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Investigations of the effects of particle morphology on granular material behaviors using a multi-sphere approach

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第6期12卷 1301-1312页

作者： Shiva Prashanth Kumar Kodicherla Guobin Gong Lei Fan Stephen Wilkinson Charles K.S.Moy Department of Civil Engineering Xi’an JiaotongeLiverpool University(XJTLU)Suzhou215123China Department of Civil Engineering and Industrial Design University of LiverpoolLiverpoolUK Department of Civil Engineering University of WollongongDubaiUAE

This article studies the influences of particle morphology on the behaviors of granular materials at both macroscopic and microscopic levels based on the discrete element method(DEM).A set of numerical tests under drained triaxial compression was performed by controlling two morphological descriptors,i.***.ratio of the smallest to the largest pebble diameter,x,and the maximum pebbleepebble intersection angle,b.These descriptors are vital in generating particle geometry and surface textures.It was found that the stress responses of all assemblies exhibited similar behavior and showed post-peak strainsoftening.The normalized stress ratio and volumetric strains flatten off and tended to reach a steady value after an axial strain of 40%.While the friction angles at peak state varied with different morphological descriptors,the friction angles at critical state showed no significant variation.Moreover,evolution of the average coordination numbers showed a dramatic exponential decay until an axial strain of about 15%after which it stabilized and was unaffected by further increase of axial strain.In addition,stress ratio q/p and strong fabric parameter fs d=fs m were found to follow an approximately linear relationship for each assembly.These findings emphasized the significance of the influences of particle morphology on the macroscopic and microscopic responses of granular materials.

关键词： Discrete element method(DEM) particle morphology Granular materials Triaxial compression Fabric

Surface reconstruction with spherical harmonics and its application for single particle crushing simulations

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第1期14卷 232-239页

作者： Deheng Wei Budi Zhao Yixiang Gan School of Civil Engineering The University of SydneySydneyNSW2006Australia School of Civil Engineering University College DublinDublinIreland

particle morphology has great influence on mechanical behaviour and hydro/thermal/electrical conductivities of granular materials.Surface reconstruction and mesh generation are critical to consider realistic particle shapes in various computational simulations.This study adopts the combined finitediscrete element method(FDEM)to investigate single particle crushing behaviour.particle shapes were reconstructed with spherical harmonic(SH)in both spherical and Cartesian coordinate systems.Furthermore,the reconstructed surface mesh qualities in two coordinate systems are investigated and compared.Although the efficiency of the two SH systems in reconstructing star-like shapes is nearly identical,SH in Cartesian coordinate system can reconstruct non-star-like shapes with the help of surface parameterisation.Meanwhile,a higher triangular mesh quality is generated with spherical coordinate.In single particle crushing tests,the low mesh quality produces more fluctuations on load-displacement curves.The particles with more surficial mesh elements tend to have a lower contact stiffness due to more contact stress concentrations induced by complexity of morphology features and more volumetric tetrahedral elements.The fracture patterns are also influenced by mesh quality and density,e.g.a particle with fewer mesh elements has a simpler fragmentation pattern.This study serves as an essential step towards modelling particle breakage using FDEM with surface mesh directly from SH reconstruction.

关键词： Numerical modelling particle morphology particle crushing/crushability particle-scale behaviour Sands

Monitoring the morphology evolution of LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)during high-temperature solid state synthesis via in situ SEM

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Journal of Energy Chemistry 2022年第3期31卷 9-15,I0001页

作者： Liang Tang Xiaopeng Cheng Rui Wu Tianci Cao Junxia Lu Yuefei Zhang Ze Zhang Institute of Microstructure and Property of Advanced Materials Faculty of Materials and ManufacturingBeijing University of TechnologyBeijing 100124China Institute of Laser Engineering Faculty of Materials and ManufacturingBeijing University of TechnologyBeijing 100124China School of Materials Science and Engineering Zhejiang UniversityHangzhou 310058ZhejiangChina

The particle morphology determined by the sintering process is the director factor affecting the electrochemical performance of Ni-rich NMC cathode materials.To prepare the ideal NMC particles,it is of great significance to understand the morphological changes during sintering process.In this work,the morphology evolution of LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NMC811)synthesis at temperature ranging from 300–1080℃were observed by in situ SEM.The uniform mixture of spherical Ni_(0.8)Mn_(0.1)Co_(0.1)(OH)_(2)precursor and lithium sources(LiOH)was employed by high temperature solid-state process inside the SEM,which enables us to observe morphology changes in real time.The results show that synthetic reaction of LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)usually includes three processes:the raw materials’dehydration,oxidation,and combination,accompanied by a significant reduction in particle size,which is important reference to control the synthesis temperature.As heating temperature rise,the morphology of mixture also changed from flake to brick-shaped.However,Ni nanoparticle formation is apparent at higher temperature~1000℃,suggesting a structural transformation from a layered to a rock-salt-like structure.Combining the in-situ observed changes in size and morphology,and with the premise of ensuring the morphology change from flakes to bricks,reducing the sintering temperature as much as possible to prevent excessive reduction in particle size and layered to a rock-salt structure transformation is recommended for prepare ideal NMC particles.

关键词： Lithium-ion battery NMC cathode In situ SEM High temperature imaging particle morphology

Characterization of ultrafine particles from hardfacing coated brake rotors

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Friction 2023年第1期11卷 125-140页

作者： Yezhe LYU Ankur SINHA Ulf OLOFSSON Stefano GIALANELLA Jens WAHLSTRÖM Department of Mechanical Engineering Sciences Lund UniversityLund SE-22100Sweden Department of Machine Design KTH Royal Institute of TechnologyStockholm SE-10044Sweden Department of Industrial Engineering University of TrentoTrento 38123Italy

Automotive brake rotors are commonly made from gray cast iron(GCI).During usage,brake rotors are gradually worn off and periodically replaced.Currently,replaced brake rotors are mostly remelted to produce brand-new cast iron products,resulting in a relatively high energy consumption and carbon footprint into the environment.In addition,automotive brakes emit airborne particles.Some of the emitted particles are categorized as ultrafine,which are sized below 100 nm,leading to a series of health and environmental impacts.In this study,two surface treatment techniques are applied,ie.,high-velocity oxygen fuel(HVOF)and laser cladding(LC),to overlay wear-resistant coatings on conventional GCI brake rotors in order to refurbish the replaced GCI brake rotor and to avoid the remelting procedure.The two coating materials are evaluated in terms of their coefficient of friction(CoF),wear,and ultrafine particle emissions,by comparing them with a typical GCI brake rotor.The results show that the CoF of the HVOF disc is higher than those of the GCI and LC discs.Meanwhile,HVOF disc has the lowest wear rate but results in the highest wear rate on the mating brake pad material.The LC disc yields a similar wear rate as the GCI disc.The ultrafine particles from the GCI and LC discs appeared primarily in round,chunky,and flake shapes.The HVOF disc emits unique needle-shaped particles.In the ultrafine particle range,the GCI and HVOF discs generate particles that are primarily below 100 nm in the running-in period and 200 nm in the steady state.Meanwhile,the LC disc emitted particles that are primarily~200 nm in the entire test run.

关键词： ultrafine particle high-velocity oxygen fuel laser cladding brake particle size distribution particle morphology

Direct measurement and theoretical prediction model of interparticle adhesion force between irregular planetary regolith particles

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International Journal of Mining Science and Technology 2023年第11期33卷 1425-1436页

作者： Heping Xie Qi Wu Yifei Liu Yachen Xie Mingzhong Gao Cunbao Li State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering Shenzhen UniversityShenzhen 518060China Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization Shenzhen UniversityShenzhen 518060China Department of Civil&Mineral Engineering University of TorontoToronto M5S 1A1Canada

Interparticle adhesion force has a controlling effect on the physical and mechanical properties of planetary regolith and rocks.The current research on the adhesion force of planetary regolith and rock particles has been primarily based on the assumption of smooth spherical particles to calculate the intergranular adhesion force;this approach lacks consideration for the adhesion force between irregular shaped particles.In our study,an innovative approach was established to directly measure the adhesion force between the arbitrary irregular shaped particles;the probe was modified using simulated lunar soil particles that were a typical representation of planetary regolith.The experimental results showed that for irregular shaped mineral particles,the particle size and mineral composition had no significant influence on the interparticle adhesion force;however,the complex morphology of the contact surface predominantly controlled the adhesion force.As the contact surface roughness increased,the adhesion force gradually decreased,and the rate of decrease gradually slowed;these results were consistent with the change trend predicted via the theoretical models of quantum electrodynamics.Moreover,a theoretical model to predict the adhesion force between the irregular shaped particles was constructed based on Rabinovich’s theory,and the prediction results were correlated with the experimental measurements.

关键词： Planetary regolith Adhesion force particle morphology Prediction model

Capability of discrete element method to investigate the macro-micro mechanical behaviours of granular soils considering different stress conditions and morphological gene mutation

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第10期15卷 2731-2745页

作者： Wei Xiong Jianfeng Wang Zhuang Cheng Department of Architecture and Civil Engineering City University of Hong KongHong KongChina Shenzhen Research Institute of City University of Hong Kong ShenzhenChina School of Civil Engineering and Architecture Wuhan University of TechnologyWuhanChina Sanya Science and Education Innovation Park Wuhan University of TechnologySanyaChina

Discrete element method(DEM)has been widely utilised to model the mechanical behaviours of granular materials.However,with simplified particle morphology or rheology-based rolling resistance models,DEM failed to describe some responses,such as the particle kinematics at the grain-scale and the principal stress ratio against axial strain at the macro-scale.This paper adopts a computed tomography(CT)-based DEM technique,including particle morphology data acquisition from micro-CT(mCT),spherical harmonic-based principal component analysis(SH-PCA)-based particle morphology reconstruction and DEM simulations,to investigate the capability of DEM with realistic particle morphology for modelling granular soils’micro-macro mechanical responses with a consideration of the initial packing state,the morphological gene mutation degree,and the confining stress condition.It is found that DEM with realistic particle morphology can reasonably reproduce granular materials’micro-macro mechanical behaviours,including the deviatoric stressevolumetric straineaxial strain response,critical state behaviour,particle kinematics,and shear band evolution.Meanwhile,the role of multiscale particle morphology in granular soils depends on the initial packing state and the confining stress condition.For the same granular soils,rougher particle surfaces with a denser initial packing state and a higher confining stress condition result in a higher degree of shear strain localisation.

关键词： Discrete element method(DEM) Spherical harmonic-based principal component analysis(SH-PCA) particle morphology Granular so

Combustion Properties of Chip-shaped Anthracite particle morphology in Circulating Fluidized Bed Boiler

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Combustion Properties of Chip-shaped Anthracite Particle Mor...

Effect of valsartan particle size and morphology on dissolution of valsartan and amlodipine tablet

中国颗粒学会第六届学术年会暨海峡两岸颗粒技术研讨会

作者： Liu Baiqian Zhang Xiaohui Wang Ligang (School of Mechanical Engineering University of Science & Technology Beijing Beijing 100083 China) School of Mechanical Engineering University of Science ＆Technology BeijingBeijing 100083China

＜正＞In this paper,according to the results of an operation test carried out in a 50MW circulating fluidized bed（CFB） boiler,the measured combustion properties of anthracite with chip-shaped morphology particles are provided.Unlike other coals combustion in CFB boiler,this kind of coal,Krumbein sphericity of bed material equal to 0.35-0.55,in combustion process could cause fluctuations in the furnace temperature,superficial gas velocity and furnace pressure.The granularities of bed material and cold ash draining are also varied with the bed temperature.Theses effects caused by the chip-shaped morphology particle are discussed.The promising results obtained here would be expected to provide the basis for the design of the large-scale CFB boiler.

关键词： particle morphology anthracite circulating fluidized bed combustion

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Effect of valsartan particle size and morphology on dissolut...

5-Nitro-1,2,4-triazole-3-one:A Review of Recent Advances

2018年第十二届中国药物制剂大会

作者：程开生臧洪梅 LI Zhiyun LI Chunni CHEN Dengjun Hefei cosource pharmaceuticals inc Anhui Medical University

OBJECTIVE The reason for the significant difference in the dissolution of valsartan and amlodipine tablet prepared from two batches of valsartan was studied. METHODS The dissolution of valsartan and amlodipine tablet was determined by using PBS4.5 as the dissolution medium. The valsartan crystal form was determined by powder X-ray diffraction. The valsartan particle size was determined by laser particle size method. particle morphology of powder valsartan, premixer and valsartan suspension for particle size determination were observed by optical microscope with reflection. The difference between two batches was compared. Sieve mixing, wet granulator shear mixing and pulverization and mixing were employed to premixing process. RESULTS The difference of amlodipine dissolution percentage in 30 min is 15%～25%. The crystal form of two batches valsartan were amorphous, and the particle sizes D50（μm）measured in 1% SDS（77.09 vs. 85.23） and liquid paraffin（9.942 vs. 7.331） were similar. There was no difference between the sieve mixing and the shear mixing process, and the premixing process parameters had no trend effect on the dissolution of valsartan and amlodipine tablet. There were significant differences in the particle morphology of the two batches of valsartan in the powder and the premix. The batch 1 and batch 2 valsartan were dendritic shape and pellet shape, respectively, while the shape in 1% SDS and liquid paraffin was not significantly different. CONCLUSION The pellet shape valsartan results in fast tablet dissolution;but the dendritic shape valsartan is opposite. Control of the valsartan powder particle morphology should be added.

关键词： valsartan particle size particle morphology

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含能材料 2019年第4期27卷 326-347,I0007页

作者： Sabrina Hanafi Djalal Trache Slimane Abdous Zineddine Bensalem Abderrahmane Mezroua UER Procedes Energetiques Ecole Militaire Polytechnique

The 3?Nitro?1,2,4?triazole?5?one(NTO)is a high energy density materials of keen interest for both commercial and scientific worlds owing to its reduced sensitivity,better thermal stability and high performances. It plays a significant role to replace the current energetic ingredients. In this review,we summarize various strategies involved in the synthesis of NTO as well as the existing approaches to tailor its particle morphology and sizes. The most prominent properties of NTO,such as insensitivity and performance,which are usually required to produce efficient formulations,have been concisely discussed. In addition,this overview reports on some newer forms of NTO including derivatives and co?crystals available in the literature,which can enhance the NTO features and extend its applications. The advantages and shortcomings of various NTO forms for specific and potential use are also highlighted together with the attempts made to overcome these issues. Therefore,efforts will certainly continue to improve characteristics and performances of NTO either by chemical modification or by co?crystallization in order to produce promising formulations for widespread applications in the near future.

关键词： Triazolone 3-nitro-1,2,4-triazole-5-one(NTO) synthesis properties particle morphology derivatives co-crystals applications