경량화 구조부재의 단면형상 변화가 축압궤특성에 미치는 영향

Abstract

The most important goals in designing automobile are safety and environment -friendless. Vehicle structure must be lightweight in order to improve fuel-efficiency and reducing exhaust fumes. Therefore, recent trend in vehicle design is aimed at improving the aims at environment- friendliness and collision safety requirements of the vehicles. For the former, the trend is toward light-weight of vehicles to improve fuel efficiency and reduce tail gas emission due to the heavier restriction on exhaust levels. CFRP(Carbon Fiber Reinforced Plastics) of the advanced composite materials as structure materials for vehicles, has a widely application in lightweight structural materials of air planes, ships and automobiles because of high strength and stiffness. In the study, experimental investigations are carried out for the CFRP circular shaped member , CFRP square shaped member, CFRP single hat shaped member and CFRP double hat shaped section member in order to study the effect of various interface number and shape of cross section under the axial collapse loading. Static collapse tests were performed with change of the stacking condition, such as interface number and shape of cross section. Also, Collapse mode and energy absorption characteristics were analyzed.

Following the above study, conclusions are drawn as below;

1. In the case of CFRP member with equal thickness, Circular shaped member , squar shaped member, single hat shaped member and double hat shaped member showed transverse shear, laminar bending, brittle fracture, localized collapsing, and its combination. Collapse mode in“ㄷ” shaped member of CFRP single hat member and CFRP double hat member showed brittle fracture mode combined with laminar bending and transverse shear.

2. In the case of static collapsing test in order to energy absorption characteristics evaluation, Energy absorption pattern of CFRP single hat shaped member and CFRP double hat shaped member show the similar behavior. CFRP double hat shaped member shows 25% higher energy absorption compared with CFRP single hat shaped member.

3. In the case of maximum collapse load, CFRP double hat shaped member is biggest of the orther CFRP members. and in the case of absorbed energy, CFRP double hat shaped member a lot of interface is biggest of the orther CFRP members. and CFRP square shaped member is most unstable. Conclusionally, the most effective energy absorption was showed in case of CFRP double shaped member and a lot of interface member. Therefore, Energy absorbing characteristics are independent on the variation of interface number.