Three dimensional finite element simulation of ring rolling

The ring rolling process is particularly demanding for FEM softwares: large pieces are deformed locally, requiring large meshes, and 10 to 20 rotations of the ring are imposed, requiring thousands of increments. An ALE technique with splitting has been built to maintain a fine mesh in the bites and a coarser one outside. To avoid large volume changes associated with the rotational movement, B-spline smoothing of the outer surface was necessary before the UL-convected nodes are moved back into the bite area. Furthermore, the one-step forward Euler time integration was replaced by a second-order, 2-step Runge-Kutta scheme. This ALE model has been implemented within the Forge3(R) implicit 3D-FEM software : (V,p) formulation, parallel version through domain partitioning, 4-node tetrahedra mini-elements, contact penalty technique, Newton-Raphson's method with line search; the linear systems of equations are solved by an iterative, Minimal Residual method with an Incomplete Cholesky factorization as a preconditioner. Force- and torque-controlled tools have been introduced. The equations and solution methods are presented with some detail, together with an application.