femodel

Finite element analysis model object

Since R2023a

Description

An femodel object contains information about a finite element problem: analysis type, geometry, material properties, boundary conditions, loads, initial conditions, and other parameters.

Creation

Syntax

model = femodel

model = femodel(AnalysisType=analysistype)

model = femodel(Geometry=geometry)

model = femodel(AnalysisType=analysistype,Geometry=geometry)

Description

model = femodel creates a finite element analysis model.

model = femodel(AnalysisType=analysistype) creates a finite element analysis model for the specified analysis type.

model = femodel(Geometry=geometry) assigns the specified geometry object to its Geometry property.

model = femodel(AnalysisType=analysistype,Geometry=geometry) creates a finite element analysis model for the specified analysis type and assigns the specified geometry object to its Geometry property.

Input Arguments

analysistype — Type of problem

"structuralStatic" | "structuralModal" | "structuralTransient" | "structuralFrequency" | "thermalSteady" | "thermalModal" | "thermalTransient" | "electrostatic" | "magnetostatic" | "electricHarmonic" | "magneticHarmonic" | "dcConduction"

Type of problem, specified as one of these values:

• "structuralStatic" creates a model for static structural analysis.

• "structuralModal" creates a model for modal structural analysis.

• "structuralTransient" creates a model for transient structural analysis.

• "structuralFrequency" creates a model for frequency response structural analysis.

• "thermalSteady" creates a model for steady-state thermal analysis.

• "thermalModal" creates a model for modal thermal analysis.

• "thermalTransient" creates a model for transient thermal analysis.

• "electrostatic" creates a model for electrostatic analysis.

• "magnetostatic" creates a model for magnetostatic analysis.

• "electricHarmonic" creates a model for harmonic electromagnetic analysis with an electric field type.

• "magneticHarmonic" creates a model for harmonic electromagnetic analysis with a magnetic field type.

• "dcConduction" creates a model for DC conduction analysis.

This argument sets the AnalysisType property.

Data Types: char | string

geometry — Geometry description

fegeometry object

Geometry description, specified as an fegeometry object. This argument sets the Geometry property.

Properties

AnalysisType — Type of problem

"structuralStatic" | "structuralModal" | "structuralTransient" | "structuralFrequency" | "thermalSteady" | "thermalModal" | "thermalTransient" | "electrostatic" | "magnetostatic" | "electricHarmonic" | "magneticHarmonic" | "dcConduction"

Type of problem, specified as "structuralStatic", "structuralModal", "structuralTransient", "structuralFrequency", "thermalSteady", "thermalModal", "thermalTransient", "electrostatic", "magnetostatic", "electricHarmonic", "magneticHarmonic", or "dcConduction".

This property is set by the analysistype input argument.

Data Types: string

Geometry — Geometry description

fegeometry object

Geometry description, specified as an fegeometry object. This property is set by the geometry input argument.

PlanarType — Type of two-dimensional problem

"planeStress" | "planeStrain" | "axisymmetric"

Type of two-dimensional problem, specified as "planeStress", "planeStrain", or "axisymmetric". This property does not apply to models with 3-D geometries.

For axisymmetric models, the toolbox assumes that the axis of rotation is the vertical axis, x=0. The x-axis represents the radial component, and the y-axis represents the axial component.

Data Types: string

MaterialProperties — Material properties

array of materialProperties objects

Material properties, specified as a 1-by-N array of materialProperties objects. Here, N is the number of faces in a 2-D geometry or number of cells in a 3-D geometry. Each materialProperties object contains material properties for one face or cell of the geometry.

Boundary Conditions

FaceBC — Boundary conditions on geometry faces

array of faceBC objects

Boundary conditions on geometry faces, specified as a 1-by-N array of faceBC objects. Here, N is the number of faces in a geometry. Each faceBC object contains boundary conditions for one face of the geometry.

EdgeBC — Boundary conditions on geometry edges

array of edgeBC objects

Boundary conditions on geometry edges, specified as a 1-by-N array of edgeBC objects. Here, N is the number of edges in a geometry. Each edgeBC object contains boundary conditions for one edge of the geometry.

VertexBC — Boundary conditions on geometry vertices

array of vertexBC objects

Boundary conditions on geometry vertices, specified as a 1-by-N array of vertexBC objects. Here, N is the number of vertices in a geometry. Each vertexBC object contains boundary conditions for one vertex of the geometry.

ROMInterfaces — Reduced-order model (ROM) interfaces

[] (default) | vector of romInterface objects

Reduced-order model interfaces, specified as a vector of romInterface objects. Here all romInterface objects must have the same RigidInterface value.

You can use a combination of vertices, edges, and faces to create each romInterface object.

ThermalRadiation — Settings for modeling thermal radiation between surfaces

[] (default) | surfaceToSurfaceSettings object

Settings for modeling thermal radiation between surfaces without conductive media, specified as a surfaceToSurfaceSettings object. The default empty value results in the surface-to-ambient solution.

Loads

CellLoad — Loads on geometry cells

array of cellLoad objects

Loads on geometry cells, specified as a 1-by-N array of cellLoad objects. Here, N is the number of cells in a geometry. Each cellLoad object contains loads for one cell of the geometry.

FaceLoad — Loads on geometry faces

array of faceLoad objects

Loads on geometry faces, specified as a 1-by-N array of faceLoad objects. Here, N is the number of faces in a geometry. Each faceLoad object contains loads for one face of the geometry.

EdgeLoad — Loads on geometry edges

array of edgeLoad objects

Loads on geometry edges, specified as a 1-by-N array of edgeLoad objects. Here, N is the number of edges in a geometry. Each edgeLoad object contains loads for one edge of the geometry.

VertexLoad — Loads on geometry vertices

array of vertexLoad objects

Loads on geometry vertices, specified as a 1-by-N array of vertexLoad objects. Here, N is the number of vertices in a geometry. Each vertexLoad object contains loads for one vertex of the geometry.

Initial Conditions

CellIC — Initial conditions on geometry cells

array of cellIC objects

Initial conditions on geometry cells, specified as a 1-by-N array of cellIC objects. Here, N is the number of cells in a geometry. Each cellIC object contains initial conditions for one cell of the geometry.

FaceIC — Initial conditions on geometry faces

array of faceIC objects

Initial conditions on geometry faces, specified as a 1-by-N array of faceIC objects. Here, N is the number of faces in a geometry. Each faceIC object contains initial conditions for one face of the geometry.

EdgeIC — Initial conditions on geometry edges

array of edgeIC objects

Initial conditions on geometry edges, specified as a 1-by-N array of edgeIC objects. Here, N is the number of edges in a geometry. Each edgeIC object contains initial conditions for one edge of the geometry.

VertexIC — Initial conditions on geometry vertices

array of vertexIC objects

Initial conditions on geometry vertices, specified as a 1-by-N array of vertexIC objects. Here, N is the number of vertices in a geometry. Each vertexIC object contains initial conditions for one vertex of the geometry.

Other Parameters

DampingAlpha — Mass proportional damping

nonnegative number

Mass proportional damping, specified as a nonnegative number.

Data Types: double

DampingBeta — Stiffness proportional damping

nonnegative number

Stiffness proportional damping, specified as a nonnegative number.

Data Types: double

ReferenceTemperature — Reference temperature for thermal load

real number

Reference temperature for a thermal load, specified as a real number. The reference temperature corresponds to the state of zero thermal stress of the model. The value 0 implies that the thermal load is specified in terms of the temperature change and its derivatives.

To specify the reference temperature for a thermal load in your model, assign the property value directly, for example, model.ReferenceTemperature = 10. To specify the thermal load itself, use cellLoad.

Data Types: double

SolverOptions — Algorithm options for PDE solvers

PDESolverOptions object

Algorithm options for the PDE solvers, specified as a PDESolverOptions object. The properties of PDESolverOptions include absolute and relative tolerances for internal ODE solvers, maximum solver iterations, and so on. For a complete list of properties, see PDESolverOptions Properties.

Constants

VacuumPermittivity — Permittivity of vacuum for entire model

positive number

Permittivity of vacuum for the entire model, specified as a positive number. This value must be consistent with the units of the model. If the model parameters are in the SI system of units, then the permittivity of vacuum must be 8.8541878128e-12.

Data Types: double

VacuumPermeability — Permeability of vacuum for entire model

positive number

Permeability of vacuum for the entire model, specified as a positive number. This value must be consistent with the units of the model. If the model parameters are in the SI system of units, then the permeability of vacuum must be 1.2566370614e-6.

StefanBoltzmann — Constant of proportionality in Stefan-Boltzmann law governing radiation heat transfer

positive number

Constant of proportionality in Stefan-Boltzmann law governing radiation heat transfer, specified as a positive number. This value must be consistent with the units of the model. Values of the Stefan-Boltzmann constant in commonly used systems of units are:

• SI —5.670367e-8 W/(m²·K⁴)

• CGS— 5.6704e-5 erg/(cm²·s·K⁴)

• US customary — 1.714e-9 BTU/(hr·ft²·R⁴)

Data Types: double

Object Functions

generateMesh	Create triangular or tetrahedral mesh
pdegplot	Plot PDE geometry
pdemesh	Plot PDE mesh
solve	Solve structural analysis, heat transfer, or electromagnetic analysis problem

Examples

Finite Element Model for Thermal Transient Analysis

Create a model for solving a thermal transient problem.

model = femodel(AnalysisType="thermalTransient")

model = 
  1×1 femodel array

Properties for analysis type: thermalTransient

            AnalysisType: "thermalTransient"
                Geometry: [0×0 fegeometry]
              PlanarType: ""
      MaterialProperties: [0×0 materialProperties]

   Boundary Conditions
                  FaceBC: [0×0 faceBC]
                  EdgeBC: [0×0 edgeBC]
                VertexBC: [0×0 vertexBC]
        ThermalRadiation: []

   Loads
                CellLoad: [0×0 cellLoad]
                FaceLoad: [0×0 faceLoad]
                EdgeLoad: [0×0 edgeLoad]
              VertexLoad: [0×0 vertexLoad]

   Initial Conditions
                  CellIC: [0×0 cellIC]
                  FaceIC: [0×0 faceIC]
                  EdgeIC: [0×0 edgeIC]
                VertexIC: [0×0 vertexIC]

   Other Parameters
            DampingAlpha: 0
             DampingBeta: 0
    ReferenceTemperature: []
           SolverOptions: [1×1 pde.PDESolverOptions]

   Constants
         StefanBoltzmann: []

  Show all properties

Finite Element Model for Static Structural Analysis of Plane-Strain Problem

Create a model for solving a static plane-strain structural problem.

Create an femodel object for solving a static structural problem, and assign a 2-D geometry to the model.

model = femodel(AnalysisType="structuralStatic", ...
                Geometry="PlateHolePlanar.stl")

model = 
  1×1 femodel array

Properties for analysis type: structuralStatic

            AnalysisType: "structuralStatic"
                Geometry: [1×1 fegeometry]
              PlanarType: "planeStress"
      MaterialProperties: [0×1 materialProperties]

   Boundary Conditions
                  FaceBC: [0×1 faceBC]
                  EdgeBC: [0×5 edgeBC]
                VertexBC: [0×5 vertexBC]

   Loads
                FaceLoad: [0×1 faceLoad]
                EdgeLoad: [0×5 edgeLoad]
              VertexLoad: [0×5 vertexLoad]

   Other Parameters
    ReferenceTemperature: []
           SolverOptions: [1×1 pde.PDESolverOptions]

  Show all properties

By default, femodel assumes that a 2-D problem is a plane-stress problem. Specify the plane-strain problem type.

model.PlanarType = "planeStrain";
model.PlanarType

ans = 
"planeStrain"

Structural Analysis of Beam

Create a geometry of a beam.

gm = multicuboid(0.5,0.1,0.1);

Plot the geometry.

pdegplot(gm,FaceAlpha=0.5, ...
            FaceLabels="on", ...
            EdgeLabels="on")

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

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

model = 
  1×1 femodel array

Properties for analysis type: structuralStatic

            AnalysisType: "structuralStatic"
                Geometry: [1×1 fegeometry]
      MaterialProperties: [0×1 materialProperties]

   Boundary Conditions
                  FaceBC: [0×6 faceBC]
                  EdgeBC: [0×12 edgeBC]
                VertexBC: [0×8 vertexBC]

   Loads
                CellLoad: [0×1 cellLoad]
                FaceLoad: [0×6 faceLoad]
                EdgeLoad: [0×12 edgeLoad]
              VertexLoad: [0×8 vertexLoad]

   Other Parameters
    ReferenceTemperature: []
           SolverOptions: [1×1 pde.PDESolverOptions]

  Show all properties

Specify Young's modulus, Poisson's ratio, and the mass density.

model.MaterialProperties = materialProperties(YoungsModulus=210e3, ...
                                              PoissonsRatio=0.3, ...
                                              MassDensity=2.7e-6);
model.MaterialProperties

ans = 
  1×1 materialProperties array

Properties for analysis type: structuralStatic

Index    CTE    PoissonsRatio    YoungsModulus    MassDensity    ShearModulus
  1      []        0.3000           210000        2.7000e-06          []     

  Show all properties

Specify a gravity load on the beam.

model.CellLoad = cellLoad(Gravity=[0;0;-9.8]);
model.CellLoad

ans = 
  1×1 cellLoad array

Properties for analysis type: structuralStatic

Index       Gravity       AngularVelocity    Temperature
  1      [0 0 -9.8000]          []               []     

  Show all properties

Specify that face 5 is a fixed boundary.

model.FaceBC(5) = faceBC(Constraint="fixed");
model.FaceBC

ans = 
  1×6 faceBC array

Properties for analysis type: structuralStatic

Index    Constraint    XDisplacement    YDisplacement    ZDisplacement
  1          []             []               []               []      
  2          []             []               []               []      
  3          []             []               []               []      
  4          []             []               []               []      
  5        fixed            []               []               []      
  6          []             []               []               []      

  Show all properties

Generate a mesh and assign the result to the model. This assignment updates the mesh stored in the Geometry property of the model.

model = generateMesh(model);

Solve the model.

R = solve(model)

R = 
  StaticStructuralResults with properties:

      Displacement: [1×1 FEStruct]
            Strain: [1×1 FEStruct]
            Stress: [1×1 FEStruct]
    VonMisesStress: [8013×1 double]
              Mesh: [1×1 FEMesh]

Plot the von Mises stress.

pdeviz(R.Mesh,R.VonMisesStress)

ans = 
  PDEVisualization with properties:

        MeshData: [1×1 FEMesh]
       NodalData: [8013×1 double]
     MeshVisible: off
    Transparency: 1
        Position: [0.1300 0.1166 0.6590 0.8084]
           Units: 'normalized'

  Show all properties

Version History

Introduced in R2023a

R2024a: ROM support for structural and thermal analysis models

You can use the reduce function to reduce structural and thermal analysis models specified as femodel objects. If the AnalysisType property of an femodel is structuralTransient or structuralModal, then reduce returns a ReducedStructuralModel object. If the AnalysisType property is thermalTransient or thermalModal, then reduce returns a ReducedThermalModel object.

To support reduced-order modeling for structural analysis, the femodel object has a new ROMInterfaces property that stores romInterface objects defining superelement interfaces and multipoint constraints.

R2023b: Specify surface-to-surface radiation settings

To support modeling thermal radiation between surfaces without conductive media, the femodel object has a new ThermalRadiation property that stores surface-to-surface radiation settings.