Does mechanical vibration have an offset ?
Does mechanical vibration have an offset ?
(OP)
Hi !
I'm new in vibration mesureing. So it might be a simple question.
Can mechanical vibration have an offset ? Is it right that if this is true the method of getting the velocity through integration doesn't work properly ?
How can i calculate the amplitude of the vibration (in mm) ? Through integration of the velocity i get the displacement but this is dependent of the sample duration. How can i get this right ?
Alot of questions ... please be patient.
Thanks alot.
Alex
I'm new in vibration mesureing. So it might be a simple question.
Can mechanical vibration have an offset ? Is it right that if this is true the method of getting the velocity through integration doesn't work properly ?
How can i calculate the amplitude of the vibration (in mm) ? Through integration of the velocity i get the displacement but this is dependent of the sample duration. How can i get this right ?
Alot of questions ... please be patient.
Thanks alot.
Alex





RE: Does mechanical vibration have an offset ?
The main problem is that the original signal may have a spurious offset or trend. Integration will greatly amplify this error. Thus, highpass filtering should usually be performed on the signal prior to integration.
Preferably, the highpass filtering should be performed on the analog signal prior to digitization.
Sincerely, Tom Irvine
http://www.vibrationdata.com
RE: Does mechanical vibration have an offset ?
Vibration parameters i.e. acceleration, velocity and displacement are mathematically related for sinusoidal wave signals. From instrumentation point of view, signals produced by the accelerometers and velocity transducers are in terms of AC while the proximity probe produce AC and DC (offset).
To get velocity through integration means that you have acceleration input signal produced from an accelerometer, which produce only AC signal. Most data collector/dynamic analyzers have this integration feature that you can select to have analog or digital integration. The obtained integrated spectrum is considered correct.
To calculate amplitude of vibration in displacement from velocity signal in time domain, you can select the dominant frequency component and use it in the equation D=V/w where D is displacement and V is the velocity and w is the frequency in rad/sec. Pay attention to the unit conversion and the type of parameter (Peak to Peak or Zero to Peak, etc)
RE: Does mechanical vibration have an offset ?
RE: Does mechanical vibration have an offset ?
RE: Does mechanical vibration have an offset ?