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This paper presents the results of a study on a tuned liquid damper (TLD). The TLD uses air and liquid inside a U-shape tank as the mass of dynamic damper of a structure. By using the Lagrange method, the dynamic equation of motion for the fluid inside the structure with this U-shape tuned liquid damper is derived. The natural frequency of the U-shape TLD is determined by finding the peak value of displacements of the liquid versus exciting accelerations. Vibration behaviours of the structure with and without U-shape TLD subjected to a simple harmonic excitation are examined in the time domain. Effects of mass ratio (mass of U-shape TLD/mass of structure) on vibration reduction are also studied.

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The paper deals with the procedure of removing a gouge phenomenon on impeller surfaces in 5-axis machining. That is, when an impeller of a centrifugal compressor is being cut, tool marks on its surfaces may exist in finish milling due to reverse movements of moving axes along a 5-axis interference-free tool path. For generating interference-free cutter location (CL) data needed in rough and semi-finish 5-axis cutting processes, first, a simple yet useful approach is proposed. To identify the potential gouge area and to solve the problem for a tool path having reverse motion directions with its moving axes in finish milling, the CL data are further smoothed to remove the reverse movements about its rotating and tilting axes. The effectiveness of this procedure has been experimentally confirmed by successful 5-axis finish milling of an impeller without leaving tool marks on its surfaces.