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Entry  Mon Nov 12 22:56:10 2012, tara, Notes, NoiseBudget, Thermoelastic noise in spacer and substrate cavity_TE_v2.png
    Reply  Tue Nov 13 01:56:24 2012, tara, Notes, NoiseBudget, Thermoelastic noise in spacer and substrate 
       Reply  Wed Nov 14 00:25:48 2012, tara, Notes, NoiseBudget, ฺBrownian noise in spacer and substrate IMG_1975.jpg
       Reply  Wed Nov 14 19:46:47 2012, tara, Notes, NoiseBudget, Thermoelastic noise in spacer and substrate substrateTE_compare.pngTE_cavity_v2.mph
          Reply  Tue Nov 20 11:50:29 2012, rana, Notes, NoiseBudget, Thermoelastic noise in spacer and substrate 
             Reply  Wed Nov 21 20:16:55 2012, rana, Notes, NoiseBudget, Thermoelastic noise in spacer and substrate 
                Reply  Mon Nov 26 15:36:46 2012, rana, Notes, NoiseBudget, Thermoelastic noise in spacer and substrate 
                   Reply  Tue Nov 27 05:30:03 2012, rana, Notes, NoiseBudget, Thermoelastic noise in spacer and substrate 
          Reply  Tue Nov 27 05:38:01 2012, tara, Notes, NoiseBudget, Thermoelastic noise in spacer and substrate TE_Brownian_compare2.pngTE_Brownian_compare2.fig
Message ID: 1075     Entry time: Wed Nov 14 00:25:48 2012     In reply to: 1074
Author: tara 
Type: Notes 
Category: NoiseBudget 
Subject: ฺBrownian noise in spacer and substrate 

 I used COMSOL model to calculated Brownian noise in substrate. This was done for cross checking my model simulation. The result from model is within 2% compared to half infinite model calculation.

I followed Levin's Direct approach to calculate Brownian noise in substrate, basically, to calculate the elastic energy inside the substrate under the applied test force. This can be done using COMSOL and analytical calculation. The comparison between the two is shown below.

U is the stored energy in substrate.

 IMG_1975.jpg

 

Note: I used the same COMSOL model for TE noise calculation. I just asked it to produce the strain energy in the substrate (no spacer).

The simulation is very close to the analytical result. So I think my spacer-cavity model and all the factors in the calculation are correct. The TE calculation is a little more complicated, since I have to calculate the gradient of expansion in COMSOL and it might be wrong somewhere. I'll check that. 

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