文档介绍：Pete Avitabile
MODAL SPACE - IN OUR OWN LITTLE WORLD
模态空间-在我们自己的小世界中
著 westrongmc译
Mrjdrgsi byse on the plate we will notice that the amplitude changes as we change the rate of oscillation of the input force. There will be increases as well as decreases in amplitude at different points as we sweep up in seems very odctince we are applying a constant force to the system yet the amplitude varies depending on the rate of oscillation ofthe input force. But this is exactly what happens -the response amplifies as we apply a force with a rate of oscillation that gets closer and closer to the natural frequency (or resonant frequency) of the system and reaches a maximum when the rate of oscillation is at the resonant frequency of the system. When you think about it, that,s pretty amazing since I am applying the same peak force all the time - only the rate of oscillation is changing!
如果现在测量平板响应，注意到当改变输入力的振荡频率时，响应幅值也发生变 化。频率升高过程中，不同时刻点上，幅值有增也有减。这好像很奇怪 因为我 们施加常力于系统，响应幅值却随输入力的振荡速率而变化。但这确确实实发生 了 一一当施加的力的振荡速率越来越接近于系统固有频率(或共振频率)时， 响应增大，当振荡速率为系统固有频率时，响应达到最大值。想想看，这真令人 惊奇，因为我每时每刻都施加了相同幅值的力-仅仅是振荡速率改变而已！
This time data providesvery useful information. But if we take the time data and transform it to the frequency domain using the Fast Fourier Transform then we can compute something called the frequency response function. Now there aresome very interesting i