The granule medium of discreteness is supposed to be continuous（Drucker-Prager model） in the existing finite element simulation analysis on the hot granule medium pressure forming（HGMF） process, so the granule med...The granule medium of discreteness is supposed to be continuous（Drucker-Prager model） in the existing finite element simulation analysis on the hot granule medium pressure forming（HGMF） process, so the granule medium may produce tensile stress in the process of pressure-transferring and flowing, which does not coincide with the reality. The analysis method, discrete element and finite element（DE-FE） coupling simulation, is proposed to solve the problem. The material parameters of simulation model are obtained by the pressure-transfer performance test of granule medium and the hot uniaxial tensile test of sheet metal. The DE-FE coupling simulation platform is established by adopting Visual Basic language. The features in the process that AA7075-T6 conical parts are formed by the HGMF process are analyzed and verified by the process test. The studies show that the results of DE-FE coupling simulation coincide well with the test results, which provides a new analysis method to solve the mechanics problem in the coupling of discrete and continuum.展开更多
The discrete element method （DEM）, developed by Cundall and 5track to solve geomecnamcai problems, is used to simulate the mechanical behavior of granules. According to the DEM, an individ ual granule can be modele...The discrete element method （DEM）, developed by Cundall and 5track to solve geomecnamcai problems, is used to simulate the mechanical behavior of granules. According to the DEM, an individ ual granule can be modeled as a realistic mechanical system consisting of primary particles bonded by interaction forces. Cranulometric properties of the model material, zeolite 4A, have been measured to determine their macro properties. To investigate the compression behavior, a compression test was performed using a strength tester on single granules between two pistons. A modeled granule consisting of more than 22,000 primary particles was generated. The micro properties of the modeled granule have been precisely set to allow its macro properties to be equivalent to the macro properties of zeolite 4A granules. To calibrate the mechanical properties, diametrical compression was simulated using two rigid walls stressed at a constant stressing velocity, The force-displacement curve of the modeled granule at compression has been calibrated by the experimental curve of zeolite 4A.展开更多
High shear wet granulation(HSWG) is one of the most poorly understood processes with known difficulties in optimization and scale up. The purpose of the current study is to develop a DEM model which can be applied und...High shear wet granulation(HSWG) is one of the most poorly understood processes with known difficulties in optimization and scale up. The purpose of the current study is to develop a DEM model which can be applied under dynamic process conditions with high predictive capacity to improve process insight. The DEM model is used to predict agglomeration as a function of impeller speed and liquid addition rate in a high shear wet granulator. The DEM model tracks dynamic formation and breakage of liquid bridges between particles as liquid binder in the system is added, and corrects for the change in material properties as a function of the binder content.展开更多
In order to reveal the force transmission features of the granules in the solid granule medium forming(SGMF) technology,the frictional characteristics of the non-metallic granule medium(NGM) under high pressure were i...In order to reveal the force transmission features of the granules in the solid granule medium forming(SGMF) technology,the frictional characteristics of the non-metallic granule medium(NGM) under high pressure were investigated by tests and simulations.And the relevant changing curves of the internal friction coefficient of the granular system under different normal pressures were obtained by self-designed shear test.By the granule volume compression test,the accurate discrete element simulation parameters were obtained,based on this,the discrete element method(DEM) was adopted to reveal the evolution law of the NGM granules movement in the sample shear process from the microscopic view.Based on the DEM,the influence of granule diameter,surface friction coefficient,normal pressure and shear velocity on the internal friction coefficient of the granular system were studied.And the parameters were conducted to be dimensionless by introducing the inertia coefficient.Finally,the expression showing power-law relationship of inertia coefficient,surface friction coefficient and internal friction coefficient is obtained.展开更多
为了研究多分散颗粒体的接触力分布规律,预估颗粒体中颗粒破碎的分布范围,采用颗粒流离散元法(discrete element method,DEM)构建不同颗粒级配(分散度)的颗粒体,对土体的三轴压缩试验进行模拟,以研究颗粒粒径对颗粒体接触力分布的影响...为了研究多分散颗粒体的接触力分布规律,预估颗粒体中颗粒破碎的分布范围,采用颗粒流离散元法(discrete element method,DEM)构建不同颗粒级配(分散度)的颗粒体,对土体的三轴压缩试验进行模拟,以研究颗粒粒径对颗粒体接触力分布的影响。通过分析不同颗粒级配试样中法向接触力的概率密度分布和累积分布,对比不同颗粒级配试样中具有相同粒径的子颗粒集的配位数分布和最大接触力,调查了颗粒级配对密实颗粒体接触力分布特性的影响。结果表明:试样中粒径较大的颗粒相比于小粒径颗粒,试样中粒径较大的颗粒会承受更大的接触力;粒径较小的子颗粒集相比于粒径较大的颗粒体具有较小的最大接触力和配位数;细颗粒倾向于分布在大颗粒包围的孔隙中,此时,细颗粒基本上不参与传递接触力;颗粒级配越好,颗粒粒径对接触力分布的影响越小。展开更多
基金Projects(5130538651305385)supported by the National Natural Science Foundation of China+1 种基金Project(E2013203093)supported by the Natural Science Foundation of Hebei ProvinceChina
文摘The granule medium of discreteness is supposed to be continuous（Drucker-Prager model） in the existing finite element simulation analysis on the hot granule medium pressure forming（HGMF） process, so the granule medium may produce tensile stress in the process of pressure-transferring and flowing, which does not coincide with the reality. The analysis method, discrete element and finite element（DE-FE） coupling simulation, is proposed to solve the problem. The material parameters of simulation model are obtained by the pressure-transfer performance test of granule medium and the hot uniaxial tensile test of sheet metal. The DE-FE coupling simulation platform is established by adopting Visual Basic language. The features in the process that AA7075-T6 conical parts are formed by the HGMF process are analyzed and verified by the process test. The studies show that the results of DE-FE coupling simulation coincide well with the test results, which provides a new analysis method to solve the mechanics problem in the coupling of discrete and continuum.
文摘The discrete element method （DEM）, developed by Cundall and 5track to solve geomecnamcai problems, is used to simulate the mechanical behavior of granules. According to the DEM, an individ ual granule can be modeled as a realistic mechanical system consisting of primary particles bonded by interaction forces. Cranulometric properties of the model material, zeolite 4A, have been measured to determine their macro properties. To investigate the compression behavior, a compression test was performed using a strength tester on single granules between two pistons. A modeled granule consisting of more than 22,000 primary particles was generated. The micro properties of the modeled granule have been precisely set to allow its macro properties to be equivalent to the macro properties of zeolite 4A granules. To calibrate the mechanical properties, diametrical compression was simulated using two rigid walls stressed at a constant stressing velocity, The force-displacement curve of the modeled granule at compression has been calibrated by the experimental curve of zeolite 4A.
基金financial support by PhR MA Foundation Starter Research Grant in Pharmaceutics
文摘High shear wet granulation(HSWG) is one of the most poorly understood processes with known difficulties in optimization and scale up. The purpose of the current study is to develop a DEM model which can be applied under dynamic process conditions with high predictive capacity to improve process insight. The DEM model is used to predict agglomeration as a function of impeller speed and liquid addition rate in a high shear wet granulator. The DEM model tracks dynamic formation and breakage of liquid bridges between particles as liquid binder in the system is added, and corrects for the change in material properties as a function of the binder content.
基金Projects(51305385,51305386)supported by the National Natural Science Foundation of ChinaProject(QN20131080)supported by the Science Research Youth Foundation of Hebei Provincial Colleges and Universities,China
文摘In order to reveal the force transmission features of the granules in the solid granule medium forming(SGMF) technology,the frictional characteristics of the non-metallic granule medium(NGM) under high pressure were investigated by tests and simulations.And the relevant changing curves of the internal friction coefficient of the granular system under different normal pressures were obtained by self-designed shear test.By the granule volume compression test,the accurate discrete element simulation parameters were obtained,based on this,the discrete element method(DEM) was adopted to reveal the evolution law of the NGM granules movement in the sample shear process from the microscopic view.Based on the DEM,the influence of granule diameter,surface friction coefficient,normal pressure and shear velocity on the internal friction coefficient of the granular system were studied.And the parameters were conducted to be dimensionless by introducing the inertia coefficient.Finally,the expression showing power-law relationship of inertia coefficient,surface friction coefficient and internal friction coefficient is obtained.
文摘为了研究多分散颗粒体的接触力分布规律,预估颗粒体中颗粒破碎的分布范围,采用颗粒流离散元法(discrete element method,DEM)构建不同颗粒级配(分散度)的颗粒体,对土体的三轴压缩试验进行模拟,以研究颗粒粒径对颗粒体接触力分布的影响。通过分析不同颗粒级配试样中法向接触力的概率密度分布和累积分布,对比不同颗粒级配试样中具有相同粒径的子颗粒集的配位数分布和最大接触力,调查了颗粒级配对密实颗粒体接触力分布特性的影响。结果表明:试样中粒径较大的颗粒相比于小粒径颗粒,试样中粒径较大的颗粒会承受更大的接触力;粒径较小的子颗粒集相比于粒径较大的颗粒体具有较小的最大接触力和配位数;细颗粒倾向于分布在大颗粒包围的孔隙中,此时,细颗粒基本上不参与传递接触力;颗粒级配越好,颗粒粒径对接触力分布的影响越小。
