The 3-D traction field in the pressure screw-pair of a 3 500 heavy and mediumplate mill press down system is successfully calculated by applying the 3-D frictional contactmultipole-BEM and the corresponding program th...The 3-D traction field in the pressure screw-pair of a 3 500 heavy and mediumplate mill press down system is successfully calculated by applying the 3-D frictional contactmultipole-BEM and the corresponding program that has been developed. The computing results show themedium diameter orientation is unreliable, especially under the interference of an outer forcecouple. Under such working conditions, the circumferential traction distribution on the screw teethis extremely uneven, which is the main reason for the destruction and short life time ofscrew-pairs. When utilizing the same precision (the relative tolerance is 10X10^(-5)), themultipole-BEM uses almost the same CPU time as used by the FEM, but the needed computer memory sizeis only one eightieth of that needed by the FEM (10 MB vs. 800 MB). The multipole-BEM is well suitedfor computing large-scale engineering problems.展开更多
A dynamic contact problem for elastic-viscoplastic materials with thermal effects is investigated. The contact is bilateral, and the friction is modeled with Tresca＇s friction law with heat exchange. A variational fo...A dynamic contact problem for elastic-viscoplastic materials with thermal effects is investigated. The contact is bilateral, and the friction is modeled with Tresca＇s friction law with heat exchange. A variational formulation of the model is derived, and the existence of a unique weak solution is proved. The proofs are based on the classical result of nonlinear first order evolution inequalities, the equations with monotone operators, and the fixed point arguments. Finally, the continuous dependence of the solution on the friction yield limit is studied.展开更多
A meshfree method based on reproducing kernel approximation and point collocation is presented for analysis of metal ring compression. The point collocation method is a true meshfree method without the employment of a...A meshfree method based on reproducing kernel approximation and point collocation is presented for analysis of metal ring compression. The point collocation method is a true meshfree method without the employment of a background mesh. It is shown that, in a point collocation approach, the remesh problem because of the mesh distortion in FEM （finite element method） and the low efficiency in Galerkin-based meshfree method are avoided. The corrected kernel functions are introduced to the stabilization of free-surface boundary conditions. The solution of symmetric ring compression problem is compared with a conventional finite element solution, and reasonable results have been obtained.展开更多
基金This project is supported by National Natural Science Foundation of China(No.50075075) National "Ten-Five" Science and Technology Project of China(No.ZZ 01-13A-02-02-03). J
文摘The 3-D traction field in the pressure screw-pair of a 3 500 heavy and mediumplate mill press down system is successfully calculated by applying the 3-D frictional contactmultipole-BEM and the corresponding program that has been developed. The computing results show themedium diameter orientation is unreliable, especially under the interference of an outer forcecouple. Under such working conditions, the circumferential traction distribution on the screw teethis extremely uneven, which is the main reason for the destruction and short life time ofscrew-pairs. When utilizing the same precision (the relative tolerance is 10X10^(-5)), themultipole-BEM uses almost the same CPU time as used by the FEM, but the needed computer memory sizeis only one eightieth of that needed by the FEM (10 MB vs. 800 MB). The multipole-BEM is well suitedfor computing large-scale engineering problems.
文摘A dynamic contact problem for elastic-viscoplastic materials with thermal effects is investigated. The contact is bilateral, and the friction is modeled with Tresca＇s friction law with heat exchange. A variational formulation of the model is derived, and the existence of a unique weak solution is proved. The proofs are based on the classical result of nonlinear first order evolution inequalities, the equations with monotone operators, and the fixed point arguments. Finally, the continuous dependence of the solution on the friction yield limit is studied.
基金the National Natural Science Foundation of China （No. 50275059）.
文摘A meshfree method based on reproducing kernel approximation and point collocation is presented for analysis of metal ring compression. The point collocation method is a true meshfree method without the employment of a background mesh. It is shown that, in a point collocation approach, the remesh problem because of the mesh distortion in FEM （finite element method） and the low efficiency in Galerkin-based meshfree method are avoided. The corrected kernel functions are introduced to the stabilization of free-surface boundary conditions. The solution of symmetric ring compression problem is compared with a conventional finite element solution, and reasonable results have been obtained.
