i am one begginner in the vib analysis ,anyone can help give me some materials to learn the knowledge of vib analysis.Thanks!

This guy is the best I know. His material is real world and easy to follow.

www.macanalysis.ca

Check out this site.
Has basic and on site assistance.

http://www.alertanalytical.com/

For interactive CD-ROM based vibration training:
http://www.reliabilitydirect.com/trainingproducts/ilearn_interactive.htm

I just had a look at the severity chart on macanalysis.ca and found it way out of line with reality in my opinion.

Sam,

I looked also, and although they are higher than most people would like to see, "way out of line with reality" doesn't seem accurate to me.

Reality is that some stuff will run at even higher amplitudes than what they show and lots of times it has to and does.

Many places are faced with much more pressing things than a fan that has been vibrating at .65 ips at running speed for 3 years. It may run another 5 years instead of 30 years, but the extra comes out of different budgets, so the "if it ain't broke don't fix it" thinking applies.

Sorry to drift off the subject.