Numerical Simulation And Interrelated Experimental Of Nonlocal Friction

In metal platic forming process,there are frictions between the material and die. Friction dsitribute format on the contace surface act importanct on metal plastic flow rule etc. mechanics parameter problem to solve in forming process. There were already carried on a lot of researches towards friction phenomenon,but understood still rarely. Friction model is one of the boundary conditions which solves mechanics problem in metal plastic forming processes. At present, Only use a simplification friction model to replaces the true friction distribute. The commonly used simplified friction model includes:Coulomb friction model and constant friction model. In mechanic of continuous media, the contact surfaces are regard as continual smooth surfaces which have shear intensity. Coulomb friction model is local character in metal plasticity forming process mechanics, namely certain point frictional effect in the contact surface will only related the state of this point. However, actually the metals surface is usually rough and the contact interface is contact with the rough surface, certain point frictional stress in the contact surface will not only directly related the state of this point, but also related the other points states in a limited neighborhood of the point ,this is a nonlocal friction effect. Therefore there is necessity use nonlocal friction model substitute coulomb friction model to consider the aperity structure on the contact interface to cause nonlocal friction effect.In this paper, nonlocal friction model is applied in the analysis of friction numerical simulation in metal plastic forming processes for the frist time .The nonlocal friction issue in forming process is study. From the microcosmic point of view,consider the asperity structure on the contact surface, nonlocal friction model with the experimental methods to explore for the frist time. The main content is as follows:Summarize domestic and international research present condition and background of friction model and nonlocal friction model in the plastic forming, leads to the main content and significance.Friction theory in the plastic forming, in common use friction model and nonlocal friction model are systematic introduced in the paper.The basic method of the finite element theory is analyzed, introduced a software ADINA 's basic profiles , ADINA modeling process and contact friction issues in ADINA.Analyzed the formation of friction in metal plastic forming process, the workpiece contact surface microcosmic morphology, gave the contact model of the micro-rough contact surface in numerical simulation in this paperApplication of the nonlocal friction model for friction problem in plastic forming to numerical analysis. Instance to don't consider the asperity on the surface and consider the asperity on the surface are respectively to analyzed. In the article situation of single hemispheroid asperity and single cone asperity carried on the nonlocal friction impact analysis.we respectively used local Coulomb friction model and non-local friction model to simulation and analysis the friction promble in the forming process, researched the relationship of depressive quantity with normal stress in the forming process and researched the distribution of friction stress and normal stress on the contace surface in a certain same moment.Nonlocal friction which consider the asperity on the surface are researched with the experimental methods, the friction coefficient were studyed and tested on the CMT Series computer control electronic universal testing machine. Through the experimental result and simulation result to comparing, educe that adapt nonlocal friction model replace the local coulomb friction model to analyzed the friction in plastic forming process, although increase complexity of the problem, but the results are more accurate, more real.The study in this paper is helpful to understand further the friction mechanism in the plastic forming processes. It is a good attempt to set up the more actual and more accurate friction model.