Process design for hydroforming of sheet metal pairs using a closed loop controlled finite element simulation

摘要

Today process parameters for hydroforming processes are determined by repeated numerical simulations based on expert process knowledge. In this paper we present a knowledge based closed loop control for finite element simulation for this task. The finite element simulation stops at well defined forming states. An analysis module estimates the future failure tendency of the actual state and stores it as well as its rating in a tree-like data base. This process tree stores all simulation states calculated so far and their ratings in sequential order. Considering this rating and the advance of the process, the best-fit process state to continue the simulation is searched in the process tree. For this state the values of the process parameters for the next simulation step are determined. The simulation is resumed with the adapted parameters. This is repeated until the end of the process or until a given abort criterion is fulfilled. The corresponding process parameters leading to a final process state can be obtained by tracing the stored intermediate states in the process tree. The presented knowledge based CA-system enables the automatic determination of process parameters for hydroforming of sheet metal pairs avoiding repetitive time- and thus cost-intensive finite element simulations.