Contact analysis of two plates

[Marko86]

Hello,

I have problem with contact analysis in 2D.
I tried with contact features and with slide line feature.
In slide line it works while load is presented as displacement, but i would like to load with force or moment. Then analysis doesnt work good. Pls if someone can explain me how to make simple problem work, and later i will use it on more complex problem. I gave simple problem in attachment, and it can be seen that only plate which is loaded is deforming while the other plate in contact doesnt.

Thanks in advance,
Marko

 

[BlasMolero]

Dear Marko,
"Edge-to-Edge" linear contact will be available in next version of NX NASTRAN 8.5 at the end of the year as part of FEMAP V11.0, then you will be able to solve this linear contact problem very easily using 2-D solid PLANE STRESS elements, or 2-D solid PLAIN STRAIN, or 2-D axysimmetric elements, as well as general 2-D Shell element.

If you want to solve this problem as nonlinear using the basic nonlinear static analysis module + sline-line contact (SOL106) please take a look to Example 28 (in FEMAP go to "HELP > Examples"):

28. Slide Line Contact - Hyperelastic Seals
Two semicircular seals are being pressed together at a given enforced displacement. The seals are the same size and shape and the rounded sides of the seals will come into contact with one another. The seals are made of a hyperelastic material and the model allows the use of plane strain elements for analysis. Contact between the rounded sides of each seal will be modeled using Slide Line Contact. Slide line contact differs from Gap contact in that is not simply a point-to-point or node-to-node representation of contact, but a 2-D relationship between a set of Master nodes and a set of Slave Nodes. This example will use the Nonlinear Static solving capability of NX Nastran.

Also take a look to Example 29:

29. 3-D Contact - Plastic Clip and Base
A plastic clip made of solid elements will come into contact with a fixed base and move through a range of motion based on enforced displacements using slide line contact.
For this example the clip and the base have already been created. The analysis process includes:
· creating Slide Line elements by selecting the Master and Slave node sets for contact
· creating an Enforced Displacement to bring the Clip into contact with the Base
· defining the analysis parameters to aid in convergence of the Nonlinear solution
· analyzing the model with NX Nastran's Nonlinear Static Solution Method
· viewing the multi-set animation of the analysis sets to understand the contact between the objects.

Your definition of contact regions is not correct at all, you defined regions based on SURFACES, but this is an "edge-to-edge" contact, only using the NONLINEAR ADVANCED MODULE (SOL601) you will be able to solve such 2-D contact problems, but contact for SOL 601 "is all node based".

Using the NonLinear Advanced module (SOL601) --please check your license, this module is an add-on of the NX NASTRAN basic system-- you will be able to solve problems like this RUBBER SEAL COMPRESSION example with hyperelastic material LARGE STRAIN model with moving rigid walls and featuring "self-contact", marvellous!!:

Best regards,
Blas.

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

IBERISA
48011 BILBAO (SPAIN)
WEB:

http://www.iberisa.com

Blog de FEMAP & NX Nastran:

http://iberisa.wordpress.com/

 

[Marko86]

Thank you Blas,

your explanation is really helpful. I did it by using slide line contact,
but as there is problem when i use desired force or moment, I actually moved the circle with displacement. I fixed the circle in three points, and then changed the displacement, until i got the desired constraint force in fixed nodes on circle.
Sum of those forces needs to be same as reaction force in contact. Therefore, I got the results i wanted.

Thank you again.
Marko