Deployable cable nets for active removal of derelict rocket bodies

Two main mechanical models have been proposed to describe the deployment and capture processes by using cable nets. In the first approach, the net is considered as a system of concentrated masses connected to each others by spring-dampers. Springs react only in tension and infinitesimal strains are considered. Alternatively, a finite element model of a cable net can be developed according to the absolute nodal coordinate formulation (ANCF). In this case, finite strains are considered through the Green-Lagrange strain tensor and a weak flexural behaviour for the cable can be included. We developed a new finite element model for the cable net, adopting the nodal positions as the main unknowns of the problem in line with the displacement-based finite element formulation (DFEF). Large displacements and finite deformations are considered through the Green-Lagrange strain tensor. Cable elements are assumed to react only in tension according to a hyper-elastic constitutive law. Global damping is introduced into the model according to Rayleigh's hypothesis. The governing equations for the dynamical problem are solved numerically by means of the Newmark method. As an illustrative example, we present the simulation of the three-dimensional deployment of a planar, square-mesh net. The proposed approach turns out to be computationally effective and accurate.