Abstract
Keywords: Short Fiber Reinforced Thermoplastics, Integrative Simulation, Mathematical Optimization, Lower Bumper Stiffener, Morphing
Important ingredients for a predictive simulation are an adequate numerical material description as well as an adapted part geometry which is best suited for withstanding the mechanical loads. The paper addresses both topics mentioned and is therefore divided into two main parts.
In the first part, the paper describes a material model approach called Integrative Simulation which had been developed at BASF and which is able to model the mechanical behaviour of short fiber reinforced thermoplastics in a very precise manner. It takes into account all relevant effects like tension/compression asymmetry, strain rate dependency and fiber induced anisotropy. In addition to that it enables the description of failure, based on all mentioned influence factors. The new approach is based on micromechanical models for the fiber and matrix phases involved and uses homogenization techniques to describe the strongly nonlinear behaviour of the compound up to failure. Verifications of the numerical model under various test conditions will be shown.
As an example for the use of the Integrative Simulation approach, the development of a Lower Bumper Stiffener (LBS) for the OPEL Corsa, model 2006 is given. The part is located behind the front bumper and builds up an additional load path to fulfil the EU wide pedestrian protection regulations according to current EU regulations.
The second part of the paper describes the successful use of optimization techniques in a serial project of another LBS application. Topology Optimization as well as nonlinear Shape Optimization techniques using Morphing were successfully applied. Especially the use of Morphing Techniques allows to overcome a main drawback in using FE-techniques: the spatially fixed description of the discretised geometry. The effect of using innovative optimization techniques in the whole development process will be clearly addressed.