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You can create lattice with varied density. The density is set by the cross section size of the beams. Thicker beams with bigger cross section size create higher density. When the beams are thicker, the balls on the beams also become larger. In the example below, you can see the difference between the beam cross section size and the ball size as you move away from the center.
Setting up lattice with varied density is comprised of the following:
Defining a volume region, where the parameters of the varied density apply.
Defining the change in the density.
Setting up other options, such as omitting beams that are smaller than a certain size and allowing tapered beam.
The Definition of the Volume for Varied Density Lattice
A volume region is defined by the references and the value of Distance:
The reference can be located in the center of the volume region, define one of its boundaries, or located outside of the lattice volume. References can be a combination of surfaces, quilts, edges, vertices, curves, curve ends, axes, points, and coordinate systems.
The size of the volume region is defined by the Distance. For points, the volume region is in a shape of a ball around the point, where the value of the distance is its radius. For curves, the volume region is a cylindrical sweep around the curve, where the value of the distance is its radius. For surfaces, the volume region is defined by surfaces that are offset to the surface on both sides, by the value of the distance.
The Rate of Size Change
When you create a uniform lattice, you set the cross section size of the beam. When you create a varied density lattice, you set another value for the beam, marked as Ref Cross Section Size. These two values are the upper and lower limits of the varied density lattice. The greater the gap between the numbers, the greater the variance of the beam cross section size.
The lattice cells are created around the reference you choose. As you moved further from the reference, the beams vary from the size you set in the Density tab, to the value you set in the Cross Section Size.
The Rate of Size Change parameter sets how quickly the beam size changed from the value specified by Ref Cross Section Size to the value specified the Cross Section Size. When Rate of Size Change is set to 1, the transition between the two sizes is linear. When Rate of Size Change is smaller than 1, the rate of the change is slower than linear. When Rate of Size Change is greater than 1, the rate of the change is quicker than linear.
Comparing Lattices with Varied Density
In the example below, two lattices with varied density were created from the same box. The volume region is set to have a higher density.
The following parameters are identical in both lattices:
On the Beam tab, the Cross Section Size is set to 3.
On the Density tab, the Ref Cross Section Size is set to 15.
On the Density tab, the highlighted curve is listed under References.
In both lattices, the biggest beams (where the cross section size is 15) are placed around the curve. Outside the limits of the cylinder surrounding that curve, the cross section size of the beams is set to 3. Inside the cylinder, the beams become narrower as you move away from the curve.
The only difference between the two lattices is the value of Distance.
 Lattice with Varied Density where Distance is set to 40 Lattice with Varied Density where Distance is set to 70 In this example, the distance is small. The bigger beams and larger balls occupy a small volume region. In this example, the distance is bigger. The bigger beams and larger balls occupy a big volume region.
Creating a Partial Lattice
You can set the lattice to fill only a partial volume of the entire volume. To determine when the lattice propagation stops, set the Minimal Beam Size.
By default, the Minimal Beam Size is set to 0 and all the lattice cells are created.
The minimal beam size must be between the value of the cross section size of the beam and the value of the reference cross section size. The cells are propagated when the actual beam cross section size is bigger than the Minimal Beam Size and smaller than the maximal value between Ref Cross Section Size and Cross Section Size. Beams narrower than the value of Minimal Beam Size are not created. In this example, the Minimal Beam Size was set to 3.1.
 When the Ref Cross Section Size is greater than the Cross Section Size, cells are created inside the region volume. When the Ref Cross Section Size is smaller than the Cross Section Size, cells are created outside the region volume.