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Shell Edge Contact

Shell Edge Contact

Shell Edge Contact

(OP)
Greetings again!  I have another NX Nastran shell element quandary.

I have a question about contacts on the edges of shell elements.  I have 2 sheets, perpendicular to each other forming a 'T'.  I would like to be able to have non-glued contact between the horizontal sheets face and the vertical sheets edge.  The surface-to-surface contact functionality does not work because there is no surface on the shell element edge.  

Would a CGAP element be useful in this situation?

Any thoughts on the topic would be greatly appreciated.

Thanks!
Dan

RE: Shell Edge Contact

Dear Dan,
Yes, in fact, CGAP node-to-node contact element is the only resource left if you want to consider the "no-penetration" contact between edge & surface. Please note that you need to activate the flag "GAPs as contact", if not the CGAP will act like a spring.

Also, surely next version of NX NASTRAN will feature the contact EDGE-TO-SURFACE, then meanwhile you need to use CGAP elements.

In the attached nastran input file I have setup a T-type contact using CGAP "compression-only" with GAP distance = 0.0 and compression stiffness = 1e6

NOTES:
======
• When a BCSET case control command exists, CGAP elements are treated as linear contact elements, if not the CGAP element will be considered as a spring.
• You can use CGAP elements in linear static analysis (SOL101) together with surface-to-surface contact defined (BCTSET bulk entries exist), or without (no BCTSET bulk entries exist). In the case where no surface-to-surface contact is defined, "n" on the BCSET case control command can point to a BCTPARM bulk entry which optionally defines PENN, PENT or PENTYP for the CGAP/linear contact elements, or to nothing if a BCTPARM bulk entry does not exist (an integer value for "n" is still required in this case).

• If you need to increase the numbr of contact iterations, then the contact control parameters on the BCTPARM bulk entry (optional) can help you adjust the contact algorithm when you are having problems getting a solution to converge and complete, or when the contact results are not as expected.

Here the example:

INIT MASTER(S)
NASTRAN SYSTEM(442)=-1, SYSTEM(319)=1
ID cgap,Femap
SOL SESTATIC
TIME 10000
CEND
  TITLE = NX Nastran Static Analysis Set
  ECHO = NONE
  DISPLACEMENT(PLOT) = ALL
  SPCFORCE(PLOT) = ALL
  OLOAD(PLOT) = ALL
  MPCFORCE(PLOT) = ALL
  GPFORCE(PLOT) = ALL
  FORCE(PLOT,CORNER) = ALL
  STRESS(PLOT,CORNER) = ALL
  BCRESULTS(TRACTION,FORCE,SEPDIS,PLOT) = ALL
  SPC = 1
  BCSET = 108
  LOAD = 1
BEGIN BULK
BCTPARM,108,MAXS,50
$ ***************************************************************************
$   Written by : Femap with NX Nastran
$   Version    : 10.3.1
$   Translator : NX Nastran
$   From Model : D:\MODELOS\test\cgap_edge2face.modfem
$   Date       : Thu Mar 08 20:18:50 2012
$   Output To  : D:\Scratch
$ ***************************************************************************
$
PARAM,POST,-1
PARAM,OGEOM,NO
PARAM,AUTOSPC,YES
PARAM,K6ROT,100.
PARAM,GRDPNT,0
CORD2C         1       0      0.      0.      0.      0.      0.      1.+FEMAPC1
+FEMAPC1      1.      0.      1.
CORD2S         2       0      0.      0.      0.      0.      0.      1.+FEMAPC2
+FEMAPC2      1.      0.      1.
$ Femap with NX Nastran Load Set 1 : Caso de Carga#1: Pressure
PLOAD4         1       9     -.1                                        
PLOAD4         1      10     -.1                                        
PLOAD4         1      11     -.1                                        
PLOAD4         1      12     -.1                                        
PLOAD4         1      13     -.1                                        
PLOAD4         1      14     -.1                                        
PLOAD4         1      15     -.1                                        
PLOAD4         1      16     -.1                                        
PLOAD4         1      17     -.1                                        
PLOAD4         1      18     -.1                                        
PLOAD4         1       1     -.1                                        
PLOAD4         1       2     -.1                                        
PLOAD4         1       3     -.1                                        
PLOAD4         1       4     -.1                                        
$ Femap with NX Nastran Constraint Set 1 : Restricciones
SPC1           1  123456      14
SPC1           1  123456      15
SPC1           1  123456      16
SPC1           1  123456      19
SPC1           1  123456      28
SPC1           1  123456      29
$ Femap with NX Nastran Property 1 : Mid-Surface t=2.
PSHELL         1       1      2.       1               1              0.
$ Femap with NX Nastran Property 2 : Mid-Surface t=2.
PSHELL         2       1      2.       1               1              0.
$ Femap with NX Nastran Property 4 : GAP Property
PGAP           4      0.      0.1000000.      0.      0.      0.      0.+       
+                                       
$ Femap with NX Nastran Material 1 : Acero (MPa)
MAT1           1 205000.              .3  7.85-9      0.      0.        +       
+           260.    260.        
GRID           1       0     24.      1.    -15.       0
GRID           2       0     24.      1.      0.       0
GRID           3       0     24.      1.     15.       0
GRID           4       0     37.      1.     15.       0
GRID           5       0     50.      1.     15.       0
GRID           6       0     50.      1.      0.       0
GRID           7       0     50.      1.    -15.       0
GRID           8       0     37.      1.    -15.       0
GRID           9       0     37.      1.      0.       0
GRID          10       0     24.      0.     15.       0
GRID          11       0     24.      0.      0.       0
GRID          12       0     24.      0.    -15.       0
GRID          13       0     24.   -12.5    -15.       0
GRID          14       0     24.    -25.    -15.       0
GRID          15       0     24.    -25.      0.       0
GRID          16       0     24.    -25.     15.       0
GRID          17       0     24.   -12.5     15.       0
GRID          18       0     24.   -12.5      0.       0
GRID          19       0    -50.      1.     15.       0
GRID          20       0   -35.2      1.     15.       0
GRID          21       0   -20.4      1.     15.       0
GRID          22       0    -5.6      1.     15.       0
GRID          23       0     9.2      1.     15.       0
GRID          24       0     9.2      1.    -15.       0
GRID          25       0    -5.6      1.    -15.       0
GRID          26       0   -20.4      1.    -15.       0
GRID          27       0   -35.2      1.    -15.       0
GRID          28       0    -50.      1.    -15.       0
GRID          29       0    -50.      1.      0.       0
GRID          30       0   -35.2      1.      0.       0
GRID          31       0   -20.4      1.      0.       0
GRID          32       0    -5.6      1.      0.       0
GRID          33       0     9.2      1.      0.       0
CQUAD4         1       1       1       2       9       8                
CQUAD4         2       1       2       3       4       9                
CQUAD4         3       1       8       9       6       7                
CQUAD4         4       1       9       4       5       6                
CQUAD4         5       2      10      11      18      17                
CQUAD4         6       2      11      12      13      18                
CQUAD4         7       2      17      18      15      16                
CQUAD4         8       2      18      13      14      15                
CQUAD4         9       1      19      20      30      29                
CQUAD4        10       1      20      21      31      30                
CQUAD4        11       1      21      22      32      31                
CQUAD4        12       1      22      23      33      32                
CQUAD4        13       1      23       3       2      33                
CQUAD4        14       1      29      30      27      28                
CQUAD4        15       1      30      31      26      27                
CQUAD4        16       1      31      32      25      26                
CQUAD4        17       1      32      33      24      25                
CQUAD4        18       1      33       2       1      24                
CGAP          19       4       1      12      1.      0.      0.
CGAP          20       4       2      11      1.      0.      0.
CGAP          21       4       3      10      1.      0.      0.
ENDDATA f56f64f1

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/

RE: Shell Edge Contact

(OP)
Wow.  Thank you for the detailed explanation and a script.

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