Multi-Patch Isogeometric Analysis of Space Rods

This paper deals with the isogeometric analysis using B-splines of space rods subject to Kirchhoff-Love hypotheses. A multi-patch isogeometric approach for the numerical analysis of the three-dimensional Kirchhoff-Love rod theory is developed. We use Bezier and B-splines interpolations and we show that they are able to attain very good accuracy for rod structures, particularly for developing a three-dimensional exact curve element with geometric torsion. The patches in general present a C-continuity in the interior and are joined with C-continuity, so that the global tangent stiffness operator in general is singular. In order to avoid the singularity in the stiffness operator several continuity conditions at the joints of the patches are required. Either parametric or geometric continuity or can be imposed. In this work, we show how parametric continuity can be imposed by means of two additional constraints.