3D FEM-DEM coupling analysis for granular-media-based thin-wall elbow tube push-bending process

Abstract

The granular-media-based thin-wall elbow push-bending process involves filling a tube with granular media and pushing the tube into a die to bend a tubular blank into an elbow shape. By means of the mechanical characteristics of granular filler, an elbow tube with t/D < 0.01 (the ratio of wall thickness to outer diameter) and R/D < 1.5 (the ratio of bending radius to outer diameter) can be formed. To investigate the interaction between thin-wall elbow and granular filler, A 3D FEM-DEM coupling numerical model is developed, which takes into account both the deformation behavior of tubular blank (continuum, finite element method FEM) and mechanical characteristics of granular filler (discrete media, discrete element method DEM). By means of the coupling model, the key forming parameters of an elbow tube such as forming force, wall thickness distribution, wrinkling are simulated and compared to experimental results.