StructuralBC Properties

(To be removed) Boundary condition or boundary load for structural analysis model

StructuralBC will be removed. Use the EdgeBC and FaceBC properties of femodel instead. (since R2023a) For more information on updating your code, see Version History.

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, specified 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, specified 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, specified 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, specified 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, specified 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, specified 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, specified 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, specified 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, specified 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, specified 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, specified 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), specified 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, specified 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, specified 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, specified 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, specified 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, specified 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, specified 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, specified 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, specified 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, specified as a character vector or a string.

Data Types: char | string

Version History

Introduced in R2017b

R2025a: To be removed

StructuralBC will be removed. Use the EdgeBC and FaceBC properties of femodel instead.

For example, you can check the boundary conditions for all faces as follows.

model = femodel(AnalysisType="structuralStatic", ...
                Geometry="Block.stl");
model.FaceBC(1) = faceBC(Constraint="fixed");
model.FaceBC(3) = faceBC(XDisplacement=0);
model.FaceBC

Alternatively, you can check the boundary conditions of particular faces.

model.FaceBC(1:3)

The unified finite element model workflow defines the type of a problem and all of its parameters as the properties of an femodel object. This object enables you to specify physical parameters for structural, thermal, and electromagnetic types of analyses. The solver in the unified workflow uses only the parameters (properties) appropriate for the current analysis type while ignoring all other properties. If you switch the analysis type by setting the AnalysisType property of the model, the solver uses the appropriate set of properties corresponding to the new analysis type.

For more help migrating your existing code that uses StructuralModel to the unified finite element workflow, see Migration from Domain-Specific to Unified Workflow.