Abstract: By analyzing the relationship among structural collision damage, collision energy transformation and collision force of ship structure, the critical collision velocity was defined as an crashworthiness index, and the crashworthiness optimization formulation was established. The fishing vessels-vessels collision was taken as an example, numerical calculation of ship right collision was carried out. The influences of striking velocity on the collision characteristic such as deformation, energy transformation and collision force of the broadside structure of the struck ship were compared, the critical velocity of struck ship structure was determined, aiming at improving the critical collision speed of struck ship structure a proposal was given. The results of numerical calculation show that it is feasible to evaluate the crashworthiness index based on the safety critical velocity.

Key words: critical velocity, fishing vessels, crashworthiness, crashworthiness index