FACEt command

[nguyenvinhhiep]

Dear all,

To give an input set for non-plane contact surface for a 3D contact problem, I have used FACEt command for 2 specific facets as follows:

surf 1
  quad
  face
  1 0 77 78 12 11
  2 0 11 12 14 13

And I also made generation for contact surface with only one direction by changing increment 0 above into another number. But I do not know how to set up an generation with both direction on contact surface since the number of increment available in FEAP is only one.

Thank you very much.

Vinh Hiep Nguyen

[Prof. R.L. Taylor]

Feap generations for facet are increments on on nodes connected to the first facet.  Yes, it is only 1-dimensional and you need to start each row separately.   For regular surfaces you can also consider use of BLOCk or BLENd to do 2-d type surfaces.

[nguyenvinhhiep]

Dear Professor Taylor,

Thank you very much for your help.
The problem has been solved by using BLENd command for both of mesh generation and contact surfaces. Of course, SNODes are defined including the center of the disk. I have tried to fix the center of disk and apply a tangential displacement through contact friction between the lower disk and a upper brick block. The disk rotate well. But when I change the disk with a ring (disk with a hole in the middle), FEAP seem not to set up the SNOD center nodes as a rotating axis.

Thank you for your time again.

Best regards,
Vinh Hiep Nguyen

[Prof. R.L. Taylor]

Yes, you do need to have a body part where you describe the SNODe.  If the problem does not have inertial effects (i.e., is not a transient solution) you may be able to introduce a RIGId body for the central part -- like the hub of a wheel with a flexible tread.  If it is transient this probably is not a viable solution.

[nguyenvinhhiep]

Dear Prof. Taylor,

Thank you for your help. I have tried the model with a rigid center part. But the solutions are not converged and I am not sure what parts of mesh are designated as rigid bodies and how to set the number of body. Explicitly, the center part consists of 4 parts of 2nd material and the outer part consists of 4 parts of 3rd material. And the input for them is simply as follows:

rigid 1                     !(part 1 of rigid body)
bloc
  cart qq nn oo 0 0 2 0 10
  1   x y z
    ...
  8

...

rigid 1                     !(part 4 of rigid body)
bloc
  cart qq nn oo 0 0 2 0 10
  1   x y z
  ...
  8

and input for outer part

flex                    !(part 1 of outer rubber part)
bloc
  cart qq nn oo 0 0 2 0 10
  1   x y z
    ...
  14

...

flex                    !(part 1 of outer rubber part)
bloc
  cart qq nn oo 0 0 2 0 10
  1   x y z
  ...
  14

and the mate commands after the end of mesh:

tie mate 2 2
tie mate 3 3
tie mate 2 3

The solution method is just quasi-static.

Thank you for your time again.

Best regards,
Vinh Hiep Nguyen