WORKSHOP 5 DRAPING A DOUBLY CURVED SURFACE WS5-1 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation

Mar120, Workshop 10, March 2001 WS5-2 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation

Mar120, Workshop 10, March 2001 WS5-3 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation Problem Description This workshop involves creating several MSC.Laminate Modeler plies for a 2D mesh on a doubly curved surface. Each ply is created or modified to show a different feature of MSC.Laminate Modeler. The features looked at are Drape(Scissor), reference angle 0 degrees Drape(Scissor), reference angle 30 degrees Drape(Scissor), different start point Drape(Scissor), show regions of different shear using color fringe Drape(Slide) Drape(Scissor), implicit step length Drape(Scissor), explicit step length The doubly curved surface and corresponding 2D mesh are created by reading(playing) an MSC.Patran session file. The material property set is created by playing a session file.

Mar120, Workshop 10, March 2001 WS5-4 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation Suggested Exercise Steps 1. Create a new database 2. Create the geometry and FEM using drapeintro_geom.ses 3. Create material using materials.ses 4. Create a new layup file in MSC.Laminate Modeler 5. Create a new LM_Material and LM_Ply 6. Create another LM_Ply 7. View the ply after modifying the maximum strain 8. Modify the ply type to Drape(Slide) 9. Investigate the effects of implicit step length 10. Investigate the effects of explicit step length.

Mar120, Workshop 10, March 2001 WS5-5 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation d e f b c Step 1. Create a New Database Create a new database. Name it drapeintro.db. a.File / New. b.Enter drapeintro as the file name. c.Click OK. d.Select MSC.Nastran as the Analysis Code. e.Select Structural as the Analysis Type. f.Click OK. a

Mar120, Workshop 10, March 2001 WS5-6 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation Step 2. Create the Geometry and FEM Using drapeintro_geom.ses Play the file drapeintro_geom.ses to create the geometry and mesh. a.File / Session / Play… b.Select drapeintro_geom.ses file. c.Click –Apply-. a b c

Mar120, Workshop 10, March 2001 WS5-7 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation Step 2. Create the Geometry and FEM (Cont.)

Mar120, Workshop 10, March 2001 WS5-8 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation Play materials.ses file to create the material. a.File / Session / Play… b.Select materials.ses file. c.Click –Apply-. Step 3. Create Material Using materials.ses a b c

Mar120, Workshop 10, March 2001 WS5-9 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation Step 4. Create a New Layup File in MSC.Laminate Modeler Create a new laminate modeler file and name it drapeintro_LM. a.Tools / Laminate Modeler / Layup/Laminate… b.Click New Layup File… c.Enter drapeintro_LM as the File Name. d.Click OK. a b c d

Mar120, Workshop 10, March 2001 WS5-10 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation Step 5. Create a New LM_Material and LM_Ply Create new laminate materials. a.Laminate Modeler: Create / LM_Material / Add. b.Select ud_t300_n5208 from the Analysis Material. c.Click –Apply-. d.Laminate Modeler: Create / LM_Ply / Add. e.Select Mat_1 from the Select LM_Material. f.Select Surface 1 as the Select Area. g.Select Node 221 as the Start Point. h.Enter Coord 0.1 as the Reference Direction. i.Enter 0 as the Reference Angle. j.Click –Apply-. a b c d e f g h i j

Mar120, Workshop 10, March 2001 WS5-11 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation Note the maximum Abs. Strain angle is about 14 degrees. Step 5. Create a New LM_Material and LM_Ply (Cont.)

Mar120, Workshop 10, March 2001 WS5-12 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation Step 6. Create Another LM_Ply Create another ply, changing the reference angle. a.Laminate Modeler: Create / LM_Ply / Add. b.Enter 30 as the Reference Angle. c.Click –Apply-. Note that this results in lower strain, about 9 degrees. So the Reference Angle affects the amount of Strain. a b c

Mar120, Workshop 10, March 2001 WS5-13 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation Check the effects of having a different starting point on strain. a.Laminate Modeler: Create / LM_Ply / Add. b.Enter Node 11 as the Start Point. c.Enter 0 as the Reference Angle. d.Click –Apply-. Note the increased strain due to greater distances from the starting point, maximum 26 degrees. The starting point is in other words controlling the shear. b c d Step 6. Create Another LM_Ply (Cont.) a

Mar120, Workshop 10, March 2001 WS5-14 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation Step 7. View the Ply after modifying the Maximum Strain View the ply after modifying the Maximum Strain. a.Laminate Modeler: Modify / LM_Ply / Recreate. b.Select Ply_3 under Existing LM_Plys c.Click Additional Controls… d.Select Material as the Control Parameter. e.Uncheck the Use Material Definition Box. f.Enter 10 as the Maximum Strain (degrees). g.Click OK. h.Click –Apply-. a c d e f g h b

Mar120, Workshop 10, March 2001 WS5-15 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation The variations of the color on the surface represents the degree of fabric strain. Since the maximum strain is set as 10 degrees, any regions of the ply with more than 10 degrees of strain has color variations. Step 7. View the Ply after modifying the Maximum Strain (Cont.)

Mar120, Workshop 10, March 2001 WS5-16 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation Step 8. Modify the Ply Type to Drape(Slide) Change the type of local draping to Drape(Slide). a.Laminate Modeler: Modify / LM_Ply / Recreate. b.Select Ply_3 from the Existing LM_Plys. c.Select Drape (Slide) as the Type. d.Click –Apply-. Try changing the Type to Drape (Slide). Notice that there are no available materials. This is because have not defined any Slide Drape materials in the LM Materials menu. It is not possible to drape with a material that has not been defined. a b c d

Mar120, Workshop 10, March 2001 WS5-17 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation Step 9. Investigate the Effects of Implicit Step Length Investigate the function of implicit step length. a.Laminate Modeler: Create / LM_Ply / Add. b.Select Mat_1 from the Select LM_Material. c.Click Additional Controls… d.Select Geometry from the Control Parameters. e.Check on Implicit as the Step Length method. f.Enter 2.0 as the Input for Step Length. g.Click OK. h.Click –Apply-. a b c d e f g h

Mar120, Workshop 10, March 2001 WS5-18 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation Notice that by assigning 2.0 as the value of the Implicit step length, for this problem, the ply representation is coarse. This means that any details of the surface will be represented more poorly than if the ply representation was finer(the step length is smaller). When using the implicit method, the step length is equal to the default value of the step length multiplied by the value of the implicit step length(a factor). The default step length is a function of the surface and its area. Step 9. Investigate the Effects of Implicit Step Length (Cont.)

Mar120, Workshop 10, March 2001 WS5-19 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation Step 10. Investigate the Effects of Explicit Step Length. Investigate the function of explicit step length. a.Laminate Modeler: Create / LM_Ply / Add. b.Select Mat_1 from the Select LM_Material. c.Click Additional Controls… d.Select Geometry from the Control Parameters. e.Check on Explicit as the Step Length method. f.Enter 2.0 as the Input for Step Length. g.Click OK. h.Click –Apply-. By selecting the Explicit method and setting the Input value to 2, the step length is assigned to 2 units(e.g. mm), instead of using 2 as the multiplying factor as for the Implicit method. a b c d e f g h

Mar120, Workshop 10, March 2001 WS5-20 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation Note that for small step lengths, such as the last one (Explicit method), the ply pattern may not cover(drape) the entire surface, but the surface may be draped with a high degree of accuracy. This is due to memory allocation limitations. The only solution is to re- drape with a larger step length, but of course by using a larger step length the accuracy of draping will be decreased. Step 10. Investigate the Effects of Explicit Step Length (Cont.)

Mar120, Workshop 10, March 2001 WS5-21 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation The amount of strain is dependent on: Starting Point Amount of area that is covered Degree of curvature of surface Reference Direction / Angle These points are obvious, but it is still very difficult to predict the exact amount of strain without a tool such as Laminate Modeler. The practical problems with excessive strain may appear during the lay up process when the fibre mat wrinkles or cannot be applied. Another problem may be that the structure fails because the strength is not as guessed because of the altered fibre angles. The conclusion is that the degree of strain is most important! For a standard cloth, the degree of straining possible can be as high as 30 degrees. For a stitched cloth the strain may be a lot greater than this. By predicting the ply strain it is possible have an idea of the production problems and solve them before starting manufacture.

Mar120, Workshop 10, March 2001 WS5-22 PAT325, Workshop 5, February 2004 Copyright 2004 MSC.Software Corporation