Mesh mating sheet bodies? 1

[magnusrm]

Hi. Im running a simplified frame FEA, made with sheet bodies and thinshell 2D mesh.
The beam is supported on shims, and in order to use the shim area for the constraint I have split the body. The whole beam, including the split bodies, is meshed in the same mesh.
The beam is loaded, and only fixed on the splitted part.

I have not found any good ways to connect the meshes, and the nodes match badly (see attatched picture). I have most experience using solid FEA, where I use mesh mating condition or surface to surface gluing.
Whats the best way of approching this problem?


I do not get any report file, and the following error IN THE f56 FILE:

USER INFORMATION MESSAGE 7555 (GMTSTD)
FINITE ELEMENT GEOMETRY CHECK RESULTS EXCEED TOLERANCE LEVELS FOR THE FOLLOWING ELEMENTS.
USER ACTION: USE THE GEOMCHECK (EXECUTIVE CONTROL STATEMENT) KEYWORD=VALUE TO CHANGE TOLERANCE VALUES IF DESIRED.
*** USER INFORMATION MESSAGE 7310 (VECPRN)
ORIGIN OF SUPERELEMENT BASIC COORDINATE SYSTEM WILL BE USED AS REFERENCE LOCATION.
RESULTANTS ABOUT ORIGIN OF SUPERELEMENT BASIC COORDINATE SYSTEM IN SUPERELEMENT BASIC SYSTEM COORDINATES.
*** SYSTEM INFORMATION MESSAGE 6916 (DFMSYN)
DECOMP ORDERING METHOD CHOSEN: BEND, ORDERING METHOD USED: BEND
*** USER INFORMATION MESSAGE 4158 (DFMSA)
---- STATISTICS FOR SPARSE DECOMPOSITION OF DATA BLOCK KLL FOLLOW
NUMBER OF NEGATIVE TERMS ON FACTOR DIAGONAL = 31
MAXIMUM RATIO OF MATRIX DIAGONAL TO FACTOR DIAGONAL = 9.8E+15 AT ROW NUMBER 305850
*** USER WARNING MESSAGE 4698 (DCMPD)
STATISTICS FOR DECOMPOSITION OF MATRIX KLL .
THE FOLLOWING DEGREES OF FREEDOM HAVE FACTOR DIAGONAL RATIOS GREATER THAN
1.00000E+07 OR HAVE NEGATIVE TERMS ON THE FACTOR DIAGONAL.
USER INFORMATION:
THIS MESSAGE MAY BE IGNORED IF NO GRID POINT IDS OR HIGH RATIO MESSAGES APPEAR IN THE TABLE ON THE NEXT PAGE.
^^^ USER FATAL MESSAGE 9137 (SEKRRS)
^^^ RUN TERMINATED DUE TO EXCESSIVE PIVOT RATIOS IN MATRIX KLL.
^^^ USER ACTION: CONSTRAIN MECHANISMS WITH SPCI OR SUPORTI ENTRIES OR SPECIFY PARAM,BAILOUT,-1 TO
^^^ CONTINUE THE RUN WITH MECHANISMS.
*** USER INFORMATION MESSAGE 4110 (OUTPX2)
END-OF-DATA SIMULATION ON FORTRAN UNIT 12
(MAXIMUM SIZE OF FORTRAN RECORDS WRITTEN = 1 WORDS.)
(NUMBER OF FORTRAN RECORDS WRITTEN = 1 RECORDS.)
(TOTAL DATA WRITTEN FOR EOF MARKER = 1 WORDS.)
1 SEPTEMBER 2, 2014 NX NASTRAN 8/25/13 PAGE 15


Running nx9.0


Thanks alot

 

[Tuw]

Hi magnusrm,

^^^ RUN TERMINATED DUE TO EXCESSIVE PIVOT RATIOS IN MATRIX KLL.

Above statement is tally with your non-coincide node/mesh condition.

Have you tried using Stitch Edge > Edge to Edge? Perform Stitch Edge to select the pair of edges that you want to mate the nodes, before you mesh. Or mesh first, stitch later, but update FEA mesh finally will do.

Tuw

 

[magnusrm]

Thank you, Tuw. That apparently did the trick!