복합재 코일스프링 설계 및 멀티스케일 기법을 적용한 수명 예측

Abstract

As the fuel efficiency of automobiles increases, the technology of light-weighting is being developed steadily. COIL Spring is a must in the suspension of automobiles, its weight reaches 10 kg, so light weight technology is needed. In this research, the fiber angle was considered 45 degrees, which generic maximize the torsion and Various angles to examine the effects of torsion and bending on the spring section. Also, coil Spring is extended not only the circular section but also the ellipse and the complex circle/ellipse section, and Stiffness and stress distribution of coil spring were analyzed. Coil spring with circular cross section was fabricated by braided carbon fiber (A&P Co.) and epoxy resin, and the accuracy of the analysis was verified by measuring the stiffness value. Also, the fatigue life of the COIL Spring was predicted by using the multi-scale Approach to consider the fatigue characteristics. As a result, it was confirmed that the stiffness can be increased by 40 degrees depending on the shape of the cross section than 45 degrees, which is meant to be the bending effect on the cross section. When the load was applied to stress ratio 0.1, the failure life of the resin and the fiber was predicted, and it was confirmed that when a maximum load of 326 kg was applied at a stress ratio of 0.1, it had a life of 106 in spring of circle/45 degree.