Tutorial - the Validate workflow

Learn how to use Smart Slice to compute as-printed part performance.

This tutorial will show you how to setup and run a Validation, and interpret the results. Complete the steps yourself (estimated completion time of 15 min.) or watch the video (3 min.).

validate_tutorial_updated_9-9-20

         The initial steps in the Validate workflow are just like any other Cura workflow.

  1. Download the STL file here.
  2. Open Cura and import the STL file. Make the following selections:
    1. Printer: Ultimaker S5
    2. Extruder 1: Material = Ultimaker ABS, Print core = AA 0.4
    3. Print profile: Normal - 0.15mm

    Next, enter the Smart Slice stage and define the use case and requirements.
  3. Enter the Smart Slice Stage.

    validate_tutorial_1Anchor surfaces are surfaces that are constrained from moving. For this lever, the 2 cylinders are the anchor surfaces.
  4. Using the Anchor selection tool, set the Selection type to Concave (the middle icon) then select the cylinder shown here.
    validate_tutorial_2
  5. Click the Add button, set the Selection type to Concave, and select the other cylinder as shown below.
    validate_tutorial_2b

    Load surfaces are surfaces where external forces are applied. The load surface for this part is the semi-circular surface at the thin end of the lever.
  6. Using the Load selection tool, set the Selection type to Concave, the Magnitude to 150 N, and the Direction to Perpendicular, then select the semi-circular surface at the end of the lever. The setup will look like this:
    validate_tutorial_3a
  7. The load arrow manipulation wheel will appear. From the Cura menu, select View > Camera position > Top View (or click the Top View icon in the lower left corner of the screen). This will change the view and make it easier to orient the arrow.
  8. Click anywhere on the perimeter of the wheel and drag the cursor to orient the load arrow as shown below.   

    validate_tutorial_3
    You have the option of entering the required minimum factor of safety and maximum deflection. Learn what these requirements are here. These requirements do not effect the results of a Validation and do not have to be defined. However, it is useful to define them so that you can easily compare the computed values with your requirements.
  9. Select the Smart Slice Requirements button and enter 2 for the Factor of Safety and 3 for the Max Deflection.
    validate_tutorial_4
    Based on this use case and the current print settings, Smart Slice will compute the stiffness and strength of the part.
  10. Click the Validate button. The solution will take about 40 seconds to complete. When it is finished, a window with results will appear. Note that your values will be slightly different if your load direction is different than what is shown in Step 8:
    validate_tutorial_5
    These results tell you if the as-printed part exceeds or fails to meet the stiffness and strength requirements you defined. In this scenario, the computed factor of safety is 1.2 which is less than the minimum required value of 2.0. The computed maximum displacement is 4.38mm which is greater than the target of 3.0mm. This means the part is failing to meet both the stiffness and strength requirements. In other words, it is under-designed. 

    What do these values mean? Multiply the factor of safety by the applied load to get the load that causes a point in the model to begin yielding (aka the yield load). For this example, the yield load is 1.2 * 150 N = 180 N. The computed maximum displacement is 4.38mm and this simply means that, given the load case we defined, the maximum displacement among all points in the model is 4.38mm. The target is 3.0mm, which means the part is less stiff than required. 

    Continue using Validate or switch to Optimize?

    At this point, you can choose to manually adjust print settings and run additional Validations until the requirements are met, or you can use Optimize to automatically let Smart Slice determine the optimal print settings. Since Validate is the focus of this tutorial, we will explore the manual process.

    There are several approaches you can take to increase the stiffness and strength of the part. You can add more material by increasing the Infill Density, Wall Line Count, or Top/Bottom Layers, for example, you can change the material, or some combination of both. To begin, the effect of varying individual settings is investigated.
  11. Change the Infill Density from 20% to 60%.
    validate_tutorial_6
  12. Since a print setting was changed, the Validation results are no longer valid and the Validate button reappears. Click Validate. After the new solution is finished, the results appear and show that the factor of safety increased to 1.4 and the max displacement decreased to 3.54mm.

    Repeating Steps 11 and 12 for other print settings will produce different results. The table below shows the effect of changing individual print settings from the default value to the value specified.

    Print setting Default value Modified value Computed minimum factor of safety Computed maximum displacement
    Infill Density 20% 60% 1.4 3.54
    Wall Line Count 4 6 1.5 3.65
    Top/Bottom Layers 8 12 1.3 3.85

    None of these scenarios are enough to meet the requirements. What happens if all of the modified settings are applied at the same time?
  13. Set the Infill Density to 60%, the Wall Line Count to 6, Top Layers to 12, and Bottom Layers to 12. Click Validate
    validate_tutorial_7-1

    In this case, the computed factor of safety = 1.7 and the max. displacement = 2.93. The stiffness requirement is met, but the factor of safety is still too low.

    Based on the table above, the Wall Line Count had the most significant effect on the factor of safety so it makes sense to further increase the Wall Line Count in order to increase the factor of safety.
  14. Run the following scenario: Infill Density = 60%, Wall Line Count = 12, Top/Bottom Layers = 12. This configuration produces these results:
    validate_tutorial_8

    Given these print settings, the factor of safety = 2.1 and the max. displacement = 2.45. Both requirements are satisfied and you can proceed to print the part.

    Summary

    This tutorial explored how to setup a use case and how to use Validate to compute as-printed part performance. By manually adjusting print settings, a set was identified that meets the requirements. Using Validate is a good way to learn what print settings have the most influence over the stiffness and strength of the part. In the Optimize tutorial, you will see how easy it is to let Smart Slice automatically determine print settings that meet the requirements and minimize print time.

 

Results generated using Ultimaker Cura 4.6.2 and Smart Slice 20.1