Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.naic.edu/~phil/hardware/telescope/unbalanced_moment_cycles_by_yr.html
Дата изменения: Thu Mar 3 00:14:09 2011
Дата индексирования: Tue Feb 5 03:16:51 2013
Кодировка:

Поисковые слова: m 63
telescope cycles by year

Number of telescope cycles using unbalanced moment

02mar11

Draft


Intro:

    The tension in members of the telescope changes as we move the dome, ch, azimuth, and tiedown tensions. The lifetime of a beam is counted in the number of times the change in tension goes through a cycle. If the change in tension during the cycle remains less then 16Kips/sqIn then  the cycle does not affect the lifetime of the member. 

    Amman and Whitney (21may10) provided a table of stress ranges for members over 100% capacity (.pdf). Using their simulator, they moved the telescope through a range of motions and looked to see how the stress changed in a particular truss (I'm not sure what they used for tiedown tensions in the calculation).


    The following sections contain:


The dataset: (top)

    The telescope position is recorded once a second to disk. Some properties of this dataset are:


Examples of telescope motions (top)

    The plots show the az, za, and unbalanced moments for various observing modes used at the telescope:

Number of cycles using change in moment: (top)

   
    The number of cycles on the telescope was computed using the change in the unbalanced moment (at a corner). The Amplitude of the change for a cycles was computed for changes greater than:  [5000,10000,15000,20000] kip feet.
    The computation constisted of:
   
The plots show the change in unbalanced moment on the telescope 2004.5 through 2010 (.ps) (.pdf) using the above definition:



Summary:

Number of telescope cycles using Amplitude of unbalanced moment change:

Number of telescope cycles
integrated 2004.5 thru 2010

Amplitude
KipFeet
corner12
totCyles
corner 4
totCycles
corner 8
TotCycles
> 5000
48665
53061
52568
> 10000
29838
28155
27620
> 15000
15469
15536
14985
> 2000
8320
8773
8384


 
Median Cycles/year
Amplitude
KipFeet
Median Yearly
cycles
> 5,000
9378
> 10,000
5418
> 15,000
2980
>20,000
1704


Unbalanced moments for typical motions:


  processing:x101/110204/agccyclesdif.pro, agccycleslev.pro

home_~phil