Dear All
Iam performing a base excitation harmonic analysis under ansys , however i need to get the nodal amplitude for each analysis step so i used *get command but unfortunatly ansys gave me an error '' "The degree of freedom solution is not available" . anyone can help me fix this problem
here it is the full code i used
*CFOPEN,results_harm,txt
! ====================================================
!!!!!!!!! Based excitatio analysis!!!!!!!!!!!!!!!!!!!!!!
! ====================================================
*CFOPEN,results_harm,txt
/SOLU
allsel,all
ANTYPE,HARM ! Harmonic analysis
hropt,full ! full harmonic response
HARFRQ,0,40, ! Frequency range of analysis
NSUBST,40, ! Number of frequency steps
hrout,off ! print results as amplitudes and phase angles
outpr,all,1
KBC,0 ! Impulse loads
nsel,s,loc,z,-b/2,b/2 ! Amplitude vibration
nsel,r,loc,x,0 ! Amplitude vibration
nsel,r,loc,y,0,a
accelx=0.0
accely=0.0
accelz=-6.0
ACEL,accelx,accely,accelz
allsel,all
*get,STOP22,NODE,1177,VOLT
*get,STOP33,NODE,1841,VOLT
*get,STOP44,NODE,6881,VOLT
*get,STOP11,NODE,6993,VOLT
!*get,disp,node,Force,u,z
*VWRITE,STOP11,STOP22,STOP33,STOP44!,disp
%0.0f,%0.0f,%0.0f,%0.0f!,%0.0f
DMPRAT,0.00878
NSEL,ALL
SOLVE
outres,all,1
FINISH
*cfclos
Directly using *get after the SOLVE may not yield the required result.
You have 40 steps in your analysis. After the solution is completed for each step, in order to retrieve the result we have to access the solution for each step. In order to do this, we need to first set (SET) the first solution step as active (by using SET command), read (*get) the required nodal solutions and write (*vwrite) them. Subsequently, this process has to be repeated for the other sets (*do,i,1,40) too. Since you have 40 steps, you would need a *do loop in order to access each of the 40 steps for which the solution has been performed.
You can experiment by modifying your code along the following lines:
/SOLU
*** your analysis steps
FINISH
*do,i,1,40 ! Loop on each solved step
set,i,1 ! Open the step
*get,,,,,, ! complete the command depending upon your requirement
*vwrite,,,,,, ! accordingly complete it
*enddo
Please try and let me know if it works.
Regards,
Hello,
The solution must be performed first and then only one can go for retrieving results for nodal degrees of freedom. From your code, it appears that you are trying to retrieve the solution before the solution has actually taken place (*get and *vwrite commnads appear before SOLVE).
Further, you may require a *do loop to retrieve nodal amplitudes corresponding to each substep of the frequency range considered.
Please do correct me if I am wrong.
Warm regards,
Nitin
Thank you Dr Nitin for the reply
Actually I changed it and put the *get command after solving according to you recommend but the same error were appeared .however , I didn't get what you mean by using *do loop can you explain me please
Directly using *get after the SOLVE may not yield the required result.
You have 40 steps in your analysis. After the solution is completed for each step, in order to retrieve the result we have to access the solution for each step. In order to do this, we need to first set (SET) the first solution step as active (by using SET command), read (*get) the required nodal solutions and write (*vwrite) them. Subsequently, this process has to be repeated for the other sets (*do,i,1,40) too. Since you have 40 steps, you would need a *do loop in order to access each of the 40 steps for which the solution has been performed.
You can experiment by modifying your code along the following lines:
/SOLU
*** your analysis steps
FINISH
*do,i,1,40 ! Loop on each solved step
set,i,1 ! Open the step
*get,,,,,, ! complete the command depending upon your requirement
*vwrite,,,,,, ! accordingly complete it
*enddo
Please try and let me know if it works.
Regards,
i tried it but no luck , if it possible i can send you the whole file to see whats the problem by your self
Thank you Dr @Claudio Pedrazzi
i even tried your recommendation but the same warning appear The degree of freedom solution is not available" . in /post26 I can get the results and plot them but for my case isn't helpful because i need to implement a feedback controller according to each step solution
Thank you guys i fixed the problem,
what i did is just divided the full frequency range into 40 steps and by means do loop i effectuated a harmonic analysis for each step then use /Post1 and set command to get the data
your recommendations were so helpful
Regards
Kouider
Great!
I would be happy to learn and know more in detail about the problem you are solving. It would be great if you could share some of your publications or point to some basic works related to your problem
Dear Nitin
iam working right now on the active vibration control of smart FGM plate using discret piezo patches (sensors/actuators) .
my work is based on three steps
1- develop a FEM model of FGM plate and design a PID controller for it based on optimization of the piezo locations and thickness under Matlab
2-implement the same model into ansys and reduce its vibration in time and fréquency response
3-implement an electric circuit as a shunt process to damp the its vibrations in time and fréquency response
and i get some funding i will performe an experimental setup
you are absolutly right i recheck my code its contain alot of solve and also no need for SET,i,1
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