pure shear loading

[Shuai Wang]

Dear all,
I would like to set a pure shear loading for 3d solid to test my user element.

I set disp BC to all external nodes with EBOU command.
I set uniform displacement in 2nd direction on z=c facet with EDIS command.
I set tangential displacement in 2nd direction on y=0 and y=b with CSURF command.
The input is something like the following. The 4th Dof is my user dof.
When I run this input, there is no displacement found on the y=0 and y=b facet. is there something wrong with the input?

Thank you for your time.


FEAP
0  0  1  3  4  8   

CONStants
  a = 1e5
  b = 1e6
  c = 1e6

MATErial 1
    USER  5
*********

BLOCk
    CARTesian,1,50,50,1,1,1,10
       1,0.0 ,0.0, 0.0
       2,a   ,0.0, 0.0
       3,a   ,b  , 0.0
       4,0.0 ,b  , 0.0
       5,0.0 ,0.0, c
       6,a   ,0.0, c
       7,a   ,b  , c
       8,0.0 ,b  , c

EBOUndary
3,c,  1,1,1,0
3,0,  1,1,1,0
2,b,  1,1,1,0
2,0,  1,1,1,0
1,a,  1,1,1,0
1,0,  1,1,1,0


load prop 1
edisp
3,c  0  2e4  0 0

csur
disp,2
surface
1,0,0,0,0
2,a,0,0,o
3,a,b,0,2e4
4,0,b,0,2e4

csur
disp,2
surface
1,0,0,c,0
2,0,b,c,2e4
3,a,b,c,2e4
4,a,0,c,0
load end

end

batch
 init,disp
end
1     1   0 0 0 1.0
5202    0   0 0 0 1.0

batch
prop,,1
end
2 5
0 0  200  0  4800  0.9    9600  1   10000 1 

[Prof. S. Govindjee]

Your boundary values are scrambled.  It is important to look at the output files to see what is being read.

In your particular case what you have defined is:

• Imposed displacements in x,y,z on all faces of the block (your EBOU command)
• For nodes with z=c, move them all 2e4 in the y direction, force x,z displacements to zero
• Your first csur command is looking of mesh facets on the plane z=0, whose outward normal is in the +z direction.  It will find none, since there are none in your mesh.  If you had a different mesh and it happened to find some it would impose a linearly increasing (with respect to x) displacement in the y direction.  Note also you have an 'o' value instead of a '0' on one of the lines which is surely a typo.
• Your second csur command is looking of mesh facets on the plane z=c, whose outward normal is in the -z direction.  It will find none, since there are none in your mesh.  If you had a different mesh and it happened to find some it would impose a linearly increasing (with respect to x) displacement in the y direction.
• All other other boundary points will have an imposed displacement of zero.

[Prof. R.L. Taylor]

Maybe do a 2x2x2 problem first so you can look at the output more easily.

You can also use graphics to look at boundary conditions