An analytical method for determination of the energy released for rupture and plastic deformation in the vessels in a given deterministic ship collision has been developed in Ref. [36]. Here the energy loss available for dissipation in structural deformations is given in closed-form expressions. The procedure is based on a 2D rigid body mechanism, where it is assumed that there is negligible strain energy for deformation outside the contact region and that this region is local and small. This implies that the collision can be considered as instantaneous and each body is assumed to exert an impulsive force on the other at the point of contact. The model includes friction between the impacting surfaces so that situations with glancing blows can be identified. At the start of the calculation, the ships involved can have forward motion, and the influences of the hydrodynamic forces due to the sudden de-acceleration of the involved vessels are in this model approximated by simple added mass coefficients. In Brown [37] this analytical method is compared to comprehensive time simulation results and good agreement is found. Tabri et al. [38] and [39] have demonstrated that the external dynamic behaviour measured in full-scale symmetric experiments can be modelled quite well by model experiments in a towing tank as well as by numerical procedures.
As an example, Fig. 12 shows the calculated energy released for crushing of two colliding identical supply vessels, at different collision angles and striking locations along the hull girder of the struck vessel. The results have been obtained by the analytical approach. From this figure it is seen that for given ship’s speeds the impact location and angle distributions play a significant role for the amount of energy released for crushing of the two vessels.