1(
2Single axisymmetric Blatz-Ko element test
3Blatz-Ko hyperelastic material harden in compression, and soften slightly in tension.
4foamlike rubber.
5Applicability: Strech ratio <= 2.0
6R0=1  inital radius
7L0=1  inital length
8G=1., nu=0.46, beta = 14.
9Cauchy stress = G*lambda^[1+2*nu]*[1-lambda^[-2*[1+nu]]]
10where lambda is = L/L0 [strech ratio].
11for lambda = 2  true stress = 3.18.
12R/R0=[L/L0]^[-nu]
13R/R0=0.73 for L/L0=2
14Refs.
15  1.  R.A. Brockman, "On the Use of the Blatz-Ko Constitutive Model in Nonlinear
16      Finite Element Analysis", Computers&Structers Vol 24, No 4, pp 607-611[1986]
17
18  2.  P.J.Blatz, W.L. Ko, "Application of Finite Elastic Theory to the Deformation
19      of Rubbery Materials", Trans. Soc. Rheol. 6,223-251[1962].
20
21Test supplied by: Osman F Buyukisik, osman@fuse.net
22)
23
24echo -no
25number_of_space_dimensions 2
26materi_velocity
27materi_displacement
28materi_stress
29materi_strain_elasti
30materi_strain_total
31end_initia
32
33node 1  0. 0.
34node 2  1. 0.
35node 3  0. 1.
36node 4  1. 1.
37element 1  -quad4 1 2 3 4
38
39group_type 0  -materi
40group_materi_elasti_young     0  3.0
41group_materi_elasti_poisson   0  0.46
42( Blatz-Ko paramaters mu, beta  mu is the linear shear modulus, beta=2*nu/[1-2*nu] )
43group_materi_hyper_blatz_ko   0  1. 14.0
44group_materi_memory 0  -total
45group_axisymmetric 0 -yes
46
47(centerline)
48geometry_line  1  0. 0. 0. 1. 1.e-1
49(lower edge)
50geometry_line  2  0. 0. 1. 0. 1.e-1
51(upper edge)
52geometry_line  3  0. 1. 1. 1. 1.e-1
53
54bounda_unknown 1  -geometry_line 2 -vely
55bounda_time    1  0. 0. 100. 0.
56bounda_unknown 2  -geometry_line 1 -velx
57bounda_time    2  0. 0. 100. 0.
58bounda_unknown 3  -geometry_line 3 -vely
59bounda_time    3  0. 0. 1. 1
60
61control_timestep  10  0.1 1.0
62control_timestep_iterations  10 10
63(
64control_print    10 -time_current
65control_print_history 10 -node_dof 4 -sigyy
66)
67
68target_item 1  -node_dof 4 -sigyy
69target_value 1  3.18021  0.01
70target_item 2  -node_dof 4 -velx
71target_value 2  -0.27 0.04
72
73end_data
74