×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Simple problem & subroutine & usdfld

Simple problem & subroutine & usdfld

Simple problem & subroutine & usdfld

(OP)
I'm trying to simulate a plate with different thickness elastic modulus.
I use subroutine and usdfld

For a rectangular plate I did.

But for a circular plate need to use a cylindrical coordinate system, because I want to simulate a different modulus of elasticity in the radial direction
I attach cae/inp file and subroutine for a rectangular plate

Need your help
Evgen

RE: Simple problem & subroutine & usdfld

Hi,

Quote:

circular plate need to use a cylindrical coordinate system
USDFLD does not provide radial coordinate but you can calculate it from Cartesian coordinates.

CODE

radial = sqrt(x**2 + y**2) 

It will work if centre of your circle is (0,0) other ways you have to use:

CODE

radial = sqrt((x-x0)**2 + (y-y0)**2) 
where x0 & y0 are coordinates of your circle in Abaqus model.

Take a look for attached example, hope this is what you need.

Regards,
Bartosz

RE: Simple problem & subroutine & usdfld

(OP)
Thank you so much, Mr. akabarten.
It helped me.
The main task - to build bone model with variable over the thickness elastic modulus.
In the article (http://www.asbweb.org/conferences/2010/abstracts/1... ), I saw something similar but for the density

there also used usdfld

What do you think how it would be correct to use your subroutine to solve this problem?
if you want I can attach bone

Evgen

RE: Simple problem & subroutine & usdfld

Hi Evgen

Idea to use USDFLD subroutine to distribute Young module over the bone volume make sense for me as long as
you are able to describe E value as function of x, y and z coordinates.

Regards,
Bartosz

RE: Simple problem & subroutine & usdfld

(OP)
Thank you very much for your help, Mr. Bartosz!
I will continue to work on the my task.
If I have any questions I'll be happy to speak to you for help.

by the way My channel on YouTube - www.youtube.com/user/abaquscae/videos
if I can be useful to you write me an email - evgenabaqus@gmail.com

by the way I'm looking for a job or PHD studies =)
if you have any information please let me know

Regards,
Evgen

RE: Simple problem & subroutine & usdfld

Hello
I need to write a subroutine (I guess USDFLD) in which the Elasticity Modulus and density change through thickness. Actually the subroutine refers to a FGM plate with a crack in it. In simple words from one side of a plate, E and density of ceramic reach to E and density of metal. The pattern of change for E and density is based on this formula: (w is thickness and x is coordinate along thickness)
A=(1/w)Ln(E2/E1)
E=(E1)eAx
Since I'm a beginner in subroutines, i don't know how exactly do that. I would be grateful if anyone can help me. Any help would be appreciated.

RE: Simple problem & subroutine & usdfld

Start looking at the example of USDFLD in the Subroutine manual.

And be aware of that:

Quote (Users Manual 21.2.1 Density)

"Density can be defined as a function of temperature and field variables. However, for all elements in Abaqus/Standard with the exception of acoustic, heat transfer, coupled temperature-displacement, and coupled thermal-electrical elements , the density is a function of the initial values of temperature and field variables and changes in volume only. It will not be updated if temperatures and field variables change during the analysis."

RE: Simple problem & subroutine & usdfld

Thanks for your answer mustaine,
I've read it but I didn't understand much.

RE: Simple problem & subroutine & usdfld

When your definitions are only done at the initial state, you might be able to do it without subroutine.
You can make your material properties temperature dependent and apply a specific initial temperature for each section point or layer of section points.

When you want to know the initial coordinates of the section points, you can create a dummy analysis and request COORD via *Element Output, Position=Integration Points. In postprocessing you can create a report to write the data into a text file.

RE: Simple problem & subroutine & usdfld

I really appreciate your help.
Why temperature dependent? I think you mean that i use a field variable.
and by the way, how could i define the exponential change pattern?

RE: Simple problem & subroutine & usdfld

When you do a non-thermal analysis, then you can use the temperature as an additional variable (like the field variable) and you can apply initial temperatures to your section points. These will be used when calculating the initial density (which can be temperature dependent). Same for elasticity.

It's your task to apply the correct initial temperatures to your section points.

But with that method you don't have to write a subroutine and get the density variation.

RE: Simple problem & subroutine & usdfld

thank you for answering.
As i said how could i define the exponential change pattern?
and if you have an example for implementation that your talking about, I would be grateful you could share it.

RE: Simple problem & subroutine & usdfld

Hi every body. I am new in subroutines, may be please let me know how I can change young module acc to change strain and through thickness? Thanks in advance,

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources