VaRTM 공정 중 발생하는 Micro-void에 의한 복합재료 강도 변화에 대한 연구

Composite materials have many engineering advantages. One of the most important properties composite materials offer is specific strength and specific modulus. For transportation applications including aerospace and automobile application, the weight of the vehicle is a critical importance for energy saving and payload increase. The VaRTM (Vacuum-assisted Resin Transfer Molding) is a kind of composite material manufacturing process. The VaRTM process has been used in many applications because of its time-saving and cost-effective characteristics. But impurity can make a problem of materials during the VaRTM process. Insertion of impurity during the VaRTM process makes internal void and this void degrades mechanical properties of materials. Relation between void generation and impurity is investigated in this study. Impurities are intentionally inserted into the laminate and optical observation is conducted. Internal voids are generated on specimens with thick impurity. Void generation is occurred between the thickness of 1.6 ~ 4.0mm. And void growth is occurred between the thickness of 3.2 ~ 4.0mm. The diameter of void is proportional to the thickness of the impurity. From these results, relation between the void generation behavior and impurity thickness is verified. Experimental results and expected results from the mathematical model show a good agreement with each other. This result notes that the environmental control during the VARTM process is very important for material reliability.목 차 Abstracts ----------------------------------------- 1 제 1 장 서론 ------------------------------------ 3 제 2 장 복합재료의 소개 ------------------------- 7 2.1 복합재료의 종류 ------------------------- 7 2.2 복합재료의 응용 분야 -------------------- 9 2.3 복합재료의 성형 공정 -------------------- 12 2.3.1 Hand Lay-up / Spray-up ------------------ 15 2.3.2 RTM(Resin Transfer Molding) ------------ 16 2.3.3 VaRTM(Vacuum-assisted Resin Transfer Molding) --- 17 2.3.4 오토클레이브(Autoclave)---------------------- 20 2.3.4 필라멘트 와인딩----------------------------- 23 제 3 장 복합재료의 Void 형성 ---------- 25 3.1 복합재료의 Void 형성 -------------------- 27 3.2 실험 재료 및 시편의 제작 ---------------- 29 3.3 실험 방법 ------------------------------- 33 3.4 실험 결과 및 고찰 ----------------------- 34 3.4.1 단면 분석 결과 -------------------------- 34 제 4 장 결론 ------------------------------------ 45 참고 문헌 ----------------------------------------- 4