The Rotational Brake (or Brake) component models a brake. A frictional torque acts between the housing and a flange and a controlled normal force presses the flange to the housing to increase friction.
Normal Force
The normal force applied to the braking surface is the product of a parameter, ${f}_{{n}_{\mathrm{max}}}$, and a normalized input signal, ${f}_{\mathrm{normalized}}$.
${f}_{n}\={f}_{{n}_{\mathrm{max}}}{f}_{\mathrm{normalized}}\phantom{\rule[-0.0ex]{3.0ex}{0.0ex}}0\le {f}_{\mathrm{normalized}}\le 1$
Friction Force
When the absolute angular velocity is not zero, the friction torque is a function of the velocity dependent friction coefficient $\mathrm{\mu}\left(w\right)$ , the normal force, ${f}_{n}$, and a geometric constant, ${c}_{\mathrm{geo}}$, which takes into account the geometry of the device and the assumptions on the friction distributions.
$\mathrm{\tau}\={c}_{\mathrm{geo}}\mathrm{\mu}\left(w\right){f}_{n}$
The geometric constant is calculated as
${c}_{\mathrm{geo}}\=N\frac{{r}_{o}\+{r}_{i}}{2}$
where ${r}_{i}$ is the inner radius, ${r}_{o}$ is the outer radius, and $N$ is the number of friction interfaces.
Friction Table
The positive part of the friction characteristic, $\mathrm{\mu}\left(w\right)\,w\ge 0$, is defined by the ${\mathrm{\mu}}_{\mathrm{pos}}$ parameter as a two-dimensional table (array) that specifies the sliding friction coefficients at given relative angular velocities. Each row has the form $\left[{w}_{\mathrm{rel}}\,\mathrm{\mu}\left({w}_{\mathrm{rel}}\right)\right]$. The first column must be ordered, $0\le {w}_{1}<{w}_{2}<\cdots <{w}_{m}$. To add rows, right-click on the value and select Edit Matrix Dimension. Only linear interpolation is supported.