请教随机振动分析和谱分析的区别？

superlxl2

如题，希望高手解答。二者输入都是频率响应曲线吗？输出结果是基于频率还是时间的？另外，二者的结果可以导入疲劳分析模块中吗？小弟想做用结果做振动疲劳分析。谢谢。

sunnygu

spectrum analysis

A response spectrum analysis has similarities to a random vibration analysis. However, unlike a random vibration analysis, responses from a response spectrum analysis are deterministic maxima. For a given excitation, the maximum response is calculated based upon the input response spectrum and the method used to combine the modal responses. The combination methods available are: the Square Root of the Sum of the Squares (SRSS), the Complete Quadratic Combination (CQC) and the Rosenblueth’s Double Sum Combination (ROSE). See Response Spectrum - Options Control Settings for further details.

random analysis

This analysis enables you to determine the response of structures to vibration loads that are random in nature. An example would be the response of a sensitive electronic component mounted in a car subjected to the vibration from the engine, pavement roughness, and acoustic pressure.

Loads such as the acceleration caused by the pavement roughness are not deterministic, that is, the time history of the load is unique every time the car runs over the same stretch of road. Hence it is not possible to predict precisely the value of the load at a point in its time history. Such load histories, however, can be characterized statistically (mean, root mean square, standard deviation). Also random loads are non-periodic and contain a multitude of frequencies. The frequency content of the time history (spectrum) is captured along with the statistics and used as the load in the random vibration analysis. This spectrum, for historical reasons, is called Power Spectral Density or PSD


In a random vibration analysis since the input excitations are statistical in nature, so are the output responses such as displacements, stresses, and so on.

Typical applications include aerospace and electronic packaging components subject to engine vibration, turbulence and acoustic pressures, tall buildings under wind load, structures subject to earthquakes, and ocean wave loading on offshore structures.

superlxl2

多谢版主的解答。还想请问随机振动的输出是频率响应的位移，力，应力等。怎么将这些结果运用到疲劳的分析中呢？

sunnygu

你查一下BASIC SIMULATION里面的fatigue分析。在提问以前在版面里面搜索一下。不要问太低级的

xbzihan

自己认为随机振动就是谱分析的一种，只是基于统计的方式而已。

platofans

:'(,我也是“太低级的”一类的了

龙腾宇内

随机振动输入的是功率谱吧，一般的谱分析只需要输入加速度vs频率的关系就够了

hupo8522

版主就从help里复制了一段儿，省事儿啊

sailing_inrt

版主需要耐心