×
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

Symmetric boundary condition- simple problem (facing issue)

Symmetric boundary condition- simple problem (facing issue)

Symmetric boundary condition- simple problem (facing issue)

(OP)
I shall be grateful if someone can help me with this

This is the scenario I have:

This problem is a pair of opposing shallow notches in a bar subject to tension. A linear elastic, plane strain idealisation is used and the results at the peak stress position are of interest.

Please see the figure in the atatchment

http://files.engineering.com/getfile.aspx?folder=3...



Using symmetry about a horizontal line gives the problem geometry shown. The vertical line of symmetry is deliberately ignored - using it would force a corner node to be at the peak stress position which would be unrepresentative of most of the component features of interest.

The remote applied traction is 100 MPa.

I'm facing the follwoing problems

I modelled the structure in NX

I applied symmetrical boundary conditions (i.e. the edge which is 38.1 mm has normal displacement as 0).

I need to apply the pressure of 100 MPa along the two edges as shown.

It is a 2D scenraion.

NX does not have the option of applying pressure on the edges.

I multiplied 100 * thickness * edge length = 100*5.05* 9.525 = 4810 N and then tried to apply as force at the polygon edge (applied on each edge as shown in the figure).

However, when I run the solution, I get a mechanism.

Can anyone please help?

Regards
Chris

RE: Symmetric boundary condition- simple problem (facing issue)

Dear Chris,
You have RIGID BODY MOVEMENT in the longitudinal direction (Y-axis).
Your model is symmetric recpect to Vertical plane Z-X, then you need to split your model and study half. In the cutting edge prescribe TY=0 to all nodes and your model will be ready to be solved.
Best regards,
Blas.

~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director

IBERISA
48004 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog de FEMAP & NX Nastran: http://iberisa.wordpress.com/

RE: Symmetric boundary condition- simple problem (facing issue)

(OP)
Dear Sir,

Yes, I had prescribed symmetrical boundary conditions (i.e. the edge which is 38.1 mm has normal displacement as 0) i.e. DOF_X = 0

It did not solve..

Can you provided a sketch of what exactly u meant or the dat file? I have several models like this and am still not really getting it

RE: Symmetric boundary condition- simple problem (facing issue)

You have symmtry in the X-axis, but in the Y-axis con move freely, please note this is plain strain, not axisymmetric analysis.
Best regards,
Blas.

~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director

IBERISA
48004 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog de FEMAP & NX Nastran: http://iberisa.wordpress.com/

RE: Symmetric boundary condition- simple problem (facing issue)

(OP)
Is it possible to upload a dat file to illustrate what exactly you meant Sir?..I will really be grateful and obliged.

RE: Symmetric boundary condition- simple problem (facing issue)

Hello!,
This is very simple problem, here you are the setup of constraints and loadings:



And the results:




Best regards,
Blas.

PD
Please do not call me by phone, if you need help I suggest to contact your NX RESELLER for FEA training -- thanks!.

~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director

IBERISA
48004 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog de FEMAP & NX Nastran: http://iberisa.wordpress.com/

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