Quantification of hydroelasticity in water impacts of flexible composite hull panels

• Impacts undertaken with velocities up to 6.0 m/s and a deadrise angle of 10°
• Trends between panel׳s flexibility, total force and applied pressure are observed.
• Correlation shown between panel rigidity and a decreasing peak pressure at the centre.
• Decreases in local velocity centre of up to 72.6% observed at 4.0 m/s.
• Decreases in deadrise angle at outer edge up to 11°, negative local deadrise angle.

Understanding the effect a flexible structure has on the loads and responses during slamming events will improve the design process for high speed marine craft. Design of hulls is typically undertaken on the assumption that the pressures applied are the same as if the hull was rigid. In reality the loads may vary due to the hydroelasticity resulting from the fluid structure interaction during the impact. This work characterises the variations in both applied pressure and panel response due to the hydroelasticity. Impacts have been undertaken using a purpose built servo-hydraulic slam testing system with impact velocities up to 6.0 m/s and a deadrise angle of 10°. The unsupported panel area was set at approx 1000×500 mm with simply supported boundaries along all four edges. Clear trends between a panel׳s flexibility and the total force and applied pressure have been observed. The changes in both loads and responses are largest at the centre and chine edge of the panel and can be related to the regions of the most significant changes in local velocity (centre) and deadrise angle (chine). Changes in the loads and responses for sandwich constructions can be attributed to the shear stiffness and shear factor as well as the flexural rigidity.