  Port-Hamiltonian (PH) systems provide a framework for modeling, analysis and
control of complex dynamical systems, where the complexity might result from
multi-physical couplings, non-trivial domains and diverse nonlinearities. A
major benefit of the PH representation is the explicit formulation of power
interfaces, so-called ports, which allow for a power-preserving interconnection
of subsystems to compose flexible multibody systems in a modular way. In this
work, we present a PH representation of geometrically exact strings with
nonlinear material behaviour. Furthermore, using structure-preserving
discretization techniques a corresponding finite-dimensional PH state space
model is developed. Applying mixed finite elements, the semi-discrete model
retains the PH structure and the ports (pairs of velocities and forces) on the
discrete level. Moreover, discrete derivatives are used in order to obtain an
energy-consistent time-stepping method. The numerical properties of the newly
devised model are investigated in a representative example. The developed PH
state space model can be used for structure-preserving simulation and model
order reduction as well as feedforward and feedback control design.
