Learning Forum

[Md_Salem]

Hi,

I am carrying out optimization process using Ansys 2022R1 workbench for geometric configuration under harmonic load.
My concern is to apply the harmonic load at the frequency of the first mode shape ( first natural frequency) which can be obtained from pre-modal analysis as a value.
I wonder if i can make the Ansys repeat the modal analysis after optimization is done (for the new geometric configuration)  and ahence extract the new first natural frequency , then repeat the optimization with the new load frequency and so on ?
In other words, can I implement the harmonic analysis to go under first natural frequency (or any aother selected natural frequency) directly from the modal analysis ?

Regards

[Chandra Sekaran]

Within the Mechanical GUI the frequency value at which to carry out the harmonic analysis has to be typed in. There is not a way to use the first natural frequency from a modal analysis. However you can potentially do this using APDL command snippets. I am thinking you can do the following:

1. in the modal analysis in Post1 *GET the first natural frequency. Write this to a file (*CFOPEN, *VWRITE, *CFCLOSE) to a known folder, say, d:\test
2. In the harmonic analysis read this frequency from the file (*VREAD) and use HROPT to apply the frequency range with NSUB,1.

 

[Md_Salem]

Hi,

I think it is pretty good trick, I will try it and let you know 

I just wonder if it is possible to achieve the process shown in the attached flowchart ?

[Md_Salem]

Hello Chandra,
I did the first part of the solution (get the 1st frequency and write it as a parameter to *.txt file) 
Now I have a problem with workbench harmonic analysis, which is how to force the solver to bypass the  (analysis setting) of workbench solver and read the analysis setting from my APDL macro code ?
*VREAD,Fd,MODES_F,TXT,E:\  !(Fd parameter for frequency & MODES_F.txt is the file)
(F12.4)             !(fortran format)
HROPT,FULL  
HROUT,ON
LUMPM,0 
!*  
EQSLV, ,0,  
PSTRES,0
!*  
HARFRQ,0,Fd,   
NSUBST,1,   
The workbench keeps telling me (invalid "Range Maximum") even if I put numerical value directly instead of Fd.
I think that the problem is in the (Analysis Setting) table which has to be filled up with values or deleted or doing a bypass to enforce workbench solver to take the analysis setting form the APDL macro

Regards