( Test 2D contact spring.
  The contactspring is compressed and sheared.
  In the first time interval, the parameters are such that 
  the contactspring sticks so that f_N = k_N u_N and f_T = k_T u_T.
  In the second time interval, the parameters are such that
  that the contactspring slips so that the shear force f_T = f f_N. )

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

start_define
  total_domain geometry_point 1
end_define
total_domain 0. 0. 1.e10

node  1  0. 0.
node  2  0. 1.
element 1  -contactspring 1 2

area_element_group_sequence_geometry 1  -total_domain
area_element_group_sequence_elementgroup 1  0 1
area_element_group_sequence_time 1  0.e-3 1.e-3

group_type 0  -contactspring
group_contactspring_stiffness 0  1.e6 1.e6
group_contactspring_friction 0  1.e20
group_contactspring_direction 0 0. 1. 0.

group_type 1  -contactspring
group_contactspring_stiffness 1  1.e6 1.e6
group_contactspring_friction 1  0.1
group_contactspring_direction 1 0. 1. 0.

bounda_unknown 0  1 -velx -vely
bounda_time    0  0.
bounda_unknown 1  2 -vely
bounda_time    1 -1.
bounda_unknown 2  2 -velx
bounda_time    2 +1.

control_timestep             10  1.e-3 2.e-3
(
control_print                10  -time_current -element_group -node_rhside
)

target_item 1  -node_rhside 1 -velx
target_value 1  200. 1.e-4
end_data
