Learning Forum

[julius.langenhorst]

Hello,

I'm looking at a simply-supported circular Euler-Bernoulli beam. I want to find out the response of the beam to a constant acceleration in the range up to 2000 Hz and plot the result in a acceleration vs. frequency plot.

How do I extract the acceleration after doing the analysis? And how would I then plot it?

Here's a snippet of my code:

! Build model
! Modal analysis
ANTYPE,MODAL
MODOPT,LANB,10,0,0
MXPAND,10,,,yes
SOLVE
/QUIT

! Response Spectrum analysis
/SOLU
ANTYPE,SPECTR
SPOPT,SPRS
SRSS,,ACEL
SVTYP,2
SED,0,1,0
FREQ,1,1000,2000
SV,,5*9.81,5*9.81,5*9.81
MMASS,ON
SOLVE
FINISH

/POST1
/INPUT,,mcom
PRNSOL,DOF
PRNSOL,U,Y
FINISH

Thanks for your answers.

[danielshaw]

A Response Spectrum Analysis (RSA) does not calculate the response at a particular frequency.  It calculates the peak response over the frequency range.  When you enter the command /INPUT,,mcom; you read the file.mcom file that contains load case commands that combine the modal resultls.  You should do a harmonic analysis (probably a mode-supe harmonic) to calculate the response vs frequency.

[julius.langenhorst]

 

Thanks for your answer.

I used mode-superposition harmonic analysis and I now got a beautiful displacement vs. frequency plot. But to plot acceleration vs. frequency I want to multiply the displacement with its corresponding frequency. The nodal information is stored in a variable using NSOL,2,12,U,Y. I could create an array parameter for the frequency but I have not found a way to combine those two. How do I do this?

EDIT: I think I found the solution by using FILLDATA to fill variables