Stopping Criterion
The parameters in the Stopping Criterion panel control when the generation process is stopped, and the material is finished.
The available parameters are Fixed Object Number, Object Solid Volume Percentage, or Grammage (g/m2).
Additionally, when the Maximum Run Time / (h) has passed, the process is stopped even when the desired stopping criterion is not achieved.
If checking Create in Current and Keep Current Objects / Structure only the criteria Fixed Object Number, Add Object Solid Volume Percentage and Maximum Run Time are available.
Fixed Object Number
When Fixed Object Number is chosen as stopping criterion, PaperGeo places the given number of fibers in the structure and then the generation stops.
Observe the effect of setting a fixed number of objects (20, 100, or 500) as stopping criterion, for the generation of a paper structure with two fiber types. All other parameters are left untouched, including the default Allow Fiber Overlap. Note how the overlapping of fibers, shown in dark orange, increases with the number of objects present in the structure.
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(Add) Object Solid Volume Percentage
The Object Solid Volume Percentage (SVP) determines the fraction of the total volume that the paper structure should have. Accepted values range from 0% to 100%. For example, a structure with an Object Solid Volume Percentage of 40% consists of 40% fibers and 60% void space. Porosity is defined as (1 – SVP/100).
Observe the difference in a structure when varying the solid volume percentage from 5% to 20% and finally to 40%, while all other parameters are left unchanged. Note that the Sheet Thickness has not changed, so that the increase in SVP has the effect of producing a denser cellulose sheet.
If Create in Current and Keep Current Objects / Structure are selected, the parameter changes to Add Object Solid Volume Percentage. Only the added solid volume percentage counts, i.e., only the fibers not overlapping with the current structure are considered for the stopping criterion. Therefore, it is important to prevent overlap, for example by checking Prohibit Overlap with Current Structure.
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Grammage
The Grammage / (g/m2) determines the weight of the resulting paper/cellulose structure.
When Grammage is checked as stopping criterion (under the Create Options tab), the Density / (g/cm3) of the fiber material(s) can be seen in the materials panels under the Fiber Options tab or must be entered if Manual instead of a Database Material (such as cellulose) is chosen.
Observe the effect of increasing the Grammage from 15 to 40 g/m2, whereas all other parameters are left unchanged.
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Maximum Run Time
The Maximum Run Time (h) becomes important when generating complex structures with elevated solid volume fraction. When Prohibit Fiber Overlap has been checked, the required number of objects in the structure may become unattainable. In that case, the structure generation is stopped after the time entered in Maximum Run Time has passed and the achieved structure is considered as the result. The analysis of the GDR result file shows any disparity between the achieved result values and the desired ones.
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How to know if the stopping criterion is achieved?
The relationship of the variables Fixed Object Number, Object Solid Volume Percentage, Grammage and Weight Percentage can be observed in the Result Viewer of the result file, under the Results - Report subtab.
In this example, a Count (Fixed Object Number) of 52 corresponds to a Volume (Object Volume Percentage) of 10.35%, a Grammage of 50.46 g/m2 and a Density of 0.2523 g/cm³.
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