Abstract
Keywords:topology optimization, fatigue simulation, dynamic loads, vibrations, multi body simulation
Every deterministic optimization leads to an optimal solution regarding the considered input parameters. Optimized structures can be sensitive regarding scattering of parameters or regarding not considered effects. E.g. topology optimization can lead to structures including thin walls or small ribs which may be sensitive regarding resonance effects. Another important factor for the usability of optimized structures are the considered loads for the optimization. To overcome the mentioned weak points an extension of the simulation process which is used for the structural optimization is presented in this article.
Coupling between durability simulation and structural optimization is available since years. Including durability analysis in the optimization procedure enables the consideration of material properties like strength limits, mean stress, notch sensitivity and technological influences. In the automotive area structures are mainly affected by non correlated dynamic multi axial loads. Durability analysis offers the direct use of complex load input for structural optimization. There is no need to reduce complex loads to simple representative load cases any more. Multiple applications prove the efficiency of the method both for shape and for topology optimization.
A further extension of the optimization procedure is to additionally include Multi Body Simulation (MBS) in the optimization loop. This approach allows an adaptation of the loads acting on the part to be optimized in each iteration. Feedback of the modified inertia behavior and stiffness to the overall system is covered by including multi body simulation into the optimization process too. This can influence results of topology optimization significantly since the material distribution varies throughout the optimization process. Dynamic effects like vibrations within the flexible structure itself can be considered by modal durability simulation. Providing these results to the optimizer leads to design changes which are fully driven by all relevant effects caused by outer loads, system interaction and structure dynamics.
In this article extended methods for the structural optimization of dynamically loaded parts in mechanical systems including durability analysis and consideration of dynamics are presented. Results of different optimization procedures will be compared and discussed.
Consideration of durability analysis and dynamic effects in the optimization procedure enables to find light weight structures for complex loadings with optimal utilization of the material. Using topology optimization in the concept phase, target oriented design development is enabled from the very beginning. This leads to a clear advantage regarding development time and costs.