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, $f_{n_{\max }}$, and a normalized input signal, $f_{\mathrm{normalized}}$.

$f_n\=f_{n_{\max }}{f}_{\mathrm{normalized}}0\le f_{\mathrm{normalized}}\le 1$

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, $\mathrm{\mu }\left(w\right)\&comma;w\ge 0$, 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 $\left[w_{\mathrm{rel}}\&comma;\mathrm{\mu }\left(w_{\mathrm{rel}}\right)\right]$. 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.

The component described in this topic is from the Modelica Standard Library. To view the original documentation, which includes author and copyright information, click here.