Elastic-Plastic Deformation of Perforated Sheets with Randomly Distributed Holes

摘要

In the present paper, perforated sheets with randomly distributed holes were set up as the plane models of damaged materials and were examined under the condition of biaxial tension. The elastic-plastic deformation of perforated sheet is also analyzed by finite element method in terms of the modified Gurson's yield function, where the anisotropy of damaged materials is taken into account through the damage tensor and the net stress tensor. The damage tensor represents the state of damage due to distributed holes and is determined by the method using voronoi tessellation which divides a perforated sheet into many polygons. Each polygon has a hole in it and is transformed into a representative unit cell which is used to define both the damage tensor and the net stress. Thus the elastic-plastic response of perforated material, where voids distribute irregularly can be described as a continuum model with internal damage variables and the experimental results show that the fracture of perforated sheets and local plastic deformation are well corresponding to the calculated results of FE analysis using the modified Gurson's yield function.