*HYPERFOAM

Keyword type: model definition, material

This option is used to define a hyperfoam material. There is one optional parameters, N. N determines the order of the strain energy potential. Default is N=1. All constants may be temperature dependent.

The hyperfoam strain energy potential takes the form

U=\sum_{i=1}^{N} \frac{2 \mu_i}{\alpha_i^2} \left[ \lambda_1^{\alpha_i}+\lambda_2^{\alpha_i}+\lambda_3^{\alpha_i}-3+\frac{1}{\beta_i}(J^{-\alpha_i \beta_i}-1) \right]

(807)

where \lambda_1, \lambda_2 and \lambda_3 are the principal stretches. The parameters \beta_i are related to the Poisson coefficients \nu_i by:

\beta_i=\frac{ \nu_i}{1 -2 \nu_i}

(808)

and

\nu_i= \frac{ \beta_i}{1+2 \beta_i}.

(809)

First line:

*HYPERFOAM
Enter parameters and their values, if needed

Following line for N=1:

\mu_{1}.
\alpha_{1}.
\nu_{1}.
Temperature.

Repeat this line if needed to define complete temperature dependence.

Following line for N=2:

\mu_{1}.
\alpha_{1}.
\mu_{2}.
\alpha_{2}.
\nu_{1}.
\nu_{2}.
Temperature.

Repeat this line if needed to define complete temperature dependence.

Following lines, in a pair, for N=3: First line of pair:

\mu_{1}.
\alpha_{1}.
\mu_{2}.
\alpha_{2}.
\mu_{3}.
\alpha_{3}.
\nu_{1}.
\nu_{2}.

Second line of pair:

\nu_{3}.
Temperature.

Repeat this pair if needed to define complete temperature dependence.

Example:

*HYPERFOAM,N=2
0.164861,8.88413,2.302e-5,-4.81798,0.,0.

defines a hyperfoam material with two terms in the series.

Example files: beamhf.