How to let FEAP read user defined input files?

[Toughunter]

Hi all,

I plan to make a user-friendly program that can read users' inputs and execute a FEM calculation, so that the users don't have to create a standard FEAP input file themselves.

For example, the user just need to provide the "thickness" of a structure layer in a .txt, then the FEAP would read the .txt and create a mesh with regard to the "thickness" parameter for the followed FEM analysis.

Maybe this is just a simple question. I am a new user to FEAP, and I guess this may require some coding in "UMESHn" files.
Can someone give me some hints? It is better if you share a sample of "reading user's inputs to create a mesh and carry out the calculations".

Thanks much.

[Prof. R.L. Taylor]

I am not clear on what you want to do.  A finite element program needs a mesh. How do you want to describe it?  A thickness is not sufficient.

[Prof. S. Govindjee]

Here is a link to an example UMESh command.   This was written 20 years ago so the style is a bit dated but it will give you an idea of how to program a user mesh command.  If I get a chance I will update the example to a better coding style.

http://faculty.ce.berkeley.edu/sanjay/FEAP/umesh1.html

[Toughunter]

I am not clear on what you want to do.  A finite element program needs a mesh. How do you want to describe it?  A thickness is not sufficient.

Hi Prof. Taylor,

Thanks for the concerns.
The attached is an example of a "user oriented" input.txt I intend to create for pavement structure analysis. In this file, the users are required to input:
1. Pavement layers, e.g. how many Asphalt Concrete lifts, how many layers in total;
2. The thickness of each layer;
3. The modulus of each layer; if 1. is entered, it represents the material is nonlinear and a Umat would be called (I already have the Umat file)
4. Possion's ratio of each layer;
5. Load: including load pressure, load area and time increment (transient static analysis)

This input file would be fed to FEAP/FEAPpv, which is supposed to create mesh files, call Umat if nonlinear material is identified, conduct the following FE analysis and output the results(displacement, stress)

The benefits are:1) The program can be shared to other people who needs to do FEM analysis but without solid FEM knowledge or FEAP experience; 2) what't more, this kind of input is a lot more efficient, especially when a bunch of analysis are to be done.

Thanks much.

[Toughunter]

Here is a link to an example UMESh command.   This was written 20 years ago so the style is a bit dated but it will give you an idea of how to program a user mesh command.  If I get a chance I will update the example to a better coding style.

http://faculty.ce.berkeley.edu/sanjay/FEAP/umesh1.html

Hi Prof. Govindjee
Thanks for the links, a good study material to start with.

Regards
You

[JStorm]

You can create a parametrised FEAP inputfile, which uses the given parameters to let FEAP creating the model. This done frequently to simplify parameter studies.

The most interesting features to accomplish such a  task are:
- PARAmeter
- INCLude
- LOOP
- SNODes
- BLENd
- TRANsform

But performing FEM without basic knowledge may causes wrong models due to wrong assumptions. Moreover, no interpretation of the results are possible and therefore such results are useless.

[Toughunter]

You can create a parametrised FEAP inputfile, which uses the given parameters to let FEAP creating the model. This done frequently to simplify parameter studies.

The most interesting features to accomplish such a  task are:
- PARAmeter
- INCLude
- LOOP
- SNODes
- BLENd
- TRANsform

But performing FEM without basic knowledge may causes wrong models due to wrong assumptions. Moreover, no interpretation of the results are possible and therefore such results are useless.

Hi JStorm,
Yes, I think the parametrised inputfile solves my problem. I start to play with it now.
I agree with you that a meaningful FEM analysis needs correct assumption and interpretation. Thanks for the advice.
Regards,
You.