Complete and partial vibration mode decoupling of national engine about torque roll axis

Internal combustion engine is one of the vibration sources in an automotive. In this study, proper stiffnesses for engine mounts of national engine are determined to improve its vibration behavior. At first, complete mode decoupling about torque roll axis is considered. However, the results show that complete decoupling is impossible. Therefore, partial mode decoupling is performed about torque roll axis. In this regard, an optimization problem is solved to achieve maximum percentage of mode decoupling about the mentioned axis. Finally, frequency response diagrams for displacement and rotation of engine, as well as, for transmitted force to the chassis are presented for nominal and optimized stiffnesses. The obtained results show that the engine movements and transmitted force to the chassis are reduced and therefore vibration behavior of the engine mounting system is improved by employing the mentioned partial mode decoupling.