Responses of Bow Flare Structures Constructed of Steel, Aluminum Alloy, and GFRP Composite under Extreme Sea Conditions

Abstract This paper evaluates the responses of equivalent stiffened panels made of steel, an aluminum alloy, and the glass fiber – reinforced plastic (GFRP) composite under extreme slamming loads. These panels are designed for bow flare structures in high-speed crafts. Their equivalence is established with respect to their designs using the same classification society rules. The analysis methods used in this work are illustrated, and slamming loads and inelastic structural responses are analyzed separately. Slamming loads are evaluated using a two-dimensional rigid bow flared section, with dynamic structural deformation and stress responses assessed through nonlinear finite-element analysis. The structures constructed of various materials are verified to meet design requirements. The primary objective of this work is to investigate the safety margin of bow flare structures constructed of steel, an aluminum alloy, and the GFRP composite under extreme sea conditions. The results show that the equivalent composite structures with larger scantlings, particularly the GFRP flat-bar stiffened structure, still exhibit considerably weaker impact strength under extreme slamming loads. The investigation of the structural responses and damage characteristics of equivalent stiffened plates under extreme slamming loads provides a reference for the potential limit state design of the bow flare structures of high-speed crafts.