of road vehicles, especially on rural roads. For practical reasons, most of rolling resistance measurements are usually performed for dry road conditions. Based on the fact that roads are wet during a considerable time over the year and as part of the projects MIR/AM, ROLRES and ROSANNE, the TUG (Technical University of Gdafisk) in Poland and VTI (Swedish National Road and Transport Research Institute) in Sweden carried out trailer rolling resistance measurements on wet road surfaces to investigate water film influence on rolling resistance on different pavements. A specially-designed trailer to measure rolling resistance has been used. The test sections were both rural roads and an abandoned airfield equipped with water film sensors mounted in the pavement. Results indicate strong influence of test speed and water film depth, as well as influence of surface texture. The increase of rolling resistance on wet surfaces is caused by both hydrodynamic phenomena and cooling effect of water that decreases tire temperature thus increasing rolling resistance. 展开更多
关键词 Tires rolling resistance road wetness water film
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High-precision Thickness Setting Models for Titanium Alloy Plate Cold Rolling without Tension 被引量:2
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作者 WANG Xiaochen YANG Quan +2 位作者 HE Fei SUN Youzhao XIAO Huifang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2015年第2期422-429,共8页
Due to its highly favorable physical and chemical properties,titanium and titanium alloy are widely used in a variety of industries.Because of the low output of a single batch,plate cold rolling without tension is the... Due to its highly favorable physical and chemical properties,titanium and titanium alloy are widely used in a variety of industries.Because of the low output of a single batch,plate cold rolling without tension is the most common rolling production method for titanium alloy.This method is lack of on-line thickness closed-loop control,with carefully thickness setting models for precision.A set of high-precision thickness setting models are proposed to suit the production method.Because of frequent variations in rolling specification,a model structural for the combination of analytical models and statistical models is adopted to replace the traditional self-learning method.The deformation resistance and friction factor,the primary factors which affect model precision,are considered as the objectives of statistical modeling.Firstly,the coefficient fitting of deformation resistance analytical model based on over-determined equations set is adopted.Additionally,a support vector machine(SVM)is applied to the modeling of the deformation resistance and friction factor.The setting models are applied to a 1450 plate-coiling mill for titanium alloy plate rolling,and then thickness precision is found consistently to be within 3%,exceeding the precision of traditional setting models with a self-learning method based on a large number of stable rolling data.Excellent application performance is obtained.The proposed research provides a set of high-precision thickness setting models which are well adapted to the characteristics of titanium alloy plate cold rolling without tension. 展开更多
关键词 titanium alloy cold rolling deformation resistance friction factor support vector machine
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Effect of Rolling Process on Comprehensive Properties of Corrosion Resistant Steel for Bottom Plate of Cargo Oil Tanks 被引量:1
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作者 于驰 王平 +1 位作者 GAO Xiuhua DU Linxiu 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2016年第2期379-386,共8页
A new kind of corrosion resistant steelfor cargo oiltanks(COT)was developed.The influences of finalrolling temperature,cooling rate,and finalcooling temperature on microstructure were investigated.The proper rolling... A new kind of corrosion resistant steelfor cargo oiltanks(COT)was developed.The influences of finalrolling temperature,cooling rate,and finalcooling temperature on microstructure were investigated.The proper rolling process parameters were obtained through multi-pass thermalsimulation test.The finalrolling temperature is about 820 ℃,the finalcooling temperature is about 600 ℃,and the cooling rate should be controlled between 10 ℃/s and 20 ℃/s.Based on the above analysis of the results,three groups of rolling samples by thermo mechanicalcontrolprocess are prepared.The tensile strength,yield strength,and toughness of the corrosion resistant steelare measured,which meet the requirements of DH36 steel,it can instruct the actualrolling production.The corrosion behaviour is also researched by weight loss and electrochemicalimpedance spectroscopic method,and it is found that the steelhas good corrosion resistance performance,the best one is No.3 steel,the corrosion rate of which is about 1/4 of the accepted criterion. 展开更多
关键词 rolling process corrosion resistant steel comprehensive properties corrosion rate
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Influence of the rolling-resistance-based shape of coarse particles on the shear responses of granular mixtures 被引量:6
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作者 Yangui Zhu Zhihong Nie Jian Gong 《Particuology》 SCIE EI CAS CSCD 2020年第5期67-82,共16页
Shear responses of dense granular mixtures of spherical coarse particles with the rolling resistance and spherical fine particles are studied via triaxial compression tests using the discrete element method.The macros... Shear responses of dense granular mixtures of spherical coarse particles with the rolling resistance and spherical fine particles are studied via triaxial compression tests using the discrete element method.The macroscale responses(shear strength and dilatancy)are examined.Comparing the results with those in the literature indicates that granular mixtures with a rolling resistance coefficient of 0.5 have similar macroscale responses to those of gravel-shaped coarse particle mixtures.We quantify the microscale responses including the percentage contributions of contact types,partial coordination number,average particle rotation,average degree of interlocking,and local structural properties,A detailed analysis of the force-fabric anisotropy reveals the mechanisms of the variations in the shear strength with the rolling resistance coefficient and the fines content.The mechanism of the variation in the shear strength with the fines content for granular mixtures with a rolling resistance coefficient of 0.5 is different from that for gravel-shaped coarse particle mixtures.Finally,we find that a rolling resistance linear model weakens the linear relationship between the stress ratio and the fabric anisotropy of strong and non-sliding contacts when the fines content is 30% and 40%. 展开更多
关键词 Granular mixture rolling resistance Particle shape Fines content Macroscale and microscale responses ANISOTROPY
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Applicability of discrete element method with spherical and clumped particles for constitutive study of granular materials 被引量:3
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作者 Tongming Qu Min Wang Yuntian Feng 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2022年第1期240-251,共12页
Discrete element method(DEM)has been intensively used to study the constitutive behaviour of granular materials.However,to what extent a real granular material can be reproduced by virtual DEM simulations remains uncl... Discrete element method(DEM)has been intensively used to study the constitutive behaviour of granular materials.However,to what extent a real granular material can be reproduced by virtual DEM simulations remains unclear.This study attempts to answer this question by comparing DEM simulations with typical features of experimental granular materials.Three groups of models with spherical and clumped particles are investigated from four perspectives:(i)deviatoric stress and volumetric behaviour;(ii)critical state behaviour;(iii)stress-dilatancy relationship;and(iv)the evolution of principal stress ratio against axial strain.The results demonstrate that DEM with spherical or clumped particles is capable of qualitatively describing macroscopic deviatoric stress responses,volumetric behaviour,and critical state behaviour observed in experiments for granular materials.On the other hand,some qualitative deviations between experiments and the investigated DEM simulations are also observed,in terms of the stress-dilatancy behaviour and principal stress ratio against axial strain,which are proven to be critical for constitutive modelling.The results demonstrate that DEM with spherical or clumped particles may not necessarily fully capture experimental features of granular materials even from a qualitative perspective.It is thus encouraged to thoroughly validate DEM with experiments when developing constitutive models based on DEM observations. 展开更多
关键词 Discrete element method(DEM) Granular materials Constitutive behaviour Deviatoric hardening model rolling resistance model Irregular particles
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Modeling deformation resistance for hot rolling based on generalized additive model 被引量:1
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作者 Wei-gang Li Chao Liu +2 位作者 Yun-tao Zhao Bin Liu Xiang-hua Liu 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2017年第12期1177-1183,共7页
A model of deformation resistance during hot strip rolling was established based on generalized additive model.Firstly,a data modeling method based on generalized additive model was given.It included the selection of ... A model of deformation resistance during hot strip rolling was established based on generalized additive model.Firstly,a data modeling method based on generalized additive model was given.It included the selection of dependent variable and independent variables of the model,the link function of dependent variable and smoothing functional form of each independent variable,estimating process of the link function and smooth functions,and the last model modification.Then,the practical modeling test was carried out based on a large amount of hot rolling process data.An integrated variable was proposed to reflect the effects of different chemical compositions such as carbon,silicon,manganese,nickel,chromium,niobium,etc.The integrated chemical composition,strain,strain rate and rolling temperature were selected as independent variables and the cubic spline as the smooth function for them.The modeling process of deformation resistance was realized by SAS software,and the influence curves of the independent variables on deformation resistance were obtained by local scoring algorithm.Some interesting phenomena were found,for example,there is a critical value of strain rate,and the deformation resistance increases before this value and then decreases.The results confirm that the new model has higher prediction accuracy than traditional ones and is suitable for carbon steel,microalloyed steel,alloyed steel and other steel grades. 展开更多
关键词 Hot rolling Deformation resistance Mathematical model Generalized additive model
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STUDY ON STYRENE-BUTADIENE BLOCK COPOLYMER FOR THE MODIFICATI0N OF TIRE TREAD
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作者 王岩 陈伟洁 +3 位作者 穆瑞凤 王用威 余丰年 刘青 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 1996年第1期34-40,共7页
This paper mainly deals with the design and synthesis of a novel styrene-butadieneblock copolymer. When this copolymer is used in the tread portion of tyres, it can improvewet skid resistance and reduce rolling resist... This paper mainly deals with the design and synthesis of a novel styrene-butadieneblock copolymer. When this copolymer is used in the tread portion of tyres, it can improvewet skid resistance and reduce rolling resistance without sacrificing its general physical-mechanical properties. The visco-elastic curve of tire tread using the novel copolymer asits rubber portion was showed. Reactivity ratios for two monomers in the polymerizingsystem were calculated. The diagrams of differelitial, integral and finite difference calculithroughout the whole molecular chain were presented. The influence of the micro- andmacro-structure of the copolymer chain on wet skid resistance and rolling resistance wasdiscussed 展开更多
关键词 Anionic solution polymerization Diblock copolymer of styrene and butadiene rolling resistance Wet skid resistance Visco-elastic property
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Improving Winter Traction and Fuel Economy of Car Tires Using Naphthenic Tire Oils
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作者 Mika Lahtinen Kamyar Alavi +2 位作者 Patrik Salomonsson Markus Hoffmann Herbert Fruhmann 《Journal of Traffic and Transportation Engineering》 2018年第1期35-41,共7页
Naphthenic tire oils were used in winter tire tread compounding. Properties of compounds were compared with similar compounds made of other safe tire oils. Retreaded passenger car winter tires were prepared using the ... Naphthenic tire oils were used in winter tire tread compounding. Properties of compounds were compared with similar compounds made of other safe tire oils. Retreaded passenger car winter tires were prepared using the compounds. Traction and rolling resistance of the tires were determined in different weather conditions.It was shown that naphthenie oils may lead to improvement of winter traction and rolling resistance without compromising other tire properties. 展开更多
关键词 Naphthenic oil winter tire snow traction ice traction dynamic properties rolling resistance fuel economy.
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Influence of Al-Si additions on mechanical properties and corrosion resistance of Mg-8Li dual-phase alloys 被引量:4
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作者 Zi-long Zhao Xue-gang Xing +2 位作者 Yi Luo Yi-de Wang Wei Liang 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2017年第4期426-429,共4页
Sheet samples of Mg-8Li,Mg-8Li-3Al,Mg-8Li-3AlSi and Mg-8Li-5AlSi alloys were obtained by hot rolling.Optical microscope,microhardness tester,nanoindentor,X-ray diffractometer and electrochemical analyzer were adopted ... Sheet samples of Mg-8Li,Mg-8Li-3Al,Mg-8Li-3AlSi and Mg-8Li-5AlSi alloys were obtained by hot rolling.Optical microscope,microhardness tester,nanoindentor,X-ray diffractometer and electrochemical analyzer were adopted to investigate the microstructures,micro-mechanical properties and corrosion resistance.Roller was preheated to 150°C before rolling process,and rolling reduction designed was about20% per pass with a total rolling reduction of 84%.The rolled plates were annealed at 200°C for 120 min.The tensile tests were performed at room temperature.Experimental results showed that both the strength and corrosion resistance of theα+βdual-phase of Mg-Li alloy were significantly improved with adding Al-Si elements.The strength enhancement was attributed to the solid solution of Al into theα-Mg matrix and into theβ-Li matrix as well as to the precipitation strengthening of Mg2 Si particles.Besides,the dendrite grains ofα-Mg transformed to equiaxed ones with addition of Al into alloy Mg-Li. 展开更多
关键词 Mg-8Li dual-phase alloy Mechanical property Corrosion resistance Hardness rolling
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Simulation of triaxial response of granular materials by modified DEM 被引量:3
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作者 WANG XiaoLiang LI JiaChun 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2014年第12期2297-2308,共12页
A modified discrete element method(DEM)with rolling effect taken into consideration is developed to examine macroscopic behavior of granular materials in this study.Dimensional analysis is firstly performed to establi... A modified discrete element method(DEM)with rolling effect taken into consideration is developed to examine macroscopic behavior of granular materials in this study.Dimensional analysis is firstly performed to establish the relationship between macroscopic mechanical behavior,mesoscale contact parameters at particle level and external loading rate.It is found that only four dimensionless parameters may govern the macroscopic mechanical behavior in bulk.The numerical triaxial apparatus was used to study their influence on the mechanical behavior of granular materials.The parametric study indicates that Poisson’s ratio only varies with stiffness ratio,while Young’s modulus is proportional to contact modulus and grows with stiffness ratio,both of which agree with the micromechanical model.The peak friction angle is dependent on both inter-particle friction angle and rolling resistance.The dilatancy angle relies on inter-particle friction angle if rolling stiffness coefficient is sufficiently large.Finally,we have recommended a calibration procedure for cohesionless soil,which was at once applied to the simulation of Chende sand using a series of triaxial compression tests.The responses of DEM model are shown in quantitative agreement with experiments.In addition,stress-strain response of triaxial extension was also obtained by numerical triaxial extension tests. 展开更多
关键词 granular materials rolling resistance DEM CALIBRATION YADE
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