Al/CFRP 적층구조물의 피로 수명 평가 기법 개발에 관한 실험적 연구

Abstract

The laminated structures of Al/CFRP are attracting attention in industries such as aerospace and automobiles due to the excellent properties of CFRP. In particular, when Al/CFRP laminated structures are used as fuel storage containers, they are exposed to repeated fatigue conditions. In this case, the fatigue life evaluation for the working load becomes an important criterion for determining the safety of use and the availability of maintenance and repair. Among the existing evaluation methods for these structures, the burst test and hydraulic repeat test require expensive facilities, or the visual observation and analysis program is somewhat subjective. Therefore, this study experimentally conducted the fatigue life evaluation that improved the shortcomings of the existing evaluation to secure the safety of the Al/CFRP laminated hybrid structure. The test specimen was made using a curved mold in consideration of the liner shape of a Type III storage container. After the fracture and fatigue tests, the fatigue life evaluation method used the strain-life method, and the life prediction used the transition life value. The results of the study show that the static load value is lower in specimens where the orientation of the laminated structure became complicated. And the transition life value is higher in specimens where the orientation of the laminated structure became complicated, which can be predicted as a result of the longer life value as the laminated structure became more complicated. These are expected to be the basis for the development of a test method that ensures the safety, economy and objectivity of real hybrid laminate structures.