環肋尺寸比例對壓力殼挫曲強度影響之探討

THE INFLUENCE OF FRAME PROPORTIONS ON BUCKLING STRENGTH OF A PRESSURE HULL

壓力殼為潛艦主要的耐壓結構，設計上為保持結構在水壓作用下的幾何完整性，常使用環狀肋骨進行結構補強，增加其抵抗面外水壓負荷及挫曲之能力，使潛艦可以潛至要求之設計深度。一般設計公式對於壓力殼的耐壓能力均用環肋與壓力殼板的組合慣性矩來評估，部分規範則是明訂肋骨的形狀比例參數，因此本研究首先以壓力容器設計規範BSI PD-5500明訂的肋骨形狀比例為標準，在相同組合慣性矩下，適當地變更環肋尺寸，並使用有限元素軟體ABAQUS進行數值模擬，評估環肋形狀比例對壓力殼耐壓能力的影響。根據模擬結果，確認PD-5500所規範的環肋形狀比例的確具有較佳的抗挫曲能力，但是仍有更好的形狀可供考慮。因此本研究進一步綜合評估不同環肋形狀對提升挫曲強度的貢獻，並依據評估結果設計新的環肋形狀，最終經由數值模擬確認，新設計的環肋比例確實可有效地提升壓力殼挫曲強度。 Pressure hull is the main structure of submarine. In order to dive to the design depth, the stiffening rings are always used to enhance the compressive and buckling strength of pressure hull, and to retain the geometric integrity of pressure hull. For general design formula, the combinative moment of inertia of cylindrical shell and stiffener is usually used to estimate compressive strength of pressure hull. However, some rules expressed the stiffener scaling in shape parameters. In this study, we referred BSI specification PD-5500 to decide the initial stiffener shape. Firstly, we assumed the combinative moment of inertia are the same, and modified the stiffener sizes appropriately. Then we used numerical simulation package ABAQUS to estimate the compressive resistance of pressure hull with different stiffener shape ratio. According to simulation results, we can find that stiffener shape ratio decided by PD-5500 has higher buckling strength than most of the other stiffener shape ratios, but not the best. Therefore, we evaluated different stiffener shape ratios comprehensively and designed new stiffener shape. Finally, we utilized numerical simulation method to confirm the new stiffener shape can enhance the buckling strength effectively.