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Message ID: 236     Entry time: Wed Feb 26 11:24:35 2020
Author: Marie K. 
Type: Summary 
Category: BS BRDs 
Subject: BS Bounce mode : BRD5_v5 & BRD6_v5 

====== Bounce Mode

Here is a summary of the BS bounce mode survey with BRD5_v5 and BRD6_v6 attached to the suspension for 6 months.
Details of the measurements are attached in the spreadsheet.

The measured transfer functions over time are shown in figure 1. We observed a single peak in the data. This is unexpected from our model.

  • There is no trend in the value of the resonant frequency.  The mean frequency is 16.660 Hz. The maximum excursion is +0.4% and the minimum is -0.2%.  
  • The Q of the mode is varying from 60 to 260, with no obvious correlation with the frequency variations. The maximum Q = 260 corresponds to a measurement with a lower amplitude of excitation (see elog xxx).

Therefore it seems that the bounce damping is pertty stable over 6 months. We didn't analyze correlations of the variations with environmental factors in the lab.

Measurements after taking off the BRD from BS:

Recall that pre-installation measurements were:

Attachment 1: BRD5&6_Winter_2019_survey_bounce_last.png  410 kB  Uploaded Wed Feb 26 14:30:43 2020  | Hide | Hide all
Attachment 2: Picture1.png  154 kB  Uploaded Wed Feb 26 14:31:47 2020  | Hide | Hide all
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