What is Hydraulic Hysteresis?

You talking about industrial or civil?

Hydraulic power unit/s (oil) or waterways etc?

same as a Hysteresis for magnetizing a coil but then different

just kidding maybe this is useful?

and some info in this paper

Hi JWSFM

Not withstanding the comments listed above by others, I thought that I would jump in and add my version!

Hysteresis of any type usually refers to the difference in reaction characteristics caused by rising and falling pressure. With hydraulics, almost always a spring is involved and it is that component that will always have a tendency to be affected by hysteresis. Following on from that, springs are usually manufactured from some type of metal and that fact alone ensures that it will be affected by temperature. As hydraulic oil will have a varying temperature due to operating a system, the characteristics of the system (switching or relieving points) will constantly vary. This is usually by only a small amount and would not affect anything other than laboratory classed equipment.

Hope this helps!

if i may :hysteresis in a closed loop sys

we look at the system when under normal operating conditions.

no leaks & temp's well with in limits.

we turn off the system. iirc, most vivid example , on aircraft " aileron droop , flap droop "... as sys psi is relaxed, the tolerances " cool "..fluid bypasses seals, ,energize system, and when normal operating psi is reached droop cured.

our term for the test of psi loss / time was called " decay rate "...

hope this helps

I understood that in control operations, hysteresis was the condition where the same output gave different results. My example is a sloppy valve handle. Opening a valve to the halfway on the handle position opens the valve less than half way. If the same handle is continued to turn all the way it opens more.

If you close the handle to the same halfway (handle) position the valve opening is different than the first case because of the slop.

Hydraulic hysteresis may be with the same pressure or volume of fluid, the output to the device in one direction may give one condition, in the other direction the same pressure or volume has a different output or final effect.

If it is temperature induced, is it possible that the tubing has changed due to thermal expansion or could be flexible parts take more volume to meet the same pressure?

Paddler

Dear, with 'Hydraulic Hysterises' I understand that the possible acute varying conditions of any

• pressure controlled system,
• 'piping segment'
• equipment and
• 'environment'

That are expected or unexpected;but envisged as possibilities.

The concept is used for analyzing/estimating & trouble shooting the undesirable circumstance.

Hope this proves useful

Best Regards

Qalander