Post-failure behavior of long wires under dynamic pulse buckling

Resumo

The phenomenon of dynamic pulse buckling, which can appear with the failure of long slender structures
under tension, as offshore structures such as risers, has drawn the attention of the interest of researchers due
to accidents and the damage they can cause to the environment. The risers connect floating units to flowlines
and other equipment on the seabed and are used for drilling and exploration of oil and gas. Experimental and
numerical researches have been conducted in reduced wire models to study post-failure behavior, mainly after the
compressive elastic unloading wave reaches the fixed end, being reflected and giving rise to a buckling located
near this end. This work addresses the finite element modeling and simulation of dynamic pulse buckling in
wire failure tests. An elastoplastic model with linear hardening is adopted for the material behavior. Explicit and
implicit integration algorithms are used for nonlinear dynamic analysis considering 2D and 3D beam elements with
large displacements and strains. The effects of the finite element type, mesh discretization, integration algorithm,
geometric imperfections, numerical damping, wire length, and time step in the post-failure behavior are assessed
and the implications of these results for the simulation of post-failure analysis of marine risers are discussed.