5.45th order

[trisha26]

Ok, I didnt really explain the problem too well before. I will try again. We have some data taken in-vehicle, where we are seeing a peak at 250Hz which is in the order of 5.45. I am thinking this is either related to a resonance or bearings of some sort. The halfshaft bearings should be order 8. But i am thinking wheel bearings. Or, this could be related to soime resonance, perhaps diff/subframe related. The diff is order 11, perhaps being pretty much half this has something to do with it?

 

[Zackman]

Trisha26, I think you might want to post some additional information such as where the transducer is mounted, transducer type, some explaination of the type of vechicle and how the data is being taken. What are your concerns? Vibration level too high, this frequency is usually not observed during data collection, etc.

Doing the math, I get a 1X frequency of 2752.29 cpm (assuming you really are taking data accurate to two decmal places). What does this frequency relate to, such as crankshaft speed or drive shaft speed?

To test for resonnace, varying the 1X frequency from some point lower than the current frequency to some point higher and see if the vibration is tracking this frequency or only occurs within some frequency range. Ideally, use a 1X phase and speed pickup and produce Bode / Polar plots of vibration versus speed. If your software is capable, set the nX filtered vibration to 5.45X instead of the typical 1X to allowing tracking of the suspect frequency.

 

[IRstuff]

Please try to keep your related postings together. This is very confusing to those who have not seen your earlier thread.

I suggest that you red-flag this posting and submit it as a reply to your original thread.

TTFN