# 4.16.2.2. Patch Command¶

patch(type, *args)

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.

patch('quad', matTag, numSubdivIJ, numSubdivJK, *crdsI, *crdsJ, *crdsK, *crdsL)

This 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)

 matTag (int) material tag associated with this fiber (UniaxialMaterial tag for a FiberSection and NDMaterial tag for use in an NDFiberSection). numSubdivIJ (int) number of subdivisions (fibers) in the IJ direction. numSubdivJK (int) number of subdivisions (fibers) in the JK direction. crdsI (list (float)) y & z-coordinates of vertex I (local coordinate system) crdsJ (list (float)) y & z-coordinates of vertex J (local coordinate system) crdsK (list (float)) y & z-coordinates of vertex K (local coordinate system) crdsL (list (float)) y & z-coordinates of vertex L (local coordinate system)
patch('rect', matTag, numSubdivY, numSubdivZ, *crdsI, *crdsJ)

This 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.

 matTag (int) material tag associated with this fiber (UniaxialMaterial tag for a FiberSection and NDMaterial tag for use in an NDFiberSection). numSubdivY (int) number of subdivisions (fibers) in local y direction. numSubdivZ (int) number of subdivisions (fibers) in local z direction. crdsI (list (float)) y & z-coordinates of vertex I (local coordinate system) crdsJ (list (float)) y & z-coordinates of vertex J (local coordinate system)
patch('circ', matTag, numSubdivCirc, numSubdivRad, *center, *rad, *ang)

This is the command to generate a circular shaped patch

 matTag (int) material tag associated with this fiber (UniaxialMaterial tag for a FiberSection and NDMaterial tag for use in an NDFiberSection). numSubdivCirc (int) number of subdivisions (fibers) in the circumferential direction (number of wedges) numSubdivRad (int) number of subdivisions (fibers) in the radial direction (number of rings) center (list (float)) y & z-coordinates of the center of the circle rad (list (float)) internal & external radius ang (list (float)) starting & ending-coordinates angles (degrees)