Composites Research

  • 제34권5호
  • /
  • Pages.283-289
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  • 2021
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  • 2288-2103(pISSN)
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  • 2288-2111(eISSN)
한국복합재료학회 (The Korean Society for Composite Materials)
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초기 결함 조건 모델에 따른 복합재 원통 구조의 좌굴 Knockdown factor 도출

Derivation of Knockdown Factors for Composite Cylinders with Various Initial Imperfection Models

  • Kim, Do-Young (Department of Aerospace Engineering, Chungnam National University) ;
  • Sim, Chang-Hoon (Department of Aerospace Engineering, Chungnam National University) ;
  • Park, Jae-Sang (Department of Aerospace Engineering, Chungnam National University) ;
  • Yoo, Joon-Tae (Launcher Structures and Materials Team, Korea Aerospace Research Institute) ;
  • Yoon, Young-Ha (Launcher Structures and Materials Team, Korea Aerospace Research Institute) ;
  • Lee, Keejoo (Future Launcher R&D Program Office, Korea Aerospace Research Institute)
  • 투고 : 2021.09.03
  • 심사 : 2021.10.18
  • 발행 : 2021.11.05
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초록

본 연구에서는 압축력을 받는 얇은 복합재 원통 구조에 대하여 기하학적 혹은 하중에 대한 초기 결함 모델을 이용하여 수치해석적으로 좌굴 Knockdown factor를 새롭게 도출하였다. 전역 좌굴이 발생하기 이전에 타원형상의 변형 형상을 갖는 복합재 원통 구조를 사용하였다. 복합재 원통 구조의 기하학적 초기 결함만 고려하기 위하여 Single Perturbation Load Approach를 이용하였으며, 기하학적 초기 결함과 더불어 하중 불균일을 함께 구현하기 위하여 Single Boundary Perturbation Approach를 사용하였다. 기하학적 초기 결함 모델의 좌굴 Knockdown factor는 NASA의 기존의 좌굴 Knockdown factor보다 약 84% 높게 도출되었으며, 좌굴 시험에 비하여서는 약 9% 낮게 도출되었다. 기하학적 초기 결함과 하중 불균일을 함께 고려하는 모델의 좌굴 Knockdown factor는 NASA의 좌굴 Knockdown factor에 비하여서는 약 75% 높게, 그리고 좌굴 시험보다 약 14% 낮게 계산되었다. 따라서, 본 연구의 좌굴 설계 기준은 고려된 초기 결함 모델과 상관없이 기존의 좌굴 설계 기준에 비하여 경량 설계의 제공이 가능함과 동시에 좌굴 시험 대비 적절히 보수적인 설계 기준을 제공할 수 있음을 확인하였다.

This paper derives numerically the buckling Knockdown factors using two different initial imperfection models, such as geometric and loading imperfection models, to investigate the unstiffened composite cylinder with an ellipse pre-buckling deformation pattern. Single Perturbation Load Approach (SPLA) is applied to represent the geometric initial imperfection of a thin-walled composite cylinder; while Single Boundary Perturbation Approach (SBPA) is used to represent the geometric and loading imperfections simultaneously. The buckling Knockdown factor derived using SPLA is higher than NASA's buckling design criteria by approximately 84%, and lower than buckling test result by 9%. The buckling Knockdown factor using SBPA is higher than NASA's buckling design criteria by about 75%, and 14% lower than the buckling test result. Therefore, it is shown that the buckling Knockdown factors derived in this study can provide a lightweight design compared to the previous buckling design criteria while they give reasonably a conservative design compared to the buckling test for both the initial imperfection models.

키워드

과제정보

본 연구는 과학기술정보통신부에서 시행한 한국형발사체개발사업의 지원을 받아 수행된 연구 결과입니다. 본 연구의 일부는 2021년도 한국복합재료학회 춘계학술대회 우수발표논문상으로 선정된 논문에서 발표되었습니다.

참고문헌

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