从具有非线性特征的衰减“拍”波形确定阻尼率的方法

本文提出一个从具有非线性特征的衰减“拍”波形确定阻尼率的方法——二次包络法。第一次包络是对衰减“拍”波形实施希尔伯特(Hilbert)变换得到的,第二次包络是以第一次包络曲线的峰谷值为基准,分段用线性插值形成的变系数指数曲线。根据第二次包络的两条曲线,用对数减量确定随响应振幅而变的阻尼率。本文以分离贮箱中液体晃动阻尼的确定为例验证了方法,结果表明精度达到了工程应用的程度。除对液体晃动的阻尼测定之外,本方法还适用于密模态高粘弹性结构的模态阻尼测定。

A METHOD TO DETERMINE THE DAMPING RATE FROM THE DECAY-BEAT WAVE WITH NONLINEAR CHARACTERISTICS

To determine the damping rate from the decay-beat wave with nonlinear characteristics, a method that is called twice envelope method is proposed. The first envelope curve is obtained by applying the Hilbert transform to a decay-beat wave. The second envelope curve is given by means of grouping Linear-extrapolation on the basis of the crest-to-ralley value for the first time enveloping curve to form an exponential expression with variable coefficients. Based upon two curves of the second time enveloping, the damping rate which varies with amplitude can be determined using logarithmic decrement.To illustrate these approaches, a example of determining the liquid sloshing damping for compartmented cylindrical tanks is presented, and the derived results show that the precision can satisfy the requirement of engineering applications. This method is the saitable for de-termineing the modal damning for the structure with thick modality and high sticky-elasticity.