Hello sir,
In one of our impulse test rig application, we need to achieve pressure rise rate of 200000 psi/sec.
To achieve that much pressure rise rate, on which parameters we have to focus more during system design stage itself?
With that ramp rate I would say you would have to worry about everything. It’s very aggressive.
But a pressure rise rate is really not enough information for anyone to make any meaningful comments about the project.
Thank you.
Currently we have considered following factors.
- Effective bulk modulus of hydraulic fluid considering entrained air & temperature at 40°C
- Oil volume under compression.
- Modulus of elasticity of tubing material.
- Accumulator sizing for supporting hydraulic pump.
- Servo valve response time.
Did any additional parameters we miss out?
A biggie would be maximum pressure expected. You can probably hit a hammer on the rod end of a cylinder and get that ramp rate but you couldn’t control it.
Do you need to control that ramp rate or just monitor something that has around that rate?
Another is number of cycles. Is this a one shot test or repeated cycles for fatigue testing. Components fail by fatigue at much lower pressures than their normal working ratings. You may need to oversize components for them to survive. Essentially, they are being tested along with the DUT.
How will you measure this pressure ramp? Every millisecond the change is 200psi. You will have to deal with the slew rate of the pressure sensor and analog inputs and also consider the controller scan time. What resolutions do you need?
Assuming this is testing for many cycles, another concern is how are you going to detect failures. If the system you design is robust, it will probably still be able to generate your pressure impulses if there is a small leak in the test sample. Sometimes this can be addressed by mist detectors in the sample chamber or possibly watching the control output to the servo valve.
In any case, sounds like an interesting project.
Pressure is around 700 bar which will be generated by using dedicated intensifier.
Don’t want to control ramp rate (5% tolerance) but just monitor UUT at that ramp rate (fatigue testing)
All component selected based on their endurance strength.
Selected controller will be RMC200.
Only we need to focus more on pressure sensor slew rate & resolution.
Thank you so much for your valuable inputs…