Composites Research

The Korean Society for Composite Materials (한국복합재료학회)
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Evaluation of Physical and Mechanical Properties based on Liquid Composite Molding

액상성형공정별 물리적/기계적 특성 비교 평가

  • Received : 2018.10.15
  • Accepted : 2018.12.04
  • Published : 2018.12.31
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Abstract

Autoclave process has been remaining as one of the most robust and stable process in fabricating structural composite part of aerospace industry. It has lots of advantages, however exhibits some disadvantages or limitations in capital investment and operation. Recently, there have been various Out-of-Autoclave process being researched and developed to overcome those limitations. In this study, laminate specimens were fabricated using LCM (Liquid Composite Molding) process, regarded as one of potential OoA process. DB (Double bagging), CAPRI (Controlled Atmospheric Pressure Resin Infusion), VAP (Vacuum Assisted Process) and Autoclave process were used for laminate specimens. Void content, Thickness, Tg (Glass Transition Temperature), ILSS (Interlaminar Shear Strength) and Flexural strength properties were evaluated for comparison. It is verified that Autoclave based specimen has uniform thickness distribution, the lowest void content and outstanding mechanical properties. And, CAPRI based specimen exhibits relatively good physical and mechanical properties over DB and VAP based specimen and comparable mechanical properties with autoclave based specimen.

오토클레이브 (Autoclave) 성형 공정은 항공산업분야의 복합재 부품 제작에 있어서 매우 안정적이고 중요한 제조방법으로서 자리매김 해왔었지만 오토클레이브가 가진 많은 장점과 함께 단점 또는 제약 사항들을 보여주고 있다. 최근에는 이러한 한계를 극복하기 위하여 다양한 탈 오토클레이브 (OoA, Out-of-Autoclave) 공정들이 연구 개발되고 있는데, 본 연구에서는 탈 오토클레이브 공정 중 하나로서 많은 관심을 받고 있는 액상성형공정 (Liquid Composite Molding)을 사용하여 시편들을 제작하고 이를 오토클레이브 공정으로 제작된 시편과 실험적으로 비교평가하였다. 액상성형공정 중 DB (Double Bagging), CAPRI (Controlled Atmospheric Pressure Resin Infusion) 및 VAP (Vacuum Assisted Process) 공정을 사용하여 시편 제작을 수행하고 내부 기공 함유량, 두께, 유리전이온도, 층간전단강도 및 굽힘강도 시험 평가를 통하여 각 제작 공정에 따른 차이를 확인할 수 있었다. 전체적으로 오토클레이브 성형 시편이 우수한 두께 균일도, 낮은 기공 함유량 및 양호한 기계적 강도 특성을 보였으며, 액상성형공정 중에서는 CAPRI 성형 시편이 DB 및 VAP 성형 시편에 비하여 상대적으로 우수한 특성을 가짐을 확인하였다.

Keywords

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Fig. 1. A400M Cargo Door Fabrication using VAP Process [8]

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Fig. 2. Schematics of (a) Double Bagging, (b) CAPRI [14] and (c) VAP [13]

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Fig. 3. Bagging Systems for Specimens (a) #1 Specimen – Double Bagging (b) #3 Specimen - VAP

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Fig. 4. Cured Laminate Specimens (#1~#4)

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Fig. 5. NDI Result

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Fig. 6. Void Content Result

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Fig. 7. Average thickness comparison for specimens (#1 DB, #2 CAPRI, #3 VAP & #4 AUTOCLAVE

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Fig. 8. Tg Test Result

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Fig. 9. ILSS Test Setup

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Fig. 10. Mechanical Test results (a) ILSS (b) Flexural Strength

Table 1. Liquid composite molding processes by category

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Table 2. Summary of Specimens

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Table 3. Summary of specimen thickness

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