GLARE의 누적손상에 대한 섬유배향의 영향 = Influences of Fiber Orientation on the Cumulative Damage in GLARE

다국어 초록 (Multilingual Abstract)

The material deficiencies in the form of pre-existing defects could be initiated cracks and fractures. The life time of materials may be associated with the size, shape, fiber orientation and loading type. thus, it is important to understand the fatigue crack initiation, growth behavior and delamination in the notches under complex stress field. But, when defects are located close to notches in composite material such as FRMLs(Fiber Reinforced Metal Laminates) which used in aerospace etc., these factors were not considered and not performed yet.
Therefore, the knowledge of fatigue crack initiation, propagation behavior and delamination mechanism from such interacting defects in FRMLs becomes a main concern of engineers engaged in fatigue life assessment.
The objective of this study is to investigate th effect of fiber orientation in GLARE(GLAss REinforced Aluminum Laminates(Al/GFRP)). GLARE consist of Al alloy sheets and glass fiber/epoxy layer. Defects were defined with stacking sequence of fiber to solve easily about the problem in this study. The fatigue test was performed using a Tension testing machine(MTS810). The fatigue crack propagation and delamination behavior near notches on the relationships between da/dN and K were considered. Analysis of notch effect and stress distribution under the tension using the Average Stress Criterion (ASC) model. The delamination shape produced between aluminum alloy sheets and fiber-adhesive layer was measured by SAM(Scanning Acoustic Microscope) This is SAM images taken around the fatigue crack. thus, it was to evaluate the delamination behavior in GLARE using delamination area(AD).
The test results showed the different fatigue crack propagation behavior and the different growing delamination features according to fiber orientation under loading pattern(bending, tension) in the GLARE.

목차 (Table of Contents)

• ABSTRACT
• LIST OF FIGURES
• LIST OF TABLES
• NOMENCLATURE
• 제 1 장 서 론
• 제 2 장 복합재료의 기본적 사항
• 2.1 복합재료의 특성
• 2.2 GLARE의 피로파괴
• 제 3 장 시험편 및 시험기기
• 3.1 시험편 제작
• 3.1.1 시험재료
• 3.1.2 GLARE 시편 제조
• 3.1.3 시험편 형상
• 3.2 피로시험기 및 시험기기
• 제 4 장 실험 방법
• 4.1 작용응력의 크기
• 4.2 균열길이 측정
• 4.3 GLARE의 층간분리 측정
• 제 5 장 실험 결과 및 고찰
• 5.1 섬유배향에 따른 피로균열전파 거동
• 5.1.1 균열길이와 피로수명
• 5.1.2 균열성장률과 응력확대계수범위
• 5.2 섬유배향에 따른 층간분리성장 거동
• 5.2.1 층간분리면적과 피로수명
• 5.2.2 균열길이와 층간분리길이
• 5.2.3 섬유배향과 층간분리형상
• 제 6 장 결 론
• 참 고 문 헌