# Patch Command

The patch command is used to generate a number of fibers over a cross-sectional area. Currently there are three types of cross-section that fibers can be generated: quadrilateral, rectangular and circular.

The following is the command to generate a quadrilateral shaped patch (the geometry of the patch is defined by four vertices: I J K L. The coordinates of each of the four vertices is specified in COUNTER CLOCKWISE sequence):

```tcl patch quad $matTag $numSubdivIJ $numSubdivJK $yI $zI $yJ $zJ $yK $zK $yL $zL ```

matTag

tag of previously defined material (UniaxialMaterial tag for a FiberSection or NDMaterial tag for use in an NDFiberSection)

numSubdivIJ

number of subdivisions (fibers) in the IJ direction.

numSubdivJK

number of subdivisions (fibers) in the JK direction.

yI zI

y & z-coordinates of vertex I (local coordinate system)

yJ zJ

y & z-coordinates of vertex J (local coordinate system)

yK zK

y & z-coordinates of vertex K (local coordinate system)

yL zL

y & z-coordinates of vertex L (local coordinate system)

QuadPatch.gif

The following is the command to generate a rectangular patch. The geometry of the patch is defined by coordinates of vertices: I and J. The first vertex, I, is the bottom-left point and the second vertex, J, is the top-right point, having as a reference the local y-z plane (look at the sketch bellow).

```tcl patch rect $matTag $numSubdivY $numSubdivZ $yI $zI $yJ $zJ ```

matTag

tag of previously defined material (UniaxialMaterial tag for a FiberSection or NDMaterial tag for use in an NDFiberSection)

numSubdivY

number of subdivisions (fibers) in the local y direction.

numSubdivZ

number of subdivisions (fibers) in the local z direction.

yI zI

y & z-coordinates of vertex I (local coordinate system)

yJ zJ

y & z-coordinates of vertex J (local coordinate system)

PatchRect.GIF

The following is the command to generate a circular shaped patch:

```tcl patch circ $matTag $numSubdivCirc $numSubdivRad $yCenter $zCenter $intRad $extRad $startAng $endAng ```

matTag

tag of previously defined material (UniaxialMaterial tag for a FiberSection or NDMaterial tag for use in an NDFiberSection)

numSubdivCirc

number of subdivisions (fibers) in the circumferential direction (number of wedges)

numSubdivRad

number of subdivisions (fibers) in the radial direction (number of rings)

yCenter zCenter

y & z-coordinates of the center of the circle

intRad

internal radius

extRad

external radius

startAng

starting angle

endAng

ending angle

CircPatch.gif

NOTES:


## Examples

patch circ $coreMatTag 8 8 0.0 0.0 0.0 $h; # define solid circular section with 64 fibers with radius $h using $coreMatTag material

patch quad $coreMatTag 8 8 -$b -$h $b -$h $b $h -$b $h; # define core patch with 8 subdivisions within a rectangle of width 2b and depth 2h


Code Developed by: Remo M. De Souza