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Optimierung eines FE-Modells auf Grundlage einer Experimentellen Modalanalyse

: Hermsdorf, N.

Chemnitz, 2008, 125 pp.
Chemnitz, TU, Dipl.-Arb., 2008
Fraunhofer IWU ()
ANSYS; FEM; FEM-tool; Methode der finiten Elemente; Modalanalyse; Strukturoptimierung; Parametermodifikation; finite element analysis; Finite Element model updating; modal analysis; parameter modification

Knowledge about the dynamic behaviour is a basic condition for a secure operation of modern machine tools. Hence numerical methods predicting the dynamic properties are gaining in importance. Usually for complex and coupled structures, the results of dynamic property calculation are yet insufficient. Therefore Finite Element model updating is a tool to improve the hypothetical factor of the analysis. Within the present thesis Finite Element modelling is performed using the example of the „Scherenkinematik”, a machine tool based on hybrid-kinematics. Initially the results of an Experimental Modal Analysis are evaluated by identifying Modal parameters and deriving possible structural modifications. In the second part of the thesis, the machines Finite Element model is created using the FEA-Software ANSYS. Afterwards the Finite Element model updating is performed by coupling ANSYS and the CAE-Software FEMtools. Therefore two approaches are formulated and tracked. It turns out, that there is no improvement of the analytical and experimental models correlation, neighter with nor without a steady reduction of the search domain needed for mode coupling. It is reasoned, that the characteristics and the results of an Finite Element updating process are affected by the quality of the model at start time and the approach as well as the technique chosen for model updating and parameter modification. Therefore the CAE-Software FEMtools is suitable to only a limited extent for Finite Element updating of strongly coupled mechanical structures as a result of the sensitivity analysis used for parameter modification.