Graphite fiber is kind of unique, if has a negative coefficient of thermal
expansion. Just about everything else has a positive coefficient of thermal
expansion. Using a resin in the correct amount can lead to structures that
have zero coefficient of thermal expansion. But, it leaves me wondering
about pressure tanks build at room temperature and heat cured. With the
thermal stress between the graphite fiber and resin set to zero at an
elevated temperature. Dropping the temperature to room temperature may be
perfectly fine for the structure, but at cryogenic temperatures the
internal thermal stress might change the properties of the structure. Flaws
might also be magnified, to much resin, or to much graphite. Or, unequal
loading between the outer and inner walls of a thick wall pressure tank.
On Sat, Sep 24, 2016 at 1:29 AM, Keith Henson <hkeithhenson@xxxxxxxxx>
wrote:
On Fri, Sep 23, 2016 at 10:08 PM,William Claybaugh
<wclaybaugh2@xxxxxxxxx> wrote:
Carbon composite is just the new code phrase for "rags"....
Ouch!
I don't know if the He tank was composite or not, but I kind of suspect it
was.
If the He tank burst, the vehicle (and payload) were doomed anyway,
but I kind of suspect bursting got parts of the He tank hot enough to
react with the LOX it had been soaking in for some time.
Decades ago Eric Drexler and I proposed aluminum and silica fiber
composites for O'Neill cylinders. Optimum design cracked the fibers
at intervals so that a failure would cause the fibers to pull out,
deforming a lot of metal and soaking up energy. If one of them did
burst, you could expect the pulled out fibers to be very hot. The
same may apply to composite He tanks.
I appreciate your comment.
Keith
Bill
