Numerical investigation of the hull girder ultimate strength under realistic cyclic loading derived from long-term hydroelastic analysis

ABSTRACT

Traditionally, the hull girder ultimate strength is determined by subjecting the structure to monotonic increasing loads. However, it is well-known that ships are continuously subjected to cyclic loads induced by waves. Therefore, some doubts are cast on the probability that alternating loads may reduce the hull girder ultimate strength. This research aims to analyze the influence of cyclic loads over the structural capacity by considering realistic loading scenarios resulting from a longterm hydroelastic analysis. The ultimate strength of a containership is analyzed numerically on a partial structural model using the nonlinear finite element approach. Different material properties are considered to investigate how the hardening and softening effects in steel affect the structural capacity. Finally, the ultimate strength determined under cyclic loading is compared to the standard ultimate strength determined under monotonic increasing loads. It is shown that for the considered containership, the cyclic loading has a negligible effect on the ultimate strength.

Keywords:

• Ultimate strength
• cyclic load
• nonlinear isotropic-kinematic hardening
• nonlinear FEM

Disclosure statement

No potential conflict of interest was reported by the author(s).