*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

$$U=\sum_{i=1}^{N} \frac{2 \mu_i}{\alpha_i^2} \left[ \lambda_1^{\al... ...ha_i}+\lambda_3^{\alpha_i}-3+\frac{1}{\beta_i}(J^{-\alpha_i \beta_i}-1) \right]$$ (183)

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:

$$\beta_i=\frac{ \nu_i}{1 -2 \nu_i}$$ (184)

and

$$\nu_i= \frac{ \beta_i}{1+2 \beta_i}.$$ (185)

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.