| 摘要 |
PURPOSE:To avoid resonance and make a structure lightweight by fixing the ring shaped structure to a stern section via upper and lower support members and supporting the upper blade section of this structure and the stern section via two struts having a streamline cross section. CONSTITUTION:Upper and lower sections of a ring shaped structure 4 are fitted to a stern section 2 via a lower support member 5b. The upper blade section 4a of the structure 4 is fitted to a stern section 2 via a strut 7 having a streamline cross section at the predetermined angle theta (near 45 deg.) in relation to a vertical line X-X passing the center of the structure 4. In this case, the inherent vibration mode of the structure 4 has a loop near theta=45 deg., 135 deg., thereby the inherent frequency is largely increased by connecting its vicinity to the stern section 2. Accordingly, resonance is avoided, the external load of the upper support member 5a is reduced, thus resulting in improvement in strength. Therefore, this structure and upper and lower support members can be made lightweight.
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