Mid-Surface Creation. Mid-Surface Tool:

Transcription

1 Mid-Surface Creation Mid-Surface Tool: Reduces 3D geometry of constant thickness to a simplified shell representation ti Automatically places surface body at mid point between 3D face pairs Allows shell element type meshing in Simulation 3D Model Mid-Surface representation 5-71

2 Mid-Surface Creation Manual Mid-Surface creation: With Face Pairs, Apply/Cancel buttons active, choose the face pair Note the order of selection determines the surface normal direction Notice the first surface picked is displayed in purple, the second is shown in pink 1 st Pick Normal 2 nd Direction Pick Resulting Surface Body 5-72

3 Mid-Surface Creation Selection Note: While in select mode (apply/cancel active) the color scheme described earlier is in effect. When the selection is finalized the selected pairs are displayed in dark and light blue. 5-73

4 Mid-Surface Creation Mid-surface details: Multiple surface pairs may be selected for a single mid-surface operation, however they must be selected as opposing pairs (see picture) Adjacent face pairs will be grouped together if within the Thickness Tolerance (see below) T1 T2 If T1 T2 < Thk Tol: surfaces are grouped Mid Surface 5-74

5 Mid-Surface Creation Mid-surface details: If gaps exist in adjacent face pairs they will be sewn together within the Sewing Tolerance Sewing Tolerance: If Gap < Sewing Tol: surfaces are grouped Gap 5-75

6 Mid-Surface Creation Automatic mid-surface creation: Switching the Selection Method from Manual to Automatic exposes several additional options Bodies to search: allows limiting search to visible bodies, selected bodies or all bodies Minimum and maximum threshold sets search range (thickness) for face pairs Extra trimming provides options for situations where trimming problems with the surface body occur (described d later) Preserve bodies allows you to save the solid bodies from which surfaces are created (default is No) 5-76

7 Mid-Surface Creation Automatic mid-surface example: Solid body is 5 mm thick When the mid-surface tool is inserted we switch to Automatic Note: the Face Pairs field used in manual mode is left 0 With a constant thickness throughout we set the min/max threshold values to 5 mm Using the drop down choice we choose Find Face Pairs Now? = Yes Continued

8 Mid-Surface Creation Automatic mid-surface example (continued): When the search is complete the number of pairs detected t d is listed in the details and displayed d graphically Mid surface creation is completed by Generating the surface body 5-78

9 Mid-Surface Creation Mixing manual and automatic selection modes: In some cases it is convenient to make an initial surface pair selection and let the automatic method complete the process Example: The model shown here contains 2 different thicknesses In this case we ll select, (manually) a face pair of each thickness We will then allow the auto face detection to complete the selection 2 mm 1 mm 5-79

10 Mid-Surface Creation We begin by manually selecting the 2 face pairs shown here Note the face pairs selected contain a 1 mm and a 2 mm pair We now change the selection method to Automatic Note the min/max threshold values are automatically defined based on our manual selections Continued

11 Mid-Surface Creation We now activate Find Face Pairs Now Notice there are 2 options (due to the pre selection of face pairs) Yes-Add to Face Pairs: adds auto detected faces to the existing face pairs selected Yes-Replace Face Pairs: will use only the auto detected faces Choosing to add face pairs allows us to complete the operation 5-81

12 Mid-Surface Creation Adding to, removing from or modifying automatic surface selection: Examples: In this case the maximum threshold was increased to intentionally detect unwanted surfaces 5-82

13 Mid-Surface Creation Clicking in the Face Pairs field activates selection mode (note the colors change to indicate this) RMB in the graphics window provides the optional selection modes In this case we can choose Remove Face Pairs then select one of the faces to be removed When selection is complete Generate to update the model Note when removing face pairs, selecting one of the faces will remove the pair 5-83

14 Mid-Surface Creation Trimming options: In cases where trimming problems occur there are several options available to attempt corrections Example: Using the previous model we generate the surface model without removing the unwanted face pairs Since the pairs created result in T junctions, trimming problems occur Notice the mid-surface branch in the tree is displayed with a yellow check indicating there is a problem 5-84

15 Mid-Surface Creation Using the RMB option we can Show Problematic Geometry The resulting plot shows regions where trimming problems have occurred The default behavior is to intersect any untrimmed surfaces with the original solid body Other options: Delete untrimmed No Extra Trimming 5-85

16 Mid Surface Creation Workshop

17 Workshop 5.4, Mid-Surface Creation - Overview Goal Familiarize users with mid-surface capabilities that are new to Workbench 10.0 Demonstrate manual and automatic pair detection Demonstrate surface extension for interfaces Model Description 2 part bracket with consistent cross sections Since the model has consistent t cross sections, shell elements will be used to mesh the model. This saves time and CPU resources. 5-87

18 Workshop 5.4, Mid-Surface Creation 1. From the workbench launcher, select Open > Design Modeler Geometry and Browse to > \bracket_mid_surface.agdb 2. In the Model Tree, note that there are 2 separate parts: Desig gnmodeler 5-88

19 Workshop 5.4, Mid-Surface Creation 3. Each body of this model has different thicknesses. These thickness dimensions will be entered into the Maximum Threshold and Minimum Threshold fields in the Details of the MidSurf object. Menu Bar > Selection Filter Edges. Use the status bar measuring tools to verify these thicknesses. Smaller Body Thickness = 1mm Larger Body Thickness = 2mm 5-89

20 Workshop 5.4, Mid-Surface Creation 4. Insert a mid-surface object Main Menu > Tools > Mid-Surface 5. In the Details of MidSurf1, change the Selection Method to Automatic 6. Enter the Minimum Threshold of 1mm and Maximum Threshold of 2mm obtained from step

21 Workshop 5.4, Mid-Surface Creation 7. Set Find Face Pairs Now? to Yes Desig gnmodeler 8. The Face Pair Automatic Selection method will select 11 face pairs. However, the automatic selection method has incorrectly identified the following features: a) A face pair that is not needed. b) A face pair whereby the normal will need to be reversed 5-91

22 Workshop 5.4, Mid-Surface Creation 9. Editing Face Pairs The face colors help to indicate the current mode when adding or removing face pairs from the selection set. 5-92

23 Workshop 5.4, Mid-Surface Creation 10. To Remove Face Pairs, Click in the Details of MidSurf1 Face Pairs to enter the selection mode (Apply / Cancel). 11. In the Graphics Window - Zoom as needed. - Click on the face to Remove. - Right click to display the Context menu. - Select : Remove Face Pairs. 12. Note how the context bar indicates Select face pairs to remove. 5-93

24 Workshop 5.4, Mid-Surface Creation 13. To Reverse Face Pairs, Click in the Details of MidSurf1 Face Pairs to enter the selection mode (Apply / Cancel). 14. In the Graphics Window - Zoom as needed. - Click on the face to Reverse. - Right click to display the Context menu. - Select : Reverse Face Pairs 15. Note how the context bar indicates Select face pairs to reverse Note that the Reverse Face pair mode operates as a toggle. 5-94

25 Workshop 5.4, Mid-Surface Creation 16. Generate the Mid-Surface Desig gnmodeler 5-95

26 Workshop 5.4, Mid-Surface Creation 17. Now, instead of two solid bodies, there are four surface bodies. They cannot be combined into a single body because the "T" intersections would cause it to be non-manifold. Also, in the final figure below, you will see that the resulting surface bodies for the back brace are automatically extended/trimmed to meet the main part of the bracket, as these were all part of one solid body originally. However, the front brace was a separate body, so it is not automatically extended. 5-96

27 Workshop 5.4, Mid-Surface Creation 18. The Surface Extension feature can be used to extend the front brace edge so that it meets the main bracket surface. Insert a Surface Extension object. Main Menu > Tools > Surface Extension Note: It may be helpful to suppress the other bodies. 5-97

28 Workshop 5.4, Mid-Surface Creation 19. Click in the Details of SurfaceExt1 Edges to enter the selection mode and select both edges (Apply / Cancel). Select: Apply 5-98

29 Workshop 5.4, Mid-Surface Creation 20. In the Details of SurfaceExt1 Extent > Change the Extent to To Next. 21. Generate Surface edges are now extended. 5-99

30 Workshop 5.4, Mid-Surface Creation Alternate Method for determining Minimum and Maximum thresholds. - In this example geometry, it was relatively easy to identify and measure the solid body thicknesses. In practice, it may be preferable to select the face pairs first, then allow the program to calculate the Minimum and Maximum thresholds. 22. Details of MidSurf1 Set: Selection Method > Manual 23. Select: Face Pair Selection mode (Apply/Cancel) 5-100

31 Workshop 5.4, Mid-Surface Creation 24. Hold CTRL key down and select the face pairs on the large bracket to represent the 2mm thickness. Use the selection rectangles in the lower left corner to choose hidden faces). 25. Then, CTRL key and select the face pairs on the small bracket to represent the 1mm thickness. Select: Face Pairs : Apply Note that 2 Face Pairs are now in the selection set. 1 Pair representing 2mm, the other representing 1mm

32 Workshop 5.4, Mid-Surface Creation 26. Select: Selection Method : Automatic Note that Minimum Threshold and Maximum Threshold have been filled in automatically. 27. Find Face Pairs Now? > Yes Add to Face Pairs 5-102

33 Workshop 5.4, Mid-Surface Creation 28. The Face Pair Automatic Selection method has selected 11 face pairs which is the same number from Step 8. Desig gnmodeler 5-103