FEA Region and Hole Commands
When using shapes to define an FEA mesh, use Region command to define material properties for elements and use Hole commands to remove elements from the mesh.
Region Commands
Once the mesh is ready to use shapes, elements within shapes are assigned to materials by using a series of Region commands (or <Body> commands in XML files). In scripted files, the Region command defines material type, thickness, and angle (needed for some anisotropic materials):
Region (matid),(thick),<(angle)> (any number of shape commands) EndRegion
In XML files, the <Body> block is:
<Body mat='(matid)' angle='(angle)' thick='(thick)'> (any number of shape commands) </Body>
where
- (matid) is the material ID for a previously defined material.
- (thick) is the thickness of the region in mm.
- (angle) is an optional angle for the material which is only relevant for anisotropic materials. It can be entered as a number or as a user-defined function of the coordinates for the element centroid. The units are degrees.
Between the Region command and the subsequent EndRegion command (or within the <Body> block), there can be any number of Rect, Oval, and PolyPt commands to define the geometry whose elements will use the region's material properties.
Hole Commands
Once the mesh is ready to use shapes, elements within shapes can be removed with a series of Hole commands (or <Hole> commands in XML files). In scripted files, the Hole command is:
Hole (any number of shape commands) EndHole
In XML files, the <Body> block is:
<Hole> (any number of shape commands) </Hole>
Between the Hole command and the subsequent EndHole command (or within the <Hole> block), there can be any number of Rect, Oval, and PolyPtcommands to define the geometry whose elements should be removed.
Rect Command
A scripted Rect command defines a region to be assign element materials or to be defined as a hole:
Rect (xmin),(xmax),(ymin),(ymax)
In XML files, the command is:
<Rect xmin='(xmin)' xmax='(xmax)' ymin='(ymin)' ymax='(ymax)'/>
where
- (xmin),(xmax),(ymin), and (ymax) are the x and y extents of the rectangle (or R and Z extents if axisymmetric). If xmax<xmin or ymax<ymin, the will be automatically switched to define the rectangle. The units are mm (or determined by a units attribute in XML files).
If the defined rectangle overlaps areas that already has assigned elements, or has been defined as a hole, those areas will be ignored.
Oval Command
A scripted Oval command defines a region to be assign element materials or to be defined as a hole:
Oval (xmin),(xmax),(ymin),(ymax)
In XML files, the command is:
<Oval xmin='(xmin)' xmax='(xmax)' ymin='(ymin)' ymax='(ymax)'/>
where
- (xmin),(xmax),(ymin), and (ymax) are the x and y extents of the rectangle (or R and Z extents if axisymmetric) that encloses the oval. If xmax<xmin or ymax<ymin, the will be automatically switched to define the oval. The units are mm (or determined by a units attribute in XML files).
If the defined oval overlaps areas that already has assigned elements, or has been defined as a hole, those areas will be ignored.
PolyPt Command
A series of PolyPt commands is used to define a polygonal region to assign element materials, or to be defined as a hole:
PolyPt (x1),(y1) PolyPt (x2),(y2) ... PolyPt (xn),(yn) PolyPt
where
- (xi),(yi) (for i = 1 to n) are the x and y, coordinates of the each point in the polygon (or R and Z if axisymmetric). If the arguments are omitted, the polygon is completed by connecting ((xn),(yn)) to ((x1),(y1)). The units are mm.
The blank PolyPt command is only needed if you need to define a second polygon in the same region. The blank command will finish the first one and the second one will start with the next PolyPt command. Intervening Rect and Oval commands or the end of a block will also stop the current polygon; in these cases the blank PolyPt is not needed.
If the defined polygon overlaps area that already has defined elements, or has been defined as a hole, those areas will be ignored.