# Viscoelastic Material Properties

1. Oct 7, 2008

### minger

Hello all; I am looking for material properties for some viscoelastic materials, specifically ones that I need to input into ANSYS for analysis.

More specifically these are the quantities that I'm looking for:

Shear Relaxation Kernel Function
$$G(\xi) = G_{\infty} + \sum^{n_G}_{i=1} G_i e^{(-\xi / \lambda^G_i)}$$

Bulk Relaxation Kernel Function
$$K(\xi) = K_{\infty} + \sum^{n_K}_{i=1} G_i e^{(-\xi / \lambda^K_i)}$$

$$G_i = C_i (G_0 - G_{\infty})$$

$$K_i = D_i (K_0 - G_{\infty})$$

Where $$\xi$$ is the reduced or pseudo time
n_G = number of Maxwell elements used to approximate the shear relaxation kernel
n_K = number of Maxwell elements used to approximate the bulk relaxation kernel
C_i = constants associated with the instantaneous response for shear behavior
D_i = constants associated with the instantaneous response for bulk behavior
G_0 = initial shear modulus
G_infinity = final shear modulus
K_0 = initial bulk modulus
K_infinity = final bulk modulus
$$\lambda^G_i$$ constants associated with a discrete relaxation spectrum in shear
$$\lambda^K_i$$ constants associated with a discrete relaxation spectrum in bulk

I've read up a little on the Maxwell model, and I really only need one element; but I'm way over my head. I really have no idea where to start.

I could really use some help, thanks.