Disc Brake

Brake disc with pressure cylinder and pads.

blockType: Engee1DMechanical.Brakes.Disc

Path in the library:

/Physical Modeling/1D Mechanical/Brakes & Detents/Rotational/Disc Brake

Description

The Disc Brake unit is a brake disc, in the form of a cylinder, which exerts pressure on one or more brake pads that contact the shaft rotor. The friction of the pads results in a braking element that counteracts the rotation of the shaft.

Model of a disc brake

This figure shows a front and left side view of a brake disc.

disc brake en

The brake disc converts the pressure in the brake cylinder into a force that is applied across the centre radius of the brake pad. The equation the unit uses to calculate the braking torque depends on the speed of the disc, , so that at ,

However, when , the torque applied by the brake is equal to the external torque applied to the rotor. The maximum value of the braking torque, in the case of , is defined as:

In both cases ,

where

- braking torque;
- is the applied pressure in the piston;
- disc rotation speed;
- number of brake pads;
- coefficient of static friction between pads and rotor;
- kinetic friction coefficient between pads and rotor;
- brake piston diameter;
- average radius of brake pad force application to the rotor disc;
- outer radius of the brake pad;
- inner radius of the brake pad.

By default, the unit simulates dry braking. You can model viscous friction by setting the Viscous friction coefficient, , to a non-zero value. The torque on the disc in a viscous friction system is:

Thermal modelling

You can model the effects of heat flow and block temperature changes using the H port, an optional non-directional port. To enable the port, select the check box for Thermal Port in the Friction settings. Enabling the thermal port also allows you to change the values for the following parameters:

Friction > Static friction coefficient vector
Friction > Coulomb friction coefficient vector
Thermal Port > Thermal mass

Ports

Input

# P — cylinder pressure
scalar

Details

An input port related to cylinder pressure.

Data types	`Float64`.
Complex numbers support	No

Conserving

# S — shaft
`rotational mechanics

Details

A non-directional port associated with a rotating disc shaft.

Program usage name

shaft_flange

# H — heat flux
`heat

Details

A non-directional port associated with heat flow.

The heat port allows modelling the heat flow between the unit and the connected network.

Dependencies

To use this port, select the Thermal Port check box.

Program usage name

thermal_port

Parameters

Geometry

# Mean pad radius — the average mounting radius of the brake pad
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

The average radius of the brake pads.

Units	`m` \| `um` \| `mm` \| `cm` \| `km` \| `in` \| `ft` \| `yd` \| `mi` \| `nmi`
Default value	`150.0 mm`
Program usage name	`mean_radius_pad`
Evaluatable	Yes

# Cylinder bore — piston diameter
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

Diameter of the brake piston.

Units	`m` \| `um` \| `mm` \| `cm` \| `km` \| `in` \| `ft` \| `yd` \| `mi` \| `nmi`
Default value	`10.0 mm`
Program usage name	`cylinder_bore`
Evaluatable	Yes

# Number of brake pads — number of pads

Details

The number of brake pads.

Default value	`2`
Program usage name	`pad_count`
Evaluatable	Yes

Friction

# Thermal Port — The thermal model

Details

Select this option to enable heat flow and temperature changes.

Default value	`false (switched off)`
Program usage name	`has_thermal_port`
Evaluatable	No

# Static friction coefficient — static friction

Details

Coefficient of static friction. The value must be greater than the value set for the Coulomb friction coefficient parameter.

Dependencies

This option is available if the Thermal Port option is not checked.

Default value	`0.9`
Program usage name	`static_friction_coefficient_const`
Evaluatable	Yes

# Coulomb friction coefficient — contact friction

Details

The coefficient of Coulomb friction on the contact surface of the pad with the disc. The value must be greater than zero.

Dependencies

This option is available if the Thermal Port option is not checked.

Default value	`0.7`
Program usage name	`coulomb_friction_coefficient_const`
Evaluatable	Yes

Details

An array of temperature values used to build a one-dimensional interpolation table of temperature and efficiency correspondence. The values of the array should increase monotonously.

Dependencies

This option is available if the Thermal Port option is checked.

Units	`K` \| `degC` \| `degF` \| `degR` \| `deltaK` \| `deltadegC` \| `deltadegF` \| `deltadegR`
Default value	`[280.0, 300.0, 320.0] K`
Program usage name	`temperature_vector`
Evaluatable	Yes

# Static friction coefficient vector — static friction vector

Details

The vector of values of the coefficients of static friction, such that:

The number of elements in the vector must be the same as the number of elements in the specified vector for the Temperature parameter.;
The values must be greater than the corresponding values specified for the Coulomb friction coefficient vector vector parameter.

Dependencies

This option is available if the Thermal Port option is checked.

Default value	`[0.9, 0.8, 0.7]`
Program usage name	`static_friction_coefficient_vector`
Evaluatable	Yes

# Coulomb friction coefficient vector — vector of contact friction

Details

The vector of values of the Coulomb friction coefficients on the contact surface of the pad with the disc, such that:

The number of elements in the vector must be the same as the number of elements in the specified vector for the Temperature parameter.;
The values are monotonously increasing;
Each value must be greater than zero.

Dependencies

This option is available if the Thermal Port option is checked.

Default value	`[0.8, 0.7, 0.6]`
Program usage name	`coulomb_friction_coefficient_vector`
Evaluatable	Yes

Details

The angular velocity at which friction changes its model from static to kinetic.

Units	`rad/s` \| `deg/s` \| `rad/min` \| `deg/min` \| `rpm` \| `rps`
Default value	`0.1 rad/s`
Program usage name	`w_breakaway`
Evaluatable	Yes

# Viscous friction coefficient — coefficient of viscous friction
N*m*s/rad | mN*m*s/rad | kN*m*s/rad | kgf*m*s/rad | lbf*ft*s/rad

Details

The viscous friction model represents the loss of energy to the cooling/lubricating fluid between the pads and the disc. To model such a system, specify a non-zero value of the viscous friction coefficient.

Units	`Nms/rad` \| `mNms/rad` \| `kNms/rad` \| `kgfms/rad` \| `lbffts/rad`
Default value	`0.0 Nms/rad`
Program usage name	`viscous_coefficient`
Evaluatable	Yes

Thermal Port

# Thermal mass — heat capacity
J/K | kJ/K

Details

The thermal energy required to change the temperature of a component by one degree. The higher the heat capacity, the more resistant the component is to temperature changes.

Dependencies

This option is available if the Thermal Port option is checked.

Units	`J/K` \| `kJ/K`
Default value	`50.0 kJ/K`
Program usage name	`thermal_mass`
Evaluatable	Yes

Initial Targets

Temperature

Priority - temperature priority
High (by default) | Low| None

Details

Temperature priority set as High, Low or None.

Dependencies

To use this port, select the check box for Thermal Port.

Value - temperature value
300 K (by default) | scalar

Details

Temperature value specified as a real scalar.

Dependencies

To use this port, select the Thermal Port checkbox.

Data types

Float64.

Examples

Simulation of the movement of an electric vehicle according to the WLTC cycle

Disc Brake

Description

Model of a disc brake

Thermal modelling

Ports

Input

Conserving

Parameters

Geometry

Friction

Thermal Port

Initial Targets

Temperature

See also

Examples