(
 Nonlinear (large deflection) test case for the truss element
 Node 1 is pinned, Node 2 is allowed to move only in the vertical
 direction. EA = 1000 psi, L  = 10 sqrt(2) inches.
                            0
  
 The truss element snaps through at a load of nearly 93.7 (in -Y dir).
 You can see the snap-thru by graphing the disy2.his file (using gnuplot?).
 Theoretical exact snap thru load is 1000.0*(1-2^(-1/3))^(3/2)=93.7016 lbf.
                        deflection 10*(1-sqrt(2^(1/3)-1))=4.9018 inches.
 Relaxation is needed 

 Osman Buyukisik   osman@fuse.net
 )

echo -no 
number_of_space_dimensions 2
materi_velocity
materi_displacement
end_initia

node 1  0 0
node 2  10 10
element 1  -truss 1 2

group_type 0  -truss
group_truss_memory 0  -updated
group_truss_area 0  1.0
group_truss_young 0  1000.0

bounda_unknown 0  2 -velx 
bounda_time    0  0. 0. 1.0e2 0.
bounda_unknown 1  1  -velx -vely
bounda_time    1  0. 0. 1.0e2 0.
bounda_force   2  2   -vely
bounda_time    2  0. 0. 1. -93.8

print_filter 1 -node_rhside 1 -vely

control_timestep                   0  1.e-1 1.
control_timestep_iterations        0  5
(
control_print                      0  -time_current -node_rhside
control_print_history              0  -node_dof 2 -disy
)

target_item    4  -node_rhside 1 -vely
target_value   4  -93.7  0.3
end_data
