Inputing acceleration time history in to ANSYS 2

[mn403]

Hi,

I have built a basic structure which i would like to subject to an earthquake signal. I have looked through the help files to find out how to input time records to ANSYS with no success.

Can someone kindly tell me how i can do this, or give me a hint of what key words i should be typing in, in the help command to get useful information.

Many thanx

 

[cbrn]

Hi,
from the subject of your post, I desume your earthquake is an acceleration.
Before being more informative, can you tell:
- which version of ANSYS you are running (things are VERY different on this point between v.11 and the previous ones)
- if the "earthquake signal" is a time-history or a spectrum.

Thanks

Regards

 

[mn403]

hi

Thank you for your quick reply, and sorry for being unclear.

I am running Ansys version 8.0,

And the earthquake signal is a time history. I also have the integrals of the signal present as time histories, namely the velocity and displacement values

Thanks alot

 

[cbrn]

Hi,

first of all, I have unfortunately to say that v.8.0 was an "unlucky" version and you are likely to have problems in running what you are trying... Perhaps not, but perhaps yes...

Well, so before v.11 there is no way to input an acceleration time-variant BC to a node, in a transient analysis: only displacements.
So you will have to use your displacement-vs-time time-history.
If it is a function, you will have to input it using the Function Editor; if it's a list of values, then you will have to define a TABLE and read the values in.
I'd suggest the Ansys Manual as the best place to learn how to do that, if you never did this before; keywords can be TABLE, Function Editor, How to Apply Loads, Chap 2.5.1.4 of Basic Analysis Guide. There are also some old threads herein on that subject.
The analysis has to be a Transient one, BUT...

if you have NO non-linearities in your model, you can also:
- calculate the acceleration spectrum (fourier analysis) of your data
- setup a Spectrum Analysis in Ansys. It will be enormously faster and resource-saving (of course, the amount of available output data won't be the same as in a Transient Analysis...)

Hope this helps...

Regards