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structuralBoundaryLoad

(To be removed) Specify boundary loads for structural model

structuralBoundaryLoad will be removed. Use faceLoad, edgeLoad, and vertexLoad instead. (since R2023a) For more information on updating your code, see Version History.

Description

structuralBoundaryLoad(structuralmodel,RegionType,RegionID,"SurfaceTraction",STval,"Pressure",Pval,"TranslationalStiffness",TSval) specifies the surface traction, pressure, and translational stiffness on the boundary of type RegionType with RegionID ID numbers.

  • Surface traction is determined as distributed normal and tangential forces acting on a boundary, resolved along the global Cartesian coordinate system.

  • Pressure must be specified in the direction that is normal to the boundary. A positive pressure value acts into the boundary (for example, compression). A negative pressure value acts away from the boundary (for example, suction).

  • Translational stiffness is a distributed spring stiffness for each translational direction. Translational stiffness is used to model an elastic foundation.

structuralBoundaryLoad does not require you to specify all three boundary loads. Depending on your structural analysis problem, you can specify one or more boundary loads by picking the corresponding arguments and omitting others. You can specify translational stiffness for any structural model. To specify pressure or surface traction, structuralmodel must be a static, transient, or frequency response model. Structural models for modal analysis cannot have pressure or surface traction.

The default boundary load is a stress-free boundary condition.

example

structuralBoundaryLoad(structuralmodel,"Vertex",VertexID,"Force",Fval) specifies concentrated force at a vertex with the VertexID number. You can specify force only if structuralmodel is a static, transient, or frequency response model. Structural models for modal analysis cannot have concentrated force.

structuralBoundaryLoad(___,"Vectorized","on") uses vectorized function evaluation when you pass a function handle as an argument. If your function handle computes in a vectorized fashion, then using this argument saves time. See Vectorization. For details on this evaluation, see Nonconstant Boundary Conditions.

Use this syntax with any of the input arguments from previous syntaxes.

structuralBoundaryLoad(___,"Pressure",Pval,Name,Value) lets you specify the form and duration of a nonconstant pressure pulse and harmonic excitation for a transient structural model without creating a function handle. When using this syntax, you must specify the model, region type and region ID, and pressure. Surface traction and translational stiffness are optional arguments. This syntax does not work for static, modal analysis, and frequency response models.

structuralBoundaryLoad(structuralmodel,"Vertex",VertexID,"Force",Fval,Name,Value) lets you specify the form and duration of a nonconstant concentrated force and harmonic excitation for a transient structural model without creating a function handle.

structuralBoundaryLoad(___,"Label",labeltext) adds a label for the structural boundary load to be used by the linearizeInput function. This function lets you pass boundary loads to the linearize function that extracts sparse linear models for use with Control System Toolbox™.

boundaryLoad = structuralBoundaryLoad(___) returns the boundary load object.

Examples

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Apply fixed boundaries and traction on two ends of a bimetallic cable.

Create a structural model.

structuralModel = createpde("structural","static-solid");

Create nested cylinders to model a bimetallic cable.

gm = multicylinder([0.01,0.015],0.05);

Assign the geometry to the structural model and plot the geometry.

structuralModel.Geometry = gm;
pdegplot(structuralModel,"CellLabels","on", ...
                         "FaceLabels","on", ...
                         "FaceAlpha",0.4)

Figure contains an axes object. The axes object contains 6 objects of type quiver, text, patch, line.

For each metal, specify Young's modulus and Poisson's ratio.

structuralProperties(structuralModel,"Cell",1,"YoungsModulus",110E9, ...
                                              "PoissonsRatio",0.28);
structuralProperties(structuralModel,"Cell",2,"YoungsModulus",210E9, ...
                                              "PoissonsRatio",0.3);

Specify that faces 1 and 4 are fixed boundaries.

structuralBC(structuralModel,"Face",[1,4],"Constraint","fixed")
ans = 
  StructuralBC with properties:

                RegionType: 'Face'
                  RegionID: [1 4]
                Vectorized: 'off'

   Boundary Constraints and Enforced Displacements
              Displacement: []
             XDisplacement: []
             YDisplacement: []
             ZDisplacement: []
                Constraint: "fixed"
                    Radius: []
                 Reference: []
                     Label: []

   Boundary Loads
                     Force: []
           SurfaceTraction: []
                  Pressure: []
    TranslationalStiffness: []
                     Label: []

Specify the surface traction for faces 2 and 5.

structuralBoundaryLoad(structuralModel, ...
                          "Face",[2,5], ...
                          "SurfaceTraction",[0;0;100])
ans = 
  StructuralBC with properties:

                RegionType: 'Face'
                  RegionID: [2 5]
                Vectorized: 'off'

   Boundary Constraints and Enforced Displacements
              Displacement: []
             XDisplacement: []
             YDisplacement: []
             ZDisplacement: []
                Constraint: []
                    Radius: []
                 Reference: []
                     Label: []

   Boundary Loads
                     Force: []
           SurfaceTraction: [3×1 double]
                  Pressure: []
    TranslationalStiffness: []
                     Label: []

Input Arguments

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Structural model, specified as a StructuralModel object. The model contains the geometry, mesh, structural properties of the material, body loads, boundary loads, and boundary conditions.

Example: structuralmodel = createpde("structural","transient-solid")

Geometric region type, specified as "Edge" for a 2-D model or "Face" for a 3-D model.

Example: structuralBoundaryLoad(structuralmodel,"Face",[2,5],"SurfaceTraction",[0,0,100])

Data Types: char | string

Geometric region ID, specified as a positive integer or vector of positive integers. Find the region IDs by using pdegplot.

Example: structuralBoundaryLoad(structuralmodel,"Face",[2,5],"SurfaceTraction",[0,0,100])

Data Types: double

Vertex ID, specified as a positive integer or vector of positive integers. Find the vertex IDs using pdegplot.

Example: structuralBoundaryLoad(structuralmodel,"Vertex",6,"Force",[0;10^4;0])

Data Types: double

Distributed normal and tangential forces on the boundary, resolved along the global Cartesian coordinate system, specified as a numeric vector or function handle. A 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. In case of a transient or frequency response analysis, STval also can be a function of time or frequency, respectively. For details, see More About.

Example: structuralBoundaryLoad(structuralmodel,"Face",[2,5],"SurfaceTraction",[0;0;100])

Data Types: double | function_handle

Pressure normal to the boundary, specified as a 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 Pval 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. In case of a transient structural model, Pval also can be a function of time. In case of a frequency response structural model, Pval 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 More About.

Example: structuralBoundaryLoad(structuralmodel,"Face",[2,5],"Pressure",10^5)

Data Types: double | function_handle

Distributed spring stiffness for each translational direction used to model elastic foundation, specified as a numeric vector or function handle. A 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. In case of a transient or frequency response analysis, TSval also can be a function of time or frequency, respectively. For details, see More About.

Example: structuralBoundaryLoad(structuralmodel,"Edge",[2,5],"TranslationalStiffness",[0;5500])

Data Types: double | function_handle

Concentrated force at a vertex, specified as a numeric vector or function handle. Use a function handle to specify concentrated force that depends time or frequency. For details, see More About.

Example: structuralBoundaryLoad(structuralmodel,"Vertex",5,"Force",[0;0;10])

Data Types: double | function_handle

Label for the structural boundary load, specified as a character vector or a string.

Data Types: char | string

Name-Value Arguments

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Example: structuralBoundaryLoad(structuralmodel,"Face",[2,5],"Pressure",10^5,"RiseTime",0.5,"FallTime",0.5,"EndTime",3)

Use one or more of the name-value pair arguments to specify the form and duration of the pressure or concentrated force pulse and harmonic excitation for a transient structural model only. Specify the pressure or force value using the Pval or Fval argument, respectively.

You can model rectangular, triangular, and trapezoidal pressure or concentrated force pulses. If the start time is 0, you can omit specifying it.

  • For a rectangular pulse, specify the start and end times.

  • For a triangular pulse, specify the start time and any two of the following times: rise time, fall time, and end time. You also can specify all three times, but they must be consistent.

  • For a trapezoidal pulse, specify all four times.

Trapezoidal pulse showing the start, rise, fall, and end times

You can model a harmonic pressure or concentrated force load by specifying its frequency and initial phase. If the initial phase is 0, you can omit specifying it.

Harmonic load showing the frequency and the initial phase

Rectangular, Triangular, or Trapezoidal Pulse

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Start time for pressure or concentrated force load, specified as a nonnegative number. Specify this argument only for transient structural models.

Example: structuralBoundaryLoad(structuralmodel,"Face",[2,5],"Pressure",10^5,"StartTime",1,"EndTime",3)

Data Types: double

End time for pressure or concentrated force load, specified as a nonnegative number equal or greater than the start time value. Specify this argument only for transient structural models.

Example: structuralBoundaryLoad(structuralmodel,"Face",[2,5],"Pressure",10^5,"StartTime",1,"EndTime",3)

Data Types: double

Rise time for pressure or concentrated force load, specified as a nonnegative number. Specify this argument only for transient structural models.

Example: structuralBoundaryLoad(structuralmodel,"Face",[2,5],"Pressure",10^5,"RiseTime",0.5,"FallTime",0.5,"EndTime",3)

Data Types: double

Fall time for pressure or concentrated force load, specified as a nonnegative number. Specify this argument only for transient structural models.

Example: structuralBoundaryLoad(structuralmodel,"Face",[2,5],"Pressure",10^5,"RiseTime",0.5,"FallTime",0.5,"EndTime",3)

Data Types: double

Harmonic Pressure or Force

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Frequency of sinusoidal pressure or concentrated force, specified as a positive number, in radians per unit of time. Specify this argument only for transient structural models.

Example: structuralBoundaryLoad(structuralmodel,"Face",[2,5],"Pressure",10^5,"Frequency",25)

Data Types: double

Phase of sinusoidal pressure or concentrated force, specified as a nonnegative number, in radians. Specify this argument only for transient structural models.

Example: structuralBoundaryLoad(structuralmodel,"Face",[2,5],"Pressure",10^5,"Frequency",25,"Phase",pi/6)

Data Types: double

Output Arguments

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Handle to boundary load, returned as a StructuralBC object. See StructuralBC Properties.

More About

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Version History

Introduced in R2017b

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