[Tochnog-users] Soil-structure interaction with the contact algorithm

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Hi Tochnogers,

I’m trying to simulate a soil-structure interaction. It consists of a thin-wall pipe embedded within a soil block, which has prescribed displacement at its boundaries. Obviously, as the soil moves downwards, and due to its lower stiffness, should ‘flow’ around the pipe, but nonetheless inducing some stresses to it, which eventually will end up in deformation of the pipe (way smaller than the soil surrounding it).

My initial idea was to use the contact algorithm because interfaces haven´t been implemented in tochnog yet. However, now I’m not sure if it’s gonna work.

I modified the file given in http://tochnog.sourceforge.net/ho_mech1.dat <http://tochnog.sourceforge.net/ho_mech1.dat>, which is a rubber ball being pressed downwards. I substituted the contact boundary by a block of the same material and set the contact with the ‘node_boundary’ option. It worked and the ball continues being deformed, but the block below was´t affected too much (some deformation was seen). Therefore, I decided to modify the stiffness of the material of the ball to be 100 times larger than the rubber, which now stays beneath the ball.

I was expecting a larger deformation of the block below due to its smaller stiffness (100 lower than the ball pressing it). However, it wasn´t the case and  the ball continues deforming more than the block, which actually presents some deformations upwards!!

Does anyone have an idea of how can I have this ‘two-bodies’ interaction. I’m attaching the modified data file if someone might find some errors.


Thank you very much in advance for your help.

cheers,

Ferney



echo -yes
number_of_space_dimensions 2
materi_velocity
materi_displacement
materi_stress
materi_strain_elasti
materi_strain_total
end_initia

node  0  0. -0.2
node  1  0. -0.1
node  2  0.  0.0
node  3  .1  0.0
node  4  .2  0.0
node  5  .1414 -0.14142
node  6  .0805 -0.06667
node 7 0 -.21
node 8 .3 -.21
node 9 .3 -.4
node 10 0 -.4

element 0 -quad4 0 5 1 6
element 1 -quad4 5 4 6 3
element 2 -quad4 1 6 2 3
element 3 -quad4  10 9 7 8

element_group 0 1
element_group 1 1
element_group 2 1
element_group 3 0

group_type 0  -materi
group_materi_memory 0  -total
group_materi_elasti_young 0  2.82
group_materi_elasti_poisson 0  0.49967

group_type 1  -materi
group_materi_memory 1  -total
group_materi_elasti_young 1  282
group_materi_elasti_poisson 1  0.249967

(left edge)
geometry_line 0  0.0 -0.2 0.0 0.0   1.e-3

(upper edge)
geometry_line 1  0.0  0.0 0.2 0.0  1.e-3

(contact line)
geometry_line 2  0.0 -0.2 1.0 -0.2 1.e-2


geometry_line 3 0 -.4 1 -.4 0.001
geometry_line 4 0 -.21 0 -.4 0.001

bounda_unknown 0  -geometry_line 0 -velx
bounda_time    0  0. 0. 100. 0.
bounda_unknown 1  -geometry_line 1 -vely
bounda_time    1  0.0 -0.15 100.0 -0.15
bounda_unknown 2 -geometry_line 3 -vely
bounda_time    2  0.0 -0.0 100.0 -0.0
bounda_unknown 3  -geometry_line 4 -velx
bounda_time    3  0. 0. 100. 0.

node_boundary  -ra 7 8 -ra -yes

contact_penalty_velocity  1.e5
contact_geometry  1 -geometry_line 2

post_node 1 -node_rhside -sum -geometry_line 1

control_mesh_refine_globally           7  -h_refinement
control_mesh_refine_globally_geometry  7  -geometry_set 0
control_mesh_refine_globally           8  -h_refinement
control_mesh_refine_globally_geometry  8  -geometry_set 0

control_timestep                      10  0.01 1.
control_timestep_iterations           10  10


control_print_gid			10 -yes

target_item 1  -post_node_result 1 -vely 
target_value 1  1.41727 0.02
end_data