  Isogeometric cohesive elements are presented for modeling two and three
dimensional delaminated composite structures. We exploit the knot insertion
algorithm offered by NURBS (Non Uniform Rational B-splines) to generate
cohesive elements along delamination planes in an automatic fashion. A complete
computational framework is presented including pre-processing, processing and
post-processing. They are explained in details and implemented in MIGFEM--an
open source Matlab Isogemetric Analysis code developed by the authors. The
composite laminates are modeled using both NURBS solid and shell elements.
Several two and three dimensional examples ranging from standard delamination
tests (the mixed mode bending test), the L-shaped specimen with a fillet, three
dimensional (3D) double cantilever beam and a 3D singly curved thick-walled
laminate are provided. To the authors' knowledge, it is the first time that
NURBS-based isogeometric analysis for two/three dimensional delamination
modeling is presented. For all examples considered, the proposed framework
outperforms conventional Lagrange finite elements.
