Re: FDC wire length changes

[Tim Whitlatch <whitey@jlab.org>]

My error. The length for each is 991mm, not 391mm. I cannot blame this 
on fat fingers....

Tim

Tim Whitlatch wrote:
> Good morning Dan,
>
> I have done some calculations this morning and here is what I came up 
> with.....
>
> From data from Fermi and Steve Christo, I use the following properties;
>
> Field wire - BeCu - 80um diameter, E=1.24e11 Pa
> Sense wire - w  - 20um diameter, E= 2.2e11 Pa
>
> For the longest (391mm) field wire tension to change from the initial 
> 140g to 120g in relaxed state, the frame would deflect about 310 um 
> inward. This is consistent with the tension from all the wires 
> contributing to frame deflection.
>
> For the longest (391mm) sense wire tension to change from 20g to 18g 
> in the relaxed state, the frame would have to deflect about 280 um 
> inward. This is consistent with the field wire deflection (close 
> enough to satisfy me).
>
> This all is in the realm of what I would have expected.
>
> Cheers,
>
>       Tim
>
> Daniel S. Carman wrote:
>> Tim,
>>
>> If you can get me some information on the expected length change
>> of the sense and field wires in the center of the wire frame due
>> to the wire load warping of the frame, I would appreciate this.  The
>> Phase 1 contract with IUCF ends on Aug. 22 and if the tension
>> phenomenon that I showed is not due to this effect, they will need
>> to work on this.
>>
>> I have estimated for the longest sense wire (991 mm), for a
>> tension change from 20 N (nominal stringing tension) to 18 N
>> (measured), the length changes only by about 20 microns.  This
>> seems like too small a number to me.  I have assumed a Young's
>> modulus for our sense wire of 3.72e11 Pa.
>>
>>
>>                 Regards,
>>
>>                     Daniel
>>
>>
>> **********************************************************************
>> *                                                                    *
>> * Dr. Daniel S. Carman                   e-mail : carman@jlab.org    *
>> * Staff Scientist                        office : (757)-269-5586     *
>> * Jefferson Laboratory                   web: www.jlab.org/~carman   *
>> *                                                                    *
>> **********************************************************************
>>
>>
>>   
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