A coupled FE-IGA technique for modeling fatigue crack growth in engineering materials.

In this paper, a novel technique has been developed by coupling the conventional finite element method (FEM) with the extended iso-geometric approach (XIGA) for modeling crack growth in engineering materials. The new proposed technique, named as the coupled FE-IGA technique, exploits the advantages of both the FEM and the XIGA. XIGA is used for the approximation of the displacement field in the region surrounding the crack surfaces, whereas the rest of the domain is discretized into conventional Lagrange finite elements. The transition elements are used to connect FEM portion of the domain with the XIGA region. The displacement approximations across the transition elements must preserve the continuity between XIGA and FEM solutions. The Ramp function approach is used for the approximation of the displacement field across the transition elements. The discontinuities such as cracks, holes, inclusions and other material interfaces are modeled independent of the mesh in coupled FE-IGA technique. The standard displacement approximations are enriched with appropriate enrichment functions, which introduce the effect of different discontinuities into the formulation. Finally, several numerical problems are solved by the coupled FE-IGA technique to demonstrate the capabilities of this novel approach in modeling fatigue crack growth in engineering materials. [ABSTRACT FROM AUTHOR]