Shape definition

@SHAPE_DEFINITION {
@SHAPE_NAME {ShapeName} {
@SHAPE_TYPE {ShpType}
@COORDINATE_TYPE {CoordType}
@ETA_COORDINATE {η} {
@CURVE_NAME {CurveName}
@SCALING_FACTOR {s1, s2, s3}
@ORIGIN {x1, x2, x3}
}
@ETA_COORDINATE {η} {
@SURFACE_NAME {SurfaceName}
@SCALING_FACTOR {s1, s2, s3}
@ORIGIN {x1, x2, x3}
}
@COMMENTS {CommentText}
}
}

NOTES

  1. To add realism to the visualization of the multibody system, external shapes can be added to specific elements of the model such as beams and rigid body masses. Shapes can be of two types, depending on the value of parameter ShpType.
    • If ShpType = CURVE, the shape will be generated based on a number of NURBS curves. For each coordinate, keyword @CURVE_NAME is expected.
    • If ShpType = SURFACE, the shape will be generated based on a number of NURBS surfaces. For each coordinate, keyword @SURFACE_NAME is expected.
  2. The shape defines a single entry table, see section~\ref{Table: Single Entry Table} of curves or surfaces a curve. Table entries consist of a sequence of coordinates that parameterize a curve, see section~\ref{Curve: Parameterization}. All the entries of the table must be defined using the same Parameterization, as specified by the keyword CoordType which can take one of the following three values.
    • If CoordType = CURVILINEAR_COORDINATE, each new entry in the table is defined by the keyword @ETA_COORDINATE. s-coordinates are used to parameterize the curve.
    • If CoordType = ETA_COORDINATE, each new entry in the table is defined by the keyword @CURVILINEAR_COORDINATE. η-coordinates are used to parameterize the curve.
    • If CoordType = AXIAL_COORDINATE, each new entry in the table is defined by the keyword @AXIAL_COORDINATE. x-coordinates are used to parameterize the curve.
  3. For a beam, the shape should be of the CURVE type and defined by a number of curves at specific coordinate locations along the curve defining the geometry of the beam. At each coordinate location, a curve CurveName is defined. This curve can be scaled and shifted with respect to the axis of the the beam using the scaling factors s1, s2, s3 and origin shifts x1, x2, x3. The curves are defined in the plane of the beam cross-section, i.e. the curve must be in the (i2, i3) plane.
  4. For rigid body masses with coincident points, the outer shape should be defined by a single surface. If the points defining the rigid body are not coincident, the shape should be defined by a number of surfaces at specific η locations along the line joining the two points of the rigid body. At each η location, a surface SurfaceName is defined. This surface can be scaled and shifted with respect to the axis joining the two points of the rigid body using the scaling factors s1, s2, s3 and origin shifts x1, x2, x3.
  5. It is possible to attach comments to the definition of the object; these comments have no effect on its definition.