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