Learning Forum

[Eduardo Ribeiro]

I am investigating the dynamical behaviour of a beam using Transient Structural analysis. In my study, I need to prescribe specific displacements for dozens of nodes simultaneously. Prescribing displacements node per node would require too much time and effort, and a named selections give the same displacements for all nodes at once. Instead, I would like to create something like this:

Node | Displacement
001: 0.00
002: 0.01
003: 0.03
...
010: 0.01
...
100: 0.02
(etc)

Does anyone know how can I create a set of displacements like this? Thanks in advance.

[Ashish Khemka]

Hi,

You can use External Data module to import the data from an excel or other text file into Transient Structural Analysis.

External Data (ansys.com)

Regards,

Ashish Khemka

[dlooman]

It might be possible if you have a value for each node in the named selection in a two column text file of node and values separated by a space or comma.  DLIST can be used afterward to check if it worked.  Mid-side nodes might interfere with this process.

*dim,d_vals,table,100,,,node         ! For 100 values 

*tread,d_vals(1),filename,txt          ! read node and displacement values from file

cmsel,s,named_selection 

d,all,ux,%d_vals% 

allsel 

dlist

[Eduardo Ribeiro]

Thank you. I have successfully imported external data from Excel (".csv") into my model following the instructions you gave me. However, for some reason Ansys will only accept static forces/displacements. To perform dynamical simulations, data must be dependent of time:

X-Coordinate | Displacement
0.00 | 0.000
0.01 | 0.001*sin(time)
0.02 | 0.003*sin(time)
(etc)

Typing "sin(time)" works for displacements/forces defined inside Ansys, but it does not work for external data. Do you know how can I solve that?

[dlooman]

If you want the displacements to be interpreted as sinusoidal do a harmonic analysis:

antype,harm

harf,value        ! frequency of sinusoid in hz

[Eduardo Ribeiro]

Is there any form of doing that in Transient Analysis? I think Harmonic Analysis does not fit my objetive because I would like to include any functions of time and not only sinusoidal ones.

[dlooman]

Probably not.  How many cycles do you need to run?