Numerical Simulation Study of Quasi-Static Loading and Dynamic Loading for Micro Bending Forming of Copper Foil

Abstract

A variety of micro forming processes has been invented, and the size effects have become a research hotspot at home and abroad. Micro bending molds with different feature sizes were designed. Quasi-static tester loading and dynamic laser shock loading with soft punch for micro bending forming was studied by numerical simulation respectively based on ANSYS implicit analysis and LS-DYNA explicit analysis. The constitutive models of workpiece are bilinear kinematic hardening model and Johnson-cook model respectively. The effects of different loading conditions and feature sizes of the die on the forming depth, equivalent plastic strain and equivalent plastic strain rate were studied. The results of numerical simulation show that, with the increasing of feature size of the mold, the forming depth under two kinds of loading conditions shows a tendency to increase. In dynamic laser shock loading, the equivalent plastic strain and equivalent plastic strain rate of the key position of the bent part would decrease with the increasing of the feature size of the die. While in quasi-static loading, the opposite law is shown. The research shows that, the flexible micro-bending processes with different loading models showed similar size effect. However, compared with quasi-static loading, in dynamic loading, the strain of forming parts is more centralized, and there is a high strain rate and better formability of the workpiece.

A Monte Carlo packing algorithm for poly-ellipsoids and its comparison with packing generation using Discrete Element Model

“…Granular material is showing very often in geotechnical engineering, petroleum engineering, material science and physics [8,17,28,30,38]. The packings of the granular material play a very important role in their mechanical behaviors, such as stress-strain response, stability, permeability and so on [34,23,39,2,27,22].…”