3D Model for Active Vibration Control of Rotating Machines Mounted on Active Machine Foot Mounts Using Vibration Mode Coupling by Asymmetry

Abstract

PurposeIn this work, active vibration control of rotating machines mounted on active machine foot mounts is investigated.MethodsTherefore, a simplified 3D model is derived and the mathematical coherences are described. Different mathematical solutions are presented for special boundary conditions and a method called “vibration mode coupling by asymmetry” is derived.ResultsIt could be shown that a symmetrical system with a machine design, where the center of gravity lies symmetrically between the machine feet with a vertical distance, and where all actuators are identical, represents a system, where all vibration shapes but one can be influenced by the controllers, when the gyroscopic effect can be neglected. In this case, a special vibration shape occurs—where the machine is only rotating at its vertical axis—which cannot be influenced by the controllers. When the stiffness and/or damping in axial and/or horizontal direction of only one actuator will be changed—which will lead to an asymmetrical system—the vibration shape with pure rotation at the vertical axis will not exist anymore. Now, the vibration shapes will become more coupled and they all can be influenced by the controllers, which is here called “vibration mode coupling by asymmetry”.ConclusionsWith the here presented method of “vibration mode coupling by asymmetry”, all vibrations mode shapes can now be active controlled.