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Rotational Brake

Brake based on Coulomb friction

 Description 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.

Connections

 Name Description Modelica ID ${\mathrm{flange}}_{a}$ Flange of left shaft flange_a ${\mathrm{flange}}_{b}$ Flange of right shaft flange_b $\mathrm{support}$ support $\mathrm{heatPort}$ heatPort ${f}_{\mathrm{normalized}}$ Real input; normalized force f_normalized

Parameters

General Parameters

 Name Default Units Description Modelica ID ${\mathrm{\mu }}_{\mathrm{pos}}$ $\left[0.,0.5\right]$ $1$ Table of sliding friction coefficients at given relative velocities mue_pos $\mathrm{peak}$ $1$ $1$ $\mathrm{peak}{\mathrm{\mu }}_{\mathrm{pos}}\left[1,2\right]$ is the static friction coefficient peak ${c}_{\mathrm{geo}}$ $1$ $1$ Geometry constant containing friction distribution assumption cgeo ${f}_{{n}_{\mathrm{max}}}$ $1$ $N$ Maximum normal force fn_max Use Heat Port $\mathrm{false}$ True (checked) means the heat port is enabled useHeatPort use Support Flange $\mathrm{false}$ True (checked) means the support flange is enabled useSupport

 Name Default Units Description Modelica ID ${\mathrm{\omega }}_{\mathrm{small}}$ $1·{10}^{10}$ $\frac{\mathrm{rad}}{s}$ The velocity reinitializes when $\left|\mathrm{\omega }\right|\le {\mathrm{\omega }}_{\mathrm{small}}$ w_small ${K}_{\mathrm{locked}}$ $0$ $1$ Gain driving the relative motion between the friction elements to 0 when locked. This parameter should only be non-zero when using the model with fixed-step integration. K_locked