In all versions of Fibersim previous to version 15, Fibersim only allowed users to select one Fill-to surface when setting up Volume Fill. One of the new abilities added to post-Fibersim 15 releases is the ability to assign multiple Fill-to surfaces to the same Volume Fill object when generating layers. Besides allowing multiple Fill-to surfaces, Volume Fill allows Fill-to surfaces to be selected that are nearly perpendicular to the laminate surface. Volume Fill also now allows setups that generate surfaces with smaller cross sections at lower step values rather than upper step values. An example that incorporates all the new abilities now allowed by the Volume Fill utility is shown below:
All three surfaces with a purple normal arrow pointing from them are the Fill-to surfaces in the above photo. The laminate surface in this photo is the fourth surface at the bottom of the photo without a purple normal arrow pointing from the surface. As you can see on the far right and left Fill-to surfaces, these surfaces are nearly perpendicular with the laminate surface. Also, the further from the laminate surface, the larger the layer cross sections become. Therefore, the smaller cross sections in this example photo occur at lower step values. Both the nearly perpendicular Fill-to surfaces and the smaller cross sections at lower step values were not allowed until the release of Fibersim 15.
When setting up a Volume Fill object that contains a smaller cross section at lower step values you must also use the following design constraint. The design constraint requires that wherever the normal of the laminate make multiple intersections through a Fill-to surface, the Fill-to surface must be split into multiple surfaces as shown in the picture below:
Lastly, when selecting multiple Fill-to surfaces, you must link all Fill-to surfaces within the same Fill-to Surface field as shown below: