Contact problem, contact detected earlier.

[saroj.bellbase99]

While solving a bending of non linear material between two dies in ANSYS mechanical APDL, the plate is bending before coming in contact with pressing die and the solution is not correct as follows. What might be the problem in here? I think the problem might be in defining the contact region.


The contact defined was bonded contact between plate and lower die where they are initially in contact, the frictional contact between lower die and plate where they weren't initially in contact and the same standard contact between the upper die and plate. The APDL commands used to define contact is as follows:
MP,MU,3,0.2 
MAT,3   
MP,EMIS,3,7.88860905221e-31 
R,3 
REAL,3  
ET,2,170
ET,3,175
KEYOPT,3,9,0
KEYOPT,3,10,0   
R,3,
RMORE,  
RMORE,,0
RMORE,0 
RMORE,,,,,,1.0  
! Generate the target surface   
ASEL,S,,,14 
ASEL,A,,,15 
ASEL,A,,,16 
CM,_TARGET,AREA 
TYPE,2  
NSLA,S,1
ESLN,S,0
ESLL,U  
ESEL,U,ENAME,,188,189   
NSLE,A,CT2  
ESURF   
CMSEL,S,_ELEMCM 
! Generate the contact surface  
ASEL,S,,,20 
CM,_CONTACT,AREA
TYPE,3  
NSLA,S,1
ESLN,S,0
NSLE,A,CT2 ! CZMESH patch (fsk qt-40109 8/2008) 
ESURF
allsel,all
MP,MU,3,0.2 
MAT,3   
R,4 
REAL,4  
ET,4,170
ET,5,175
KEYOPT,5,9,0
KEYOPT,5,10,0   
R,4,
RMORE,  
RMORE,,0
RMORE,0 
! Generate the target surface   
ASEL,S,,,5  
ASEL,A,,,7  
CM,_TARGET,AREA 
TYPE,4  
NSLA,S,1
ESLN,S,0
ESLL,U  
ESEL,U,ENAME,,188,189   
NSLE,A,CT2  
ESURF   
CMSEL,S,_ELEMCM 
! Generate the contact surface  
ASEL,S,,,19 
CM,_CONTACT,AREA
TYPE,5  
NSLA,S,1
ESLN,S,0
NSLE,A,CT2 ! CZMESH patch (fsk qt-40109 8/2008) 
ESURF
allsel,all
MP,MU,4,0.2 
MAT,4   
MP,EMIS,4,7.88860905221e-31 
R,5 
REAL,5  
ET,6,170
ET,7,175
R,5,,,1.0,0.1,0,
RMORE,,,1.0E20,0.0,1.0, 
RMORE,0.0,0,1.0,,1.0,0.5
RMORE,0,1.0,1.0,0.0,,1.0
RMORE,10.0,,,,,1.0  
KEYOPT,7,4,0
KEYOPT,7,5,0
KEYOPT,7,7,0
KEYOPT,7,8,0
KEYOPT,7,9,0
KEYOPT,7,10,0   
KEYOPT,7,11,0   
KEYOPT,7,12,3   
KEYOPT,7,14,0   
KEYOPT,7,18,0   
KEYOPT,7,2,0
KEYOPT,6,5,0
! Generate the target surface   
ASEL,S,,,6  
CM,_TARGET,AREA 
TYPE,6  
NSLA,S,1
ESLN,S,0
ESLL,U  
ESEL,U,ENAME,,188,189   
NSLE,A,CT2  
ESURF   
CMSEL,S,_ELEMCM 
! Generate the contact surface  
ASEL,S,,,19 
CM,_CONTACT,AREA
TYPE,7  
NSLA,S,1
ESLN,S,0
NSLE,A,CT2 ! CZMESH patch (fsk qt-40109 8/2008) 
ESURF


The contact between area 6 and 19 is bonded type.
The contact between area 5,7 and 19 is standard type.
The contact between area 14,15,16 and 20 is standard type.

[Erik Kostson]

For corrct forming bahaviour I would sugegst to use this :

https://www.ansys.com/en-gb/products/structures/ansys-forming

 

All the best

 

Erik

 

Perhaps other forum members can chime in here for your question

[saroj.bellbase99]

 

Is there not a way to do this simulation correctly in ansys mechanical apdl? Rather than moving on to another platform, I wanna know how to solve this specific problem if there is a way to do it properly. This is a viscoelastic forming problem.

 

[peteroznewman]

Don't use bonded contact if the material is not bonded to the die.  Use only frictional contact.

[saroj.bellbase99]

I tried that but the solution won't converge. What I really would like to know is what could the problem for the simullation to appear as above i.e. detecting contact without actually coming in contact. Is there could be any problem in modelling for such problem to occur?