Abstract
KEYWORDS – FRF, Modal Response, Sensitivity, Super Elements, Sub-structuring ABSTRACT – Improving the NVH performance of a complicated structure, such as vehicle, involves either long solving times for full FE runs or complicated procedures and many files to handle in case of reduced models. On the other hand, numerous "what-if" studies should be conducted to reach a conclusion since the tools used (modal contribution, TPA) spot where the problem appears but do not suggest how this can be fixed. This paper proposes a new way of orchestrating all NVH processes from within a uniform environment. It also presents a new tool that directly suggests to the analyst measures to improve performance.
BETA CAE Systems has developed a unified environment for facilitating all different stages of an NVH analysis from the creation of reduced components to assembling, setting up different load cases, calculating and post-processing. Based on a simple diagram view, all actions are streamlined and automated through the suggested way of work. Subsequently different design iterations and "what-if" studies can be conducted repeatedly in minimum time. This approach is further enhanced through the introduction of an innovative diagnostic tool resembling a sensitivity analysis which can directly guide the analyst to a tangible and feasible modification of the structure. This can lead to improved performance and thus minimise the number of "what-if" studies needed to reach the same decision. This method is tested on a full vehicle model.
Starting from creating reduced representations for individual FE components, the model is then assembled and set-up. Initial calculations are conducted within the same environment and the NVH performance problem is identified. The new methodology for sensitivity analysis is applied showing the area in which the analyst needs to interfere. Beam stiffeners are added in real time and the model is solved again confirming the improvement in performance. According to this, a new FE design for the component is proposed and the model is run again exhibiting improved performance with minimum effort. The component with its new design is then reduced to the lightest possible representation further accelerating all future simulation calculations and allowing time to focus on another component to improving the overall performance. The new suite for NVH analysis delivers final results faster. Using the new sensitivity analysis, the analyst is directed towards the correct modifications avoiding unnecessary simulation calculations and "what-if" studies.