1、WORKSHOP 9ANCHOR GEOMETRY CREATIONANCHOR GEOMETRY CREATIONWorkshop ObjectivesCreate a B-rep solid from just surfaces. Some of the surfaces are obtained by importing an IGES file, and others are obtained by creating them in Patran.Problem DescriptionCreate surfaces by importing an IGES file, using ex

2、isting surface edges, and breaking existing surfaces.One of the surfaces that is to be created is general trimmed; its creation is done using Auto Chain. Another surface that is to be created is done using two surface edges. Some surfaces must be deleted, because if they were retained they would be

3、inside the B-rep solid.Surfaces are created for the application of either constraints or pressure.Software VersionPatran 2008r1Key Concepts and StepsDatabase: Create a new databaseGeometry: Import surfaces via an IGES fileGeometry: Create surfaces using existing surface edgesTrimmed surfaceParametri

4、c surface from two edgesGeometry: Create surfaces by breaking existing surfacesEdit/ Surface/ BreakGeometry: Delete unwanted surfacesDelete/ SurfaceANCHOR GEOMETRY CREATIONStep 1. Create a New DatabaseCreate new database:Click File / New.Enter anchor as file name.Click OK.Set the Tolerance to Based

5、on Model.Enter 70 for Model Dimension.Set Analysis Code as Nastran and Analysis Type to Structural.Click OK.abcdefgStep 2. Import an IGES fileImport an IGES file:Click File / Import.Select Model for Object and IGES for Source.Select Anchor.igs for File name.Click Apply.Click OK in Import Summary win

6、dow.abcdeStep 2. Import an IGES file (Cont.)Step 3. View imported modelUse icons for viewing:Click Iso 3 View icon.Click Fit view icon.Click Smooth shaded icon.Click on the Mouse rotate XY icon and use the middle button of the mouse to rotate as needed.abcdStep 4. Create First Missing Surface Using

7、Two EdgesCreate Missing Surface:Rotate the model, as needed, to achieve the view as shown.Geometry: Create/ Surface/ Curve.Select 2 Curve for Option.Select the two edges as shown, for Starting Curve List and Ending Curve List.bacddStep 5. Create Second Missing SurfaceUse the trimmed method to create

8、 surface:Geometry: Create / Surface / Trimmed.Select Planar for Option.Click Auto Chain.Rotate the model and zoom in as needed to achieve this view.Select the curve shown in the figure for Select a Start Curve.abcdeeStep 5. Create Second Missing Surface (Cont.)While navigating around the free surfac

9、e edges, it is necessary to use the Next and OK buttons in the Auto Chain form. Magenta colored dots will indicate which curve is being selected:At the first set of edges encountered (two edges one vertical and the other horizontal going to the left) Patran chooses the vertical one. Click Next.This

10、causes Patran to choose the other edge which is desired. Click OK.Continue to OK the correct edges and Next the wrong edges shown in the figures, until a closed path of edges is specified.Click Stop and then click Cancel.Wrong edges, so click NextCorrect edges, so click OKfgfghiStep 5. Create Second

11、 Missing Surface (Cont.)Use trimmed method to create surface:Click in Outer Loop List box.Click on Curve icon and select Curve 1 for Outer Loop List.Click Apply.Click Yes for deleting original curves.jlkmkStep 6. Delete Unnecessary Internal SurfacesDelete surfaces that are not to be in the interior

12、of the solid that is being created:Geometry: Delete/ Any.Uncheck Auto Execute.For Geometric Entity List, shift select the two surfaces shown in the figure.Click Apply.abcdcStep 7. Create Points at Center of ArcsCreate point at the center of the arc for cylindrical coordinate system:Geometry: Create/

13、 Point/ ArcCenter.Uncheck Auto Execute.Select the two edges for Curve List as shown.Click Apply.abcdcStep 8. Create Coord SystemCreate cylindrical coordinate system using 3Point method:Geometry: Create / Coord / 3Point.Select Cylindrical for Type.Click on the Wireframe icon and the Point size icon (

14、increase Point size).Select Origin as shown.Select the point for Point on Axis 3 (Z-axis) as shown.Select the point for Point on Plane 1-3 as shown.Reduce the Point size and shade the model using the Smooth shaded icon.OriginPoint on Axis 3Point on Plane 1-3defabdefccgStep 9. Create CurveCreate curv

15、e by translating surface edge:Geometry: Transform/ Curve/ Translate.Select Curvilinear in Refer. CF for Type of Transformation.Select Coord 1 for Refer. Coordinate Frame.Enter for Translation Vector.Select the curve as shown for Curve List.abcdeceStep 10. Break SurfaceBreak a surface into two surfac

16、es:Geometry: Edit/ Surface/ Break.Select Curve for Option.Select the Surface for Surface List as shown.Click the Curve icon.Select the Curve as shown for Break Curve List.Click Yes for deleting original surfaces.abccedfeStep 11. Break Surface by ParametricUse parametric option to break surface for a

17、pplication of pressure on top of hole:Geometry: Edit / Surface / Break.Select Parametric for Option.Select Constant v Direction for Break Direction.Select 0.5 for Break Curve Parametric Value.Select the Surface as shown for Surface List (Surface 11 should be broken horizontally).Click Yes for deleti

18、ng original surfaces.abcdefeStep 12. Add Vertices For CongruencyAdd vertices so that the surfaces will be congruent where Surface 11 was broken:Geometry: Edit/ Surface/ Add Vertex.Make sure Auto Execute checked.Select the surface as shown for Surface.Select the Point as shown for Point List.Repeat f

19、or the other side using the above steps.Click Fit View icon.abcdcdefStep 13. Mirror SurfacesMirror surfaces:Set the display to Iso 3 View.Geometry: Transform/ Surface/ Mirror.Click in the Define Mirror Plane Normal, then click on the 3 points for the plane icon.Hold shift, Select three points for De

20、fine Mirror Plane Normal. The 3 points selected can be anywhere in the plane.Select all surfaces for Surface List.bacecdeStep 13. Mirror Surfaces (Cont.)Mirror surfaces again:Click in the Define Mirror Plane Normal, then click on the 3 points for the plane icon.Hold shift, Select three points for Define Mirror Plane Normal. The 3 points selected can be anywhere in the plane.Select all surfaces for Surface List.ffhghStep 14. Create B-rep SolidCreate B-rep solid from the congruent surfaces:Geometry: Create/ Solid/ B-rep.Select all su