Symmetric boundary condition- simple problem (facing issue)

[nastranuser123]

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=3f283bfc-9991-42ee-9f08-9f0fe19caf57&file=notch.jpg

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

 

[nastranuser123]

Hi,

I have uploaded the dat file into the location below

http://files.engineering.com/getfil...5b-b94c-94b4abf31b8b&file=sim1-solution_1.dat

Thanks,
Chris

 

[BlasMolero]

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/

 

[nastranuser123]

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

 

[BlasMolero]

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/

 

[nastranuser123]

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

 

[nastranuser123]

For example, see this problem

http://www.adina.com/adinadownloads/primer/prob02.pdf

It is similar, he just makes normal displacement as 0 at the 2 cutting edges.

I did id at one cutting edge.

 

[BlasMolero]

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/