소형 지면 효과 비행체의 경량화 탄소-에폭시 복합재 동체의 구조설계 및 안전성 연구

Abstract

In this study, structural design, safety and stability on the fuselage of a small scale WIG (Wing in Ground Effect) vehicle was investigated. The Carbon-Epoxy composite material was used in designing fuselage structure, and the honeycomb sandwich skin, ring frame, longeron 'semi-monocoque' type structure was adopted. Fuselage loads may be classified as symmetric load(Load case 1), Unsymmetric load(Load case 2), and loads experienced at the center of fuselage at splash down. However splash down loads may still be divided into head on loads(Load case 3-2), and at the aft belly point(Load case 3-3). The skin is designed to withstand buckling with the improved last design using sandwich structure where the skin form part of the fuselage weight.'T' shaped stringers were used together with U shaped ring frame that are in 3 parts, wing attachment ring frame, tail wing attachment ring frame and front, rear ring frame. F.E.M.(Finite element method) was used for structural analysis of the fuselage with about 19080 mesh grids generated. Natural frequency analysis together with Cambell diagram was used to determine the occurrence of resonance. The Carbon/Epoxy material was selected for the major structure, and the aluminum honeycomb core sandwich structural type was adopted for improvement of lightness and structural stability and for its less component parts than steel structure All the advantages of Carbon/Epoxy led to its choice as the material of use with a slight decrease in the number of ply used. From static strength analysis results using finite element method of the commercial code 'NASTRAN/ PATRAN', it was found that finally designed fuselage configuration with the Al honeycomb sandwich structure has structural safety as well as stability even though the designs weight is a little bit heavier than the target weight.