Journal of the Society of Naval Architects of Korea (대한조선학회논문집)

The Society of Naval Architects of Korea (대한조선학회)
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A Study on Inelastic Whipping Responses in a Navy Ship by Underwater Explosion

수중 폭발에 의한 함체의 비탄성 휘핑 응답에 관한 연구

  • Kim, Hyunwoo (Dept. of Naval Architecture & Ocean Engineering, Inha University) ;
  • Seo, Jae Hoon (Dept. of Naval Architecture & Ocean Engineering, Inha University) ;
  • Choung, Joonmo (Dept. of Naval Architecture & Ocean Engineering, Inha University)
  • 김현우 (인하대학교 조선해양공학과) ;
  • 서재훈 (인하대학교 조선해양공학과) ;
  • 정준모 (인하대학교 조선해양공학과)
  • Received : 2021.06.22
  • Accepted : 2021.10.25
  • Published : 2021.12.20
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Abstract

The primary effect of the far-field underwater explosion (UNDEX) is the whipping of the ship hull girder. This paper aims to verify why inelastic effects should be considered in the whipping response estimations from the UNDEX simulations. A navy ship was modeled using Timoshenko beam elements over the ship length uniformly keeping the constant midship section modulus. The transient UNDEX pressure was produced using two types of the Geers-Hunter doubly-asymptotic models: compressible and incompressible fluids. Because the UNDEX model based on incompressible fluid assumption provided more increased fluid volume acceleration in the bubble phase, the incompressible fluid-based UNDEX model was adopted for the inelastic whipping response analyses. The non-linear hull girder bending moment-curvature curve was used to embed inelastic effects in the UNDEX analyses where the Smith method was applied to derive the non-linear stiffness. We assumed two stand-off distances to see more apparent inelastic effects: 40.5 m and 35.5 m. In the case of the 35.5 m stand-off distance, there was a statistically significant inelastic effect in terms of the average of peak moments and the average exceeding proportional limit moments. For the conservative design of a naval ship under UNDEX, it is recommended to use incompressible fluid. In the viewpoint of cost-effective naval ship design, the inelastic effects should be taken into account.

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Acknowledgement

본 연구는 2020년도 산업통상자원부의 재원으로 한국에너지 기술평가원 (KETEP)의 지원을 받아 수행되었습니다. (No. 20203030020230)

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