Re: shock wave as pressure builds in a vacuum?

[Bernard Cleyet <anngeorg@PACBELL.NET>]

I haven't read carefully so the following may be irrelevant:

I think Stefan is stuck with Be -- is not this for X-ray detection?  If
so, another material will fluoresce and overly complicate the data.

I suspect a very large number of materials are tougher than Be.   I mean
the ability to absorb energy without fracture, as measured, for example,
by a Charpy test *.  If fluorescence is not a problem, a composite such
as Kapton with a carbon film vacuum deposited would be appropriate.  If
I remember correctly such composites are not brittle, yet have a Y of ~
100k PSI.

With so much engineering data on this problem available, I'm surprised
Stefan has this problem.

For example I find that Be has two forms (BCC and HCP)  Therefor, it may
be heat treatable.
Tho such treatment will make Be harder it may also inhibit crack
propagation.


* A more appropriate test for brittle materials?:
http://www.terratek.com/equipment/fracto_1.htm

QGS (quick Google search):

"Fracture Toughness of Beryllium" with D.O. Harris; Journal of
Materials, Vol. 3, No. 1, pp. 59-72, 1968.


Effect of temperature on spall failure of some metals and alloys:  "The
computational analysis of shock-wave loading and spall failure
conditions was performed using a program of numerical calculation of
one-dimensional elastic-plastic flows. "
http://www.eps.org/aps/meet/SHOCK99/baps/abs/S2400006.html


 17.28 STRENGTHENING OF BERYLLIUM AT THE EARLY STAGE OF LOW TEMPERATURE
NEUTRON IRRADIATION
 G.A. Sernyaev: http://www.pnl.gov/icfrm9/session17.html

bc


Roger Haar wrote:

> Stefan,
>         I am not sure the Be windows are tougher than
> your polymer ( kaptan?? ).
>
>         If you are looking for solutions, I am wondering
> if the solid state detectors like made by AMPTEK
> (www.amptek.com)  or Contech (www.contech.com)
> could be retrofitted.  The Amptek are what was in
> the "nose" of the Martian Rover. These seem to be
> in the $2500-$5000 range.  These detectors are
> small but you might be able to get them closer.
>
>         I am guessing you are replacing your own windows
> because it cost us about $1000 to get Ortec to
> replace the Be window + refurbish.
>
> Thanks
> Roger Haar