( Test 2d contact springs.
  The upper nodes of the quad4 move with velocity -1. downwards,
  so the lower nodes of the quad4 should move with velocity -0.5
  downwards because of the contact springs. )

echo -no
number_of_space_dimensions 2
materi_velocity
materi_velocity_integrated
materi_stress
end_initia

options_mesh -fixed_in_space -fixed_in_space
options_convection -no

node  1  0. 0.
node  2  1. 0.
node  3  0. 1.
node  4  1. 1.
node 11  0. 0.
node 12  1. 0.
element 1  -quad4 1 2 3 4
element 2  -contactspring 1 11
element 3  -contactspring 2 12

element_group 1  0
element_group 2  1
element_group 3  1

group_type 0  -materi
group_materi_elasti_young 0  1.0
group_materi_memory 0  -updated_without_rotation

group_type 1  -contactspring
group_contactspring_stiffness 1  0.5 0.5
group_contactspring_friction 1  1.e6
group_contactspring_direction 1 0. 1. 0.

bounda_unknown 0  -ra 11 12 -ra -velx -vely
bounda_time    0  0.
bounda_unknown 1  -ra 3 4 -ra -velx
bounda_time    1  0.
bounda_unknown 2  -ra 3 4 -ra -vely
bounda_time    2  -1.

print_filter 1  -node_dof -all -velx -vely -sigxx -sigxy -sigyy

control_timestep             10  1.e-3 1.e-3
control_timestep_iterations  10  2
(
control_print                10  -time_current -node_dof
)

target_item  1  -node_dof 1 -vely
target_value 1  -0.5 1.e-4
target_item  2  -node_dof 2 -vely
target_value 2  -0.5 1.e-4
end_data
