The exact material behavior is not known a priori in a collision event involving ships or offshore structures due to the vast number of ships with different materials and the variation in material properties from manufacturer to manufacturer and from material batch to batch. Hence, assumptions are necessary when calculating the resistance to a collision event.
A common starting point can be the requirements to the material quality set by regulatory bodies, often giving a range of allowable yield stress, ultimate stress and elongation at ultimate stress. This leaves the actual hardening response to the engineer.
This paper investigates the consequences of different choices of plastic work hardening calibrated to the same assumption of yield stress, ultimate stress and elongation at failure. Non-linear finite element analysis of ship collision is utilized. The findings are discussed, and some recommendations given.
The simulations shows that the collision response is highly sensitive to the actual material response; initial yield stress, tensile strength, strain at tensile strength and the rate of work hardening are all essential in this context.