噪声控制中阻尼与隔离处理的一般原则

阻尼处理和隔离处理是机械噪声控制中两种主要降噪技术。本文将统计能量分析理论和能量估算方法相结合,研究了噪声控制中复杂结构阻尼与隔离处理最佳选择的问题。从复杂结构中总的噪声辐射功率表达式入手,得出了结构判别参数 K,总结出了复杂结构中最佳阻尼处理与隔离处理的一般原则。在实际工程中,结构判别参数容易获得,一般原则便于使用。以耦合平行板结构为例,进行了一系列验证实验,其实验结果与一般原则完全一致。

General Principles of Damping and Isolation Treatments for Complex Structures in Machinery Noise Control

Damping and isolation treatments have been mainly noise reduction mea- sures and the subject of intensive investigation for many years in machinery noise control.Various theories and techniques about damping and isolation treatments have been obtained.It has been shown in reference6] that in some eases damping treatments may have a slight effect on noise reduction,and iso- lation treatments,generally believed to reduce noise,may sometimes,on the contrary,increase the total sound power radiated from a complex structure. The optimum selection between damping and isolation treatments for noise control of a complex structure has not been investigated yet. Statistical Energy Analysis9] (SEA) offers a very powerful means for estimating the distribution of vibrational energy in a complex structure, and Energy Accountancy Method7] (EAM) provides a technique to predict the sound power radiated from individual bodies or lumped systems.In this paper,the two methods have been combined to form the theory of the opti- mum selection between damping and isolation treatments for a complex struc- ture in machinery noise control;the judging parameter,K,for engineering application has been obtained and the general principles of the optimum selec- tion between damping and isolation treatments for a complex structure in ma- chinery noise control have been summarized.These are believed to be signifi- cant extensions to the theories of noise control and can be applied not only to reduce sound power radiated from machines,but also to guide the design of lower-noise machines. The judging parameter,K,is the function of structural parameters and the radiation efficiency of the vibrational structure.It is the most important parameter for judging the capability of sound radiated from individual bodies, and the fundamental parameter for applying the general principles, In practical engineering,the judging parameter,K,is easy to decide if the vibration structural parameters are known.The general principles are con- venient to be applied to guiding machinery noise reduction treatment. The general principles have been applied to the coupled-plate structures. It is shown that the general principles are in good agreement with experiments.