40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  40m Log  Not logged in ELOG logo
Entry  Thu Aug 11 16:09:05 2011, Nicole, Summary, SUS, Bode Plot for TT Suspension 6x
    Reply  Fri Aug 12 14:15:07 2011, Nicole, Summary, SUS, Bode Plot for TT Suspension EXPrigidvsflex.jpg
       Reply  Fri Aug 12 15:34:16 2011, Nicole, Summary, SUS, Bode Plot for TT Suspension RIGIDexp_model.jpgflexmodcomp.jpg
Message ID: 5208     Entry time: Fri Aug 12 15:34:16 2011     In reply to: 5206
Author: Nicole 
Type: Summary 
Category: SUS 
Subject: Bode Plot for TT Suspension 

Quote:

Here is my bode plot comparing the flexibly-supported and rigidly-supported EDCs (both with no bar)

It seems as if the rigidly-supported EDC has better isolation below 10 Hz (the mathematically-determined Matlab model predicted this...that for the same magnet strength, the rigid system would have a lower Q than the flexible system). Above 10 Hz (the resonance for the flexibly-supported EDCs seem to be at 9.8 Hz) , we can see that the flexibly-supported EDC has slightly better isolation? I may need to take additional measurements of the transfer function of the flexibly-supported EDC (20 Hz to 100 Hz?)  to hopefully get a less-noisy transfer function at higher frequencies. The isolation does not appear to be that much better in the noisy region (above 20Hz). This may be because of the noise (possibly from the electromagnetic field from the shaker interfering with the magnets in the TT?). There is a 3rd resonance peak at about 22 Hz. I'm not sure what causes this peak...I want to confirm it with an FFT measurement of the flexibly-supported EDC (20 Hz to 40 Hz?)

 

 

EXPrigidvsflex.jpg

 

 

 Since the last post, I have found from the Characterization of TT data (from Jenne) that the resonant frequency of the cantilever springs for TT #4 (the model I am using) have a resonant frequency at 22 Hz. They are in fact inducing the 3rd resonance peak.

 

Here is a bode plot (CORRECTLY SCALED) comparing the rigidly-supported EDCs (model and experimental transfer functions)

RIGIDexp_model.jpg

 

Here is a bode plot comparing the flexibly-supported EDCs (model and experimental transfer functions). I have been working on this graph for FOREVER and with the set parameters, this is is close as I can get it (I've been mixing and matching parameters for well over an hour > <). I think that experimentally, the TTs have better isolation than the model because they have additional damping properties (i.e. cantilever blades that cause resonance peak at 22 Hz). Also, there may be a slight deviation because my model assumes that all four EDCs are a single EDC.

flexmodcomp.jpg

ELOG V3.1.3-