柔性基础双层隔振系统隔振效果评价的研究

Evaluation of Vibration Isolation Effect of Double-layer Isolation Systems with Flexible Foundations

在考虑基础柔性的情况下,用由机械阻抗给出的评价参数来评价双层隔振系统的隔振效果无法直观地反映基础的刚度对隔振效果的影响。建立柔性基础双层隔振系统力学模型,根据力传递率、插入损失、振级落差、传递功率流率和插入功率流率5种隔振效果评价参数的定义推导并给出它们的物理参数表达式,这些表达式可以直观反映基础刚度对隔振效果的影响。并基于一个双层隔振系统的实例,分别分析基础刚度取值对力传递率、插入损失、振级落差、传递功率流率和插入功率流率随激振频率变化的规律的影响,得出如下结论:对于柔性基础双层隔振系统,5种隔振效果评价参数对隔振效果的评价结果受基础刚度的影响各不相同,用力传递率评价得到的评价结果差异较小,用插入损失和插入功率流率评价得到的评价结果有一些差异,用振级落差和传递功率流率评价得到的评价结果差异较大。

In the case of considering the flexibility of foundation, the evaluation parameters given by mechanical impedance cannot directly reflect the influence of the foundation's stiffness on the isolation effect for the evaluation of the isolation effect of the double-layer isolation system. In this paper, the mechanical model of the double-layer isolation system with a flexible foundation is established. Five parameters for isolation efficiency evaluation associated with force transmissibility, insertion loss, vibration level difference, transfer power flow rate and insert power flow rate are defined respectively and their physical expressions are derived. These expressions can intuitively reflect the influence of the foundation's stiffness on the isolation effect. Based on the example of a double-layer isolation system, the influence of foundation's stiffness on the variation rules of the 5 evaluation parameters vs. the excitation frequency are analyzed respectively. It is concluded that for the double-layer isolation system with flexible foundation, the results of isolation effect evaluation based on the five evaluation parameters are different due to the influence of the foundation's stiffness. The results based on the force transmissibility have small differences, while the results based on the insertion loss and insertion power flow rate have some differences, and the results based on the vibration level difference and transfer power flow rate have large differences.