Translational spring with variable spring stiffness
The block represents a translational spring with variable spring stiffness. A physical signal input port provides the variable spring stiffness. The magnitude of the spring force is equal to the product of the physical signal input and the relative linear displacement between the two translational conserving ports. A minimum spring rate prevents non-physical values.
The translational spring force satisfies the following expression:
The parameters are:
F — Force transmitted through the spring between the two translational conserving ports
K — Spring rate (stiffness)
Kmin — Minimum allowed spring rate (stiffness)
x — Relative displacement between the two translational conserving ports according to
xinit — initial spring deformation
xR — Absolute displacement of translational conserving port R
xC — Absolute displacement of translational conserving port C
The block applies equal and opposite spring forces on the two translational conserving ports. The sign of the spring force acting on port R is equal to the sign of the relative linear displacement between the two ports. A positive linear velocity corresponds to a positive spring force acting on port R, and a negative spring force of equal magnitude acting on port C.
Minimum value allowed for the spring rate. The physical signal input saturates below the specified value. The parameter must be greater than zero. The default value is 1. The default unit is N/m
Initial displacement between the two translational conserving ports. The default value is 0. The default unit is m.
Specify the desired initial values of the block dynamical variables. These variables guide model assembly at simulation time zero. When two or more variables conflict with each other, the priority setting determines which of the variables to satisfy. For more information, see Set Priority and Initial Target for Block Variables.
Variables that you can specify include:
f — Spring force
v — Deformation rate
x — Translational deformation
|K||Physical signal input port representing the variable spring stiffness|
|C||Translational conserving port|
|R||Translational Conserving port|