Papers by Author: Xue Bin Zhang

Abstract: A single-point load will be applied on the ring in the cold ring rolling process when the ring vibrates violently. This arouses hourglass in finite element simulation of the process using reduced integration element. A one-point quadrature element with hourglass control developed by Hu is used, and the user-defined control parameters are not required. Hourglass energy can be reduced to 3 percent of the internal energy. The element is applied to simulation of a pure radial cold ring rolling with rectangular section. Compared with the experimental results, the simulation results are proved to be accurate. Key-Words: one-point quadrature; Hourglass control; finite element; cold ring rolling

Abstract: Hourglass is obviously aroused in cold ring rolling simulation with reduced integration element because of ring vibrating violently and small contact area of ring and rollers. In the developed numerical simulation code named RingForm, two methods are used to control the hourglass. The first method is combination of artificial damping and artificial stiffness. The second is one-point quadrature element with hourglass control, which need not user-defined control parameters. Hourglass energy can be reduced to 3 percent of the internal energy. Using the latter, good elements are acquired, while computational efficiency is obviously lower than the former.

Abstract: A dynamic explicit finite element solver is developed for numerical simulation of metal ring rolling process, which is a complex process of material nonlinearity, geometric nonlinearity and contact nonlinearity. An elastro-plastic dynamic explicit finite element equation and central difference algorithm are used. To control hourglass, a stable matrix hourglass control method is used to ensure energy balance in the simulation. Two-step method of global search and local search is used to reduce the contact judging time. In the elastic-plastic stress updating, tangent forecasting and radical return algorithm are used to eliminate the stress deviate from the yield surface. The accuracy and stability of the solver is verified by comparison of two ring rolling processes with the experimental results.