A NEW DAMPER DESIGN FOR MACHINE-TOOL STRUCTURES - THE REPLICATED INTERNAL VISCOUS DAMPER

Good stiffness and damping are each necessary, but not individually sufficient, requirements for a precision machine. Damping provided by the materials and joints in a machine are typically low. This article introduces the concept of an internal damping device: a replicated internal viscous damper. This type of damper uses internal beams covered with a viscous fluid that are then replicated in place inside structural members. The viscous fluid first acts as a mold release and then as a very thin viscous shear layer. The design theory is developed and shown to agree with experimental results. Amplification at resonance factors (i. e., the quality factor Q) on the order of 20 are obtainable (one to two orders of magnitude better damped than many types of materials). This enables machine tool and instrument design engineers to worry less about material damping considerations, which can help to increase design options.