Numerical modeling of cable-rigid-body structural systems using the NP-FEM method

Resumo

This work presents a numerical formulation based on the Finite Element Method (FEM) to solve non-
linear dynamic problems involving cable-rigid-body structural systems. The Nodal Position Finite Element

Method (NP-FEM), used for cable modeling, is a simple and robust method that resolves directly the position of
cable nodes instead of indirectly using displacements. In this way, a polar decomposition of the cable elastic
deformations and rigid body rotations are not necessary, eliminating errors in the incremental approximations
existing in classic FEM formulations. The method is suitable for simulating cables with large rigid body
rotations and small elastic axial deformations. The body linked to the cable is treated as a rigid body with six
degrees of freedom and the cable-rigid-body coupling is done by creating an extra, massless, cable element with
a very large axial rigidity to simulate the rigid link between the cable free end and the center of gravity (CG) of
the rigid body. The algorithm is verified through comparisons with other authors, using their own numerical
codes or commercials software, and experimental predictions. Results are very close to those of the references
and proved that the formulation proposed here is quite efficient, reliable and stable for the examples simulated.