Issue with contact in SOL 400

[drewd423]

I'm trying to use contact regions to get connect my parts together, rather than try to line up all the nodes. It seems to work, sort of. If you look at the attached image, some of the nodes stay glued to the surfaces in contact, some do not. I've defined my BCONTACT, BCBODY1, BSURF, BCONECT, and BCONPRG cards per the Quick Reference Guide. The model solves and don't get any errors. But changing ERROR doesn't seem to have an effect on the results.

I pasted the relevant parts of the BDF file below, but I can attach the whole thing if necessary.

BCONTACT = 600

.
.
.

BCBODY1        1              3D  DEFORM       1
BCBODY1        2              3D  DEFORM       2
BCBODY1        3              3D  DEFORM       3
BCBODY1        4              3D  DEFORM       4

BSURF          1    3080    3084    3088    3092    3096    3100    3104+       
etc...

BCONECT      600     700                                                +
+         SLAVES       2       4                                        +
+        MASTERS       1       3

BCONPRG      700           IGLUE       1   JGLUE       0 ISEARCH       0+
+          COPTS       1   COPTM       1   ERROR   0.001

 

[dfreire]

Hello,

A good contact definition is quite difficult to define, but there are some guidelines that one should use. I think they can be found in the nonlinear guide (specific for SOL400).
- It is recommended that the slave bodies IDs be lower than the master IDs. However you use ISEARCH=0, that will activate double check, so it will be fine, but should expend more computacional time.
- Master bodies mesh size should be greater than slaves bodies mesh size. The both recommendations will achieve a better projection of slave nodes.
- BCTABLE, as the QRG v2017 says, "Defines a contact table used in SOL 101 and SOLs 400 and 700 only. The BCTABL1 option is the preferred method to defining contact interactions for SOL 101 and SOL 400". Maybe you should try to define the contact with BCTABLE instead of BCONECT. I have always used BCTABLE and I have never had any problem.
- I assume looking at the image that the model is defined with first order elements. Contact sometimes have difficulties with the higher order elements.
- You can set the ERROR at a higher value, so it will help to find out if there is an existing gap that is making a bad contact.

I hope it helps.