Jetting succeeded by accumulation is the characteristic of the vacuum filling,which is different from the conventional pressure-driven flow.In order to simulate this kind of flow,a three-dimensional theoretical model ...Jetting succeeded by accumulation is the characteristic of the vacuum filling,which is different from the conventional pressure-driven flow.In order to simulate this kind of flow,a three-dimensional theoretical model in terms of incompressible and viscous flow is established,and an iterative method combined with finite element method(FEM)is proposed to solve the flow problem.The Lagranian-VOF method is constructed to trace the jetting and accumulated flow fronts.Based on the proposed model and algorithm,a simulation program is developed to predict the velocity,pressure,temperature,and advancement progress.To validate the model and algorithm,a visual experimental equipment for vacuum filling is designed and construted.The vacuum filling experiments with different viscous materials and negative pressures were conducted and compared with the corresponding simulations.The results show the flow front shape closely depends on the fluid viscosity and less relates to the vacuum pressure.展开更多
Nonlinear formulations of the meshless local Petrov-Galerkin （MLPG） method are presented for geometrically nonlinear problems. The method requires no mesh in computation and therefore avoids mesh distortion difficul...Nonlinear formulations of the meshless local Petrov-Galerkin （MLPG） method are presented for geometrically nonlinear problems. The method requires no mesh in computation and therefore avoids mesh distortion difficulties in the large deformation analysis. The essential boundary conditions in the present formulation axe imposed by a penalty method. An incremental and iterative solution procedure is used to solve geometrically nonlinear problems. Several examples are presented to demonstrate the effectiveness of the method in geometrically nonlinear problems analysis. Numerical results show that the MLPG method is an effective one and that the values of the unknown variable are quite accurate.展开更多
基金the National Science Foundation of China(No.11672271)Shenzhen Zhaowei Machinery&Electronics CO.,LTD.(No.20210035A and 20210035B)for this research work are gratefully acknowledged.
文摘Jetting succeeded by accumulation is the characteristic of the vacuum filling,which is different from the conventional pressure-driven flow.In order to simulate this kind of flow,a three-dimensional theoretical model in terms of incompressible and viscous flow is established,and an iterative method combined with finite element method(FEM)is proposed to solve the flow problem.The Lagranian-VOF method is constructed to trace the jetting and accumulated flow fronts.Based on the proposed model and algorithm,a simulation program is developed to predict the velocity,pressure,temperature,and advancement progress.To validate the model and algorithm,a visual experimental equipment for vacuum filling is designed and construted.The vacuum filling experiments with different viscous materials and negative pressures were conducted and compared with the corresponding simulations.The results show the flow front shape closely depends on the fluid viscosity and less relates to the vacuum pressure.
基金Project supported by the National 973 Program (No.2004CB719402), the National Natural Science Foundation of China (No. 10372030)the Open Research Projects supported by the Project Fund of the Hubei Province Key Lab of Mechanical Transmission & Manufacturing Engineering Wuhan University of Science & Technology (No.2003A16).
文摘Nonlinear formulations of the meshless local Petrov-Galerkin （MLPG） method are presented for geometrically nonlinear problems. The method requires no mesh in computation and therefore avoids mesh distortion difficulties in the large deformation analysis. The essential boundary conditions in the present formulation axe imposed by a penalty method. An incremental and iterative solution procedure is used to solve geometrically nonlinear problems. Several examples are presented to demonstrate the effectiveness of the method in geometrically nonlinear problems analysis. Numerical results show that the MLPG method is an effective one and that the values of the unknown variable are quite accurate.
