Hi to everyone.
You folk are amazing!
I've been here on my own, and you come along knowing lots of solutions.
I'm in information-overload with all the great leads you've given.
Plus I've just done a week and a half of calculations on testing
methods and really really need to give my head time-out.

You asked about this device.
I'll share with you
http://www.weldsmith.co.uk/tech/fatg...hyd_inner.html
It's an idea for a metal fatigue test, particularly of welds.

So in this rig, the sample is inaccessible, inside the hydraulic
cylinder immersed in the hydraulic fluid.

For the advantages you get, the disadvantages are "nothing".
This test could be running for days to 10's of days, by the way.
It's "high stakes".

Even where you can stop the test and approach the sample, you don't,
in reality. Gets you nothing additional.

The test stops when the sample breaks...

Welding the sample to the "pistons" has more advantages than
disadvantages (one would reckon).
Small and stiff.

A "contraption"? Yes. However - so long as you do a "scattergun"
approach, you have a significant likelihood that some try will work.
You have to be very open-minded, because you can have "dead-certs"
which don't work, and "shouldn't work" which delivers and then some.
You can find the science was wrong, or incomplete, and by giving it a
try anyway you find that out, as well as getting results.

I'll get my head around the info - the links and hints.

Like be back in a little while...

Best wishes all,
Rich S