Ductile Materials Microvoid Nucleation Around Inclusions And Their Subsequent Damage Evolution Of A Preliminary Study

Micro-void evolution which includes void nucleation, growth and coalescence is the critical Ihctor causing the damage of ductile material& But most of researchers supposed voids are preexist in materials before. So they paid more attention to the latter evolution of voids. In fact, the nucleation is a continnous process throughout plastic defonnation and has great influence on the damage development of materials. It needs to breakup the old research fi~me and do some more research on the detailed mechanism of void evolution. In present paper; the damage mechanism based on void model of micro-scale has been studied using elastic-plastic large deformation FEM. The main work is as follows: I. The effects of different stress tiiaxiality and incision scale on the void nucleation have been studiecL According to the numerical simulation. it is found that the stress triaxiality is and the bigger inclusion is easily induced in voids nucleation. 2. By means of controlling the macroscopic stress triaxality history and lode parameters damage evolution process of void molded has been simulated. The results showing: I The stress triaxiality have rariarkably effects on the deformation of cell .. voids and the evolution of voids. (1) when the stress triaxality is lo~r Voids nucleation nearly exist in the whole process. The influence of nucleation on the evolution of micro voids con not be ignored and the existence of inclusion constrains voids changing in shape. But when the stress triaxality is higher the process of voids nucleation is transitory. Voids nucleation have less effect on its latter evolution of voids and voids changes mainly in volume. But even in these higher stress tziaxiality when lode parameter takes the value of zero. It is noticed that the inclusion obviously affects the voids deformation by using the three dimension cell model. This denotes the void nucleation takes important role in the damage evolution of ductile materials and it needs to study the process of nucleation when analyzing the evolution of micro-void including inclusions.(2) The choice of cell models has less effect an the analysis of materials damage.(3) The paste values between inclusion and matrix affect voids evolution. II Theme are different affects on void defomiing and its evolution under different lode parameter but same stress triaxiality, and this affects is contact with stress trraxiality. 111 The reciprocity of inclusions affect macro-sale damage of materials.