In naval ships, some methods or devices are acquired both to cut off the transmission of vibration from shipboard machineries and to protect them from external shock loading. One of the approaches is to install the passive mountings between machinery and a flexible supporting structure. More advanced performance has become necessary recently so far as at high frequencies in order to retain the stealth function of certain types of naval vessels.For the purpose of this research, a novel hybrid mount for shipboard machinery installed on naval ships was developed. The mount is combined with a rubber mount and piezostack actuators. The rubber mount is one of the most popular and effective passive mounts to have been applied to various vibration systems to date. The piezostack actuator is featured by a fast response time, small displacement and low power consumption. Through a series of experimental tests conducted in accordance with MIL-M-17185A(SHIPS), MIL-M-17508F(SH), and MIL-S-901D which are US military specifications related to the performance requirements of the mount, it has been confirmed that the hybrid mount shows more effective performance for use in naval ships.
A macro-parametric approach, which is a history-based method of parametric CAD model exchange, has recently been proposed. CAD models can be exchanged in the form of a macro file that comprises a sequence of modeling commands. As a set of event-driven commands, a standard macro file can transfer the designer intent such as parameters, features and constraints. Moreover, it is suitable for a network environment because standard macro commands are open and explicit, and the data size is small. This paper introduces XML technology to represent the macroparametric exchange. Using XML to represent macro-parametric commands enables the management of a large amount of dynamic content, Web-enabled distributed applications, and the inherent characteristics of structure and validation.
A B-spline based higher order panel method (hereinafter, HiPan) is developed for the motion of bodies in ideal fluid, either of infinite extent or with free boundary surface. In this method, both the geometry and the potential are represented by B-splines, and it guarantees more accurate results than most potential based panel methods. In the present work, we apply the HiPan, which differs with the works at MIT in evaluating the induction integrals, to two major marine hydrodynamic problems: analysis of propulsive performance of the marine propellers and the motion of the floating bodies on the free surface. The present HiPan is shown superior to the constant panel method (hereinafter, CoPan) in predicting flow quantities in the area of the thin trailing edge and blade tip of the propeller. Numerical results are validated by comparison with experimental measurements.
An experimental method to estimate the added mass of a marine propeller has been developed for the axial rigid body motion in still water, and the experiments have been
This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License(http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.Shipboard equipment in naval ships should be designed to be safe under the shock load. Very high stress due to the shock load can be effectively reduced by the resilient mounts considering the mount capacity and dynamic characteristics. An optimum arrangement of resilient mount installed to absorb the shock energy is addressed to assess the safety of ship structure and shipboard equipment subjected to the shock load. Structural responses are analyzed for both frame structure supporting the shipboard equipment subject to the shock load with and without the resilient mounts. The shock absorbability of the resilient mount is evaluated by the results of structural response analysis; meanwhile, several types of shock analyses considering the arrangement of resilient mounts are carried out and the shock responses are compared to verify the effect of the arrangement. Thereafter, optimum arrangements are obtained by means of Genetic algorithm (GA) considering the different capacities of resilient mount. Stress, deformation and dynamic feature at the frame structure supporting the shipboard equipment under the shock load are also discussed in order to meet the capacity of resilient mount.
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