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An MPI parallel DEM-IMB-LBM framework for simulating fluid-solid interaction problems 被引量:2
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作者 Ming Xia Liuhong Deng +3 位作者 Fengqiang Gong Tongming Qu Y.T.Feng Jin Yu 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第6期2219-2231,共13页
The high-resolution DEM-IMB-LBM model can accurately describe pore-scale fluid-solid interactions,but its potential for use in geotechnical engineering analysis has not been fully unleashed due to its prohibitive comp... The high-resolution DEM-IMB-LBM model can accurately describe pore-scale fluid-solid interactions,but its potential for use in geotechnical engineering analysis has not been fully unleashed due to its prohibitive computational costs.To overcome this limitation,a message passing interface(MPI)parallel DEM-IMB-LBM framework is proposed aimed at enhancing computation efficiency.This framework utilises a static domain decomposition scheme,with the entire computation domain being decomposed into multiple subdomains according to predefined processors.A detailed parallel strategy is employed for both contact detection and hydrodynamic force calculation.In particular,a particle ID re-numbering scheme is proposed to handle particle transitions across sub-domain interfaces.Two benchmarks are conducted to validate the accuracy and overall performance of the proposed framework.Subsequently,the framework is applied to simulate scenarios involving multi-particle sedimentation and submarine landslides.The numerical examples effectively demonstrate the robustness and applicability of the MPI parallel DEM-IMB-LBM framework. 展开更多
关键词 Discrete element method(DEM) Lattice Boltzmann method(LBM) Immersed moving boundary(IMB) Multi-cores parallelization Message passing interface(MPI) CPU Submarine landslides
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A refined deviatoric hardening plastic model for sand
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作者 Min Wang Tongming Qu +2 位作者 Yuntian Feng Teng Liang Liangtong Zhan 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第7期2813-2821,共9页
The classical deviatoric hardening models are capable of characterizing the mechanical response of granular materials for a broad range of degrees of compaction.This work finds that it has limitations in accurately pr... The classical deviatoric hardening models are capable of characterizing the mechanical response of granular materials for a broad range of degrees of compaction.This work finds that it has limitations in accurately predicting the volumetric deformation characteristics under a wide range of confining/consolidation pressures.The issue stems from the pressure independent hardening law in the classical deviatoric hardening model.To overcome this problem,we propose a refined deviatoric hardening model in which a pressure-dependent hardening law is developed based on experimental observations.Comparisons between numerical results and laboratory triaxial tests indicate that the improved model succeeds in capturing the volumetric deformation behavior under various confining/consolidation pressure conditions for both dense and loose sands.Furthermore,to examine the importance of the improved deviatoric hardening model,it is combined with the bounding surface plasticity theory to investigate the mechanical response of loose sand under complex cyclic loadings and different initial consolidation pressures.It is proved that the proposed pressure-dependent deviatoric hardening law is capable of predicting the volumetric deformation characteristics to a satisfactory degree and plays an important role in the simulation of complex deformations for granular geomaterials. 展开更多
关键词 Elasto-plastic deformation Isotropic hardening Deviatoric plastic strain Granular material Kinematic hardening Bounding surface
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Additive manufacturing of sustainable biomaterials for biomedical applications 被引量:2
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作者 Zia Ullah Arif Muhammad Yasir Khalid +5 位作者 Reza Noroozi Mokarram Hossain Hao Tian Harvey Shi Ali Tariq Seeram Ramakrishna Rehan Umer 《Asian Journal of Pharmaceutical Sciences》 SCIE CAS 2023年第3期1-36,共36页
Biopolymers are promising environmentally benign materials applicable in multifarious applications.They are especially favorable in implantable biomedical devices thanks to their excellent unique properties,including ... Biopolymers are promising environmentally benign materials applicable in multifarious applications.They are especially favorable in implantable biomedical devices thanks to their excellent unique properties,including bioactivity,renewability,bioresorbability,biocompatibility,biodegradability and hydrophilicity.Additive manufacturing(AM)is a flexible and intricate manufacturing technology,which is widely used to fabricate biopolymer-based customized products and structures for advanced healthcare systems.Three-dimensional(3D)printing of these sustainable materials is applied in functional clinical settings including wound dressing,drug delivery systems,medical implants and tissue engineering.The present review highlights recent advancements in different types of biopolymers,such as proteins and polysaccharides,which are employed to develop different biomedical products by using extrusion,vat polymerization,laser and inkjet 3D printing techniques in addition to normal bioprinting and four-dimensional(4D)bioprinting techniques.It also incorporates the influence of nanoparticles on the biological and mechanical performances of 3D-printed tissue scaffolds,and addresses current challenges as well as future developments of environmentally friendly polymeric materials manufactured through the AMtechniques.Ideally,there is a need for more focused research on the adequate blending of these biodegradable biopolymers for achieving useful results in targeted biomedical areas.We envision that biopolymer-based 3D-printed composites have the potential to revolutionize the biomedical sector in the near future. 展开更多
关键词 3D printing Biopolymers BIOMEDICAL Tissue engineering Sustainable biomaterials Additive manufacturing
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Introduction to the Special Issue on Computational Mechanics of Granular Materials and its Engineering Applications
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作者 Shunying Ji Michael Zhuravkov +1 位作者 Zongyan Zhou Yuntian Feng 《Computer Modeling in Engineering & Sciences》 SCIE EI 2022年第7期1-3,共3页
1 Introduction The purpose of this special issue“Computational Mechanics of Granular Materials and its Engineering Applications”is to introduce the latest research progress in computational mechanics and engineering... 1 Introduction The purpose of this special issue“Computational Mechanics of Granular Materials and its Engineering Applications”is to introduce the latest research progress in computational mechanics and engineering applications of granular materials,with particular emphasis on the theoretical constructions of arbitrarily shaped particles,flow pattern transitions,bond-fracture model,neural network algorithm,CFD-DEM coupled method,and coarse-graining model,and to improve our understanding of the physical and mechanical properties of granular systems from the perspective of practical engineering applications. 展开更多
关键词 SHAPED TRANSITIONS NEURAL
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Multi-layer perceptron-based data-driven multiscale modelling of granular materials with a novel Frobenius norm-based internal variable 被引量:1
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作者 Mengqi Wang Y.T.Feng +1 位作者 Shaoheng Guan Tongming Qu 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第6期2198-2218,共21页
One objective of developing machine learning(ML)-based material models is to integrate them with well-established numerical methods to solve boundary value problems(BVPs).In the family of ML models,recurrent neural ne... One objective of developing machine learning(ML)-based material models is to integrate them with well-established numerical methods to solve boundary value problems(BVPs).In the family of ML models,recurrent neural networks(RNNs)have been extensively applied to capture history-dependent constitutive responses of granular materials,but these multiple-step-based neural networks are neither sufficiently efficient nor aligned with the standard finite element method(FEM).Single-step-based neural networks like the multi-layer perceptron(MLP)are an alternative to bypass the above issues but have to introduce some internal variables to encode complex loading histories.In this work,one novel Frobenius norm-based internal variable,together with the Fourier layer and residual architectureenhanced MLP model,is crafted to replicate the history-dependent constitutive features of representative volume element(RVE)for granular materials.The obtained ML models are then seamlessly embedded into the FEM to solve the BVP of a biaxial compression case and a rigid strip footing case.The obtained solutions are comparable to results from the FEM-DEM multiscale modelling but achieve significantly improved efficiency.The results demonstrate the applicability of the proposed internal variable in enabling MLP to capture highly nonlinear constitutive responses of granular materials. 展开更多
关键词 Granular materials History-dependence Multi-layer perceptron(MLP) Discrete element method FEM-DEM Machine learning
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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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Discrete Element Modelling of Dynamic Behaviour of Rockfills forResisting High Speed Projectile Penetration 被引量:3
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作者 Tingting Zhao Y.T.Feng +2 位作者 Jie Zhang Zhihua Wang Zhiyong Wang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2021年第5期721-735,共15页
This paper presents a convex polyhedral based discrete element method for modelling the dynamic behaviour ofrockfills for resisting high speed projectile penetration. The contact between two convex polyhedra is define... This paper presents a convex polyhedral based discrete element method for modelling the dynamic behaviour ofrockfills for resisting high speed projectile penetration. The contact between two convex polyhedra is defined by theMinkowski overlap and determined by the GJK and EPA algorithm. The contact force is calculated by a Minkowskioverlap based normal model. The rotational motion of polyhedral particles is solved by employing a quaternionbased orientation representation scheme. The energy-conserving nature of the polyhedral DEM method ensures arobust and effective modelling of convex particle systems. The method is applied to simulate the dynamic behaviourof a rockfill system under impact of a high speed projectile. The rockfill sample is generated by a three-dimensionalVoronoi meso method with a specific particle size distribution. The penetrating process of the projectile strikingthe rockfill target is simulated. Some physical quantities associated with the projectile such as the residual velocity,penetration resistance, and deflection angle are monitored which can reflect the influence of the characteristics ofthe rockfill target on its anti-penetration performance. It can be concluded that the developed polyhedral DEMmethod is a very promising numerical approach in analysing the dynamic behaviour of rockfill systems subject tohigh speed projectile impact. 展开更多
关键词 Discrete element method minkowski overlap polyhedral particles rockfill protection system high speed projectile penetration
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Comparison between wave generation methods for numerical simulation of bimodal seas 被引量:2
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作者 Daniel A.Thompson Harshinie Karunarathna Dominic Reeve 《Water Science and Engineering》 EI CAS CSCD 2016年第1期3-13,共11页
This paper describes an investigation of the generation of desired sea states in a numerical wave model. Bimodal sea states containing energetic swell components can be coastal hazards along coastlines exposed to larg... This paper describes an investigation of the generation of desired sea states in a numerical wave model. Bimodal sea states containing energetic swell components can be coastal hazards along coastlines exposed to large oceanic fetches. Investigating the effects of long-period bimodal seas requires large computational domains and increased running time to ensure the development of the desired sea state. Long computational runs can cause mass stability issues due to the Stokes drift and wave reflection, which in turn affect results through the variation of the water level. A numerical wave flume, NEWRANS, was used to investigate two wave generation methods: the wave paddle method, allowing for a smaller domain; and the internal mass source function method, providing an open boundary allowing reflected waves to leave the domain. The two wave generation methods were validated against experimental data by comparing the wave generation accuracy and the variance of mass in the model during simulations. Results show that the wave paddle method not only accurately generates the desired sea state but also provides a more stable simulation, in which mass fluctuation has less of an effect on the water depth during the long-duration simulations. As a result, it is suggested that the wave paddle method with active wave absorption is preferable to the internal wave maker option when investigating intermediate-depth long-period bimodal seas for long-duration simulations. 展开更多
关键词 Wave modeling Wave generation RANS Swell wave Bimodal sea Long-period waves
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Performance of a data-driven technique applied to changes in wave height and its effect on beach response 被引量:1
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作者 José M.Horrillo-Caraballo Harshinie Karunarathna +1 位作者 Shun-qi Pan Dominic Reeve 《Water Science and Engineering》 EI CAS CSCD 2016年第1期42-51,共10页
In this study the medium-term response of beach profiles was investigated at two sites: a gently sloping sandy beach and a steeper mixed sand and gravel beach. The former is the Duck site in North Carolina, on the ea... In this study the medium-term response of beach profiles was investigated at two sites: a gently sloping sandy beach and a steeper mixed sand and gravel beach. The former is the Duck site in North Carolina, on the east coast of the USA, which is exposed to Atlantic Ocean swells and storm waves, and the latter is the Milford-on-Sea site at Christchurch Bay, on the south coast of England, which is partially sheltered from Atlantic swells but has a directionally bimodal wave exposure. The data sets comprise detailed bathymetric surveys of beach profiles covering a period of more than 25 years for the Duck site and over 18 years for the Milford-on-Sea site. The structure of the data sets and the data-driven methods are described. Canonical correlation analysis (CCA) was used to find linkages between the wave characteristics and beach profiles. The sensitivity of the linkages was investigated by deploying a wave height threshold to filter out the smaller waves incrementally. The results of the analysis indicate that, for the gently sloping sandy beach, waves of all heights are important to the morphological response. For the mixed sand and gravel beach, filtering the smaller waves improves the statistical fit and it suggests that low-height waves do not play a primary role in the medium-term morohological resoonse, which is primarily driven by the intermittent larger storm waves. 展开更多
关键词 Beach profile Canonical correlation analysis Data-driven technique Empirical orthogonal function FORECAST Statistical model Wave height threshold
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Preface for special section on coastal flood risk
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作者 Dominic Reeve 《Water Science and Engineering》 EI CAS CSCD 2016年第1期1-2,共2页
Global concerns about changes in the world's climate have been well documented. The consequent impacts on coastal cities, agriculture, and coastal mariculture are difficult to quantify, but it is clear that there is ... Global concerns about changes in the world's climate have been well documented. The consequent impacts on coastal cities, agriculture, and coastal mariculture are difficult to quantify, but it is clear that there is a need for both better estimates of future climate and improved forecasting of storms and their impacts. 展开更多
关键词 Preface for special section on coastal flood risk
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Dynamic hydraulic jump and retrograde sedimentation in an open channel induced by sediment supply: experimental study and SPH simulation 被引量:3
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作者 ZHENG Xiao-gang CHEN Ri-dong +2 位作者 LUO Min KAZEMI Ehsan LIU Xing-nian 《Journal of Mountain Science》 SCIE CSCD 2019年第8期1913-1927,共15页
Mountainous torrents often carry large amounts of loose materials into the rivers, thus causing strong sediment transport. Experimentally it was found for the first time that when the intensive sediment motion occurs ... Mountainous torrents often carry large amounts of loose materials into the rivers, thus causing strong sediment transport. Experimentally it was found for the first time that when the intensive sediment motion occurs downstream over a gentle slope, the siltation of the riverbed is induced and the sediment particles can move upstream rapidly in the form of a retrograde sand wave, resulting in a higher water level along the river. To further study the complex mechanisms of this problem, a sediment mass model in the framework of the Smoothed Particle Hydrodynamics(SPH) method was presented to simulate the riverbed evolution, sediment particle motion, and the generation and development of dynamic hydraulic jump under the condition of sufficient sediment supply over a steep slope with varying angles. Because the sediment is not a continuous medium, the marker particle tracking approach was proposed to represent a piece of sediment with a marked sediment particle. The twophase SPH model realizes the interaction between the sediment and fluid by moving the bed boundary particles up and down, so it can reasonably treat the fluid-sediment interfaces with high CPU efficiency. The critical triggering condition of sediment motion, the propagation of the hydraulic jump and the initial siltation position were all systematically studied. The experimental and numerical results revealed the extra disastrous sediment effect in a mountainous flood. The findings will be useful references to the disaster prevention and mitigation in mountainous rivers. 展开更多
关键词 DYNAMIC hydraulic jump RETROGRADE SEDIMENTATION SEDIMENT supply Mountainous river Smoothed PARTICLE Hydrodynamics MARKED SEDIMENT PARTICLE
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Deep Learning Predicts Stress–Strain Relations of Granular Materials Based on Triaxial Testing Data 被引量:4
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作者 Tongming Qu Shaocheng Di +3 位作者 Y.T.Feng Min Wang Tingting Zhao Mengqi Wang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2021年第7期129-144,共16页
This study presents an AI-based constitutive modelling framework wherein the prediction model directly learns from triaxial testing data by combining discrete element modelling(DEM)and deep learning.A constitutive lea... This study presents an AI-based constitutive modelling framework wherein the prediction model directly learns from triaxial testing data by combining discrete element modelling(DEM)and deep learning.A constitutive learning strategy is proposed based on the generally accepted frame-indifference assumption in constructing material constitutive models.The low-dimensional principal stress-strain sequence pairs,measured from discrete element modelling of triaxial testing,are used to train recurrent neural networks,and then the predicted principal stress sequence is augmented to other high-dimensional or general stress tensor via coordinate transformation.Through detailed hyperparameter investigations,it is found that long short-term memory(LSTM)and gated recurrent unit(GRU)networks have similar prediction performance in constitutive modelling problems,and both satisfactorily predict the stress responses of granular materials subjected to a given unseen strain path.Furthermore,the unique merits and ongoing challenges of data-driven constitutive models for granular materials are discussed. 展开更多
关键词 Deep learning granular materials constitutive modelling discrete element modelling coordinate transformation LSTM GRU
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主轴式滚磨光整加工弹塑性接触力修正计算 被引量:3
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作者 王娜 杨胜强 +2 位作者 赵婷婷 曹波 赵恺 《表面技术》 EI CAS CSCD 北大核心 2020年第8期333-341,共9页
目的基于对主轴式滚磨光整加工弹塑性接触力修正系数研究的思路,探究主轴式滚磨光整加工过程中工件及滚抛磨块之间的碰撞接触力与碰撞接触速度之间的定量关系。方法采用EDEM系统中的Hertz-Mindlin接触模型进行模拟仿真,首先以Hertz接触... 目的基于对主轴式滚磨光整加工弹塑性接触力修正系数研究的思路,探究主轴式滚磨光整加工过程中工件及滚抛磨块之间的碰撞接触力与碰撞接触速度之间的定量关系。方法采用EDEM系统中的Hertz-Mindlin接触模型进行模拟仿真,首先以Hertz接触理论以及牛顿第二定律为基础,推导弹性正面碰撞接触力与碰撞接触速度之间的关系表达式,然后在Thornton弹塑性假设的基础上建立滚抛磨块与工件之间弹塑性接触力与碰撞接触速度之间的关系表达式,并将不同转速下工件与滚抛磨块之间的弹塑性正面碰撞接触力计算结果与实验测试结果进行对比分析,最后通过量化结构变位系数进一步修正弹塑性接触力计算公式。结果基于Hertz接触理论、牛顿第二定律以及Thornton接触力学模型,推导了出速度修正系数表达式,且速度修正系数在0.32~0.58之间。同时考虑结构变位修正系数,基于Matlab,经过试算求得结构的变位修正系数在0.50~2.41之间,修正后的弹塑性接触力计算结果与实验测试结果的相对误差在0.122%~8.901%之间。结论滚抛磨块与工件之间的弹塑性接触力计算公式,理论依据充分,参数明确,可以为滚磨光整加工实际工艺制定提供可信的计算方法。 展开更多
关键词 主轴式滚磨光整加工 EDEM仿真模拟 HERTZ接触理论 弹塑性接触力 修正系数
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主轴式滚磨光整加工接触力修正系数研究 被引量:3
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作者 王娜 杨胜强 +1 位作者 曹波 赵婷婷 《机械设计与制造》 北大核心 2020年第4期131-136,共6页
高端装备关重件多采用主轴式滚磨光整加工提高零件表面完整性,传统的用反复实验摸索滚磨光整工艺的办法存在工件提供难或数量少的实际问题。基于EDEM仿真主轴式滚磨光整加工可以为工艺制定提供有效的帮助,但模拟仿真与实际工况的差异性... 高端装备关重件多采用主轴式滚磨光整加工提高零件表面完整性,传统的用反复实验摸索滚磨光整工艺的办法存在工件提供难或数量少的实际问题。基于EDEM仿真主轴式滚磨光整加工可以为工艺制定提供有效的帮助,但模拟仿真与实际工况的差异性尚未可知。将滚抛磨块尺寸、滚筒转速以及加工位置作为影响接触力大小的评价指标,考虑仿真模拟与实验验证的可比性,设计构建了与仿真模拟完全相同的实验装置和工艺参数环境,选用Hertz-Mindlin无滑移接触模型进行模拟仿真,探究模拟仿真与实验测试得到的工件与滚抛磨块之间的法向接触力的规律性。通过量化接触对象球径比、加工位置以及滚筒转速对于接触力的影响,推导出接触力相关修正系数的表达式,进而建立包含接触对象球径比和速位影响系数的滚抛磨块与工件之间的接触力计算公式,并验证了不同径向位置处接触力计算公式的适用性。结果表明:球径比系数在(2.6664~2.9601)之间,其值与滚抛磨块尺寸成负相关关系;速位修正系数在(0.9519~1.9097)之间;采用修正后接触力表达式进行分析计算,计算结果与实验测试结果相对误差值在(0.08~18.91)%之间,该方法可以为滚磨光整加工实际工艺磨块与工件之间接触力提供可信的计算方法。 展开更多
关键词 主轴式滚磨光整加工 Hertz-Mindlin无滑移接触模型 球径比 速位修正系数 接触力
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Everything you always wanted to know about SDPD~★(~★but were afraid to ask) 被引量:2
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作者 M. ELLERO P. ESPANOL 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2018年第1期103-124,共22页
An overview of the smoothed dissipative particle dynamics (SDPD) method is presented in a format that tries to quickly answer questions that often arise among users and newcomers. It is hoped that the status of SDPD... An overview of the smoothed dissipative particle dynamics (SDPD) method is presented in a format that tries to quickly answer questions that often arise among users and newcomers. It is hoped that the status of SDPD is clarified as a mesoscopic particle model and its potentials and limitations are highlighted, as compared with other methods. 展开更多
关键词 mesoscopic particle method dissipative particle dynamics (DPD) smoothedparticle hydrodynamics (SPH) complex fluid
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Determination of strain-dependent soil water retention characteristics from gradation curve
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作者 Min Wang GNPande +1 位作者 Stan Pietruszczak Z.X.Zeng 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2020年第6期1356-1360,共5页
The importance of soil water retention characteristics in modelling the hydro-mechanical response of unsaturated soils has been well recognised by many investigators in recent years.Determination of strain-dependent s... The importance of soil water retention characteristics in modelling the hydro-mechanical response of unsaturated soils has been well recognised by many investigators in recent years.Determination of strain-dependent soil water retention curve(SWRC)is likely to be extraordinarily difficult.The first two authors have recently shown that SWRC can be computed from the gradation curve and the calculation result is consistent with the experimental results obtained from pressure plate tests.In this paper,based on a hypothesis related to change in the pore size distribution(POSD)due to volumetric strain of soil skeleton,a method to compute strain-dependent SWRC is presented.It is found that at initial degrees of saturation higher than 0.8,the influence of volumetric strain may be marginal whilst at initial degrees of saturation lower than 0.8,its influence is likely to be substantial.In all cases,the gradation curve of the soil affects the SWRC. 展开更多
关键词 Soil water retention curve(SWRC) Gradation curve Pore size distribution(POSD) Unsaturated soil
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Modelling the Influence of Air Jet Configurations on Non-Woven Steel Fibre Mixing in the Melt Overflow Process
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作者 Ismail Abubakar Hugh Gong +2 位作者 Sathish K. Nammi Lee Marston James Deane 《Modeling and Numerical Simulation of Material Science》 2022年第2期24-45,共22页
The mixing of non-woven steel fibres in melt overflow process for use in automotive muffler systems was simulated. The aim was to identify optimum parameters for achieving a good fibre mix. Numerical models of mixing ... The mixing of non-woven steel fibres in melt overflow process for use in automotive muffler systems was simulated. The aim was to identify optimum parameters for achieving a good fibre mix. Numerical models of mixing chambers of melt overflow process were developed. Multiphysics analyses involving heat transfer, fluid flow and particle tracking were carried out using COMSOL code. The influence of air jet configurations on the fibre distribution was studied. The fibres settled on the moving bed within the mixing chamber were examined for their uniformity. The effect of additional air jets to the existing chamber in a range of regions was explored. An optimum configuration was identified by analyzing the compactness of the particle clusters deposited in the simulation and validated using pixel data acquired from real time imaging. The results showed that by employing dual air jets at the front end of the chamber, the density of the fibre material has improved. We conclude that through multi-physics modelling, it was possible to identify the optimum air-jet configurations leading to fibre uniformity and its distribution. This work also paves the way for incorporating a vision system to evaluate fibre density in real time. 展开更多
关键词 Non-Woven Steel Fibre Steel Fibre Casting Melt and Overflow Pneumatic Conveying Multi-Physics Simulation
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Efficient calculation of fluid-induced wall shear stress within tissue engineering scaffolds by an empirical model
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作者 Husham Ahmed Matthew Bedding-Tyrrell +3 位作者 Davide Deganello Zhidao Xia Yi Xiong Feihu Zhao 《Medicine in Novel Technology and Devices》 2023年第2期267-271,共5页
Mechanical stimulation,such as fluid-induced wall shear stress(WSS),is known that can influence the cellular behaviours.Therefore,in some tissue engineering experiments in vitro,mechanical stimulation is applied via b... Mechanical stimulation,such as fluid-induced wall shear stress(WSS),is known that can influence the cellular behaviours.Therefore,in some tissue engineering experiments in vitro,mechanical stimulation is applied via bioreactors to the cells in cell culturing to study cell physiology and pathology.In 3D cell culturing,porous scaffolds are used for housing the cells.It is known that the scaffold porous geometries can influence the scaffold permeability and internal WSS in a bioreactor(such as perfusion bioreactor).To calculate the WSS generated on cells within scaffolds,usually computational fluid dynamics(CFD)simulation is needed.However,the limitations of the computational method for WSS calculation are:(i)the high time cost of the CFD simulation(in particular for the highly irregular geometries);(ii)accessibility to the CFD model for some cell culturing experimentalists due to the knowledge gap.To address these limitations,this study aims to develop an empirical model for calculating the WSS based on scaffold permeability.This model can allow the tissue engineers to efficiently calculate the WSS generated within the scaffold and/or determine the bioreactor loading without performing the computational simulations. 展开更多
关键词 Wall shear stress PERMEABILITY Empirical model Tissue engineering scaffold BIOREACTOR
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Finite element analysis for wellbore stability of transversely isotropic rock with hydraulic-mechanical-damage coupling 被引量:4
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作者 WANG YongLiang LIUZhanLi +1 位作者 YANG HengLin ZHUANG Zhuo 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2017年第1期133-145,共13页
The finite element analysis (FEA) technology by hydraulic-mechanical-damage (HMD) coupling is proposed in this paper for wellbore stability analysis of transversely isotropic rock, developed basing on the recently... The finite element analysis (FEA) technology by hydraulic-mechanical-damage (HMD) coupling is proposed in this paper for wellbore stability analysis of transversely isotropic rock, developed basing on the recently established FEA technology for iso- tropic rock. The finite element (FE) solutions of numerical wellbore model, damage tensor calculation and Pariseau strength criterion for transversely isotropic rock are developed for researching the wellbore failure characteristics and computing the collapse and fracture pressure of laminated rock as shale reservoirs. The classic Blot constitutive for rock as porous medium is introduced to establish a set of FE equations coupling with elastic solid deformation and seepage flow. To be in accord with the inclined wellbore situation, the coordinate transformation for global, wellbore, in-situ stress and transversely isotropic for- mation coordinate systems is established for describing the in-situ stress field and the results in laminated rock. To be in accord with the practical situation, a three-dimensional FIE model is developed, in which several other auxiliary technologies are com- prehensively utilized, e.g., the typical Weibull distribution function for heterogeneous material description and adaptive tech- nology for mesh refinement. The damage tensor calculation technology for transversely isotropic rock are realized from the well-developed continuum damage variable of isotropic rock. The rock is subsequently developed into a novel conceptual and practical model considering the stress and permeability with the damage. The proposed method utilizing Parisean strength cri- terion fully reflects the strength parameters parallel or perpendicular to bedding of the transversely isotropic rock. To this end, an effective and reliable numerically three-step FEA strategy is well established. Numerical examples are given to show that the proposed method can establish efficient and applicable FE model and be suitable for analyzing the state of pore pressure and stress surrounding wellbore, furthermore to demonstrate the effectiveness and reliability of the instability analysis of wellbore failure region and the safe mud weight computation for collapse and fracture pressure of transversely isotropic rock. 展开更多
关键词 finite element analysis wellbore stability transversely isotropic rock damage tensor hydraulic-mechanical-damagecoupling
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Finite element analysis for inclined wellbore stability of transversely iso-tropic rock with HMCD coupling based on weak plane strength criterion 被引量:1
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作者 WANG YongLiang ZHUANG Zhuo +2 位作者 LIU ZhanLi YANG HengLin LI ChenFeng 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2017年第4期624-637,共14页
The finite element analysis(FEA) technology by hydraulic-mechanical-chemical-damage(HMCD) coupling is proposed in this paper for inclined wellbore stability analysis of water-sensitive and laminated rock, developed ba... The finite element analysis(FEA) technology by hydraulic-mechanical-chemical-damage(HMCD) coupling is proposed in this paper for inclined wellbore stability analysis of water-sensitive and laminated rock, developed basing on the recently established FEA technology for transversely isotropic rock with hydraulic-mechanical-damage(HMD) coupling. The chemical activity of the drilling fluid is considered as phenomenological hydration behavior, the moisture content and parameters of rock considering hydration could be determined with time. The finite element(FE) solutions of numerical wellbore model considering the chemical activity of drilling fluid, damage tensor calculation and weak plane strength criterion for transversely isotropic rock are developed for researching the wellbore failure characteristics and computing the time-dependent collapse and fracture pressure of laminated rock as shale reservoirs. A three-dimensional FE model and elastic solid deformation and seepage flow coupled equations are developed, and the damage tensor calculation technology for transversely isotropic rock are realized by introducing effect of the hydration and the stress state under the current load. The proposed method utilizing weak plane strength criterion fully reflects the strength parameters in rock matrix and weak plane. To the end, an effective and reliable numerically three-step FEA strategy is well established for wellbore stability analysis. Numerical examples are given to show that the proposed method can establish efficient and applicable FE model and be suitable for analyzing the timedependsolutions of pore pressure and stresses, and the evolution region considering the hydration surrounding wellbore,furthermore to compute the collapse cycling time and the safe mud weight for collapse and fracture pressure of transversely isotropic rock. 展开更多
关键词 finite element analysis wellbore stability transversely isotropic rock hydraulic-mechanical-chemical-damage coupling weak plane strength criterion
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