Marine structures are mostly made of metals and always experience complex random loading during their service periods. The fatigue crack growth behaviors of metal materials have been proved from laboratory tests to be...Marine structures are mostly made of metals and always experience complex random loading during their service periods. The fatigue crack growth behaviors of metal materials have been proved from laboratory tests to be sensitive to the loading sequence encountered. In order to take account of the loading sequence effect, fatigue life prediction should be based on fatigue crack propagation（FCP） theory rather than the currently used cumulative fatigue damage（CFD） theory. A unified fatigue life prediction（UFLP） method for marine structures has been proposed by the authors＇ group. In order to apply the UFLP method for newly designed structures, authorities such as the classification societies should provide a standardized load-time history（SLH） such as the TWIST and FALSTAFF sequences for transport and fighter aircraft. This paper mainly aims at proposing a procedure to generate the SLHs for marine structures based on a short-term loading sample and to provide an illustration on how to use the presented SLH to a typical tubular T-joint in an offshore platform based on the UFLP method.展开更多
针对齿轮箱的振动噪声问题,提出了一种基于齿轮载荷静态传递误差(load static transfer error,LSTE)优化的减振降噪方法。通过建立齿廓修形齿轮的时变啮合刚度解析模型,并采用Timoshenko梁单元构建齿轮-转子-轴承耦合动力学模型,系统揭...针对齿轮箱的振动噪声问题,提出了一种基于齿轮载荷静态传递误差(load static transfer error,LSTE)优化的减振降噪方法。通过建立齿廓修形齿轮的时变啮合刚度解析模型,并采用Timoshenko梁单元构建齿轮-转子-轴承耦合动力学模型,系统揭示了不同修形量和修形曲线下齿轮LSTE与系统动力学响应之间的关系。在此基础上,采用遗传算法对齿轮LSTE相对峰峰值进行优化,获得最优修形参数组合。最后结合有限元/边界元法,分析了修形优化前后齿轮箱的噪声辐射特性。研究结果表明,经遗传算法优化后的修形参数可使主动轮位移幅频响应幅值与加速度幅频响应幅值相较其他修形参数均显著降低,齿轮箱辐射声功率级均方根值由未修形时的38.66 dB降至修形优化后25.32 dB,降幅达34.51%,降噪效果显著。研究成果为齿轮传动系统的低噪声设计提供了理论依据。展开更多
基金financially supported by the Fourth Term of"333 Engineering"Program of Jiangsu Province(Grant No.BRA2011116)Youth Foundation of Jiangsu Province(Grant No.BK2012095)Special Program for Hadal Science and Technology of Shanghai Ocean University(Grant No.HAST-T-2013-01)
文摘Marine structures are mostly made of metals and always experience complex random loading during their service periods. The fatigue crack growth behaviors of metal materials have been proved from laboratory tests to be sensitive to the loading sequence encountered. In order to take account of the loading sequence effect, fatigue life prediction should be based on fatigue crack propagation（FCP） theory rather than the currently used cumulative fatigue damage（CFD） theory. A unified fatigue life prediction（UFLP） method for marine structures has been proposed by the authors＇ group. In order to apply the UFLP method for newly designed structures, authorities such as the classification societies should provide a standardized load-time history（SLH） such as the TWIST and FALSTAFF sequences for transport and fighter aircraft. This paper mainly aims at proposing a procedure to generate the SLHs for marine structures based on a short-term loading sample and to provide an illustration on how to use the presented SLH to a typical tubular T-joint in an offshore platform based on the UFLP method.
