• Title/Summary/Keyword: 가스구체 압력파

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Whipping factor - a Measure of Damage Potential of an UNDEX Bubble Pulse (휘핑계수-수중폭발 가스구체 압력파 크기의 척도)

  • Kwon, Jeong-Il;Chung, Jung-Hoon;Lee, Sang-Gab
    • Journal of the Society of Naval Architects of Korea
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    • v.42 no.6 s.144
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    • pp.637-643
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    • 2005
  • A new novel Whipping Factor is proposed as a measure of the ship damage potential due to an underwater explosion bubble pulse. The factor was derived from the relationships among the charge weight, its depth and the fluid acceleration due to pulsating gas bubble. From the whipping response analyses for three uniform Timoshenko beams with similar characteristics of real naval surface ships, we have confirmed the maximum bending moment responses of beams due to whipping are almost same if the applied whipping factor is constant regardless of the charge weights and depths, which could validate the proposed whipping factor.

Integrated Structural Dynamic Response Analysis considering the UNDEX Shock Wave and Gas Bubble Pulse (수중폭발 충격파와 가스구체 압력파를 함께 고려한 구조물의 동적응답해석)

  • Lee, Sang-Gab;Hwon, Jeong-Il;Chung, Jung-Hoon
    • Journal of the Society of Naval Architects of Korea
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    • v.44 no.2 s.152
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    • pp.148-153
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    • 2007
  • Two typical impact loadings, shock wave and gas bubble pulse, due to UNDEX(UNDerwater EXplosion), should be considered together for the closest response analysis of structure subjected to UNDEX to a reality. Since these two impact loadings have different response time bands, however, their response characteristics of structure are different from each other. It is impossible to consider these effectively under the current computational environment and the mathematical model has not yet been developed. Whereas Hicks model approximates the fluid-structure interaction due to gas bubble pulse as virtual mass effect, treating the flow by the response of gas bubble after shock wave as incompressible ideal fluid contrary to the compressible flow due to shock wave, Geers-Hunter model could make the closest response analysis of structure under UNDEX to a real one as a mathematical model considering the fluid-structure interaction due to shock wave and gas bubble pulse together using acoustic wave theory and DAA(Doubly Asymptotic Approximation). In this study, the application and effectiveness of integrated dynamic response analysis of submerged structure was examined with the analysis of the shock wave and gas bubble pulse together.

Comparison of UNDEX Whipping Response of Hull Girder according to Modeling Methods (해석모델링 방법에 따른 선체거더의 수중폭발 휘핑응답 비교)

  • Kwon, Jeong-Il;Chung, Jung-Hoon;Lee, Sang-Gab
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.42 no.6 s.144
    • /
    • pp.631-636
    • /
    • 2005
  • One and three dimensional whipping response analyses of a naval surface combatant subjected to an underwater explosion bubble pulse were carried out to compare the efficiency and accuracy according to the modeling methods. In 1-D analysis, program UNDEXWHIP developed by KIMM was used, which is based on the thin-walled Timoshenko's beam theory and on the modal analysis method using wetted vibratory modes of the hull girder. In 3-D analysis, three finite element models were suggested using LS-DYNA/USA code, such as 3-D beam model considering geometric shape of wetted side shell, coarse and fine 3-D F.E. models. Through the comparison of results from the 1-D and 3-D analyses, it could be confirmed that 1-D analysis result is in good agreement with 3-D analysis ones, and that fine 3-D F.E. model, shock analysis one, is also used both in the shock response and whipping response analyses for the analyst effort and time savings.