40m
QIL
Cryo_Lab
CTN
SUS_Lab
TCS_Lab
OMC_Lab
CRIME_Lab
FEA
ENG_Labs
OptContFac
Mariner
WBEEShop
|
40m Log |
Not logged in |
 |
|
Wed Nov 11 12:50:10 2009, Jenne, Update, PEM, Seismometer Noise Characteristics
|
Thu Apr 22 20:28:40 2010, Jenne, Update, PEM, Seismometer Noise Characteristics
|
Thu May 27 23:59:54 2010, rana, Update, PEM, New Foam Box installed
|
Fri May 28 00:40:53 2010, rana, Update, PEM, DAQ down
|
Fri May 28 10:44:47 2010, josephb, Update, PEM, DAQ down
|
Tue Jun 8 18:39:36 2010, rana, Update, PEM, DAQ down
|
Tue Jun 8 20:52:25 2010, josephb, Update, PEM, DAQ up (for the moment)
|
Fri May 28 11:26:35 2010, Jenne, Update, PEM, New Foam Box installed
|
Tue Jun 1 11:47:14 2010, steve, Update, PEM, lead balls on concrete
|
Wed Jun 9 19:47:08 2010, nancy, Update, PEM, lead balls on concrete
|
Thu Jun 10 07:53:14 2010, Alberto, Update, PEM, LaTeXlabs
|
Thu Jun 10 10:58:02 2010, Koji, Update, General, LaTeXlabs
|
Thu Jun 10 11:10:21 2010, Alberto, Update, General, LaTeXlabs
|
|
Message ID: 3060
Entry time: Wed Jun 9 19:47:08 2010
In reply to: 3024
Reply to this: 3062
|
Author: |
nancy |
Type: |
Update |
Category: |
PEM |
Subject: |
lead balls on concrete |
|
|
Quote: |
Quote: |
Valera and I put the 2 Guralps and the Ranger onto the big granite slab and then put the new big yellow foam box on top of it.
There is a problem with the setup. I believe that the lead balls under the slab are not sitting right. We need to cut out the tile so the thing sits directly on some steel inserts.
You can see from the dataviewer trend that the horizontal directions got a lot noisier as soon as we put the things on the slab.
|
The tiles were cut out in 1.5" ID circle to insure that the 7/16" OD lead balls would not touch the tiles on Wednesday, May 26, 2010
Granite surface plate specifications: grade B, 18" x 24" x 3" , 139 lbs
These balls and granite plate were removed by Rana in entry log #3018 at 5-31-2010
|
I tried to calculate the frequency of resonance using Rayleigh's method. approximated the geometry of lead to be that of a perfect cylinder, and the deformation in the lead by the deflection in a cantilever under a shear strain.
this rough calculation gives an answer of 170Hz and depends on the dimensions of each lead, number of leads, and mass of the granite. But the flaw pointed out is that this calculation doesnot depend on the dimension of the granite slab, nor on the exact placing of the lead spheres with respect toteh COM of the slab.
I will put up the calculations details later, and also try to do a FEM analysis of the problem.
BTW, latex launched this new thing for writing pdfs. doesnot require any installations. check http://docs.latexlab.org |