FEA - Simulation of Bending Processes with LS-DYNA

Over the past few years new car body concepts have space frame structures. The consequent application of space frames results in a reduction of weight, fuel consumption, and costs of a body while maintaining a high safety standard. These structures consist mainly of closed profiles and hydroformed components. Prior to the hydroforming process, the profiles are usually pre-bent. The bending of tubes is a crucial step in the hydroforming process chain. For a successful hydroforming the bending demands high precision, reproducibility, and process reliability. These bending operations are frequently performed with parameters which are already on their limit. For the design of hydroformed components it is unavoidable to ensure all process steps by means of FEA (Finite Element Analysis) - simulation. Especially for a precise prediction of the feasibility of the bending process and the subsequent process steps it is necessary to consider all parameters and tools (e.g. mandrel) in the simulation. This results in very complex simulation models which make great demands on the simulation programs concerning precision, contact and friction. The contents of this paper deals with the finite element simulation of complex bending processes by using the non- linear simulation program LS-DYNA. In the first part of the paper the simulation of the Rotary Draw Bending with a mandrel is shown by means of a practical component and the results from simulation are compared and validated with experiments. In the second part the new Free-Bending technique is introduced by an example. Both bending techniques offer new possibilities and application ranges in the field of hydroforming.