How to apply load at different rates in ANSYS workbench?

[h.eltaher]

Hi,

I have a structure that I wish to study its response under different rates of the same load.

The structure is a vertical hollow cylinder. Its lower end is fixed. I applied a displacement load to the upper end so it is being compressed to a defined value.
Using Ansys workbench explicit and changing the end time takes an extremely long time for time values larger than .001 sec. I tried using Ansys static but I could not figure out how to do it there.

How can I vary the speed at which the cylinder is compressed? either in static or explicit.

Thanks
H

 

[rickfischer51]

First, stability of explicit FEA is governed by t = L/c where t is the critical time step, L is the size of the smallest element in the model, and c is the speed of sound in in your material. When you increase the duration of your load, your time step remains fixed, and you need more time steps to reach the longer duration. So yes, increasing your load duration will increase your run time. You may want to review your mesh. If you have small elements needed only to model small features of no consequence to your solution, refine your model so as to remove the small elements.

Second, you cant evaluate response at different load rates with a static implicit solution. There is no strain rate term in such an analysis. You need to run it at as transient dynamic.

Rick Fischer
Principal Engineer
Argonne National Laboratory

 

[h.eltaher]

Thank you for your reply.

So does transient dynamic include strain rate effects in the analysis?

 

[rickfischer51]

#2 wasnt correct. Run it as a static analysis.

Rick Fischer
Principal Engineer
Argonne National Laboratory

 

[h.eltaher]

Thank you for clarification.
Can you guide me into how this can be implemented in WB static. I've been fiddling with Analysis Settings: step controls but to no avail. I need to know how to vary the speed at which the top surface moves down as shown in the uploaded photo. I've also uploaded a zip file of the project.
I will appreciate any help in this regard as I was not able to find any in ANSYS help.
Thanks

https://files.engineering.com/getfi...a6de-4c07-85ff-ff950f1b6983&file=problem.wbpz

https://files.engineering.com/getfi...3b-542a-4aa3-8620-c19e3dbebdf2&file=photo.png