A practical method to determine the dynamic fracture strain for the nonlinear finite element analysis of structural crashworthiness in ship–ship collisions

ABSTRACT

Ship–ship collisions continue to occur regardless of efforts to prevent them. The collisions involve highly nonlinear characteristics associated with structural crashworthiness, including crushing and fracture as well as buckling and plastic collapse. When applying nonlinear finite element analysis (NLFEA) to solve these problems, a reliable critical fracture strain accounting for strain-rate effects due to collision speed must be implemented. This study proposes a practical method to estimate the dynamic fracture strain to be used for the structural crashworthiness analysis associated with the collisions. For this purpose, the strain-rate characteristics in struck ship were investigated by NLFEA, in which the striking vessel was assigned various velocities in the range of practical ship speeds. Based on computations, an empirical formula was developed to calculate the strain rate at a given collision speed, allowing for a practical estimation of the dynamic fracture strain. The formula is validated by a comparison with experiment.

KEYWORDS:

• Ship–ship collision
• structural crashworthiness
• strain rate
• dynamic fracture strain
• nonlinear finite element analysis

Acknowledgments

The present study was undertaken in the Korea Ship and Offshore Research Institute at Pusan National University which has been a Lloyd's Register Foundation Research Centre of Excellence. This work was supported by a 2-Year Research Grant of Pusan National University.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

2-Year Research Grant of Pusan National University.