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07-16-2015 02:21 PM

My name is Harsh Bhatt.I am new to nastran and I need to do below mentioned problem in the same.

My problem has two plates,one moving and one is fixed.There is a plastic cylinder betwwn the two and presuure is acting on both the sides of cylinder and also on the two plates.

When I am running the simulation I am not getting the exact result which I should get[Deformation of the cylinder].The cylinder should squeeze in between two plates. My project detail [2D].

Here in 3D

Please help me.....Waiting for the valuable reply.

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07-20-2015 07:27 AM

Dear Harsh,

First at all this is a 2-D solid problem, then you can use the simplification of either 2-D Plane Stress or 2-D Plain Strain, this will help a lot to reduce both computational times & stability problems:

- In
**2-D SOLID PLANE STRESS**the element idealization has zero stress in the thickness direction. These elements represent structures that are**thin**relative to their lateral dimensions and planar. - In
**2-D SOLID PLAIN STRAIN**the element idealization has zero strain in the thickness direction. These elements represent structures that are**very thick**relative to their lateral dimensions.

This is a complex contact nonlinear problem, then if you are new in FINITE ELEMENT ANALYSIS you are starting the "house for the roof", you need to request FEA training from your local SIEMENS VAR in your country, learning FEA is not inmediate, it requires time and effort from your side to get knowdledge of element & analysis types, the cost of every solution and element types, the results you get using each element type, etc..

Back to the problem: this is a nonlinear analysis, here the linear contact using NX NASTRAN (SOL101) is useless because contacting parts are not touching (you have a GAP between cylinder and plates) then large displacements effect (nonlinearity by the geometry) exist. But also you have a PLASTIC cylinder, then the problem is non linear for the material as well: you have a fully nonlinear problem!!.

You can start setting all materials properties as linear, if the contact + large displacement nonlinear solution converge, then add the material nonlinearities at the end.

You need to define **edge-to-edge contact**, manually defining contact regions properly. I suggest to use NX NASTRAN Advanced Nonlinear solver (SOL601).

Best regards,

Blas.

Blas Molero Hidalgo, Ingeniero Industrial, Director

IBERISA • 48004 BILBAO (SPAIN)

WEB: http://www.iberisa.com

Blog Femap-NX Nastran: http://iberisa.wordpress.com/

IBERISA • 48004 BILBAO (SPAIN)

WEB: http://www.iberisa.com

Blog Femap-NX Nastran: http://iberisa.wordpress.com/

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