20.1.5 Controlling the singularity at the crack tip for a small-strain analysis

If the geometry of the crack region defines a sharp crack, the strain field becomes singular at the crack tip, as described in Constructing a fracture mechanics mesh for small-strain analysis” in “Contour integral evaluation, Section 7.10.2 of the ABAQUS Analysis User's Manual. Including the singularity in your model for a small-strain analysis improves the accuracy of the contour integral and the stress and strain calculations.

To include the singularity in your contour integral estimates, click the Singularity tab in the Crack editor and choose the desired position of the midside node and degenerate element control. For detailed instructions, see Controlling the singularity at the crack tip, Section 20.1.10.

In addition, you must do the following in the Mesh module:

When you mesh the crack front, ABAQUS does the following:

An instance of an orphan mesh part is always a dependent instance. As a result, you cannot adjust the midside nodes of instances of orphan mesh parts in the assembly. For more information, see What is the difference between editing an orphan mesh part, a meshed part, and a meshed part instance in the assembly?, Section 41.2. You must display the original orphan mesh part and use the Edit Mesh toolset to adjust the position of the midsize nodes. For more information, see Adjusting the position of midside nodes, Section 41.5.5. In addition, you cannot create collapsed elements from triangular and wedge elements of an orphan mesh.