( Total lagrange Solid.
  Compression of bar. 
  The analytical force solution for a material with a linear relation between 
  2nd Piola-Kirchoff stress tensor and Green-Lagrange strain tensor is:
  F = 0.5 E A_0 (L/L_0) ( (L/L_0)**2 - 1 )
  with A_0 initial area, L_0 initial length, L actual length, E young modulus.
  For a compression of a half this gives here F = 0.375.
)

echo -no
number_of_space_dimensions 1
materi_velocity
materi_displacement
materi_strain_total
materi_stress
end_initia

node 1  0
node 2  1

element 1 -bar2 1 2

group_type 0  -materi
group_materi_elasti_young 0  2.0
group_materi_memory 0  -total_piola

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

print_filter 0 -node_dof -all -disx -eptxx -sigxx 

control_timestep      0  1.e-2 0.50
(
control_print         0  -time_current -node_dof
control_print_data_versus_data 0  -node_dof 2 -disx -node_rhside 2 -velx 
)

target_item 0  -node_rhside 2 -velx
target_value   0  0.375 1.e-8
end_data
