Setting Material Orientation

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The Rotate command rotates material axes to define the initial orientation when using anisotropic materials:

Introduction

The Region command (or <Body> command in XML) and the BMPRegion command let you specify a single rotation angle for material rotation about the z axis. This options has two limitations. First, the angle has to be constant or the same for all material points. Second, it is only rotation about the z axis and therefore insufficient for specifying arbitrary orientation in 3D simulations. The Rotate command solves both this issues because it can set variable angles (with a user-defined function) and can set rotation about x and y axes as well.

Rotate Command

In script files, the rotate command, which must be within a Region command or a BMPRegion command is: 

Rotate (axis),(angle),<(axis2),(angle2)>,<(axis3),(angle3)>

In XML files, the rotate command is several commands, all of which must be within a <Body> command or a <BMPRegion> command: 

<RotateX>(angle)</RotateX>
<RotateY>(angle)</RotateY>
<RotateZ>(angle)</RotateZ>
<Unrotate/>

where

  • (axis) is the rotation axis which must be x, y, or z (or 1, 2, or 3). For 2D and axisymmetric analyses, only z (or 3) is allowed (and it means rotation about θ axis if axisymmetric). (axis) can alternatively be reset to remove all transformations. You can then apply new transformations. This option makes it possible to have different transformations apply to different shapes within the same Region command.
  • (angle) is a rotation angle or a user-defined function of material point coordinates (x, y, and z) that evaluates to a position-dependent angle. The angle or the result of a [User Defined Functions|function]] must be in degrees.

In scripted files, the optional <(axis2),(angle2)> and <(axis3),(angle3)> pairs let you specify upto three rotations in a single rotation command. IN XML files, multiple rotations are created by combining the various rotate commands. Also in XML files, the reset option for (axis) is done instead by using the <Unrotate/> command.

MPM Notes

  1. Rotate commands can only used with <a href="region.html">Region</a> blocks or within <a href="bmpregion.html">BMPRegion</a> blocks (in MPM only). The reset, however, can only be used in <a href="region.html">Region</a> blocks.
  2. You apply rotations in order by using one to three commands. There are two physical pictures:
    • You can imagine sitting on the material coordinate system with the material in its final position and then and defining a series of clockwise rotations about the material axes that transform the x-y-z analysis axes into the material axes. In right-handed, 3D coordinates, if your right hand fingers wrap in the rotation direction, your thumb will point in the positive direction for the rotation axis when the rotation is counter clockwise. This rotation appears counter clockwise when viewed from positive to negative direction on the rotation axis, but appears a clockwise when viewed from negative to positive direction.
    • Alternatively (and identically) you can imagine sitting on the analysis coordinate system and defining a series of counter-clockwise rotations about analysis axes that transform the material axes into the analysis axes.
  3. All single and double angle rotations are allowed (x, y, z, xy, xz, yx, yz, zx, and zy). When doing three rotations, the only schemes currently supported are zyx and zyz. It is easy to add more if needed (or to rearrange coordinates to make one of these work).
  4. 2D calculations only allow z axis rotation (which is θ axis if axisymmetric), which can be done with either an angle option in the <a href="region.html">Region command</a> or a single Rotate z,angle command. You will need to use the Rotate command option if you want to set the angle with a <a href="function.html">user-defined function</a>.
  5. Use of any Rotate commands within a <a href="region.html">Region</a> block will override any angle setting in the <a href="region.html">Region command</a> (i.e., that specified angle will be ignored).
  6. Use of any Rotate commands within a <a href="bmpregion.html">BMPRegion</a> block will override any Angle setting in an <a href="intensity.html">Intensity</a> command. Furthermore the chosen rotation angles will apply to all material points defined in the current <a href="bmpregion.html">BMPRegion</a> block. Finally, if the <a href="bmpregion.html">BMPRegion</a> block defines an angle-mask file, that file will override all Rotate commands.


Explain out to set angle in MPM which is either angle on the Region command or Rotate command within regions

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