Abstract:
Prediction of damage to hull panelling during dynamic slamming impacts is critical in the design of safe vessels. Modern composite hull design often utilises high ductility polymeric foams in a sandwich construction for regions likely to undergo slamming during operation. The nature of these constructions, which have large failure strains compared with metallic constructions, can result in panelling that undergoes significant deformations during slamming impacts. These deformations have been shown to affect the applied pressure distribution and magnitude. This paper addresses how the stress state in the core varies as a result of flexibility in hull panelling. Experiments have been undertaken on a range of sandwich construction panels using the custom Servo-hydraulic Slam Testing System (SSTS). Rectangular glass-fibre/epoxy skin sandwich panel specimens of dimensions 1030±5 mm x 540±05 mm were manufactured using a resin infusion process with Gurit M130 as their core material. The thickness of the GRP skins was varied between panels. Testing has been undertaken on the panels at 10° with vertical impact velocities between 1.0 m/s and 9.5 m/s. The panel’s integrity is monitored throughout the impacts using bi-axial resistive strain gauges. The velocities at which both yield and ultimate failure occur have been identified. Variations in both the yield and failure speeds of the panels have been observed experimentally. These variations are linked to the varying levels of deformation between the panels resulting in different pressure distributions. These findings highlight the necessity to consider both strength and stiffness in scenarios where fluid-structure interaction may be present as a change in stiffness may lead to an inadvertent change in effective strength.