material elastic [
	 name = steel
	 rho = 1e3   # density
	 E   = 1e3   # young's modulus
	 nu  = 0.0 # poisson's ratio
]

material cohesive_linear [
	 name = TG_cohesive
	 beta = 0
	 G_cI = 10
         sigma_c = 100
]

material cohesive_linear [
	 name = IG_cohesive
	 beta = 0
	 G_cI = 10
         sigma_c = 20
]