How to model the rivet connections in airplane fuselage panel?

[notekit]

I am currently modeling the static deformation of an Airbus fuselage part. The part has three main components, shell, frames and stringers. They are connected with rivets.

At the moment, I model the rivet joints by merge all the nodes in the contact area together. This assumes that the whole contacting areas is moving together not just the rivet joints. Do anybody have a better idea on how to model this connections?

Thank you very much!

 

[ScottMf]

Usually when modeling bolt connections I use a macro that takes in the location, radius, and length of the hole, and connects the nodes from each side to the other using beam elements. If you would like to see the macro let me know.

~Scott

 

[notekit]

Dear Scott,

Thank you very much for your reply and yes I would like to see the macro. It would be very thankful.

From what I understand, you connect different parts with beam elements at the holes, right? I think it is a very interesting idea. And how do you model the contacting surfaces between parts. Do you couple the degree of freedom perpendicular to the surface? I have thought about using contact elements like TARGET or CONTACT between the part but I think the computation time will be quite long.

Thanks again for your help!
Note

 

[ScottMf]

Here is the code I use to create the bolts. Usually for the analysis I am doing the contact between the surfaces is not that important so I don't bother modeling it. Coupling the degrees of freedom sounds like a good idea. It may also be possible to optomize this code using local coordinate systems rather than moving the working plane and then creating a CS. Let me know if you have any questions.

~Scott



!***********************************************************
!Bolt Creates a bolt joint
!**********************************************************

!-----------------------------------------------------------
!Passed arguments
!-----------------------------------------------------------
Xh =ARG1 !X location
Yh =ARG2 !Y location
Zh =ARG3 !Z location
Radius =ARG4 !Hole Radius
Thickness1 =ARG5 !thickness in direction 1
Thickness2 =ARG6 !Thickness in direction 2
HolePlane =ARG7 !Hole plane 'XY' or 'XZ' or 'YZ' plane
!Normal to the hole

ignoreNum=3 !Constant set to create only every n beams
/NOPR

!-----------------------------------------------------------
!Setup
!-----------------------------------------------------------

/PREP7
ALLSEL

*GET,Last_ET,ETYP,,NUM,MAX
NextElem = Last_ET+1
*GET,Last_Real,RCON,,NUM,MAX
nReal = Last_Real+1
*GET,Last_Mat,MAT,,NUM,MAX
nMat = Last_Mat+1
*GET,mnode,NODE,,NUM,MAX
PointNode = mnode+1
*GET,csMax,CDSY,,NUM,MAX
*IF,csMax,LE,10,THEN
CSnum = 11
*ELSE
CSnum=csMax+1
*ENDIF
CSYS,0
WPCSYS,,0


!-----------------------------------------------------------
!Element definition for beams
!-----------------------------------------------------------
ET,NextElem,4 !Define element as a BEAM4 and set constants
KEYOPT,NextElem,6,1
r,nReal,8,8,8,8,8
MP,EX,nMat,1.000000e+07
MP,NUXY,nMat,0.300000e+00
MP,DENS,nMat,0.00000e+00
!----------------------------------------------------------
!Select nodes from one side to connect
!----------------------------------------------------------

WPOFFS,Xh,Yh,Zh
*IF,HolePlane,EQ,'XY',THEN
WPROTA,0,0,0
*ELSEIF,HolePlane,EQ,'XZ',THEN
WPROTA,0,-90,0
*ELSEIF,HolePlane,EQ,'YZ',THEN
WPROTA,0,0,90
*ENDIF
CSWPLA,CSnum,1
CSnum = CSnum+1
NALL
NSEL,S,LOC,X,0,Radius
NSEL,R,LOC,Z,0,Thickness1
CM,Set1,NODE
!Return to the global coordinate system
ALLSEL


!-----------------------------------------------------------
!Select nodes for second side
!-----------------------------------------------------------

NSEL,S,LOC,X,0,Radius
NSEL,R,LOC,Z,0,-Thickness2
CM,Set2,NODE
CM,Set2Full,NODE
!Return to the global coordinate system
CSYS,0
WPCSYS,,0


!-----------------------------------------------------------
!Connect nodes from both sides
!-----------------------------------------------------------
/NOPR
TYPE,NextElem
REAL,nReal
MAT,nMat
Other1=1
Other2=1
*GET,i2node,NODE,,COUNT
CMSEL,S,Set1
*GET,i1node,NODE,,COUNT
*DOWHILE,i1node
/NOPR
CMSEL,S,Set1
*GET,Low1,NODE,,NUM,MIN
*DOWHILE,i2node
*IF,Other2,EQ,ignoreNum,THEN
Other2=1
*CYCLE
*ENDIF
/NOPR
CMSEL,S,Set2
*GET,Low2,NODE,,NUM,MIN
NSEL,U,NODE,,Low2
CM,Set2,NODE
i2node=i2node-1
*IF,Other1,EQ,ignoreNum,THEN
Other1=1
*CYCLE
*ENDIF
*IF,Low1,EQ,Low2,THEN
*CYCLE
*ELSE
E,Low1,Low2
*ENDIF
Other1=Other1+1
*ENDDO
CMSEL,S,Set2Full
CM,Set2,NODE
*GET,i2node,NODE,,COUNT
CMSEL,S,Set1
NSEL,U,NODE,,Low1
CM,Set1,NODE
i1node=i1node-1
Other2=Other2+1
*ENDDO
/NOPR
!-----------------------------------------------------------
!End
!-----------------------------------------------------------
!Return to the global coordinate system
CSYS,0
WPCSYS,,0
ALLSEL
FINISH
/SHOW,3d
/GOPR
/EOF

 

[notekit]

Thanksss! I will look at the code and try it on my model.

Note

 

[ScottMf]

I cleaned up my code a little more and made it a little more adjustible and the output is more informative now.

~Scott

!*****************************************************************
!Bolt Creates a bolt joint
!*****************************************************************

*GET,StartTime,ACTIVE,0,TIME,CPU

!-----------------------------------------------------------------
!Passed arguments
!-----------------------------------------------------------------
Xh =ARG1
Yh =ARG2
Zh =ARG3
Radius =ARG4
Thickness1 =ARG5
Thickness2 =ARG6
HolePlane =ARG7

ignoreNum =7 !Creates beams only every N Selected nodes.
MaxBeams =50 !Set to negative if you wish to create all beams
/NOPR

!-----------------------------------------------------------------
!Setup
!-----------------------------------------------------------------

/PREP7
ALLSEL

*GET,Last_ET,ETYP,,NUM,MAX
NextElem = Last_ET+1
*GET,Last_Real,RCON,,NUM,MAX
nReal = Last_Real+1
*GET,Last_Mat,MAT,,NUM,MAX
nMat = Last_Mat+1
*GET,mnode,NODE,,NUM,MAX
PointNode = mnode+1
*GET,csMax,CDSY,,NUM,MAX
*IF,csMax,LE,10,THEN
CSnum = 11
*ELSE
CSnum=csMax+1
*ENDIF
CSYS,0
WPCSYS,,0

!-----------------------------------------------------------------
!Element definition for beams
!-----------------------------------------------------------------

ET,NextElem,4 !Define element as a BEAM4 and set constants
KEYOPT,NextElem,6,1
r,nReal,8,8,8,8,8
MP,EX,nMat,1.000000e+07
MP,NUXY,nMat,0.300000e+00
MP,DENS,nMat,0.00000e+00

!-----------------------------------------------------------------
!Select nodes from one side to connect
!-----------------------------------------------------------------

WPOFFS,Xh,Yh,Zh
*IF,HolePlane,EQ,'XY',THEN
WPROTA,0,0,0
*ELSEIF,HolePlane,EQ,'XZ',THEN
WPROTA,0,-90,0
*ELSEIF,HolePlane,EQ,'YZ',THEN
WPROTA,0,0,90
*ENDIF
CSWPLA,CSnum,1
CSnum = CSnum+1
NALL
NSEL,S,LOC,X,0,Radius
NSEL,R,LOC,Z,0,Thickness1
CM,Set1,NODE
*GET,i1node,NODE,,COUNT
/COM,Nodes selected from first side = %i1node%.
!Return to the global coordinate system
NALL

!-----------------------------------------------------------------
!Select nodes for second side
!-----------------------------------------------------------------

NSEL,S,LOC,X,0,Radius
NSEL,R,LOC,Z,0,-Thickness2
CM,Set2,NODE
CM,Set2Full,NODE
*GET,i2node,NODE,,COUNT
/COM,Nodes selected from second side = %i2node%.
!Return to the global coordinate system
CSYS,0
WPCSYS,,0

!-----------------------------------------------------------------
!Connect nodes from both sides
!-----------------------------------------------------------------

TYPE,NextElem
REAL,nReal
MAT,nMat
Other1=1
Other2=1
BeamCount=0
*GET,i2node,NODE,,COUNT
CMSEL,S,Set1
*GET,i1node,NODE,,COUNT
*DOWHILE,i1node
/NOPR
CMSEL,S,Set1
*GET,Low1,NODE,,NUM,MIN
NSEL,U,NODE,,Low1
CM,Set1,NODE
i1node=i1node-1
*IF,Other1,LT,IgnoreNum,THEN
Other1=Other1+1
*CYCLE
*ENDIF
CMSEL,S,Set2Full
CM,Set2,NODE
*GET,i2node,NODE,,COUNT
*DOWHILE,i2node
/NOPR
CMSEL,S,Set2
*GET,Low2,NODE,,NUM,MIN
NSEL,U,NODE,,Low2
CM,Set2,NODE
i2node=i2node-1
*IF,Other2,LT,ignoreNum,THEN
Other2=Other2+1
*CYCLE
*ENDIF
*IF,Low1,EQ,Low2,THEN
*CYCLE
*ENDIF
E,Low1,Low2
BeamCount=BeamCount+1
*IF,BeamCount,EQ,MaxBeams,THEN
i1node=0
i2node=0
*CYCLE
*ENDIF
Other2=1
Other1=1
*ENDDO
*ENDDO
/NOPR

*GET,EndTime,ACTIVE,0,TIME,CPU
CalcTime=EndTime-StartTime

/COM,-----------------------------------------------------------------
/COM,End with %BeamCount% beams created in %CalcTime% seconds.
/COM,-----------------------------------------------------------------

!Return to the global coordinate system
CSYS,0
WPCSYS,,0
ALLSEL
FINISH
/GOPR
/EOF