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Rotational Clutch

Clutch based on Coulomb friction

 

Description

Connections

Parameters

Modelica Standard Library

Description

The Rotational Clutch (or Clutch) component models a clutch controlled by an input signal. Two rotational flanges are pressed together via a normal force.

Normal Force

The normal force applied to the clutch surface is the product of a parameter, fnmax, and a normalized input signal, fnormalized.

fn=fnmaxfnormalized0fnormalized1

Friction Force

When the absolute angular velocity is not zero, the friction torque is a function of the velocity dependent friction coefficient μw , the normal force, fn, and a geometric constant, cgeo, which takes into account the geometry of the device and the assumptions on the friction distributions.

τ=cgeoμwfn

The geometric constant is calculated as

cgeo=Nro+ri2

where ri is the inner radius, ro is the outer radius, and N is the number of friction interfaces.

Friction Table

The positive part of the friction characteristic, μw&comma;w0, is defined by the μpos parameter as a two-dimensional table (array) that specifies the sliding friction coefficients at given relative angular velocities. Each row has the form wrel&comma;μwrel. The first column must be ordered, 0w1<w2<<wm. To add rows, right-click on the value and select Edit Matrix Dimension. Only linear interpolation is supported.

Connections

Name

Description

Modelica ID

flangea

Left flange of compliant 1-dim. rotational component

flange_a

flangeb

Right flange of compliant 1-dim. rotational component

flange_b

heatPort

Optional heat port

heatPort

fnormalized

Real input; normalized force

f_normalized

Parameters

General Parameters

Name

Default

Units

Description

Modelica ID

μpos

0.&comma;0.5

1

Table of sliding friction coefficients at given relative velocities

mue_pos

peak

1

1

peakμpos1&comma;2 is the static friction coefficient

peak

cgeo

1

1

Geometry constant containing friction distribution assumption

cgeo

fnmax

1

N

Maximum normal force

fn_max

Use Heat Port

false

 

True (checked) means the heat port is enabled

useHeatPort

Advanced Parameters

Name

Default

Units

Description

Modelica ID

φnominal

1·10−4

rad

Nominal value of φrel (used for scaling)

phi_nominal

State Select

prefer

 

Prioritize φrel and wrel as states

stateSelect

ωsmall

1·1010

rads

The velocity reinitializes when ωωsmall

w_small

Klocked

0

 

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

Modelica Standard Library

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.

See Also

1-D Mechanical Overview

Rotational Clutches and Brakes