【作者】 闫旭；

【导师】 于洪亮；

【作者基本信息】 大连海事大学 ， 轮机工程， 2009， 硕士

【摘要】 船舶主机系统的减振降噪问题一直是船舶工程中的研究热点之一,随着主机日益高速化、大型化发展,对主机系统隔振的要求也随之增加。为确保主机系统合理适度的振动噪声水平,目前常采用的技术措施有单层隔振系统、双层底隔振系统以及浮筏隔振系统等,同时还有主动隔振、阻尼隔振等技术。浮筏隔振系统作为一种有效的振动控制方法,在国外实船上已经取得了良好的隔振效果,但由于其系统中多个机组振动并存、系统构成相对复杂等原因,浮筏隔振系统中的振动情况复杂、其隔振效果也难以简单评价。因此为进一步提高主机隔振系统的隔振性能,浮筏隔振系统的隔振效应等问题需要进一步的详细研究,同时这也能为其它隔振系统的研究分析提供全面有效的科学依据。计算机辅助工程技术的快速发展使得有限元分析方法在大型工程领域内得到了良好的推广,对于一些复杂结构系统的振动问题可以方便地利用有限元数值计算获得准确的计算结果。本文针对浮筏隔振系统,建立了两机组浮筏隔振系统模型。其中基于有限元数值方法,采用弹簧单元模拟隔振器,采用结构体模拟机体和浮筏筏体,以质量单元模拟附加质量等分析了浮筏筏体上的附加质量和浮筏上两个机组的激振力对浮筏隔振系统振动响应的影响。计算结果表明,浮筏隔振系统的振动频率随着筏体上附加质量的增加而下降。当单个机体力作用时,附加质量对浮筏筏体振动响应的影响效果较为显著,而对主机自身振动响应的影响有限。当浮筏上两个机组共同工作时,激振力幅值的变化也可明显影响筏体的振动响应,但对机体上的影响甚小。分析工作具有一定的工程意义,为以后的隔振设计提供了有益的科学参考。更多还原

【Abstract】 The vibration and noise control problem of ship main engine system is always a hotspot in the ship engineering research. According to the speed-up and maximizing of the ship main engine, the demand of better isolation of main engine system is also heightening. To maintain the moderate vibration and noise level of main engine, there are some usual measures to make that, which includes the mono-layer isolation system, double-deck isolation system and floating raft isolation system, meanwhile, includes the initiative isolation and damp isolation techniques.The floating raft system, as an effective measure to control vibration, has been used in the abroad ships and obtained a well isolation, but there are many machine units, and the whole system is complex, so the vibration of floating raft system is not a simple problem, and the estimating of isolation is also a hard work. Hence, the isolation effect of floating system needs to be researched more, to better the isolation of the main engine isolation system. At the same time, the study can offer more complete and valid scientific proofs for other isolations. The Computer Aided Engineering has developed rapidly, and the finite element method can be used to solve many engineering problems, what’s more, the exact results could also be gained by the numerical computation for some vibration problems in a complex system.The model of a floating raft isolation system with two machine units is built to master the characteristic factors of the floating raft system, which aims at the floating isolation system, based on law-researching and characteristic-seeing. In this paper, two factors were analyzed, including the added mass of floating raft body and the forces of double machines on the floating raft. To study the effect of two factors on the floating raft isolation system, the vibration isolator was modeled by spring element, the machine body and floating raft body were modeled by structure body element, and the added mass was modeled by the mass element, in the finite element method. The numerical results show that the frequency of floating raft isolation system decreases with the increase of added mass on the floating raft body, and when a single force takes action, the response of floating raft body is affected more evidently by the added mass, and the response of machine body is affected a little. When the forces of double machines take action simultaneously, the response of floating raft body is affected largely by the amplitude change of excited force, but the response of machine body is not affectted much. On the whole, this analysis project has some significance of engineering, and can offer the virtual science reference for the latter isolation designing更多还原