Darting in composite design is used to relieve stress in areas where the composite is either wrinkling or bridging. Bridging is when the fiber cells are shortened along the direction through the Ply origin. This occurs where there is not enough composite material to cover the tool surface and the material needs to stretch to cover the entire surface. To relieve this type of stress, a V-dart is used
A V-dart is created in the Plies form in the Additional Geometry section. Click the downward arrow to open the dart list and select V-Shape Dart. The V-Dart Dialog will popup and create a new dart. The Darts can also be accessed in the Manufacturing section of the Applications tree.
A V-Shape Dart is created by specifying two curves, either by placing points or selecting curves. When defining by points, the first curve needs to consist of at least two points, and the second must consist of at least one. To ensure that the two curves meet, Fibersim will use the first point of the first curve as the first point in the second curve (and to denote the “top” of the dart), so only the bottom point of the second curve needs to be defined. Then click the Generate Dart button to create the Dart feature.
Once the Dart feature is generated, rerun the producibility to see the effect of the dart on the ply draping. The section of red stress is now relieved. An additional patch ply can be created using the V-shaped dart geometry as its boundary (and an origin point on the upper flange of the part, in the gap created by the V-dart). Doing so will result in a butt-splice, but the dart curves can be offset if an overlap splice is required.