Main Help → All Commands → FEA Mesh / MPM Grid and Material Points → BMPRegion
Material points are normally added to an MPM analysis by using a series of Region
commands. For FEA analyses, the object is usually defined by a series of Area
commands. Both MPM and FEA can define parts of the object using digitized image(s) of the object by using BMPRegion
commands.
A BMPRegion
command reads a gray-scale BMP file and assigns material points or FEA element properties according to intensities in the file. Between the BMPRegion
command and the subsequent EndRegion
command, are a series of commands to define the file data and to map intensities to different material types. An optional second file can be a mask BMP file with intensities that determine the material angle for anisotropic materials. A subordinate command Intensity
will map those intensities to different angles.
The structure is:
BMPRegion (bmppath),(width),<(height)>,<(scheme)>,<(anglepath)>,<(prop),(value)>... (oneOrigin
command to map image origin to the grid) (Intensity
commands to to map materials and angles to gray levels) (optionalRotate
commands for anisotropic material angles) EndRegion
where
(bmppath)
is the full or relative path name to the BMP file. Most BMP styles are allowed and the data are converted to 256 levels of gray (or intensity for RGB files).(width)
and (height)
are the width and height of the image. These can be specified as follows:
(height)
only, enter (width)
more negative than -1e8).(scheme)
specfies a rotation scheme if BMP files are provided to determine those angles. The scheme must by "Z" for 2D simulations (all rotations are about the z axis) or can be any 1 axis, 2 axes, or 3 axes scheme beginning in Z (e.g., "ZYZ"). The (scheme)
must be followed by one (anglesPath)
for each axis in the scheme. Because 2D simulations must always be "Z", the (scheme)
can be omitted and replaced with the one (anglesPath)
.
(anglepath)
,... are 1 to 3 (one for each axis defined in (scheme)
) optional full or relative path names to BMP files whose intensities determine a material angle for rotation about the corresponding axis in (scheme)
(or z axis if (scheme)
is omitted). The angles can set Euler angles to orient the material axes at the start of simulations with anisotropic materials. The files must be an uncompressed, gray-scale, BMP files with 8 or less bits per pixel. The file must be exactly the same size (horizontal and vertical pixels) as the image file in (bmppath)
. The gray scale values are mapped to angles by using Intensity commands. The relation of axes to Euler angles determine the initial rotation matrix for each particle.(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 (note: to enter property pairs without prior optional parameters, enter a value for (height), set (scheme)="", and skip (anglesPath)). The current option is:
"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.If you set the "res" in a BMPReion that differs from the default setting, the code will no longer check to make sure particles are not overlapping. The user is therefore responsible using images with non-overlapping material points. 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.
BMPRegion
groups on the same block of space. The subsequent images will only fill space that was not filled by prior images.BMPRegion
block can apply transformations to the material axes to define initial orientation of selected material points in the body. Rotations set using this command will override angles set in Intensity commands, but will be overridden by angles set with a mask BMP file used to map material angles. Furthermore, Rotate commands can only be used in BMPRegion
blocks when doing MPM analyses.