# Loaded-Contact Translational Friction

Loaded-contact friction between two sliding surfaces

**Libraries:**

Simscape /
Driveline /
Brakes & Detents /
Translational

## Description

The Loaded-Contact Translational Friction block simulates friction between two sliding surfaces loaded with a normal force.

The block is implemented as a structural component based on the Fundamental Friction Clutch block. From the locked state, the two surfaces unlock if the exerted force exceeds the static friction, as defined by the static coefficient of friction and current normal force. For details on how the locking and unlocking are modeled, see the Fundamental Friction Clutch block reference page.

Force is transmitted for normal forces larger than the **Threshold
force** parameter.

### Equations

The block simulates friction between two sliding surfaces loaded with a normal force. When the two sliding surfaces are not locked, the friction force is determined with these equations:

$$F=N\xb7\mu \xb7\text{sign}({v}_{rel})+{F}_{\text{visc}},$$

$${F}_{visc}={\mu}_{\text{visc}}\xb7\text{}{v}_{rel},$$

where:

*F*is the transmitted force.*N*is the normal force.*μ*is the friction coefficient.*v*is the relative velocity._{rel}*F*is the viscous drag force._{visc}*μ*is the viscous drag force coefficient._{visc}

### Velocity-Dependent Model

You can model the effects of rotational velocity change by selecting a
velocity-dependent model. To choose a velocity-dependent model, in
the **Friction** settings, set the
**Friction model** parameter to
```
Velocity-dependent kinetic friction
coefficient
```

. For information about a friction
model that depends on both velocity and temperature, see Thermal, Velocity-Dependent Model.

For the velocity-dependent model these related parameters become
visible in the **Friction** settings:

**Relative velocity vector****Kinetic friction coefficient vector****Friction coefficient interpolation method****Friction coefficient extrapolation method**

### Thermal Model

You can model the effects of heat flow and temperature change by
selecting a temperature-dependent model. To choose a
temperature-dependent model, in the **Friction**
settings, set the **Friction model** parameter to
```
Temperature-dependent friction
coefficients
```

. For information about a friction
model that depends on both velocity and temperature, see Thermal, Velocity-Dependent Model.

For the temperature-dependent model, thermal port
**H** and these settings are visible:

In the

**Friction**settings:**Temperature vector****Static friction coefficient vector****Kinetic friction coefficient vector****Friction coefficient interpolation method****Friction coefficient extrapolation method**

In the

**Thermal Port**settings:**Thermal mass****Initial Temperature**

### Thermal, Velocity-Dependent Model

You can model the effects of rotational velocity change and heat flow
by selecting a velocity-dependent and temperature-dependent model.
To choose a model that depends on both velocity and temperature, in
the **Friction** settings, set the
**Friction model** parameter to
```
Temperature and velocity-dependent friction
coefficients
```

.

For the velocity-dependent and temperature-dependent model, thermal
port **H** and these related settings and
parameters become visible:

In the

**Friction**settings:**Relative velocity vector****Temperature vector****Static friction coefficient vector****Kinetic friction coefficient matrix****Friction coefficient interpolation method****Friction coefficient extrapolation method**

In the

**Thermal Port**settings:**Thermal mass****Initial Temperature**

### Faults

To model a fault in the Loaded-Contact Translational Friction block, in the
**Faults** section, click the **Add fault** hyperlink next
to the fault that you want to model. When the Add Fault window opens, you can to specify the
fault properties. For more information about fault modeling, see Fault Behavior Modeling and Fault Triggering.

When you trigger a fault, the clutch responds according to the
**Behavior when faulted** setting for the
remainder of the simulation. The fault options are:

`Cannot transmit power`

`Cannot unlock`

### Limitations and Assumptions

The model does not account for body mass. Add mass terms externally to the

**B**and**F**ports as required.The model computes the transmitted force assuming a uniform distribution of the normal force.

## Ports

### Input

### Conserving

## Parameters

## Extended Capabilities

## Version History

**Introduced in R2011a**