- #1
serbring
- 269
- 2
Hi all,
I have a suspension system that is mounted in a vehicle and I must evaluate its behaviour. So I have measured the acceleration at the suspended mass and at the base. Since I haven't a bench I was obbliged to test it during vehicle driving. All signal are sampled at 500Hz. In the next picture you can see the PSD of: the excitation signal (blue line), suspended mass acceleration signal (black line) and its fitting (red line).
http://img717.imageshack.us/f/fitting.png/
As you can see from the picture the excitation PSD has 5 peaks at 1.7Hz,2.25Hz, 3.4Hz 4.5Hz and 5.1Hz.
As you can understand 3.4, 5.1 are multiple of 1.7, instead 4.5 is a multiple of 2.25. Is it usual to have peaks that are multiples from another? Should it be related to a fundamental frequencies of a specific mode or to a system non linearities? I need to understand this, for improving my mathematical model. I hope to have correctly explained my question, if not please ask me.
Any suggestions are really appreciated.
I have a suspension system that is mounted in a vehicle and I must evaluate its behaviour. So I have measured the acceleration at the suspended mass and at the base. Since I haven't a bench I was obbliged to test it during vehicle driving. All signal are sampled at 500Hz. In the next picture you can see the PSD of: the excitation signal (blue line), suspended mass acceleration signal (black line) and its fitting (red line).
http://img717.imageshack.us/f/fitting.png/
As you can see from the picture the excitation PSD has 5 peaks at 1.7Hz,2.25Hz, 3.4Hz 4.5Hz and 5.1Hz.
As you can understand 3.4, 5.1 are multiple of 1.7, instead 4.5 is a multiple of 2.25. Is it usual to have peaks that are multiples from another? Should it be related to a fundamental frequencies of a specific mode or to a system non linearities? I need to understand this, for improving my mathematical model. I hope to have correctly explained my question, if not please ask me.
Any suggestions are really appreciated.
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