Great Lakes bulk carriers of recent construction are propelled by geared diesel machinery. Although this machinery is similar to propulsion sets that have been used successfully in numerous other vessel types, it has experienced failures in sufficient number to suggest that the Lakes ships present unique service features. This report explores the hypothesis that a significant unique feature is deflection of hull in way of the machinery spaces, with consequent upsetting of the transmission equipment alignment. Hull deflections are analyzed by a detailed finite-element model of the aft end of the hull, using the University of Michigan MSAP IV computer program. The analysis is applied to two ships built in the late 1970's (identified as Ship A and Ship B) under the extremes of loading that these ships can experience. Displacements and rotations are found at nodes that represent significant points (e.g. shaft bearings) within the machinery. Machinery alignment specifications of reduction gear builders, of ship designers and builders, and the alignment practices of the ship builders, are reviewed. Since these specifications and techniques are not based on ability to predict hull deflections in service, this report discusses how such predictions, based on the finite element analyses, can modify them.
Deflections of Hull Propulsion Shafting of Great Lakes Ore Carriers
1981
92 pages
Report
Keine Angabe
Englisch
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