Implementation of Virtual Point Transformation and Modal analysis for automotive Rim and Hub.

The thesis project is based on the implementation of the Virtual Point Transformation method and modal Analysis of an automotive Rim and Hub. In the context of Substructuring, applied on the Component-based TPA methodology for example, it’s fundamental for the success of the calculations that the connections are well defined between Active (source) and Passive (receiver) side. Unfortunately for most of the real cases, the connection points cannot be excited and measured at the exact point of the connection location. To address these issues, the Virtual Point Transformation is the solution. As an example imagine the assemble between wheel and knuckle. Using VPT is possible to reduce the assembly for a single connection point in the centre of the wheel. The Virtual Point Transformation could represent a solution when there is no clear interface definition at connections, which is useful for Load Estimation, Substructuring, CaE correlation and Hybrid Analysis. The challenges that have to be faced are: obtaining high quality transfer functions at precise locations, obtaining transfer functions at difficult to access positions, obtaining Translational and Rotational transfer functions (DOFs) and include only the Local Rigid deformation modes. For these challenges the solution is the Virtual Point Transformation. This method require the assumption of Local rigidity in the connection and as input the Geometry Information and FRFs. The applications that involve the use of the Virtual Point Transformation are: for the Transmission in order to improve the Frequency Based Substructuring; to manage the Road Noise for spindle forces/moments and Frequency Based Substructuring; the last is Heating Ventilation and Air Conditioning (HVAC). On this project the Virtual Point Transformation Method is implemented in simulation on an Automotive Rim that has been meshed on the software Simcenter 3D. The results from the Modal Frequency Response analysis are computed from the software Siemens Nastran. The Virtual Point Transformation method is also implemented on the coupled Hub and Rim. As an introduction there was reported the applications of the SOL 103, SOL 108 and SOL 111 on a beam of steel, in order to study the dynamic response of the body in the frequency domain. Then has been analyzed on CAE the possible errors that can ensue on setting-up the test bench for the experiments on an Automotive Rin and how they can influence the accuracy of VPT. Furthermore will be showed the importance of the rigidity hypothesis for the method and how can it be useful to avoid nonlinearities ensuing from flexibility. The last subject of the project is to analyze the various cases of coupling exploiting the SOL103 and SOL111 as well as leveraging the Virtual Point Transformation to show how the different cases of coupling are affected from different rigidities.