Abaqus - XFEM and Fracture Mechanics

Hello SIMULIA community,

We have certain questions regarding the use of XFEM in Abaqus.

  1. Why is the contour integral not available for second order hexahedral elements with XFEM enrichment?
  2. It is well known that at the boundary of enriched and non-enriched elements a layer of elements (blending elements) can have some nodes enriched while other are not enriched. This can cause accuracy issues. Proposed solutions include using correction in blending elements (for e.g. see https://onlinelibrary.wiley.com/doi/10.1002/nme.2259). Is this implemented in Abaqus?
  3. A recent enhancement seems to have allowed second order tetrahedral elements to be used for conventional FE method contour integral. Is there an example of how the mesh need to look like at the crack tip? In other words is a focused mesh around crack tip/front necessary? Is there an example file where this feature is exercised?
  4. Abaqus manual says for XFEM "virtual crack extension direction are determined by Abaqus/Standard". What is the criterion for picking a virtual crack extension direction?

Thank you in advance for your contributions!


XFEM Structures FractureMechanics  Abaqus