Defence Research Establishment Atlantic Dartmouth, Nova Scotia Canada
This paper describes an improved approach to finite element modelling 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 cutouts, which would have a common set of 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 can be undertaken for these classes in advance to determine suitable meshing parameters which can be stored in a database and used to quickly generate the required detail meshes when required. The overall time to produce a ship detail mesh is reduced from several days using general purpose finite element model generators to a couple of hours. This improved detail meshing approach is being incorporated into an overall finite element based ship structural analysis program which uses global ship displacement results in a semi-automated top-down analysis of structural details. Specialized spectral sea load codes are used with the global ship model to produce stress spectra or extreme loads in the details for fatigue or ultimate strength analysis. Overall, this approach greatly reduces the time necessary to undertake complex analysis of ship structural details.