기본설계 단계에서의 금속/비금속 보강판의 구조 안전성 평가

Abstract

Stiffened plates require simple fabrication methods and have good strength to weight ratios. For these reasons, they can easily be seen in marine vessels as important secondary structural members. Examples of marine vessels that utilize stiffened plated structure are cargo/navy vessels to fast marine craft like hydrofoil and WIG (Wing-In-Ground effect). A conventional flat-bar stiffened metallic plate is a typical example and has extensively been used in marine industry. Structural topology of this conventional stiffened plate has been varied as manufacturing techniques advanced and new building materials introduced. Examples are FRP (Fibre Reinforced Plastics) composites materials and environment friendly closed manufacturing technique like VARIM (Vacuum Assisted Resin Infusion Molding). Thus an efficient systematic assessment of various structural topologies is an important task for marine designers especially at the preliminary design stage where the choice of materials and the configurations of the stiffened plate can be defined before a final decision on the selection of the stiffened plate. In this paper, a systematic assessment of metallic and non-metallic stiffened plates under a lateral pressure load was performed using statistically determinate approach. A flat-bar stiffened aluminium plate was exemplified and its alternatives were proposed as hat-section stiffened CFRP and GFRP single skin plates, and monocoque CFRP and GFRP sandwich plates having a PVC foam core. These structures were analysed using elastic closed-form solutions in conjunction with a set of stress and deflection limits obtained from practice as design constraints. As results, geometry dimensions and weights were calculated when the given deign constraint were satisfied. From this, the most efficient structural topology was identified.