浮筏隔振系统有限元模型中基座的等效方法

在浮筏隔振系统中,由于实际基座模型和边界条件比较复杂,其有限元模型通常难以建立。提出基座的等效方法,首先测试基座安装点的原点导纳和传递导纳,然后根据有效点导纳的方法,将各安装点之间的耦合进行简化,将基座等效为多个独立的支撑单元,构成浮筏隔振系统完整的有限元模型。建立等效的浮筏隔振系统有限元模型,估算等效前后两种浮筏隔振系统有限元模型的隔振效果,等效模型的计算结果与参考模型较一致,不论是振级落差的总体趋势还是峰值点,都比较吻合,计算出的振级落差总级相差1.5 dB左右,可以满足工程实际要求。

Equivalent Machinery Base Method for Finite Element Analysis of Floating Raft Isolation System

For floating raft isolation system,finite element models of machinery base is difficult to model because of the complex boundary conditions and geometry.An equivalent method was proposed for this pur pose.First,the ordinary and transfer mobility of machinery base were obtained from measurement.Next,according to the theory of effective point mobility,simplifying the coupled effect between mounting point of machinery base;then the machinery base was equivalent as several uncoupled support elements;mean while the full finite element models of floating raft isolation system was established.An illustration of this methodology was given with a floating raft model.The vibration level fall(VLF)was applied to assess the effect of vibration isolating.The comparison of the full model and the equivalent model shows that the re sults agree well,and the difference of the overall VLF is about 1.5 dB.