Design of aluminium alloy platings for pleasure vessels under slamming loads

This paper focuses on the bottom platings’ design of pleasure vessels, made up of aluminium alloy, under impact slamming loads. Despite of the classical rule approach, a direct scantling procedure is adopted, evaluating such pressure loads by the Wagner’s expanding plate model, corrected with the air tripping effects. The ship transverse section is schematized as a rigid wedge entering a body of water and a rectangular type of impulse history is assumed, too. Subsequently, to analyze the impact load related response, the rigid-plastic theory is applied, subdividing the ultimate strength design formulation into two steps, namely the quasi-static and the dynamic one. The correction proposed by Cowper & Symonds is also applied, to account for the effects of the strain rate on the aluminium alloy yielding strength. Finally, some numerical analyses are carried out, varying the plating aspect ratio, the transverse section deadrise angle, as well as the initial impact velocity between the plate and the water surface.