Modal Energy Propagation Method in Coupled systems of Rigid and Flexible Structure

Abstract

The crankcase and oil pan in an internal combustion engine or the frame and panel in an automobiles are coupled systems of the flexible and rigid structure. In these systems, vibration of the flexible structure often becomes one of the major noise sources when the excitation force is applied to the rigid structure. Though the rigidity changes, mass addition and damping treatment are employed for noise control of these structures, FEM and modal analysis technique are not sufficient to carry out the effective low noise design. In this paper, new low noise design approach, Modal energy propagation method, is proposed based on the modal synthesis method and the vibration power flow between the eigen mode of the rigid and flexible structures. Reducing large vibration power flow between the eigen mode of each structure brings effective low noise design. This method is formulated based on the modal synthesis method which employs the vibratory characteristics of each structure and static deformation caused by the displacement of the connecting points. This method is applied to vibration control of the box and cover model and the availability of vibration power flow control approach are discussed.