Crack growth analysis in a double-lug bracket
This analysis demonstrates growth of a crack in one of the lugs of a double-lug bracket. The pin passing through the lugs is modelled as a rigid body with contact definitions on the inner lug surfaces. The loading is a constant amplitude displacement on the pin.
The region into which the crack is inserted is partitioned from the rest of the model to allow hex elements near the crack with tets elsewhere. The initial crack has radius 0.25mm and is located at the chamfered outer corner of one of the lugs (Figures 4 to 7).
As the crack grows around the chamfer and the other 90 degree corner on the inside of the lug, the mesh is allowed relax. This introduces some smoothing to the original hard edges of the model but allows the crack to be grown across the entire cross-section in a single analysis.
The animations and growth profiles show that the crack grows in a very slightly non-planar fashion.
This model is also available as a multi-crack example using the remeshing method.
Figure 1 - Intact model
Figure 2 - Meshed model
Figure 3 - Close-up of the lug in the uncracked mesh into which the crack is to be placed
Figure 4 - Close-up of the lug in the uncracked mesh into which the crack is to be placed, cut away to show the initial crack plane
Figure 5 - Close-up of the cracked mesh, cut away to show the initial crack plane
Figure 6 - Uncracked mesh, cut view
Figure 7 - Initial cracked mesh, cut view
Figure 8 - Crack profiles shown in the Zencrack GUI
Figure 13 - Crack profiles showing tracer lines for the 0.1, 0.5 and 0.9 parametric distance positions
Figure 14 - Ki vs crack growth at 0.1, 0.5 and 0.9 parametric distances along the crack fronts
Figure 15 - Crack growth vs cycles at 0.1, 0.5 and 0.9 parametric distances along the crack fronts