请教功率谱密度问题

jingrenzhi

对时域离散信号求取功率谱密度,得到的共振频率是否是结构的固有频率?直接做FFT得到的共振频率是否是结构的固有频率?谢谢

[ 本帖最后由 zhangnan3509 于 2007-9-3 09:34 编辑 ]

pengweicai

理论上应该是，但是信号中会存在干扰，所以有些可能不是。需要识别。才能判断。

jingrenzhi

谢谢!我现在有这样一组数据,请帮忙求一下功率谱密度!
x=[3.108450e-02
6.311096e-03
6.122705e-03
1.987524e-02
2.496180e-02
3.579427e-03
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caichengtao

楼上的，希望你能把数据存成一个数据文件，作为附件上传！节省论坛版面空间啊！

jingrenzhi

谢谢提醒!可是我不知道怎么贴附件呀?

sunning

在发表帖子时，上传附件就可以了

sunning

你的采样频率是多少？

sunning

我把你的数据分析了一下，用功率谱画了图
不知道你的采样频率是多少，看到你的数据是1024个，我就取采样频率是4096Hz了
第一阶频率大概是200Hz左右

wanyeqing2003

响应的峰值不一定在共振频率处。

共振频率或者固有频率应该由传递函数来确定。

sunning

wanyeqing2003 说的对，共振频率应该是模态的概念，要通过测量FRF来获得
我这个只是将他给的数据进行了自功率谱转换，得到响应的谱线
激励频率为一个（或多个）时的响应谱线的峰值，只代表在此激励频率下的最大响应值，而不一定是该结构的固有频率。如果激励频率中包含有固有频率的话，那这个峰值就是结构的固有频率。不过这似乎有点右果推因的感觉，所以要获得固有频率还是做结构的模态。

jingrenzhi

谢谢,我的采样频率应该是500!
请把您做功率谱的程序共享下好吗?我再学学!谢谢!