Platform Modeling

    Usually, any code performing electromagnetic calculations requires, as a part of the input, a target model.

    In order for a model to be acceptable to a particular computational software, it must satisfy a set of specific requirements determined by the design and algorithms of this software.

    Some computational systems include components for building target models, and some assume that the models, in suitable format, must be supplied by the user.

    DOVA was conceived and designed to utilize already existing  platform models.

    Such models may be available from an aircraft manufacturer or a commercial vendor. They may have also been generated with the use of scanning technology or  built with one of the many commercially available design packages.

    Typically, aircraft or other platform models are created by computer aided design (CAD) software systems which let the user output a representation of the model in some electronic format, usually, specific for the utilized CAD system.

    In order to exchange information between different CAD systems, various translators/converters have been developed.

    Such translators are supposed to make a representation developed by one system readable by another system.

    However, such a translation/conversion can be a very complex process and certain information in this process may be lost or distorted.

    Consequently, as a general rule, it is a good practice to examine the model for consistency and absence of defects.

    In order to make this task easier for the DOVA user, we identified several very basic requirements that models intended to be analyzed with DOVA should satisfy.

The following list, broken into two groups, describes these requirements.

  1. The aircraft surface should consist of planar triangular facets (triangles).
  2. Any pair of surface triangles should either have no points in common, or have only one common edge, or a common vertex. Overlaps are not allowed.
  3. Each edge of a surface triangle should be shared by exactly two triangles.
  4. The aircraft surface must be connected, that is, on such surface it should be possible to connect any two points with a continuous curve lying completely on the surface.
  5. The aircraft surface is oriented by the outward normal.
  6. Interior parts, such as chairs, internal walls, devices, etc. should be removed.
  7. Engine inlets should be closed.
  8. Let l(e) denote the length of an edge e (the specific units of length are not important). m = min l(e) and M = max l(e), where the min and max are taken over all edges on the surface. It is desirable that M/m < 20 and m > 0.1
  9. Let a(T) and A(T) denote, respectively, the smallest and the largest angle (in degrees) in a triangle T. Let p = min a(T) and P = max A(T), where the min and max are taken over all surface triangles. It is desirable that p > 5 degrees and P < 175 degrees.
A large number of currently available CAD files representing realistic platform models have the potential of being utilized for electromagnetic simulations and analyses, possibly after some preprocessing. Model verification and necessary preprocessing can be accomplished with Matis' specially developed system GeomFix.

Read about GeomFix
a ToolBox for Evaluating and Fixing Geometry of Surface Models.

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SERVICES:  Fixing Geometry   Computing Patterns