Studies on Vibration Response, Damping Characteristics and Fatigue Strength of Ship Structure

船舶结构振动响应、阻尼特性及疲劳强度研究

• 批准号: 61302051
• 负责人: MATSUURA Yoshikazu
• 金额: $ 4.86万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Co-operative Research (A)
• 财政年份: 1986
• 资助国家: 日本
• 起止时间: 1986 至 1987
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-61302051/
• 关键词: damping characteristics; logarithmic decrement; local vibration; fatigue limit; random loading; 振動応力; 振動応答; 減衰特性; 疲労亀裂; 切欠き; 共振

Prevention of ship vibration is an important problem, because excessive vibration on a ship is uncomfortable for her passengers and crew and often causes fatigue damages in the structural members. Therefore, studies on damping characteristics and fatigue strength of ship structural members are necessary.Forced bending vibration experiments were carried out on the steel beams of rectangular cross section with a number of sprung mass. The experimental results showed the large value of logarithmic decrement for the beams mentioned above compared with beams without sprung mass. So it is concluded that the local vibration of the substructures of a ship will be useful in reducing the resonant vibration amplitude.Studies on fatigue strength of ship structural members showed the following results. The value of fafigue limit decreases under random loading condition, to which ships are subjected during service period. So there is possibility that fatigue damge for structural members with high elastic stress concentration factor will be accumulated under random loading condition. A study on fatigue strength of aft structure of a ship was also carried out. Some cracks were found at the corner of frame connection in the aft peak tank of a Ro-Ro ship and cause of these damages was due to the resonance between natural vibration of aft peak tank and propeller surface force.

船舶振动的预防是一个重要的问题，因为船舶的过度振动会使其乘客和船员感到不适，并经常导致结构构件的疲劳损伤。因此，有必要对船舶结构构件的减振特性和疲劳强度进行研究。对多个弹簧质量的矩形截面钢梁进行了强迫弯曲振动试验。实验结果表明，与没有弹簧质量的梁相比，上述梁的对数衰减值较大。由此可见，船体下部结构的局部振动有助于减小船体的共振振动幅值。在随机载荷条件下，船舶在服役期间所受的疲劳极限值减小。因此，具有较高弹性应力集中系数的结构构件在随机荷载作用下存在累积疲劳损伤的可能性。并对某船尾部结构的疲劳强度进行了研究。某滚装船尾尖舱框架节点拐角处出现裂纹，其原因是尾尖舱固有振动与螺旋桨表面力共振所致。