J. Kissel, J. Warner

After getting all of the mechanical labor out of the way (see LHO aLOG 26452), Jim and I took to the B&K system for our first attempt at characterizing the resonant frequencies of ISI HAM6 blade springs and GS13 cans. No excitingly awesome results here; mostly just me writing stuff down for future reference. Stay tuned for more substantive results after tomorrow's work is complete.

-------------

We hit in two locations with accelerometer as close to the blade spring and GS13 can hit locations as possible. The blade hit location was roughly in the middle of the blade, stroking the hammer upward into the blade. Today's data is from Corner 3's blade alone. The accelerometer location was very similar to what's shown in pg 1 of LHO aLOG 25472's attachment. The GS13 Can hit location -- the H1 GS13 -- again suffered an awkward hammer stroke from beneath the can (because we didn't take the outer wall off). The accelerometer for this hit was mounted on the outer side wall just above the can.

We hit in two locations simply because it was the first data we'd seen and it wasn't processed well enough to confirm that we can see both systems of resonance in the blade-spring hit location. Attached are the data, processed. Though the three axes indicate different mode shapes, we weren't particularly careful about aligning the DOFs with any other reference set of coordinates. We'll try harder tomorrow.

The processed data is attached.

We expect the blade spring's 1st bending resonance to be at ~153 [Hz], and indeed that's exactly what we see. No surprise there. We see some more resonant features in the blade-hit location data which I have not specifically called out with data tips. Those resonances are a function of the blade modes vs. other body modes of the table will be more clearly identified once we damp them, so I'll wait for that.

As far as the GS13 can location, we expect its resonant modes to be around ~1.2 and 1.6 kHz. However, with the accelerometer close to the GS13 can there don't really appear to be any features in the data other than a 1.1 kHz mode. Looking back at the blade-hit location, there're feature more akin to those expected. Again, we'll see once we apply the damping material what modes are truly of these structure, but the message is that we can stick with the one blade-spring location for the accelerometer in each corner.

Much more to come tomorrow!

------------
Details:
The data has been exported from the B&K laptop and ported over to Sei SVN, the data lives here:
/ligo/svncommon/SeiSVN/seismic/HAM-ISI/H1/HAM6/Data/BandK/
2016-04-05_1315PDT_H1ISIHAM6_BladeSpringHit_Corner3_X_Reference.txt
2016-04-05_1315PDT_H1ISIHAM6_BladeSpringHit_Corner3_Y_Reference.txt
2016-04-05_1315PDT_H1ISIHAM6_BladeSpringHit_Corner3_Z_Reference.txt
2016-04-05_1322PDT_H1ISIHAM6_GS13CanHit_H1_X_Reference.txt
2016-04-05_1322PDT_H1ISIHAM6_GS13CanHit_H1_Y_Reference.txt
2016-04-05_1322PDT_H1ISIHAM6_GS13CanHit_H1_Z_Reference.txt

and the script to process the data lives here:
/ligo/svncommon/SeiSVN/seismic/HAM-ISI/H1/HAM6/Scripts/BandK
process_bandkdata_20160405.m

-----------------

For those who can imagine the B&K software window and have gotten as far as finishing the measurement:
In order to export the data after the measurement is taken, one must 
- go the "Validation" step on the left bar
- go to the upper left corner and click the "display" button
- choose the measurement number of your most recent measurement, selecting one of the accelerometer's DOFs at time
- right click on the resulting plot, select "properties" from the bottom of the menu, go to the "options" tab of the pop-up window
- make sure that the options are set to export as a PULSE ASCII format 4.2 (it doesn't really matter which one of the two of those options; I chose the upper one. I think the lower just adds more info to the header, which we don't use anyways).
- hit the copy to clipboard button.
- open up a text editor (the windows default is "notepad"), paste in the ASCII, and save as text.
- You *can* then wrestle with Tortoise SVN, but I didn't bother. I just pulled out the external disk and brought it over to sensible machine, and loaded in the data there.