Justifications for using ANCF Finite Elements - Technical Report # MBS2022-4-UIC

This report provides the justifications for introducing and using the finite elements (FE) of the absolute nodal coordinate formulation (ANCF). These elements have specific features that distinguish them from conventional finite elements and make them more suited for the large displacement analysis of multibody system (MBS) applications. Furthermore, the continuum kinematic description of fully parameterized ANCF elements cannot be ignored when interpreting the ANCF numerical results and comparing these results with results obtained using semi-discrete models often used with conventional beams and analytical solutions that are based on more simplifying assumptions. For example, torsion is associated with space-curve geometry and is not one of the basic continuum-mechanics shear-strain modes. ANCF displacement fields allow increasing the order of interpolation without increasing the number of nodes or using the noncommutative finite rotations. Such displacement fields also allow developing lower-dimension infinitesimal rotation ANCF/CRBF finite elements without lowering the order of the interpolation.