An Enhanced Cohesive Crack Element for XFEM using a Double Enriched Displacement Field

Applying the principles of the eXtended Finite ElementMethod a partly cracked cohesive element is developed. The element is based on a double enrichment of the standard displacement field, which allows the element to model equal stresses at the both sides of the crack in the crack-tip element. The formulation is implemented for the 3 node Constant Strain Triangle (CST). A general stress calculation in the cracked elements is presented, the principle is based on an area weighing of the stresses in the cracked elements, which gives a continuous transition from the uncracked respectively the fully cracked element. The performance of the developed element is tested in a Three Point Bending Test, where the partly cracked element gives a good over all structural response. Furthermore the partly cracked element gives results without the often seen zigzag behaviour on the load-deflection curve.