VIBRATIONAL POWER TRANSMISSION FROM A MACHINE TO ITS SUPPORTING CYLINDRICAL SHELL

Power flows from a vibratory machine to its supporting structure are of primary concern in a passive or active isolation system design. Although in the literature there is a fair number of investigations on the power inputs to beams, plates or the like, few attempts have been made for other commonly used structures such as cylindrical shells. In this paper, the vibratory power flows from a rigid-body machine to an elastic cylindrical shell are studied considering the contributions of the non-radial (tangential and axial) displacements and forces. In particular, it is argued that the notion that the motion of a thin shell is primarily radial does not necessarily dictate that the power transmissions are predominantly carried out by the radial displacement. This point is subsequently illuminated through numerical examples. Another issue discussed here is concerned with the effects on the power flows of the cross couplings of the (different) displacement components. It is shown that even though the contributions of the cross couplings are usually insignificant, they may become important if the vibration isolators are substantially hard as compared with the local shell stiffness or impedance. This assertion is particularly useful when an experimental technique is used to measure the vibratory power flows into a supporting structure.