Core Concepts
The critical tearing energy in single edge notch fracture tests for viscoelastic elastomers is heavily influenced by the material's viscoelastic properties (especially non-equilibrium elasticity and nonlinear viscosity) and loading rate, rather than solely by its intrinsic fracture energy.
Stats
The study uses specimens of length L = 15 mm, width H = 4 mm, and thickness B = 0.5 mm.
Three different crack lengths are considered: A = 1.9, 2, 2.1 mm.
The equilibrium elasticity is characterized by µ1 = 0.09 MPa, α1 = 0.5, µ2 = 0.01 MPa, and α2 = 2.5.
The non-equilibrium elasticity is varied to represent weaker, equal, and stronger growth conditions compared to the equilibrium elasticity.
Three viscosity types are examined: constant, shear-thinning, and deformation-dependent.
The initial relaxation time is kept constant at τ0 = 1 s for all cases.
Nine global stretch rates are simulated, ranging from ˙Λ0 = 10−3 s−1 to ˙Λ0 = 103 s−1, including the purely elastic limit (˙Λ0 = 0+) and the "pseudo-elastic" limit (˙Λ0 = +∞).
A representative critical energy release rate of Gc = 150 N/m is used.