

Hello Siva,


I talked to Hans Chen, our servovalve engineer, and have some numbers
for model parameters.


 


Servo-valve parameters:


overlap: 0.06 %              (Brad may be altering this number to make
model match experimental results, so 0.1% may be OK too)


rated pressure: 1000 psi


rated flow: 845 gpm        (3200 liter/min)


 


Actuator parameters:


leakage: 0.0013 gpm/psi 


We are not sure how leakage is interpreted, if it is servovalve null
flow then this number is close.  Null flow is the leakage through the
valve with the spool centered at midstroke (zero command) and 3000 psi
at P port, 0 psi on R port.


 


Accumulator parameters:


volume: 40 gal per HSM plus 150 gal for each accumulator stand enabled.


 


I think a single actuator model could include 1 HSM and 2 accum
stands=340 gal total.  For very dynamic tests you could "turn on" more
accumulator stands, or if you are using multiple dynamic actuators you
may have to reduce the effective accumulation per actuator.  It should
be OK to assign a fraction of a accum stand to each actuator, ie if the
test requires 3 dynamic actuators you could turn on all 4 accumulator
stands so each actuator would get 40 gal HSM + (4 stands)*(150 gal)/(3
actuators) = 240 gal each actuator.


 


precharge: 1600 psi        we charged all P accumulators to 1600 psi to
maximize energy storage.


pumpFlow: 720 gpm       you have four HPU's in your pump room, each =
180 gpm, if all pumps were turned on you would get 720 gpm.


 


If the data file requires a pumpFlow for each actuator, you will have to
pro-rate the total pump flow by the rated flow capacity of each
servovalve active in the test.


 


I hope this helps, if you have questions give me a call.


 


Regards,


 


Jeff Lundbeck


Mechanical Engineer


MTS Systems Corporation


ph:  952-937-4543


fax:  952-937-4515


email:  jeff.lundbeck@mts.com


 


-----Original Message-----
From: Siva Mettupalayam [mailto:siva@nees.buffalo.edu] 
Sent: Wednesday, August 04, 2004 12:16 PM
To: Lundbeck, Jeff
Subject: Model parameters


 


Jeff,


 


I couldn't find Brad yet. In the meanwhile, here's a list of parameters
in the model and their values corresponding to the table at Reno.


 


Servo-valve parameters:


overlap: 0.1 %


rated pressure: 1000 psi


rated flow: 500 gpm


 


Actuator parameters:


leakage: 0.0013 gpm/psi


 


Accumulator parameters:


volume: 240 gal (40 gal per actuator)


precharge: 1000 psi


pumpFlow: 720 gpm


 


Would it be possible to find out the corresponding values for our
dynamic actuators? Thank you.


 


Siva