Learning Forum

[oglawal2]

Hi good day,

 

I wrote an input file from a workbench model to use in apdl. However, I also need to get the nodal acceleration and force reaction at contact region (as I am simulating impact). Will the script below be correct for obtaining the nodal acceleration? also, how do I get the contact force?

 

/POST26
NSOL,2,1595,ACC,X
STORE,MERGE
*GET,size,VARI,,NSETS
*dim,ACC_X,array,size
VGET,ACC_X(1),2
*CFOPEN,acc.txt
*VWRITE,ACC_X(1)
(F10.5,F12.2)
*CFCLOSE

[Avnish Pandey]

Hi Lawal,

The commnads look fine. Try plotting the acceleration as well.

To determine the contact forces, you can select the contact elements, followed by selecting the associated nodes and then extracting the nodal forces using the commands given below:

/POST1

set,last

ESEL,s,ename,,CONTA171     !select contact elements either by ename or type
NSLE,s
ESLN,s
NFORCE

You can also explore GUI options to track contact behavior in APDL.

https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v241/en/ans_ctec/Hlp_ctec_guiaids.html

 

[oglawal2]

Thank you. Also, I have two load steps from 0 to 0.4s, and from 0.4 to 6s. I want to record the output at equally spaced points and get a total of 600 result points. In workbench I do 40 for first load step and 560 for second load step. How do I specify this in apdl?

[Avnish Pandey]

Hi,

To define the integration time step (ITS) you will need to find out the highest frequency in the spectrum of the impact load. You can obtain it from the FFT of the signal and modal analysis of the structure. As a standard practice, the max. time step should be less than 1/20th of the period of the highest frequency of interest.

Check these links for more information:

/forum/forums/topic/auto-time-stepping-in-transient-structure/

https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v241/en/ans_str/Hlp_G_STRXMPL.html

https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v241/en/ans_str/Hlp_G_STR5_12.html

https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v241/en/ans_str/Hlp_G_STR5_5.html

 

[oglawal2]

For extracting the contact force, I have multiple contact regions in my model, how do I specify the exact one I want (it is a frictionless surface to solid contact). Also, should I use post 26 since I am interested in time history of the force?

 

I already defined the integration time step in my workbench model but my challenge is how to store the results at equally spaced points. There is an option to do this in workbench and I wonder what the equivalent way is in workbench.

 

Thanks again for your help.