Main Help → All Commands → FEA Mesh / MPM Grid and Material Points → Region
This command can add material points to an MPM calculation or assign material types to elements in an FEA calculation.
Material points are added to an MPM analysis by using a series of Region
commands and BMPRegion
commands. The Region
command defines material type, initial velocities, thickness, and angle (needed for some Material types). Between the Region
command and the subsequent EndRegion
command, there can be any number of geometric commands that define the geometry to be filled with material points. For 2D MPM, the structure is:
Region (id),(velx),(vely),(thick),<(prop),(value)>... (one optional Transform command) (optional Rotate commands) (optional AngularMom0 command) (any number of 2D shape commands) EndRegion
For 3D MPM, the structure is:
Region (id),(velx),(vely),(velz),<(prop),(value)> (one optional Transform command) (optional Rotate commands) (optional AngularMom0 command) (any number of 3D shape commands) EndRegion
where
(id)
is the material ID for a previously defined material.(velx)
, (vely)
, and (velz)
are the initial velocities for all material points to be in the region in the x
, y
, and z
directions (z
for 3D only), respectively. They can be numerical values or user-defined functions of position position. The units are velocity units.(thick)
is the thickness of the region for 2D analyses in length units(prop),(value)
are optional pairs of arguments to specify other initial conditions for the particles in the region, where (prop)
is property name and (value)
is its value. The property options are:
"angle"
for angle for the material which is only relevant for anisotropic materials. The units are degrees."temp"
for particle temperature. The units are degrees."conc"
for particle concentration."pp"
for particle pore pressure in pressure units."res"
is to optionally set the number of material points along each axis in each element of the background grid for this region to differ from the default setting.When using anisotropic materials, Rotate commands within a Region
block can apply transformations to the material axes to define initial orientation of selected material points in the body.
If you set the "res" in a region that differs from the default setting, the code will no longer check to make sure particles are not overlapping. The user is therefore responsible for defining non-overlapping regions. Note also that this setting can use any valid number per element side and is not limited to the values allowed when choosing the default setting.
If you want void spaces within a region with no material points, you can use Hole Commands before the Region command or can use nested shapes with the Cut command.
One way to create a complicated FEA mesh, especially for composite materials with complex structures of subelements, is to define them with shape commands rather the Area commands. Once the mesh is ready, the Region
command defines material type, thickness, and angle (needed for some Material types). Between the Region
command and the subsequent EndRegion
command, there can be any number of geometric shape command that define the geometry whose elements will use that material. The structure for 2D FEA is:
Region (id),(thick),<(angle)> (any number of 2D shape commands) EndRegion
where
(id)
is the material ID for a previously defined material.(thick)
is the thickness of the region in length units.(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.If you want void spaces within a region to remove elements, you can use Hole Commands before the Region command or can use nested shapes with the Cut command.