"Richard Smith" wrote in message ...
....
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".
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You might be able to significantly reduce the 80KW power demand if the
pressure source is a small flywheel-driven piston built into the fixed end
of the cylinder to minimize flow friction loss, that absorbs the pressure
energy as it retracts. You'd add oil/bleed air until a pressure sensor
signal peaks at the desired pressure.

This could require some custom machining and knowledge of using an
oscilloscope. Are those acceptable for you?

When I was in the automated testing business we had to figure times for high
count operations such as testing each cell on a memory chip wafer, often in
conversation without a calculator. There are 86,400 seconds in a day. 1
million seconds (cycles?) is 11.57 days. A micro-year is 31.5 seconds. 1 US
billion (10^9) seconds is 31.7 years.

https://www.youtube.com/watch?v=hj7LRuusFqo