경량화용 CFRP 사이드부재의 충격압궤 특성

Abstract

The ability to protect passengers on an automobile accident depends on the condition of the collision, structural integrity, etc. The front-end members of vehicles must absorb the impact energy effectively to ensure passenger’s safety in front-end collision. Therefore, the designing vehicles should be more concerned on the aspect of securing safety performance, the while, it also should consider reducing weight of vehicle structural member. 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 CFRP side members in order to study the effect of various stacking condition and shape of section. Impact collapse tests were performed with change of the stacking condition, such as fiber orientation angle, interface number and shape of section. Collapse mode and energy absorption characteristics were analyzed. Following the above study, conclusions are drawn as below;

1. The CFRP side member was collapsed according to the different orientation angles by compounding of the 4 different modes: transverse shearing, laminar bending, brittle fracture, and local buckling. When the fiber orientation angle is small, the member absorbed energy by laminar bending. As the fiber orientation angle increases, the member was absorbed energy by local buckling and matrix crack due to transverse shearing. 2. As the fiber orientation angle increases, as shown the total absorbed energy increases linearly. energy absorption was most effective when the fiber orientation angle of CFRP was 15°. 3. The total absorbed energy increases to the 6 interface number with increasing interface number. However, decreasing trend is observed on moving to the 7 interface number. 4. The total energy absorption capability of the members increases as the sectional area ratio (sectional area ratio of flat member to "∩" shaped member) increase due to stress concentration on their edges. 5. The total absorbed energy of Al/CFRP side member assumed slightly lower than that of combined effect of the CFRP member and the aluminum member alone. The interaction effect was not shown because inner aluminum member applied load to the outer CFRP member in the form of hoop stress therefore the aluminum and the CFRP member were split each other.