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Computational Modal Analyses for the Propellant Tank and Small-Scaled First-Stage Models of Liquid-Propulsion Launch Vehicles

우주 발사체 추진제 탱크 및 축소 1단 모델의 전산 모드 해석 연구

  • Sim, Chang-Hoon (Department of Aerospace Engineering, Chungnam National University) ;
  • Kim, Geun-Sang (Department of Aerospace Engineering, Chungnam National University) ;
  • Kim, Dong-Goen (Department of Aerospace Engineering, Chungnam National University) ;
  • Kim, In-Gul (Department of Aerospace Engineering, Chungnam National University) ;
  • Park, Soon-Hong (Launcher Structures and Materials Team, Korea Aerospace Research Institute) ;
  • Park, Jae-Sang (Department of Aerospace Engineering, Chungnam National University)
  • 심창훈 (충남대학교 항공우주공학과) ;
  • 김근상 (충남대학교 항공우주공학과) ;
  • 김동건 (충남대학교 항공우주공학과) ;
  • 김인걸 (충남대학교 항공우주공학과) ;
  • 박순홍 (한국항공우주연구원 발사체 구조팀) ;
  • 박재상 (충남대학교 항공우주공학과)
  • Received : 2018.02.02
  • Accepted : 2018.06.09
  • Published : 2018.06.30

Abstract

This research aims to establish the finite-element modeling techniques for computational modal analyses of liquid propellants and flange joints of launch-vehicle structures. MSC.NASTRAN is used for the present computational modal analyses of the liquid-propellant tank and the small-scaled first-stage model. By means of the correlation between the measured and computed natural frequencies, the finite modeling techniques for liquid propellants and flange joints of launch-vehicle structures are established appropriately. This modal analysis using the virtual-mass method predicts well the bell mode of the liquid-propellant tank containing liquid. In addition, the present computation using RBE2 elements for modeling of flange joints predicts the first and second bending-mode frequencies within a relative error of 10%, which is better than the measured frequencies obtained from the modal test, for the small-scaled first-stage model containing liquid.

액체 추진 우주 발사체의 모드 시험을 대체 혹은 보완할 수 있는 신뢰성 있는 전산 모드 해석 기법의 정립을 위하여 액체 추진제 및 플렌지 조인트의 유한요소 모델링 기법을 정립하였다. 본 연구에서는 추진제 탱크 모델과 발사체 1단 축소 모델에 대하여 MSC.NASTRAN을 이용하여 전산 모드 해석을 수행 후, 모드 시험의 고유 진동수를 비교하여 모델링 및 해석 기법을 검증하였다. 추진제 탱크의 경우 가상질량 기법을 이용하여 액체 추진제를 모델링하였으며, 추진제 탱크의 종 모드 (bell mode)를 잘 예측하였다. 액체 추진제를 포함한 발사체 1단 축소 모델에 대하여, 보정된 재료 물성치와 RBE2 요소를 사용한 플렌지 조인트의 모델링 기법은 각각의 플렌지에서 24개의 볼트 조인트를 사용한 모델에 대하여 10% 이내의 오차의 1차 및 2차 굽힘 모드의 고유 진동수를 적절하게 계산하였다.

Keywords

References

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