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Schikorra, M.; Schomäcker, M.; Kleiner, M.: :
In: Simulation of Complex Flows (CFD) – Application and Trends, NAFEMS, Wiesbaden, 2004
The production of continuously reinforced profiles by use of aluminum as base material and a reinforcement made of steel or carbon offers a great potential for modern lightweight constructions. Within this scope, they present the potential for an increase in usage of space frame constructions in automotive or aerospace engineering. But the insertion of reinforcement in the material flow of the extrusion process leads to a significant local perturbation inside of the forming tool: while the velocity of the base material increases due to the increasing press ration the velocity of the reinforcement remains constant at the profiles out-coming velocity. These effect leads in the compound zone to the induction of tensile stresses into the reinforcement which result in failures like cracking during the extrusion process. By use of a coupled thermo-mechanical finite element simulation with the commercial fecodes Superform from MSC and HyperXtrude from Altair the velocity fields of an extrusion process with and without reinforcement were calculated and the resulting stress components were analysed. Based on these results, a process optimisation to reduce stresses on the reinforcement have been carried out, for example by a modification of the tool geometry. The numerical results went along with experiments to verify the calculated failures and the optimised process.