extrude

Vertically extrude 2-D geometry or specified faces of 3-D geometry

Syntax

h = extrude(g,height)

h = extrude(g,FaceID,height)

Description

h = extrude(g,height) creates a 3-D discrete geometry by extruding a 2-D geometry along the z-axis by the value of height. You can create a stacked multilayered 3-D discrete geometry by specifying height as a vector of thicknesses of the layers.

h = extrude(g,FaceID,height) extrudes specified faces of a 3-D geometry along the direction normal to the faces. Here, FaceID specifies which faces to extrude. You can extrude faces into multiple layers by specifying height as a vector of thicknesses of the layers.

All of the specified faces must be flat and have the same orientation. The extruded volumes must not intersect with each other or with the existing geometry.

Examples

Single Layer Extrusion

Create a 3-D geometry by extruding a 2-D geometry along the z-axis.

Create a PDE model.

model = createpde;

Import a 2-D geometry.

g = importGeometry(model,"PlateHolePlanar.stl");

Plot the geometry and display the face labels.

pdegplot(g,"FaceLabels","on")

Create a 3-D geometry by extruding the 2-D geometry along the z-axis by 5 units.

extrude(g,5)

ans = 
  DiscreteGeometry with properties:

       NumCells: 1
       NumFaces: 7
       NumEdges: 15
    NumVertices: 10
       Vertices: [10×3 double]

Plot the new geometry and display the face labels.

pdegplot(g,"FaceLabels","on","FaceAlpha",0.5)

Multiple Layer Extrusion

Create a stacked multilayered 3-D geometry by extruding a 2-D geometry along the z-axis.

Create a PDE model.

model = createpde;

Import a geometry.

g = importGeometry(model,"PlateHolePlanar.stl")

g = 
  DiscreteGeometry with properties:

       NumCells: 0
       NumFaces: 1
       NumEdges: 5
    NumVertices: 5
       Vertices: [5×3 double]

Plot the geometry and display the face labels.

pdegplot(g,"FaceLabels","on")

Create a 3-D geometry consisting of three blocks with holes stacked on top of each other. The heights of the blocks are 5, 10, and 20 units.

extrude(g,[5,10,20])

ans = 
  DiscreteGeometry with properties:

       NumCells: 3
       NumFaces: 19
       NumEdges: 35
    NumVertices: 20
       Vertices: [20×3 double]

Plot the new geometry and display the cell labels.

pdegplot(g,"CellLabels","on","FaceAlpha",0.5)

Geometry with an Added Vertex

Extrude a 2-D geometry that has a vertex added by the addVertex function. The layers of the extruded geometry all have a corresponding vertex, but there are no edges between these vertices.

Create a PDE model.

model = createpde;

Import a geometry.

g = importGeometry(model,"PlateHolePlanar.stl");

Plot the geometry and display the vertex labels.

pdegplot(g,"VertexLabels","on")

Add a new vertex on the right edge.

addVertex(g,"Coordinates",[10 12]);

Plot the new geometry and display the vertex labels.

pdegplot(g,"FaceLabels","on","VertexLabels","on")

Create a 3-D geometry consisting of three blocks with holes stacked on top of each other. The heights of the blocks are 5, 10, and 20 units.

extrude(g,[5,10,20])

ans = 
  DiscreteGeometry with properties:

       NumCells: 3
       NumFaces: 19
       NumEdges: 35
    NumVertices: 24
       Vertices: [24×3 double]

Plot the new geometry and display the vertex labels. The extrude function replicates the added vertex V6 into three new vertices: V12, V18, and V24. It does not create edges between these vertices.

pdegplot(g,"VertexLabels","on","FaceAlpha",0.5)

Geometry with an Added Face

Extrude a 2-D geometry that has a face added by the addFace function.

Create a PDE model.

model = createpde;

Import a geometry.

g = importGeometry(model,"PlateHolePlanar.stl");

Plot the geometry and display the face and edge labels.

pdegplot(g,"FaceLabels","on","EdgeLabels","on")

Fill the hole in the center by adding a face.

addFace(g,5)

ans = 
  DiscreteGeometry with properties:

       NumCells: 0
       NumFaces: 2
       NumEdges: 5
    NumVertices: 5
       Vertices: [5×3 double]

Plot the modified geometry.

pdegplot(g,"FaceLabels","on")

Create a 3-D geometry by extruding the 2-D geometry along the z-axis by 2 units.

extrude(g,2)

ans = 
  DiscreteGeometry with properties:

       NumCells: 2
       NumFaces: 9
       NumEdges: 15
    NumVertices: 10
       Vertices: [10×3 double]

Plot the new geometry and display the cell labels.

pdegplot(g,"CellLabels","on","FaceAlpha",0.5)

Faces of 3-D Geometry

Extrude specified faces of a 3-D geometry.

Import the geometry and plot it with the face and edge labels.

g = importGeometry("PlateHolePlanar.stl");
pdegplot(g,"FaceLabels","on","EdgeLabels","on")

Fill the hole in the center by adding a face. Plot the modified geometry.

addFace(g,5);
pdegplot(g,"FaceLabels","on")

Create a 3-D geometry by extruding the 2-D geometry along the z-axis by 2 units.

extrude(g,2);

Plot the new geometry with the cell and face labels.

pdegplot(g,"CellLabels","on","Facelabels","on","FaceAlpha",0.5)

Now, extrude the center face of the geometry by 5 units.

extrude(g,4,5);

Plot the resulting geometry with the cell labels.

pdegplot(g,"CellLabels","on","FaceAlpha",0.5)

Now, call extrude again, and this time specify a vector of heights. The function extrudes all specified faces by each of the specified heights, which creates multiple layers.

extrude(g,[1 2],[3 4]);
pdegplot(g,"CellLabels","on","FaceAlpha",0.5)

Input Arguments

g — Geometry

fegeometry object | DiscreteGeometry object | AnalyticGeometry object

Geometry, specified as an fegeometry object, a DiscreteGeometry object, or an AnalyticGeometry object.

height — Cell heights

positive real number | vector of positive real numbers

Cell heights, specified as a positive real number or a vector of positive real numbers.

If height is a vector and g is a 2-D geometry, then height(i) specifies the height of the ith layer of a multilayered (stacked) 3-D geometry. Each layer constitutes a new cell.

If g is a 3-D geometry, the function extrudes all specified faces into several layers, with height(i) specifying the height of the ith layer.

Example: extrude(g,5.5)

FaceID — Faces to extrude in 3-D geometry

positive real number | vector of positive real numbers

Faces to extrude in 3-D geometry, specified as a positive real number or a vector of positive real numbers. If height is a vector, then the function extrudes all specified faces into several layers, same as it does for 2-D geometries.

Output Arguments

h — Resulting geometry

fegeometry object | handle

Resulting geometry, returned as an fegeometry object or a handle.

• If the original geometry g is an fegeometry object, then h is a new fegeometry object representing the modified geometry. The original geometry g remains unchanged.

• If the original geometry g is a DiscreteGeometry object, then h is a handle to the modified DiscreteGeometry object g.

• If g is an AnalyticGeometry object, then h is a handle to a new DiscreteGeometry object. The original geometry g remains unchanged.

Tips

• After modifying a geometry, regenerate the mesh to ensure a proper mesh association with the new geometry.

• If a 2-D geometry has new vertices added by using the addVertex function, extrude replicates the new vertices on each new layer of the extruded 3-D geometry, but it does not connect these vertices by edges.

• If g is an fegeometry or AnalyticGeometry object, and you want to replace it with the modified geometry, assign the output to the original geometry, for example, g = extrude(g,20).

Version History

Introduced in R2020b

R2023a: Finite element model

extrude now accepts geometries specified by fegeometry objects.

R2021a: Extrude specified faces of a 3-D geometry

In addition to extruding 2-D geometries into 3-D geometries, the function now lets you extrude specified faces of a 3-D geometry. The function extrudes specified faces along the direction normal to the faces.