"Jim Wilkins" writes:

"Joe Gwinn" wrote in message
...
...
If the motor runs slow, so does the oscillation cycle, in direct
proportion.

Joe Gwinn
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If the expected fatigue life is 2 million cycles, the test time at 1
cycle per second is three weeks. I think a good solution would be a
closed loop based on a pressure sensor that shows when the high and
low limit pressures have been reached, so the controller can switch
between the fill and dump solenoid valves as rapidly as fluid flow
permits.

If I had to build a prototype of the tester the controller would be an
old laptop (or desktop) with a printer port, the data bits driving a
successive-approximation A/D converter to measure the pressure sensor
and two control bits operating the fill and dump solenoid valves.

QBasic running in DOS gives full unhindered access to all of the
printer port bits for input and output, unlike Windows. An Arduino
could also work but the laptop has the advantages of a huge hard drive
to store data, the keyboard for control, and the LCD on which QBasic
can display the cycle count and a graph of the pressure.
http://www.nicolasbize.com/blog/30-y...till-the-best/

This simple resistor network outputs a voltage proportional to the
binary code from the port bits:
https://www.tek.com/blog/tutorial-di...rsion-r-2r-dac

The other electronics are an analog comparator (LM311) driving a
printer port status bit that tells if the sensor output voltage is
more or less than the DAC output, and the two high current solenoid
valve drivers.

Stunning detail.
I see that with
* test method and hardware
* control and data acquisition
2million cycles would be a start. With well-performing welds, you'd
want to get out to 20million cycles or more
(200Million is something around what a ship or bridge gets in its
entire period of service, but can be a bit of an ask in test).
I've programmed in Basic. Access to devices / ports - hadn't thought
about it being that convenient and tailor-made.