# faceLoad

## Description

A `faceLoad`

object contains a description of a load on a face of
a geometry. An `femodel`

object contains
an array of `faceLoad`

objects in its `FaceLoad`

property.

## Creation

### Description

`model.FaceLoad(`

creates a `FaceID`

) = faceLoad(Name=Value)`faceLoad`

object and sets properties using one
or more name-value arguments. This syntax assigns the specified structural, thermal, or
electromagnetic load to the specified faces of the geometry stored in the
`femodel`

object `model`

. For example,
`model.FaceLoad(1) = faceLoad(ChargeDensity=0.3)`

specifies the charge
density on face 1.

`model.FaceLoad = faceLoad(Name=Value)`

assigns the
specified property to the entire geometry. For example, ```
model.FaceLoad =
faceLoad(Gravity=[0 -9.8])
```

specifies the gravity load on all faces of a 2-D
geometry.

### Input Arguments

`FaceID`

— Face IDs

vector of positive integers

Face IDs, specified as a vector of positive integers. Find the face IDs using
`pdegplot`

with the
`FaceLabels`

value set to `"on"`

.

**Data Types: **`double`

## Properties

`Temperature`

— Thermal load

real number | `SteadyStateThermalResults`

object | `TransientThermalResults`

object

Thermal load, specified as a real number,
`SteadyStateThermalResults`

object, or
`TransientThermalResults`

object. This property must be specified in
units consistent with those of the geometry and material properties. For
`TransientThermalResults`

, you can access results for a particular
time-step by using the `filterByIndex`

function.

**Tip**

If you specify a thermal load, you must also specify a reference temperature
using `model.ReferenceTemperature`

. For details, see the
description of the `ReferenceTemperature`

property in `femodel`

.

**Data Types: **`double`

`Heat`

— Heat source term

real number | function handle

Heat source term, specified as a real number or function handle. Use a function handle to specify an internal heat source that depends on space, time, or temperature. For details, see Nonconstant Parameters of Finite Element Model.

`Pressure`

— Pressure normal to boundary

real number | function handle

Pressure normal to the boundary, specified as a real number or function handle. A positive-value pressure acts into the boundary (for example, compression), while a negative-value pressure acts away from the boundary (for example, suction).

If you specify `Pressure`

as a function handle, the function must
return a row vector where each column corresponds to the value of pressure at the
boundary coordinates provided by the solver. For a transient structural model,
`Pressure`

also can be a function of time. For a frequency response
structural model, `Pressure`

can be a function of frequency (when
specified as a function handle) or a constant pressure with the same magnitude for a
broad frequency spectrum. For details, see Nonconstant Parameters of Finite Element Model.

**Data Types: **`double`

| `function_handle`

`ConvectionCoefficient`

— Convection to ambient boundary condition,

real number | function handle

Convection to ambient boundary condition, specified as a real number or function handle. Use a function handle to specify a convection coefficient that depends on space and time. For details, see Nonconstant Parameters of Finite Element Model.

Specify ambient temperature using the `AmbientTemperature`

property. The value of `ConvectionCoefficient`

is positive for heat
convection into the ambient environment.

**Data Types: **`double`

| `function_handle`

`AmbientTemperature`

— Ambient temperature

real number

Ambient temperature, specified as a real number. The ambient temperature value is required for specifying convection and radiation boundary conditions.

**Data Types: **`double`

`Emissivity`

— Radiation emissivity coefficient

number in the range (0, 1)

Radiation emissivity coefficient, specified as a number in the range (0, 1).

Specify ambient temperature using the `AmbientTemperature`

property
and the Stefan-Boltzmann constant using the `femodel`

properties. The value of `Emissivity`

is positive for heat radiation
into the ambient environment.

**Data Types: **`double`

`SurfaceTraction`

— Normal and tangential distributed forces on boundary

vector | function handle

Normal and tangential distributed forces on the boundary (in the global Cartesian coordinate system), specified as a vector of three elements or a function handle.

If you specify `SurfaceTraction`

as a function handle, the function
must return a three-row matrix. Each column of the matrix corresponds to the surface
traction vector at the boundary coordinates provided by the solver. For a transient or
frequency response analysis, surface traction also can be a function of time or
frequency, respectively. For details, see Nonconstant Parameters of Finite Element Model.

**Data Types: **`double`

| `function_handle`

`TranslationalStiffness`

— Distributed spring stiffness

vector | function handle

Distributed spring stiffness for each translational direction used to model an elastic foundation, specified as a vector of three elements or a function handle.

If you specify `TranslationalStiffness`

as a function handle, the
function must return a three-row matrix. Each column of the matrix corresponds to the
stiffness vector at the boundary coordinates provided by the solver. For a transient or
frequency response analysis, translational stiffness also can be a function of time or
frequency, respectively. For details, see Nonconstant Parameters of Finite Element Model.

**Data Types: **`double`

| `function_handle`

`Gravity`

— Acceleration due to gravity

vector

Acceleration due to gravity, specified as a vector of two elements.

**Data Types: **`double`

`AngularVelocity`

— Angular velocity for modeling centrifugal loading in an axisymmetric model

positive number

Angular velocity for modeling centrifugal loading in an axisymmetric model, specified as a positive number.

**Data Types: **`double`

`ChargeDensity`

— Charge density

real number | function handle

Charge density, specified as a real number or function handle. Use a function handle to specify a charge density that depends on the coordinates. For details, see Nonconstant Parameters of Finite Element Model.

**Data Types: **`double`

| `function_handle`

`CurrentDensity`

— Current density

real number | vector | function handle | `ConductionResults`

object

Current density, specified as a real number, vector, function handle, or `ConductionResults`

object. Use a function handle to specify a nonconstant current density. For details, see
Nonconstant Parameters of Finite Element Model.

For magnetostatic analysis, the current density must be:

A real number or a function handle for a 2-D model. The toolbox does not support conduction results as a source of current density for a 2-D magnetostatic analysis.

A vector of three elements, a

`ConductionResults`

object, or a function handle for a 3-D model

For harmonic analysis with an electric field type, the toolbox multiplies the
specified current density by `-i`

and by frequency. The current density
must be:

A vector of two elements or a function handle that depends on the coordinates for a 2-D model

A vector of three elements or a function handle that depends on the coordinates for a 3-D model

For harmonic analysis with a magnetic field type, the toolbox uses the curl of the specified current density. The current density must be:

A number or a function handle that depends on the coordinates for a 2-D model

A vector of three elements or a function handle that depends on the coordinates for a 3-D model

**Data Types: **`double`

| `function_handle`

`Magnetization`

— Magnetization

vector | function handle

Magnetization, specified as a vector of two elements for a 2-D model, vector of three elements for a 3-D model, or function handle. Use a function handle to specify a magnetization that depends on coordinates. For details, see Nonconstant Parameters of Finite Element Model.

**Data Types: **`double`

| `function_handle`

`SurfaceCurrentDensity`

— Surface current density

real number | function handle

Surface current density in the direction normal to the boundary, specified as a real number or function handle. The solver uses a surface current density boundary condition for a DC conduction analysis. Use a function handle to specify a surface current density that depends on the coordinates. For details, see Nonconstant Parameters of Finite Element Model.

**Data Types: **`double`

| `function_handle`

## Examples

### Surface Traction on Specified Boundaries

Specify surface traction for an `femodel`

object representing a static structural problem.

Create and plot a geometry that consists of two nested cylinders.

```
gm = multicylinder([0.01,0.015],0.05);
pdegplot(gm,FaceLabels="on",FaceAlpha=0.4);
```

Create an `femodel`

object for solving a static structural problem, and assign the geometry to the model.

model = femodel(AnalysisType="structuralStatic", ... Geometry=gm);

Specify the surface traction for faces 2 and 5.

model.FaceLoad([2 5]) = faceLoad(SurfaceTraction=[0 0 100]); model.FaceLoad([2 5]).SurfaceTraction

`ans = `*1×3*
0 0 100

`ans = `*1×3*
0 0 100

### Angular Velocity of Spinning Disk

Specify angular velocity for an `femodel`

object representing a static structural problem. For this analysis, simplify the 3-D axisymmetric model to a 2-D model.

Create a rectangular geometry that represents an spinning disk. The inner radius of the disk is 0.05, and the outer radius is 0.2. The thickness of the disk is 0.05.

gm = decsg([3 4 0.05 0.2 0.2 0.05 -0.025 -0.025 0.025 0.025]');

Plot the geometry with the face labels.

```
pdegplot(gm,FaceLabels="on");
xlim([0.04 0.21])
ylim([-0.03 0.03])
```

Create an `femodel`

object for solving an axisymmetric static structural problem, and assign the geometry to the model.

model = femodel(AnalysisType="structuralStatic", ... Geometry=gm); model.PlanarType = "axisymmetric";

Apply centrifugal load due to spinning of the disk. Assume that the disk is spinning at 104.7 rad/s.

model.FaceLoad = faceLoad(AngularVelocity=104.7); model.FaceLoad

ans = 1x1 faceLoad array Properties for analysis type: structuralStatic Index Gravity AngularVelocity Temperature Pressure TranslationalStiffness 1 [] 104.7000 [] [] [] Show all properties

## Version History

**Introduced in R2023a**

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