| Research Abstract |
Objective of the experimental investigations was the design of the colloidal damper and experiments upon this novel principle of mechanical energy dissipation, in order to transform an academic idea into a real product. In order to achieve this it is very important to establish the properties of energy dissipation of the porous material. A colloidal damper static test rig was designed and manufactured. Using this test rig, new porous materials suitable for colloidal damper were found, and the hydrophobic coating of the porous material was improved in order to assure better efficiency. In the previous research the dissipated energy of the nth hysteresis was only 50% of the 1st hysteresis energy. With new materials found, the dissipated energy of the nth hysteresis was increased at 92-93% of the 1st hysteresis energy. Influence of the end-capping was also clarified. Relation between the mean pore diameter of porous material and the optimum length of the coating molecule was understood. T
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hese results will be presented this year in September at the International Conference on Noise and Vibration Engineering, Belgium.
Concerning the dynamic performances of the colloidal damper, a single test rig and a double test rig were designed and manufactured. Using these test rigs the influence of the design parameters on the colloidal damper performances was clarified. These results were presented at the 10th Asia-Pacific Vibration Conference, Australia. Next, in order to estimate the reliability of the colloidal damper, the strength of the porous matrix and its hydrophobic coating were investigated. It was found that structure of porous material and its hydrophobic coating are not affected by high-pressures.
Objective of the theoretical investigations was basic research in order to develop a generalized hydrodynamic theory for the fluid flow into a nano-porous matrix from hydrophobized silica gel. Generalized hydrodynamic theory means that basic structure of Navier-Stokes equations is kept, but in order to include the relation between the macroscopic flow and molecular interactions of the liquid with the hydrophobic coating, slip is allowed on the solid wall. Fully description of the slip boundary condition requires knowledge of the surface diffusion coefficient, i.e., the heights of energy barriers. An original model, based on the heterogeneity of the coating molecules, was proposed for estimation of the energy barriers. Using this model, in order to maximize the dissipated energy, relation between the mean pore diameter of silica gel and the optimum length of the coating molecule was clarified. Theoretical results were in agreement with experimental findings. These results will be presented this year in July at the 5th International ASME Symposium on Computational Technology for Fluid / Thermal / Chemical / Stressed Systems with Industrial Applications, USA and also in ELSEVIER, Journal of Colloid and Interface Science. Less
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