Method of testing for dynamic output forces from jet elements is studied, the handwidth is large in testing with this method. By establishing a model of the test system and simulating it, principles of how inherent fe...Method of testing for dynamic output forces from jet elements is studied, the handwidth is large in testing with this method. By establishing a model of the test system and simulating it, principles of how inherent features of the test system affect the dynamic force test are found out. Thus a theoretical foundation is given for the design and error modification to the actual test system.展开更多
A structured method to generate conformal finite element(FE)mesh for realistic 3D woven textile reinforced composite is proposed.It is based on a voxel structure mesh reconstruction framework and aims to provide accur...A structured method to generate conformal finite element(FE)mesh for realistic 3D woven textile reinforced composite is proposed.It is based on a voxel structure mesh reconstruction framework and aims to provide accurate composite model at yarn level with material properties ready for use in commercial FE software.The textile representative volume element(RVE)is generated at filament level implementing the digital element method.Yarn structure is determined by filament bundle with variant cross-section shapes along its path.Yarn surface is then extracted using the Delaunay triangulation algorithm and a surface mesh is initiated.Then,the mesh domain is defined and constructed by voxel structure.Periodic boundary conditions,inter-yarn,and yarnmatrix interfaces are eliminated by re-mesh and mesh optimization.An element splitting rule is established to split the voxel unit into sub-elements to create smooth interface.A 3D orthogonal weave fabric reinforced composite is generated and simulated under compressive load.The composite structure and damage morphology are in good agreement with those of the experiment.展开更多
The resources and environmental problems are the two most fundamental issues facing all nations in the world. Everything in and on the Earth - minerals, animals and plants -is made from one, or generally some combinat...The resources and environmental problems are the two most fundamental issues facing all nations in the world. Everything in and on the Earth - minerals, animals and plants -is made from one, or generally some combination of, chemical elements, which are scientifically listed in the periodic table. Thus it is important to understand the present abundance and spatial distribution of all the elements across the Earth＇s surface. Such kinds of data can only be obtained at present and for the foreseeable future by on-earth geochemical mapping at all scales. The 30-year efforts made by Chinese geochemists in carrying out multi-element, multi-media, multi-scale geochemical mapping projects to delineate 39-76 element distribution at home and abroad culminated in a successful case of high- quality geochemical data acquirement. The new idea for a four-level plan for global geochemical mapping was advanced to obtain global data in the foreseeable future and the collection of updated geochemical information. Such information needs to be easily accessible not only by the science community, but also by industry, agriculture, governments, and even individuals, by all who would make an effort to promote sustainable riving on our planet. The concept of a Digital Element Earth （DEE） fulfills the aims.展开更多
Being the two primary approaches for full-field kinematics measurements, both subset-based local digital image correlation （DIC） and finite element-based global DIC have been extensively studied. Nowadays, most comm...Being the two primary approaches for full-field kinematics measurements, both subset-based local digital image correlation （DIC） and finite element-based global DIC have been extensively studied. Nowadays, most commercial DIC systems employ local DIC algorithm because of its advantages of straight forward principle and higher efficiency. However, several researchers argue that global DIC can provide better displacement results due to the displacement continuity constraint among adjacent elements. As such, thoroughly examining the performance of these two different DIC methods seems to be highly necessary. Here, the random errors associated with local DIC and two global DIC methods are theoretically analyzed at first. Subsequently, based on the same algorithmic details and parameters during analyses of numerical and real experiments, the performance of the different DIC approaches is fairly compared. Theoretical and experimental results reveal that local DIC outperforms its global counterpart in terms of both displacement results and computational efficiency when element （subset） size is no less than 11 pixels.展开更多
The failure behavior of the three-dimensional(3D)woven composites under tension are evaluated via experimentation and simulation.To accurately depict the intricate geometry of the woven composites,including the fluctu...The failure behavior of the three-dimensional(3D)woven composites under tension are evaluated via experimentation and simulation.To accurately depict the intricate geometry of the woven composites,including the fluctuation of yarn paths,variations in cross-section,and resin distribution,the image-aided digital elements modeling approach is employed.Subsequently,to further assess both the tensile performance and damage response,a realistic voxel model is established with the integration of a well-suited progressive damage model.The obtained stress-strain curves align with the experimental results,and damage progression and underlying mechanisms involved are clearly revealed.Specifically,when subjected to warp tension,severe transverse damage and fiber bundle pull-out towards the warp yarns are observed within the curved section.Similarly,under weft loading,longitudinal damage is found to occur in the weft yarns,while the warp yarns suffer from transverse damage,leading to the formation of a smooth and brittle crack.Ultimately,the findings of this study hold potential to advance the engineering applications of the3D woven composites.展开更多
The application of a digital modelling method that can faithfully take account of three-dimensional shape and inherent physical and chemical properties of each particulate component provides an essential tool in decom...The application of a digital modelling method that can faithfully take account of three-dimensional shape and inherent physical and chemical properties of each particulate component provides an essential tool in decommissioning design. This is useful in handling of high, medium and low level radioactive waste. The processes involve making decisions on where to cut existing plant components and then how to pack these components into boxes, which are then cemented and kept for long term storage as the level of radioactive declines with time. We illustrate the utility of the method and its ability to take data at plant scale （m-scale） and then deduce behaviours at sub millimetre scale in the packed containers. A variety of modelling approaches are used as a part of this approach including cutting algorithms, geometric and dynamic （distinct element） force models, and lattice Boltzmann methods. These methods are applicable to other complex particulate systems including simulation of waste, building recycling, heap leaching and related minerals processes. The paper introduces the basic concepts of this multi-scale and multi-model approach.展开更多
文摘Method of testing for dynamic output forces from jet elements is studied, the handwidth is large in testing with this method. By establishing a model of the test system and simulating it, principles of how inherent features of the test system affect the dynamic force test are found out. Thus a theoretical foundation is given for the design and error modification to the actual test system.
基金co-supported by the Chongqing Natural Science Foundation General Project,China(No.CSTB2022NSCQ-MSX1115)。
文摘A structured method to generate conformal finite element(FE)mesh for realistic 3D woven textile reinforced composite is proposed.It is based on a voxel structure mesh reconstruction framework and aims to provide accurate composite model at yarn level with material properties ready for use in commercial FE software.The textile representative volume element(RVE)is generated at filament level implementing the digital element method.Yarn structure is determined by filament bundle with variant cross-section shapes along its path.Yarn surface is then extracted using the Delaunay triangulation algorithm and a surface mesh is initiated.Then,the mesh domain is defined and constructed by voxel structure.Periodic boundary conditions,inter-yarn,and yarnmatrix interfaces are eliminated by re-mesh and mesh optimization.An element splitting rule is established to split the voxel unit into sub-elements to create smooth interface.A 3D orthogonal weave fabric reinforced composite is generated and simulated under compressive load.The composite structure and damage morphology are in good agreement with those of the experiment.
基金the Ministry of Land and Resources,China Geological Survey and the Ministry of Science and Technology for the research funding of the projects:SinoProbe 04,NSFC 40673066973 Project 2007CB411406the CGS project of 76 elements geochemical mapping of South China
文摘The resources and environmental problems are the two most fundamental issues facing all nations in the world. Everything in and on the Earth - minerals, animals and plants -is made from one, or generally some combination of, chemical elements, which are scientifically listed in the periodic table. Thus it is important to understand the present abundance and spatial distribution of all the elements across the Earth＇s surface. Such kinds of data can only be obtained at present and for the foreseeable future by on-earth geochemical mapping at all scales. The 30-year efforts made by Chinese geochemists in carrying out multi-element, multi-media, multi-scale geochemical mapping projects to delineate 39-76 element distribution at home and abroad culminated in a successful case of high- quality geochemical data acquirement. The new idea for a four-level plan for global geochemical mapping was advanced to obtain global data in the foreseeable future and the collection of updated geochemical information. Such information needs to be easily accessible not only by the science community, but also by industry, agriculture, governments, and even individuals, by all who would make an effort to promote sustainable riving on our planet. The concept of a Digital Element Earth （DEE） fulfills the aims.
基金supported by the Science Fund of State Key Laboratory of Automotive Safety and Energy(KF16162)
文摘Being the two primary approaches for full-field kinematics measurements, both subset-based local digital image correlation （DIC） and finite element-based global DIC have been extensively studied. Nowadays, most commercial DIC systems employ local DIC algorithm because of its advantages of straight forward principle and higher efficiency. However, several researchers argue that global DIC can provide better displacement results due to the displacement continuity constraint among adjacent elements. As such, thoroughly examining the performance of these two different DIC methods seems to be highly necessary. Here, the random errors associated with local DIC and two global DIC methods are theoretically analyzed at first. Subsequently, based on the same algorithmic details and parameters during analyses of numerical and real experiments, the performance of the different DIC approaches is fairly compared. Theoretical and experimental results reveal that local DIC outperforms its global counterpart in terms of both displacement results and computational efficiency when element （subset） size is no less than 11 pixels.
基金supported by the National Natural Science Foundation of China(Nos.U2241240,12172045,12221002 and 12202119)。
文摘The failure behavior of the three-dimensional(3D)woven composites under tension are evaluated via experimentation and simulation.To accurately depict the intricate geometry of the woven composites,including the fluctuation of yarn paths,variations in cross-section,and resin distribution,the image-aided digital elements modeling approach is employed.Subsequently,to further assess both the tensile performance and damage response,a realistic voxel model is established with the integration of a well-suited progressive damage model.The obtained stress-strain curves align with the experimental results,and damage progression and underlying mechanisms involved are clearly revealed.Specifically,when subjected to warp tension,severe transverse damage and fiber bundle pull-out towards the warp yarns are observed within the curved section.Similarly,under weft loading,longitudinal damage is found to occur in the weft yarns,while the warp yarns suffer from transverse damage,leading to the formation of a smooth and brittle crack.Ultimately,the findings of this study hold potential to advance the engineering applications of the3D woven composites.
基金supported by the UK Engineeringand Physical Sciences Research Council Knowledge Secondment Scheme
文摘The application of a digital modelling method that can faithfully take account of three-dimensional shape and inherent physical and chemical properties of each particulate component provides an essential tool in decommissioning design. This is useful in handling of high, medium and low level radioactive waste. The processes involve making decisions on where to cut existing plant components and then how to pack these components into boxes, which are then cemented and kept for long term storage as the level of radioactive declines with time. We illustrate the utility of the method and its ability to take data at plant scale （m-scale） and then deduce behaviours at sub millimetre scale in the packed containers. A variety of modelling approaches are used as a part of this approach including cutting algorithms, geometric and dynamic （distinct element） force models, and lattice Boltzmann methods. These methods are applicable to other complex particulate systems including simulation of waste, building recycling, heap leaching and related minerals processes. The paper introduces the basic concepts of this multi-scale and multi-model approach.
