in-situ stretch¶
Module: solid
Category: nlconstraint
Type string: "in-situ stretch"
Parameters¶
| Name | Description | Default | Units |
|---|---|---|---|
update |
update | true | [] |
tolerance |
tolerance | 0 | [] |
min_iters |
min_iters | 0 | [] |
max_iters |
max_iters | -1 | [] |
max_stretch |
max_stretch | 0 | [] |
isochoric |
isochoric | true | [] |
Description¶
The in-situ stretch constraint can be used as a prestrain update rule to enforce the fiber stretch induced by the initial prestrain gradient. As with the in-situ stretch generator option, this rule has an isochoric version and an uniaxial version for the update rule.
\[
\mathbf{G}_{iso}=\mathbf{Q}\left[\begin{array}{ccc}
\lambda^{-1}\\
& \lambda^{1/2}\\
& & \lambda^{1/2}
\end{array}\right]\mathbf{Q^{\mathrm{\mathit{T}}}},\qquad\mathbf{G}_{uni}=\mathbf{Q}\left[\begin{array}{ccc}
\lambda^{-1}\\
& 1\\
& & 1
\end{array}\right]\mathbf{Q^{\mathit{T}}}
\]
where \(\lambda^{2}=\mathbf{a}_{0}\cdot\mathbf{C}^{k}\cdot\mathbf{a}_{0}\), is the fiber stretch induced by the distortion.
Example:
<constraint type="in-situ stretch">
<tolerance>0.01</tolerance>
<isochoric>1</isochoric>
</constraint>