• Title, Summary, Keyword: 보강원통쉘

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Acoustic Radiation Analysis of Stiffened Cylindrical shell and Vibrational Velocity by FFT (보강 원통형 몰수체의 음향방사 해석과 FFT에 의한 진동 해석)

  • 배수룡;이헌곤;홍진숙
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.128-133
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    • 1993
  • 본 연구에서는 보강 원통쉘에 대하여 주위 유체의 영향을 고려하여 진동 및 음향방사를 해석하였다. 원통셀의 운동방정식은 Donnell 이론을 적용하였으 며, Contour 적분을 풀지 않고 FFT 알고리즘(Fast Fourier Transform Algorithm)을 이용하여 원통쉘의 진동을 계산하였다. 현재까지의 방사패턴에 관한 연구는 주로 원주 방향에 집중되어 왔으나, 보강 원통쉘의 방사패턴은 원추파 모형에 가까우므로 극좌표 .theta. 방향에 대한 음향방사 패턴에 관한 연구가 이루어져야 한다. 그러므로, 본 연구에서는 극좌표에 관한 방사패턴 에 관하여 주로 고찰하였다.

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Dynamic stability of anisotropic cylindrical shells (이방성 원통쉘의 동적 안정성)

  • Lu, Sung Y.;Chon, W. Kim
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.5 no.3
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    • pp.178-182
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    • 1981
  • 쉘이 복합재로 제작되었거나 보강재를 사용하였을때에는 쉘요소의 역학적 특성은 방향성을 가지게 된다. 이 논문에서는 선형관계식을 사용하여 동적 표면가동을 받는 이방성원통쉘의 안정성을 고려하여 다루었다. 재료의 이방성을 고려하여 3방향 즉, 축방향, 둘레방향 및 반경향의 실성항이 포함된 운동방장실을 유도하였다. 동적 안전성의 해석은 Bolotin 의 방법을 따랐으며 근사해를 행렬식행으로 제시하였다. 수직열로 외압을 받는 원통쉘의 좌단을 다루었으며 본 이론과 고전이론 사이의 차이점을 검토하였다.

Review on the Cylindrical Shell Research (원통쉘 연구의 현황과 전망)

  • Lee, Young-Shin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.1
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    • pp.1-26
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    • 2009
  • Cylindrical shells of isotropic and composite laminated materials are being used many engineering applications. This paper reviews the literature focusing on various aspects of shell research. The aspects of research receiving interest here are the cylindrical theory being used, the stress, buckling analysis and the impact analysis. The vibration analyses and stiffening characteristics of the cylindrical shell are investigated. The design optimizations of the cylindrical shell are reviewed. The studies on the conical and spherical shell are also reviewed. This review aticles contain 236 referencees.

Dynamic Behavior Analysis of Stiffened Cylindrical Shell Filled with Fluid (내부가 유체로 채워진 보강원통쉘의 동적거동 해석)

  • Youm, Ki-Un;Yoon, Kyung-Ho;Lee, Young-Shin;Kim, Jong-Kiun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.9
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    • pp.2875-2886
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    • 1996
  • This work present the experimental resutls for the free vibration of unstiffened, stiffened cylindrical shell filled with air, half water and full water. The natural frequencies and mode shapes of unstiffened, stiffened cylindrical shell are obtained experimentally also. The natural frequencies of stiffened cylindrical shell were generally highter than those of unstiffened cylindrical shell and natural requencies were decreased as cylindrical shell was filled with water. The effect of circumferential stiffener in the first mode was shown that natural frequency more increased 25% at air environment, 29% at half water environment and 37% at full water than those of unstiffened cylindrical shell, respectively. Also, the natural frequencies were decreased according to the added mass effect of fluid in the shell of unstiffened and stiffened cylindrical shell. The six mode shape results of all cases are simular and given. The natural frequencies are determined for a wide range of parameters : e.g. unstiffened shell, and filled with air, half and full water. The effects of varying the parameters on the free vibration frequencies and mode shapes are discussed.

Optimum Design of Stiffeners in the Stiffened Cylindrical Shells Based on Structural Stability (좌굴을 고려한 원통쉘 보강재의 최적설계에 대하여)

  • 장창두;한성곤
    • Computational Structural Engineering
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    • v.6 no.3
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    • pp.81-88
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    • 1993
  • An efficient approach to the buckling analysis of stiffened cylindrical shells with rings and stringers under the axial and the lateral pressure loadings is presented. By this approach, the local buckling as well as overall buckling behavior has been investigated considering the discreteness of stiffeners and appropriate adoption of displacement functions. Some design criteria based on structural stability to determine optimum scantlings of stiffeners are also suggested. It is shown that the optimum scantlings of stiffeners can be designed from the condition of equal local and overall buckling strength.

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Free Vibration of the Composite Laminated Cylindrical Shells Stiffened with the Axial Stiffeners (길이방향으로 보강된 복합재료 원통쉘의 자유진동)

  • Lee, Young-Shin;Kim, Young-Wann
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.7
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    • pp.2223-2233
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    • 1996
  • The analytical solutions for the free vibration of cross-ply laminated composite cyllindrical shell with axial stiffeners(stringers) are presented usint the energy method. The stiffeners are taken to be smeared over the surface of shell with the smeared stffener theory. The effect of the parameters such as the stacking sequences, the shell thichness, the shell radius-to stringer depth ratio, the stringer depth-to width ratio, the shell length-to radius ratio are studied. By comparison with the previously published experimental results and the analytical results for the stiffened isotropic cylindrical shell and the unstiffened orthotropic composite laminated cylindrical shell, it is shown that natural frequencies can be determined with adequate accuracy.

Analysis of Underwater Acoustic Radiation of SWATH vessel using Transfer Function Method (전달함수법을 이용한 SWATH선의 수중 음향 방사 해석)

  • 김재호
    • Journal of the Korea Institute of Military Science and Technology
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    • v.6 no.2
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    • pp.20-34
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    • 2003
  • The good sea-keeping capability of the SWATH(Small Waterplane Area Twin Hull) ship has been attractive for research or surveillance vessels. Especially, for the naval ships accomplishing the underwater acoustic missions, it is necessary to access and minimize the underwater radiated noise level generated by the ships. Therefore, acoustic signature management and control are very important topics for these vessels. Underwater radiation pattern in the low frequency range is dominated by the tonals from the vibration of onboard machinery. In this work, the radiated noise level generated by the propulsion machine in the submerged hull is predicted using the transfer function technique and the hull transfer function for the submerged hull is determined by analyzing the longitudinal/circumferential stiffened infinitely long cylindrical shell and considering the empirical database of the previous vessels. It is confirmed that the transfer function technique can give useful information for identifying the noise source and estimating its contribution to the total radiatied noise level.