Friction in 2-D model

[MBrown]

Hello All,

I'm having a bit of trouble implementing friction between 2 surfaces in my model. Everything else runs fine and the contact pair works, just without friction. Below is the code I'm using and it directly follows the mesh data.

...material data and parameters...
...mesh data...

CONTact ON

SURFace 1
    LINE 2
    FACEt
   1   0    3 216
   2   1  216 217
   125 0  339 340
        126 0  340   2 

SURFace 2
    LINE 2
    FACEt
   1   1  7534 7535
   20  0  7553 7554

MATErial, 2
    STANdard
    FRICtion COULomb 0.53

PAIR 1
    NTOS 1 2
    SOLM PENAlty 1e7
    MATE,,2 1
    TOLE,,1e-8 1e-8 1e-8

END

...batch instructions...

Along with wanting to know if this seems correct, I have another question or two...

1) when defining the friction coeff. where it says:

MATErial, 2
    STANdard
    FRICtion COULomb 0.53

do you have to define the coefficient of all materials in contact? For example, Material 1 and 2 are in contact and need a coefficient of friction between them, can I simply define it for material 2 or must I define it for both material 1 and 2?

2) is there anything that I may be missing in the material data above the mesh data where all other material properties are defined? From the manual, it seemed that nothing extra was needed there to implement friction, but I want to make sure.

Thanks,
Michael

[Prof. R.L. Taylor]

Check either user manual or contact manual.  You may need a penalty value for the friction treatment (after the normal one).  But frictional contact is more sensitive than normal contact so try smaller steps too.

Also check output file to see what it says for the defined contact parts.

[MBrown]

Hi Prof. Taylor,

Thanks for your help. I've pulled the following from the Contact material data in the output file. I believe the problem is in one of the "pair feature" sections below where the material for each surface is defined.  It seems as if I've defined the material for surface 1 to be 1 (it should be 2) and there is no material defined for surface 2 (as the manual doesn't ever define friction for more than one material). Also, I get similar answers decreasing my steps quite a bit, and as far as I can tell, I've followed the contact manual closely. At this point, it is guess and check for me. If there is a clear reason why I may not be getting what I hope to get, I'd love to hear your ideas. I've also attached the input file.

Cheers,
Michael

    C o n t a c t   M a t e r i a l   D a t a

     Data Set for Material Number         1

     Contact Material Type             STAN

     Non-deformable Material with Coulomb Friction
       Type Declaration Data:         

     FRIC: Data for Friction
       Friction Model                  COULomb
       Friction Coefficient             5.30000E-01

     C o n t a c t   P a i r   D a t a

     Data Set for Pair Number             1
     Contact Pair Type:                NTOS

     Node-to-Segment Contact Model
       Slave  Surface                     1
       Master Surface                     2

       P a i r   F e a t u r e:        SOLM
       Solution Method:                PENA
         PENA - Penalty               
         LAGM - Lagrangian Multiplier 
         CROC - Cross-Constraint       
         SHAK - Shake  (Explicit Only)
         RATT - Rattle (Explicit Only)
       Normal     Penalty              1.00000E+07
       Tangential Penalty              0.00000E+00
       Normal Force Limit              0.00000E+00

       P a i r   F e a t u r e:        (this part does not show in plain text. I have attached a picture below)
       Contact Material Model:         
         Material for Surface 1           1
         Material for Surface 2       

       P a i r   F e a t u r e:        TOLE
       Contact Tolerances:
         Initial Penetration Tolerance  1.00000E-08
         Open Gap Tolerance             1.00000E-08
         Out of Facet Tolerance         1.00000E-08

  ---------------------------- END OF CONTACT INPUTS -------------------------