Two-node 3-dimensional dashpot (DASHPOTA) next up previous contents
Next: Two-node 3-dimensional spring (SPRINGA) Up: Element Types Previous: Two-node unidirectional gap element   Contents

Two-node 3-dimensional dashpot (DASHPOTA)

The dashpot element is defined between two nodes (Figure 63). The force in node 2 amounts to:

$\displaystyle \boldsymbol{F_2}=c (\boldsymbol{v_2}-\boldsymbol{v_1}) \cdot \frac{(\boldsymbol{x_2}-\boldsymbol{x_1})}{L}$ (8)

where c is the dashpot coefficient, $ \boldsymbol{v}$ is the velocity vector, $ \boldsymbol{X}$ is the actual location of the nodes and $ L$ is the distance between them. Right now, only linear dashpots are allowed, i.e. the dashpot coefficient is constant (i.e. it does not depend on the relative velocity. However, it can depend on the temperature). It is defined using the *DASHPOT keyword card.

Figure 63: Definition of a DASHPOTA element
\begin{figure}\epsfig{file=dashpot.eps,width=5cm}\end{figure}

The two-node three-dimensional dashpot element is considered as a genuine three-dimensional element. Consequently, if it is connected to a 2D element with special restraints on the third direction (plane stress, plane strain or axisymmetric elements) the user has to take care of the third dimension does not induce rigid body motions in the dashpot nodes.

The dashpot element can only be used in linear dynamic calculations characterized by the *MODAL DYNAMIC keyword card.


next up previous contents
Next: Two-node 3-dimensional spring (SPRINGA) Up: Element Types Previous: Two-node unidirectional gap element   Contents
guido dhondt 2012-10-06