torsion spring¶
Module: solid
Category: discretematerial
Type string: "torsion spring"
Parameters¶
| Name | Description | Default | Units |
|---|---|---|---|
r |
r | 0 | [] |
Description¶
The torsion spring applies a force that aims to restore a discrete element's orientation to the reference configuration.
\[
\mathbf{f} = r\,\left({\mathbf{e}_0} \cdot{\mathbf{e}_t}\right) \mathbf{P}\, {\mathbf{e}_0}
\]
where \(\mathbf{e}_0\) is a unit vector along the discrete element's axis in the reference configuration, and similar for \(\mathbf{e}_t\), and
\[
\mathbf{P} =\frac{1}{l} \left( \mathbf{I} - \mathbf{e}_t \times \mathbf{e}_t \right)
\]
Here, \(l\) is the current length of the discrete element.