High-Performance Stringer-Stiffened Composite Hull Structures under Slamming Loads: The Effects of Hydroelasticity and Non-Uniform Pressure Distributions

Water impacts form a critical load for the outer hull panels of small high-speed marine craft. These result in a highly localised non-uniform pressure pulse, which propagates along a hull panel as it is immersed. While slamming is multi-faceted and stochastic, the severity of the impact is primarily a function of the vertical impact velocity and the angle between the panel and free surface, known as the deadrise. Due to the complexities of water impacts, design standards —such as those defined in ISO 12215-5— recommend that hull panels are designed based on a static uniform pressure. However, these are unable to produce the same strain state as a water impact, leading to a disconnect between real-world and as-designed performance. This study addresses this gap using hydroelastic simulations of the slamming of a stringer-stiffened panel typical of current generations of ocean-going racing yachts, and makes suggestions to improve the analysis of such structures during the design process. Results indicate that the structural response of such panels depends on the location of the pressure pulse and the effects of hydroelasticity, which are not accounted for when using a uniform pressure. The Authors recommend that design processes may be improved by statically solving for key instants during the water impact using analytically derived non-uniform pressures. Such a method reduces the discrepancy between real-world and as-designed laminate strains to only 33.6%, compared to the 65.8% reported when using a uniform pressure load, representing a significant improvement over the current design standards. Keywords stringer-stiffened composite panels; marine hull structures; slamming loads; constant velocity water impacts; hat/omega stringers