A passenger ship has long spanned deck panels with thin plate and small stiffness compared with a general merchant ship from the viewpoint of the structural arrangement. It is difficult to reinforce and improve wide panels and local structures of a passenger ship because of its interior design when they have vibration problems. Moreover, the allowable vibratory limit for a passenger ship is much lower than that of a commercial ship. In this paper, the paths and magnitude of vibration energy for the long spanned large panel induced by major excitation sources of a passenger ship and the characteristics are introduced. Also, in order to minimize energy transmission to a large panel of the ship, case studies of vibration intensity analysis for the several modification methods of a large panel are described.
The capacitance technique was used to measure the minimum oil film thickness in engine bearing and the central oil film thickness between cam and tappet. This method is based on the measurement of total capacitance of oil film. For the measurement of the oil film thickness between cam and tappet, two surfaces were assumed to be flat and parallel within the Hertzian region and all the measured capacitance originated from this region. Shear rates from the measured minimum oil film thickness are over 10$^{6}$ sec$^{-1}$ in the greater part in both two cases. The minimum oil film thickness in engine bearing is larger than the surface roughness. Between cam and tappet it is mostly smaller than the surface roughness. In spite of the awkward restriction of the reliability of measured oil film thickness, it was known that the capacitance technique makes it possible to measure the oil film thickness in elastohydrodynamic and mixed lubrication regimes as well as in hydrodynamic regime. Therefore, it is also possible to classify the lubrication regimes based on the oil film thickness.
This paper reports on the dynamics and friction characteristics of piston skirt with consideration of mixed lubrication. Piston skirt is an important part of the engine that transforms fuel into mechanical energy. The durability and low friction characteristics are important recent issues in piston skirt design. In this paper, the piston skirt motion is analyzed with consideration of mixed lubrication and piston skirt tilting motion. The entire trajectory of piston motion is obtained by using transient numerical method. Also various parameter studies are performed for piston skirt design and the development of lower frictional engine.
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