Optimization of a vehicle motor model for vibrational isolation via a primal-dual interior-point algorithm

Abstract

The mount project is extremely important to ensure good isolation of equipment that generates vibration, be it a motor, a hydraulic pump, a compressor, among others. For the mount project, the positioning of the mount and its stiffness are very important characteristics, as they influence the behavior of the independence of the movement directions and also the isolation performance. For the application of mount project in powertrains, this is not different, as the high isolation performance of the mount is extremely important to ensure the reduction of vibration transmission from the powertrain and, for this, the stiffness of the mount and its attachment point must be adequately selected. Another important factor in the mount project is the modal purity, which quantifies the decoupling between the degrees of freedom, and the greater the modal purity, the greater the decoupling of each degree of freedom in each direction. This is important to reduce the vibrational effects transmitted from a given force in a given direction and also for better control of the vibrational distribution of the system. To describe the modal purity, it is necessary to have information on the natural frequencies and vibration modes of the powertrain suspended on the mounts. To evaluate the isolation performance, the stiffness and damping of the mount must be carefully determined to ensure good isolation. Analytical solutions are developed taking into account the parameters of stiffness, mount damping, mount position, mount angle, mass and the inertia tensor. With these analytical solutions, it was possible to develop an optimization process using optimization algorithms with the objective of finding the parameters that generate high vibrational isolation performance and high modal purity. With this optimization process, it will be possible to improve efficiency in project development by reducing the number of prototypes and tests. After optimization, an increase in vibrational isolation between 1 and 7 dB was observed through the results when compared with the isolation before the optimization. Regarding the modal purity performance, the results also showed significant improvements, where the modal purity of each degree of freedom was generally higher than 85%, whereas, before optimization, there were modal purities below 50%.