Numerical simulations are performed to examine the packing behavior of human red blood cells(RBCs). A combined ?nite-discrete element method(FDEM) is utilized, in which the RBCs are modeled as no-friction and no-adhes...Numerical simulations are performed to examine the packing behavior of human red blood cells(RBCs). A combined ?nite-discrete element method(FDEM) is utilized, in which the RBCs are modeled as no-friction and no-adhesion solid bodies. The packed volume and the void ratio of a large number of randomly packed RBCs are clari?ed,and the effects of the RBC shape, the mesh size, the cell number, and the container size are investigated. The results show that the packed human RBCs with normal shape have a void ratio of 28.45%, which is slightly higher than that of the ?at or thick cells used in this study. Such information is bene?cial to the further understanding on the geometric features of human RBCs and the research on RBC simulations.展开更多
The aim of this study is to investigate the asphalt mixture anisotropy of both the modulus and Poisson＇s ratio due to air voids using a discrete element modeling simulation method. Three three-dimensional cubic digit...The aim of this study is to investigate the asphalt mixture anisotropy of both the modulus and Poisson＇s ratio due to air voids using a discrete element modeling simulation method. Three three-dimensional cubic digital samples of asphalt mixture with different shapes of single air void were built using discrete element software PFC^（3D）. The aggregate gradation, air voids and mastic included in the digital samples were modeled using different contact models, with due consideration of the volumetric fractions of the different phases. Laboratory uniaxial complex modulus test and indirect tensile strength test were conducted to obtain material input parameters for numerical modeling. Simulation of the uniaxial cyclic compressive tests was performed on the three cubic samples loaded in three different directions. Dynamic modulus in three directions and Poisson＇s ratio in six directions were calculated from the compression stress-strain responses. Results show that both the modulus and Poisson＇s ratio are dependent on the preferential orientation of air voids. The anisotropy of the modulus and Poisson＇s ratio increases as the pressure loading on the asphalt mixture increases. Compared to the modulus, Poisson＇s ratio due to air voids has been shown to be more anisotropic. The maximum of Poisson＇s ratio and modulus is shown to be up to 80% and 11% higher than the minimum, respectively.展开更多
为了研究层间脱空对隧道复合式路面竖向位移和最大剪应力的影响,考虑重载的作用,采用ABAQUS建立复合式隧道路面模型,分析脱空区域大小对竖向位移和最大剪应力的影响。结果表明:脱空区域对复合式隧道路面的竖向位移、两车轮中心位移差和...为了研究层间脱空对隧道复合式路面竖向位移和最大剪应力的影响,考虑重载的作用,采用ABAQUS建立复合式隧道路面模型,分析脱空区域大小对竖向位移和最大剪应力的影响。结果表明:脱空区域对复合式隧道路面的竖向位移、两车轮中心位移差和最大剪应力的影响显著;随着脱空区域的增大,竖向位移先急剧增大随后增长速率放缓,两车轮荷载中心位移差先增大后减小;当脱空区域面积大于0.0225 m 2时,最大剪应力最大值从下面层顶移动至下面层底部脱空区域;随着轴重的增加,脱空区域一侧车轮中心路表位移、两车轮中心路表位移差、最大剪应力最大值均增大。展开更多
基金Project supported by the Engineering and Physical Sciences Research Council(EPSRC)Turbulence Consortium Grant(No.EP/G069581/1)the Marie Curie International Incoming Fellowship(No.PIIF-GA-253453)
文摘Numerical simulations are performed to examine the packing behavior of human red blood cells(RBCs). A combined ?nite-discrete element method(FDEM) is utilized, in which the RBCs are modeled as no-friction and no-adhesion solid bodies. The packed volume and the void ratio of a large number of randomly packed RBCs are clari?ed,and the effects of the RBC shape, the mesh size, the cell number, and the container size are investigated. The results show that the packed human RBCs with normal shape have a void ratio of 28.45%, which is slightly higher than that of the ?at or thick cells used in this study. Such information is bene?cial to the further understanding on the geometric features of human RBCs and the research on RBC simulations.
基金Funded by the National Natural Science Foundation of China(No.51208178)the Fundamental Research Funds for the Central Universities(No.2015B17014)
文摘The aim of this study is to investigate the asphalt mixture anisotropy of both the modulus and Poisson＇s ratio due to air voids using a discrete element modeling simulation method. Three three-dimensional cubic digital samples of asphalt mixture with different shapes of single air void were built using discrete element software PFC^（3D）. The aggregate gradation, air voids and mastic included in the digital samples were modeled using different contact models, with due consideration of the volumetric fractions of the different phases. Laboratory uniaxial complex modulus test and indirect tensile strength test were conducted to obtain material input parameters for numerical modeling. Simulation of the uniaxial cyclic compressive tests was performed on the three cubic samples loaded in three different directions. Dynamic modulus in three directions and Poisson＇s ratio in six directions were calculated from the compression stress-strain responses. Results show that both the modulus and Poisson＇s ratio are dependent on the preferential orientation of air voids. The anisotropy of the modulus and Poisson＇s ratio increases as the pressure loading on the asphalt mixture increases. Compared to the modulus, Poisson＇s ratio due to air voids has been shown to be more anisotropic. The maximum of Poisson＇s ratio and modulus is shown to be up to 80% and 11% higher than the minimum, respectively.
文摘为了研究层间脱空对隧道复合式路面竖向位移和最大剪应力的影响,考虑重载的作用,采用ABAQUS建立复合式隧道路面模型,分析脱空区域大小对竖向位移和最大剪应力的影响。结果表明:脱空区域对复合式隧道路面的竖向位移、两车轮中心位移差和最大剪应力的影响显著;随着脱空区域的增大,竖向位移先急剧增大随后增长速率放缓,两车轮荷载中心位移差先增大后减小;当脱空区域面积大于0.0225 m 2时,最大剪应力最大值从下面层顶移动至下面层底部脱空区域;随着轴重的增加,脱空区域一侧车轮中心路表位移、两车轮中心路表位移差、最大剪应力最大值均增大。
