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  Fri Jan 5 19:19:25 2018, rana, Configuration, SEI, Barry Controls 'air puck' instead of 'VOPO style' breadboard mm_slm.jpgScreen_Shot_2018-01-05_at_7.25.47_PM.png
    Reply  Wed Jan 10 16:27:02 2018, Steve, Configuration, SEI, load cell for weight measurement stacis3LoadCells.png
       Reply  Wed May 2 10:03:58 2018, Steve, HowTo, SEI, preparation of load cell measurement at ETMX 6x
          Reply  Thu May 3 09:56:42 2018, Steve, HowTo, SEI, preparation of load cell measurement at ETMX 
             Reply  Mon May 14 08:55:40 2018, Dennis Coyne, HowTo, SEI, preparation of load cell measurement at ETMX 
    Reply  Tue Jan 23 16:02:05 2018, Steve, Configuration, SEI, load cells stacis3LoadCells.pngDSC00025.JPGDSC00026.JPG
Message ID: 13840     Entry time: Mon May 14 08:55:40 2018     In reply to: 13809
Author: Dennis Coyne 
Type: HowTo 
Category: SEI 
Subject: preparation of load cell measurement at ETMX 

follow up email from Dennis 5-13-2018. The last line agrees with the numbers in elog13821.

Hi Steve & Gautam,

I've made some measurements of the spare (damaged) 40m bellows. Unfortunately neither of our coordinate measurement arms are currently set up (and I couldn't find an appropriate micrometer or caliper), so I could not (yet) directly measure the thickness. However from the other dimensional measurements, and a measurement of the axial stiffness (100 lb/in), and calculations (from the Standards of the Expansion Joint Manufacturers Association (EJMA), 6th ed., 1993) I infer a thickness of 0.010 inch in . This is close to a value of 0.012 in used by MDC Vacuum for bellows of about this size.

I calculate that the maximum allowable torsional rotation is 1.3 mrad. This corresponds to a differential height, across the 32 in span between support points, of 0.041 in.

In addition using the EJMA formulas I find that one can laterally displace the bellows by 0.50 inch (assuming a simultaneous axial displacement of 0.25 inch, but no torsion), but no more than ~200 times. I might be good to stay well below this limit, say no more than ~0.25 inch (6 mm).

If interested I've uploaded my calculations as a file associated with the bellows drawing at D990577-A/v1.

BTW in some notes that I was given (by either Larry Jones or Alan Weinstein) related to the 40m Stacis units, I see a sketch from Steve dated 3/2000 faxed to TMC which indicates 1200 lbs on each of two Stacis units and 2400 on the third Stacis.

ELOG V3.1.3-