Detail Analysis of Ship Structures
Defence Research Establishment Atlantic Dartmouth, Nova Scotia Canada
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This paper describes an improved approach to finite element modeling of ship structural details for design and in-service assessment. Specialized meshing algorithms have been developed which create finite element meshes of three-dimensional detail structure from predefined templates of the detail boundaries and associated meshing parameters. The ship structural details are divided into classes such as stiffener intersections, brackets, bulkhead-stiffener intersections or cut-outs, which have-common meshing parameters. Classes can be identified from lists of standard ship structural details produced by classification societies or for a specific ship type. Parametric stress analyses have been undertaken for these classes in advance to determine suitable finite element size distributions which are stored in a database and used to quickly generate the selected detail meshes when required. A relational object oriented global ship model is currently being developed from which users can graphically select a connection. The connection is checked against the predefined templates and the geometric parameters describing the detail are collected to direct the mesh development. Early use of this approach shows that it has the potential to reduce the overall time to produce a ship detail mesh from several days, using general-purpose finite element model generators, to under an hour. This improved detail meshing approach is being incorporated into an overall finite element based ship structural analysis program that uses global ship displacement results in a semi-automated top-down analysis of structural details. Overall, this approach will significantly reduce the time necessary to undertake complex analysis of ship structural details.