Fluidless electronic vibration isolator
Mohammad Jalali Mashayekhi
Date of Issue2008
School of Mechanical and Aerospace Engineering
Vibration isolation is an important issue in automotive and aerospace industry. Because of the increasing importance of fuel consumption reduction, there is a huge trend to construct vehicles with lighter bodies and more power intensive engines. But lighter and more power intensive engines tend to deteriorate the vibration isolation properties of the vehicle. Hydraulic engine mounts are one of the most popular vibration isolators used in industry, to provide cabin noise and vibration isolation. They have been in use in automotive industry since 1962. Their dynamic stiffness is frequency dependent. They provide the best vibration isolation at a frequency called "notch frequency". Significant improvements in vibration isolation using hydraulic engine mounts have been reported in the literature. However due to the complicated fluid structure interaction, their design procedure is somewhat based on trial and error which is a very time consuming and costly method. Because of this trial and error method the manufacturing of fluid mounts is also costly. In addition, as times goes on the dynamic characteristics of the hydraulic engine mount will change. So after a period of operation the engine mount needs to be retuned. The retuning procedure of hydraulic engine mounts is time consuming and costly. In this work the bond graph modeling technique is employed to design the electromechanical equivalent of typical hydraulic engine mount. The objective of this project is to remove the fluid and replace it with a more tunable mechanism. The advantage of the electronic (non-fluid based) engine mount over hydraulic (fluid based) engine mounts is that its dynamic stiffness especially the notch frequency is sensitive to electronic components.