# StructuralBC Properties

Boundary condition or boundary load for structural analysis model

A `StructuralBC`

object specifies the type of
PDE boundary condition or boundary load on a set of geometry boundaries. A `StructuralModel`

object contains a vector of `StructuralBC`

objects in
its `BoundaryConditions.StructuralBCAssignments`

property.

To specify boundary conditions for your model, use the `structuralBC`

function. To specify boundary loads, use `structuralBoundaryLoad`

.

## Properties of StructuralBC

`RegionType`

— Geometric region type

`'Face'`

for 3-D geometry | `'Edge'`

for 2-D geometry

Geometric region type, returned as `'Face'`

for a 3-D
geometry or `'Edge'`

for a 2-D geometry.

**Data Types: **`char`

| `string`

`RegionID`

— Geometric region ID

vector of positive integers

Geometric region ID, returned as a vector of positive integers. Find the
region IDs by using `pdegplot`

with
`'FaceLabels'`

(3-D) or `'EdgeLabels'`

(2-D) set to `'on'`

.

**Data Types: **`double`

`Vectorized`

— Vectorized function evaluation

`'off'`

(default) | `'on'`

Vectorized function evaluation, returned as `'off'`

or
`'on'`

. This evaluation applies when you pass a
function handle as an argument. To save time in the function handle
evaluation, specify `'on'`

, assuming that your function
handle computes in a vectorized fashion. See Vectorization. For details on
this evaluation, see Nonconstant Boundary Conditions.

**Data Types: **`char`

| `string`

## Boundary Constraints and Enforced Displacements

`Displacement`

— Enforced displacement

numeric vector | function handle

Enforced displacement, returned as a numeric vector or function handle. The numeric vector must contain two elements for a 2-D model and three elements for a 3-D model. The function must return a two-row matrix for a 2-D model and a three-row matrix for a 3-D model. Each column of the matrix must correspond to the enforced displacement vector at the boundary coordinates provided by the solver.

**Data Types: **`double`

| `function_handle`

`XDisplacement`

— x-component of enforced displacement

number | function handle

x-component of the enforced displacement, returned as a number or function handle. The function must return a row vector. Each column of the vector must correspond to the value of the x-component of the enforced displacement at the boundary coordinates provided by the solver.

For axisymmetric models, this property contains the radial component (r-component) of the enforced displacement.

**Data Types: **`double`

| `function_handle`

`YDisplacement`

— y-component of enforced displacement

number | function handle

y-component of the enforced displacement, returned as a number or function handle. The function must return a row vector. Each column of the vector must correspond to the value of the y-component of the enforced displacement at the boundary coordinates provided by the solver.

For axisymmetric models, this property contains the axial component (z-component) of the enforced displacement.

**Data Types: **`double`

| `function_handle`

`ZDisplacement`

— z-component of enforced displacement

number | function handle

z-component of the enforced displacement, returned as a number or function handle. The function must return a row vector. Each column of the vector must correspond to the value of the z-component of the enforced displacement at the boundary coordinates provided by the solver.

**Data Types: **`double`

| `function_handle`

`Constraint`

— Standard structural boundary constraints

`'free'`

| `'fixed'`

| `'roller'`

| `'symmetric'`

| `'multipoint'`

Standard structural boundary constraints, returned as
`'free'`

,`'fixed'`

,`'roller'`

,
`'symmetric'`

, or
`'multipoint'`

.

**Data Types: **`char`

`Radius`

— Radius of circle (for 2-D geometry) or sphere (for 3-D geometry) around reference point location for multipoint constraint

positive number

Radius of a circle (for a 2-D geometry) or a sphere (for a 3-D geometry) around the reference point location for the multipoint constraint, returned as a positive number.

**Data Types: **`double`

`Reference`

— Reference point location for multipoint constraint

2-by-1 numeric vector | 3-by-1 numeric vector

Reference point location for the multipoint constraint, returned as a 2-by-1 (for a 2-D geometry) or 3-by-1 (for a 3-D geometry) numeric vector.

**Data Types: **`double`

## Boundary Loads

`Force`

— Concentrated force

numeric vector | function handle

Concentrated force at a vertex, returned as a numeric vector or function handle.

**Data Types: **`double`

| `function_handle`

`SurfaceTraction`

— Normal and tangential distributed forces on boundary

numeric vector | function handle

Normal and tangential distributed forces on the boundary (in the global Cartesian coordinates system), returned as a numeric vector or function handle. The numeric vector must contain two elements for a 2-D model and three elements for a 3-D model. The function must return a two-row matrix for a 2-D model and a three-row matrix for a 3-D model. Each column of the matrix must correspond to the surface traction vector at the boundary coordinates provided by the solver.

**Data Types: **`double`

| `function_handle`

`Pressure`

— Pressure normal to boundary

number | function handle

Pressure normal to the boundary, returned as a number or function handle. The function must return a row vector in which each column corresponds to the value of pressure at the boundary coordinates provided by the solver. A positive value of pressure acts in the direction of the outward normal to the boundary.

**Data Types: **`double`

| `function_handle`

`TranslationalStiffness`

— Distributed spring stiffness

numeric vector | function handle

Distributed spring stiffness for each translational direction used to model an elastic foundation, returned as a numeric vector or function handle. The numeric vector must contain two elements for a 2-D model and three elements for a 3-D model. The custom function must return a two-row matrix for a 2-D model and a three-row matrix for a 3-D model. Each column of this matrix corresponds to the stiffness vector at the boundary coordinates provided by the solver.

**Data Types: **`double`

| `function_handle`

## Time Variation of Force, Pressure, or Enforced Displacement

`StartTime`

— Start time for displacement component, pressure, or concentrated force load

nonnegative number

Start time for a displacement component, the pressure, or the concentrated force load, returned as a nonnegative number.

**Data Types: **`double`

`EndTime`

— End time for displacement component, pressure, or concentrated force load

nonnegative number

End time for a displacement component, the pressure, or the concentrated force load, returned as a nonnegative number.

**Data Types: **`double`

`RiseTime`

— Rise time for displacement component, pressure, or concentrated force load

nonnegative number

Rise time for a displacement component, the pressure, or the concentrated force load, returned as a nonnegative number.

**Data Types: **`double`

`FallTime`

— Fall time for displacement component, pressure, or concentrated force load

nonnegative number

Fall time for a displacement component, the pressure, or the concentrated force load, returned as a nonnegative number.

**Data Types: **`double`

## Sinusoidal Variation of Force, Pressure, or Enforced Displacement

`Frequency`

— Frequency of sinusoidal displacement component, sinusoidal pressure, or concentrated force

positive number

Frequency of a sinusoidal displacement component, the sinusoidal pressure, or the concentrated force, returned as a positive number, in radians per unit of time.

**Data Types: **`double`

`Phase`

— Phase of sinusoidal displacement component, sinusoidal pressure, or concentrated force

nonnegative number

Phase of a sinusoidal displacement component, the sinusoidal pressure, or the concentrated force, returned as a nonnegative number, in radians per unit of time.

**Data Types: **`double`

`Label`

— Label for use with `linearizeInput`

character vector | string

Label for use with `linearizeInput`

, returned as a
character vector or a string.

**Data Types: **`char`

| `string`

## See Also

`findStructuralBC`

| `structuralBC`

| `structuralBoundaryLoad`

| `structuralSEInterface`

| StructuralSEIAssignment Properties

**Introduced in R2017b**

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