Difference between revisions of "MPM Region and Hole Commands"
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== Region Commands == | == Region Commands == | ||
Once the [[MPM Grid Generation|background grid is created]], material points are added to the grid using a series of <tt>Region</tt> commands | Once the [[MPM Grid Generation|background grid is created]], material points are added to the grid using a series of <tt>Region</tt> commands. In scripted files, the <tt>Region</tt> command defines material type, initial velocity, thickness (in 2D), and optionally an [[Setting Material Orientation|initial angle]] (for some [[Material Models|anisotropic materials]]), temperature, and concentration. The command is | ||
Region (matid),(velx),(vely),(velz) or (thick),<(property),(value)>... | Region (matid),(velx),(vely),(velz) or (thick),<(property),(value)>... | ||
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EndRegion | EndRegion | ||
In <tt>XML</tt> files, | In <tt>XML</tt> files, <tt>Region</tt> command are replaced by <tt><Body></tt> commands and optionally one <tt>PointList</tt> block. All these element must be within the single <tt>MaterialPoints</tt> element in the input file: | ||
<MaterialPoints> | <MaterialPoints> | ||
<PointList> | <PointList> | ||
(see help on | (see help on PointList block) | ||
</PointList> | </PointList> | ||
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* <tt>(matid)</tt> is the material ID for a previously defined [[Material Command Block|material]]. | * <tt>(matid)</tt> is the material ID for a previously defined [[Material Command Block|material]]. | ||
* <tt>(velx)</tt>, <tt>(vely)</tt>, and <tt>(velz)</tt> are the components of the initial velocity | * <tt>(velx)</tt>, <tt>(vely)</tt>, and <tt>(velz)</tt> are the components of the initial velocity for all particles in the region (<tt>velz</tt> is only used for 3D simulations). The units or mm/sec. | ||
* <tt>(thick)</tt> is the thickness of each material point in mm. The thickness is only used for planar 2D calculations. In scripted files, the thickness parameter | * <tt>(thick)</tt> is the thickness of each material point in mm. The thickness is only used for planar 2D calculations. In scripted files for axisymmetric calculations, the thickness parameter is still required, but it is only used for parameter alignment (its value is ignored). | ||
Besides the above required parameters, you can provide optional parameters to set initial conditions for all particles in the region. In scripted files, the optional parameters appear in pairs. The first item in the pair (''i.e.'', <tt>(property)</tt>) is the name of the property to set and the second item (''i.e.'', <tt>(value)</tt>) is the initial value for that property. In <tt>XML</tt> files, the optional properties are set using optional attributes: | |||
* <tt>angle,(angle)</tt> to set the initial rotation angle for the material axes about the z axis. The units are degrees. This parameter is sufficient for 2D | * <tt>angle,(angle)</tt> to set the initial rotation angle for the material axes about the z axis. The units are degrees. This parameter is sufficient for 2D analyses with constant material angle. See help on [[Setting Material Orientation|setting material angles]] for methods to set variable angles or to set more than one rotation angle in 3D calculations. | ||
* <tt>temp,(temp)</tt> to set the initial particle temperature. The units are degrees. | * <tt>temp,(temp)</tt> to set the initial particle temperature. The units are degrees. | ||
* <tt>conc,(conc)</tt> to set the initial particle [[Diffusion Calculations#Diffusion Material Properties|concentration potential]]. The dimensionless concentration potential must be from 0 to 1. Only used when doing [[Diffusion Calculations|diffusion]] calculations. | * <tt>conc,(conc)</tt> to set the initial particle [[Diffusion Calculations#Diffusion Material Properties|concentration potential]]. The dimensionless concentration potential must be from 0 to 1. Only used when doing [[Diffusion Calculations|diffusion]] calculations. | ||
* <tt>(wtconc)</tt>to set concentration | * <tt>(wtconc)</tt>to set concentration by weight fraction concentration instead of by [[Diffusion Calculations#Diffusion Material Properties|concentration potential]]. The resulting potential will be <tt>(wtconc)</tt> divided by the material's [[Common Material Properties#Basic Properties|saturation concentration]]. This option is only available in <tt>XML</tt> input files. The units are dimensionless and must be from 0 to the material's [[Common Material Properties#Basic Properties|saturation concentration]]. Only used when doing [[Diffusion Calculations|diffusion]] calculations. | ||
Between the <tt>Region</tt> command and the subsequent <tt>EndRegion</tt> command (or within | Between the <tt>Region</tt> command and the subsequent <tt>EndRegion</tt> command (or within each <tt><Body></tt> element), there can be any number of shape commands to define material point positions. The details on these shape command are given elsewhere: | ||
* [[2D MPM Shape Commands]] | * [[2D MPM Shape Commands]] | ||
* [[3D MPM Shape Commands]] | * [[3D MPM Shape Commands]] | ||
The optional [[PointList Block]] can be used to define individual material points, each with individual initial conditions. The option is only available to <tt>XML</tt> input files. | |||
== Hole Commands == | == Hole Commands == | ||
Revision as of 14:41, 20 November 2013
In MPM, the most common way to discretize an object is to add material points to the background grid using Region commands and to designate regions of the grid has having no material points using Hole commands. Enclosed in these commands are various shape commands to define the object. An alternative and powerful option for discretizing an object is to create material points automatically from an image of the object.
Region Commands
Once the background grid is created, material points are added to the grid using a series of Region commands. In scripted files, the Region command defines material type, initial velocity, thickness (in 2D), and optionally an initial angle (for some anisotropic materials), temperature, and concentration. The command is
Region (matid),(velx),(vely),(velz) or (thick),<(property),(value)>... (any number of shape commands) EndRegion
In XML files, Region command are replaced by <Body> commands and optionally one PointList block. All these element must be within the single MaterialPoints element in the input file:
<MaterialPoints>
<PointList>
(see help on PointList block)
</PointList>
<Body mat='(matid)' vx='(velx)' vy='(vely)' vz='(velz)' thick='(thick)'
angle='(angle)' temp='(temp)' conc='(conc)' wtconc='(wtconc)'>
(any number of shape commands)
</Body>
....
</MaterialPoints>
where
- (matid) is the material ID for a previously defined material.
- (velx), (vely), and (velz) are the components of the initial velocity for all particles in the region (velz is only used for 3D simulations). The units or mm/sec.
- (thick) is the thickness of each material point in mm. The thickness is only used for planar 2D calculations. In scripted files for axisymmetric calculations, the thickness parameter is still required, but it is only used for parameter alignment (its value is ignored).
Besides the above required parameters, you can provide optional parameters to set initial conditions for all particles in the region. In scripted files, the optional parameters appear in pairs. The first item in the pair (i.e., (property)) is the name of the property to set and the second item (i.e., (value)) is the initial value for that property. In XML files, the optional properties are set using optional attributes:
- angle,(angle) to set the initial rotation angle for the material axes about the z axis. The units are degrees. This parameter is sufficient for 2D analyses with constant material angle. See help on setting material angles for methods to set variable angles or to set more than one rotation angle in 3D calculations.
- temp,(temp) to set the initial particle temperature. The units are degrees.
- conc,(conc) to set the initial particle concentration potential. The dimensionless concentration potential must be from 0 to 1. Only used when doing diffusion calculations.
- (wtconc)to set concentration by weight fraction concentration instead of by concentration potential. The resulting potential will be (wtconc) divided by the material's saturation concentration. This option is only available in XML input files. The units are dimensionless and must be from 0 to the material's saturation concentration. Only used when doing diffusion calculations.
Between the Region command and the subsequent EndRegion command (or within each <Body> element), there can be any number of shape commands to define material point positions. The details on these shape command are given elsewhere:
The optional PointList Block can be used to define individual material points, each with individual initial conditions. The option is only available to XML input files.
Hole Commands
The Hole command is used to designate regions of the grid that should not have any material points. In scripted files, the Hole command is:
Hole (any number of shape commands) EndHole
In XML files, the <Hole> 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 shape commands to define hole locations. The details on these shape command are given elsewhere:
An object with holes is create by a sequence of Region and Hole commands. Each Region command fills every location within its shapes with a material point unless that location was previous designated as a hole. Each Hole command designates every location within its shapes as not having a material point, but, if the a location already has a material point, that point is left intact. In other words, the order of these commands is crucial. By selecting the correctly order, you have greatly flexibility in creating objects with solid regions and void (or hole) regions.