Mechanical Behavior And Process Experiment Research Of Pore-formig By Diamond Nano Indentation

The diamond nano indentation pore is a new method for ultro-micro hole forming,it presses through a metal plate with a glass substrate by the conical diamond indenter with its point nose circle,it's feed and blunt micro-scale are nanoscale.It is of great significance to study the mechanical behavior and related process parameters for accurately form pores and improve the quality of micropores.This paper will study the elasto-plastic deformation,fracture behavior and forming process of copper sheets in the process of press-forming holes,combining the theoretical analysis,numerical simulation and experiment examination.First,mathematical model has been established that conical pressure head loads on semi-infinite body vertically,and the solution method of stress and displacement is obtained according to Elastoplastic mechanics.Establishing continuous damage model and analyzing the copper's contact damage,to get the critical load of plastic zone,conical crack and radial crack.By the analysis of acoustic emission signal in the preliminary experiment,the conclusion is gotten that cackle belongs to ?type(Tensile type)and ?type(Shear type).Through analyzing the stress state of crack tip,the maximum principal stress and maximum shear stress are reached when the driving crack.According to Griffith energy theory,the fracture criterion of copper's destabilization is obtained.To ensure that the copper sheet is made into a hole and the substrate is not damaged,establishing the mathematical model of a diamond cone press-into the substrate,and expressions of substrate's elastic deformation are inferred.Then,doing numerical simulation with DEFORM-3D,analyse the plastic flow,stress distribution change,three direction displacement law and the stretch or compression of copper material in the press process,revealing the plastic deformation characteristics of copper sheets and the pore forming mechanism of unilateral ultra micropore.The displacement and stress state of the substrate were analyzed,and the elastic deformation of the substrate was within the theoretical range.Analysis of microstructure evolution of copper sheets by Microstructure module,summing up the regularity of grain size variation of copper sheet in the process of printing and verify them through metallographic analysis experiments.Finally,a set of optimum technological parameters was obtained by the diamond nano indentation test.Summarizing the forming law of materials,testing and analyzing sample's fracture form and surface topography.The necessity and accuracy of theoretical research and numerical simulation is verified,to established foundation to the forming technology of single side ultra micropore of diamond nanoscale,which has independent property right.