DYNAMIC STABILITY OF NONLINEAR BARGE-TOWING SYSTEM

A method for predicting the dynamic stability of a nonlinear barge-towing system is presented in which the equations of motion of the dynamic system are first transformed into a six-dimensional state-space equation. The governing equation is then linearised by using the Taylor series expanding with respect to the equilibrium configurations of the towed barge. It is found that the stability conditions of a towing system are determined by the signs of the real part of some associated eigenvalues: Positive and negative I's will result in unstable and stable dynamic responses, respectively and 0 corresponds to the marginally stable condition. The reliability of the foregoing criteria is confirmed by the time histories (simulations) of the nonlinear barge-towing system. The effects of the stabilising skegs and the length and material of the towrope are also studied. Numerical results show that the skegs significantly improve the course stability of the towed barge and that the length and material of the towrope are also key factors affecting the dynamic stability of the barge-towing system.