Hydro-plastic slamming

Abstract

Ships and offshore structures will unavoidably experience water impacts (slamming) through-out their service time. During slamming, the coupling between hydrodynamic pressure and the elastic structural response, termed as hydro-elasticity, has been studied extensively. However, when the structure is encountered by steep and energetic waves in extreme sea states, structural stresses may exceed the material yield stress, causing large plastic flow and structural damage. This hydro-elastoplastic slamming phenomenon has rarely been studied. Recently, we formulated an analytical solution to the hydro-plastic response of beams and stiffened panels subjected to extreme water slamming (Yu et al., 2018a, Yu et al., 2018b), coupling the hydrodynamic loading and the structural response. The model assumes that in the extreme slamming events, plastic structural deformation energy is dominant and the elastic effect can be neglected. This paper briefly introduces the idea behind the analytical hydro-plastic slamming model. Non-dimensional parameters governing the hydro-plastic phenomenon are identified and discussed. A validation of the model is presented by comparison with multi-material Arbitrary Lagrangian Eulerian (ALE) simulations in LS-DYNA. The results are discussed. The resulting non-dimensional curves are good candidates as design curves for designing against extreme water slamming in Accidental Limit States (ALS).