new femap tutorial bracket assembly - ata siemens solution … · 2015. 2. 6. · preceding...

FEMAP TUTORIAL

Bracket Assembly

Femap 11.1

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ATA Engineering FEMAP 11.1

Bracket Assembly Tutorial in Femap

Content subject to change without notice. © 2015 ATA Engineering, Inc. Femap is a trademark of Siemens PLM Software, Inc.

Software:Femap 11.1

Difficulty Level:Beginner

Preceding Tutorial:None

Input files required:bracket_assembly_ex.x_t

Overview

This document provides a written description of a demonstration of various Femap capabilities. The model will be made from a simple generic bracket geometry file.

This tutorial is part of a series of free Siemens PLM Software training resources provided by ATA. More tutorials, whitepapers, videos, and macros are available on ATA’s PLM Software website:http://www.ata-plmsoftware.com/resources

http://www.ata-plmsoftware.com/resources



1 Content subject to change without notice. © 2015 ATA Engineering, Inc. Femap is a trademark of Siemens PLM Software, Inc.

Concepts

• Importing and simplifying geometry

• Generating mid-surfaces and preparing geometry for meshing

• Creating materials and various properties (shell, solid, and beam)

• Meshing with quad and tetrahedral elements, checking mesh quality, and using mesh controls to adjust the mesh

• Applying constraints and bearing loads

• Creating a connection property, defining regions of contact, and applying the connection to the model

• Analyzing and post-processing the deformation of the model




Table of Contents

1. INTRODUCTION 31.1. Input Files Required 31.2. Output Files Created 3

2. IMPORT AND SIMPLIFY GEOMETRY 42.1. Import the geometry into femap and “Clean it up” 42.2. Use the Model Info tree to display the base bracket 72.3. Generate mid-surfaces for the base bracket 82.4. Prepare the base bracket for meshing 92.5. Prepare the Arm for meshing 12

3. MESH GEOMETRY 133.1. Create the materials 143.2. Create the shell property 153.3. Create the solid property 153.4. Create the beam property to represent the bolts 163.5. Mesh the base bracket 163.6. Mesh the arm with tetrahedral elements 203.7. Create the bar elements 23

4. APPLY LOADS AND CONSTRAINTS 264.1. Apply Constraints 264.2. Apply Loads 27

5. APPLY CONNECTION BETWEEN ARM AND BRACKET 295.1. Create a Connection Property 295.2. Define the Regions of Contact 295.3. Apply the Connection between the Arm and the Base Bracket 31

6. ANALYSIS 326.1. Run Analysis 32




Tutorial

1. Introduction

This document introduces Femap with NX Nastran by demonstrating an entire assembly analysis cycle. To begin, a finite element model is created from basic CAD geometry of a bracket assembly.

1.1. Input Files Required The following files will be provided: bracket_assembly_ex.x_t

1.2. Output Files Created The following files will be created during this demonstration: bracket_assembly_ex.modfem

Figure 1-1: ▶ Femap demonstration model




2. Import and Simplify Geometry

The Parasolid geometry will be imported into Femap and then it will be simplified to remove some extra holes and chamfers. Then a mid- surface will be generated for meshing.

2.1. Import the Geometry into Femap and Simplify

1. File →→ Import →→ Geometry

2. Set the Title to BRACKET ASSEMBLY

3. Set the Geometry Scale Factor to 1000. Uncheck Increment Layer and check Increment Color. The Geometry Scale factor defines the units (with 1000 being millimeters and 39.37 being inches). Increment Layer imports each part in the assembly into separate layers. Increment Color sets the outlines of each different part to be different colors.

4. Use Geometry →→ Surface →→ Remove Hole to remove the holes

5. Pick the two small holes on the tabs of the bracket.

Figure 2-1: ▶Import the geometry




Figure 2-2: ▶Remove the holes from the tabs

Click OK to remove the holes.

6. Use Geometry→→ Solid →→ Remove Face to remove the chamfers.

7. Use the highlighter to verify the selected faces in the selection.

Click OK to remove the chamfers

8. Remove the geometry tabs.

9. Use Geometry →→ Solid →→ Slice Along Face to remove the tabs of the geometry.

Figure 2-3: ▶Click the highlighter icon in the dialog to show the selected faces




10. Use Delete →→ Geometry →→ Solid to remove the tabs.

11. Remove the extra faces on the bracket, using Geometry →→ Solid →→ Remove Face.

Figure 2-4: ▶Select the side face of the bracket

Figure 2-5: ▶Use the highlighter to make sure only the tabs are removed




2.2. Use the Model Info Tree to Display the Base Bracket

Using the Model Info Pane, expand Geometry. The geometry containing the base bracket is now untitled, as it has been edited. Select the base bracket geometry. Right-click on the corresponding check box and select Show Selected Only.

Figure 2-6: ▶Remove the extra face by merging it with the adjacent faces

Figure 2-7: ▶Remove the extra face by merging it with the adjacent faces




2.3. Generate Mid-Surfaces for the Base Bracket

1. Use Geometry →→ Mid-surface →→ Offset Tangent Surface to generate mid-surfaces for the bracket.

2. Accept the default Tangency Tolerance of 0.1 and the Offset distance of 1.5. Note that the 1.5 mm is half the thickness of the original bracket. Accept the dialog to delete the original solid.

Figure 2-8: ▶Select the top surface as the seed surface

Figure 2-9: ▶Creating the mid-surface




2.4. Prepare the Base Bracket for Meshing

With the base bracket mid-surfaced as shown, the next steps are to create geometry features for map meshing around the holes. Washers and pad features will be used to do this.

1. First, make sure that Geometry →→ Curve – From Surface →→ Update Surfaces is toggled on. This is indicated by a blue outline around the icon. This is a very useful command, and it should be toggled on when you want commands to update the surfaces when doing tasks such as projecting or intersecting curves onto surfaces.

Figure 2-10: ▶Add geometry features to the mid-surface for map meshing

Figure 2-11: ▶Update Surfaces is toggled on




2. Next, use Geometry →→ Curve – From Surface →→ Offset Curve/Washer to create washers for all of the holes on the bracket.

3. Enter an offset of 5 for the washers.

4. Now create pad features to help with map meshing around the holes: Use Geometry →→ Curve from Surface →→ Pad to create pad geometry around the large arcs on the bracket base first.

5. Use the default pad size factor of 1.0

6. Pick the outer arcs created by the washer and not the holes.

Figure 2-12: ▶Create washers around each hole

Figure 2-13: ▶Set the offset of the washers to 5

Figure 2-14: ▶Select the outer arc




7. Next, create the pad geometry around the smaller holes on the base bracket. For these, use a pad size factor of 1.25. Again, select the outer arcs created by the washer.

8. Use Tools →→ Entity Editor to open the editor if it is not already open. In the Model Info box, select the geometry named Offset Edge Imprint that contains the Base Bracket.

9. Unlock the Entity Editor by clicking the lock button. Change the title to Base Bracket. Click Update Model to save the change.

Figure 2-15: ▶Select the region to split

Figure 2-16: ▶The prepared base bracket

Figure 2-17: ▶The Entity Editor toolbox




2.5. Prepare the Arm for Meshing

1. Select the geometry containing the arm. Right-click and select Activate to activate the part and ensure that all new curves appear in this part. Right-click on the corresponding check box and select Show Selected Only to display the arm.

2. Create washer geometry around all of the holes in the arm. Use an offset of 5. Also, select the holes on the bottom side of the arm. For the clevis, pick only the outer holes.

Figure 2-18: ▶The arm component

Figure 2-19: ▶Washers being added to the arm using an offset of 5




Figure 2-20: ▶The mapped geometry

3. The resulting geometry looks like that shown here:

Now, set the transparency of the surfaces on the arm solid to see the other surfaces and to improve the display. Specify a transparency value of 75%. Use Modify →→ Transparency →→ Surface. Click Pick^ and select Box. Use the box selection to select the entire arm and click OK. Set the transparency to 75.

4. Use the Entity Editor to change the name of the geometry to Arm.

5. Save the file.

3. Mesh Geometry Now, create materials and properties for the different model regions and

mesh and connect the meshes. Bar elements and RBE2 elements will be used to represent the bolts. The materials shown will be used for the meshes. The base bracket will be map meshed while the arm model will be meshed with tetrahedral elements.

Figure 3-1: ▶Material assignments




3.1. Create the Materials

1. Create materials 11, 12, and 13 by expanding the Model icon in the Model Info toolbox, right-clicking the Materials icon, and specifying to create a new material. Click Load to load a material, and be sure to change the library to the mm library. Load and choose library mat_eng_mm-N-tonne-degC-Watts.esp.

Figure 3-2: ▶Load the library to access the required materials

Figure 3-3: ▶Use the search bar to quickly find materials

Figure 3-4: ▶Use a double-digit number for the Material ID. Single-digit numbers are used by internal processes (import, scripts etc.).




2. Now with this library selected, pick Stainless Steel 316 Specialty for material 11, Aluminum 2024 Annealed Wrought for material 12, and Stainless Steel 17-4 PH for material 13.

3.2. Create the Shell Property

1. To create a new property, right-click the Properties icon under Model in the Model Info toolbox. Select New. Click Elem/Property Type and set the value to Plate.

2. Pick material 11, set the property id to 11, and define the title to be “base_bracket_3mm”. Set the thickness to 3 mm. Click OK.

3.3. Create the Solid Property

1. Click Elem/Property Type and set the value to solid. Enter an ID of 12 and title of “arm_solid”. Select material 12 for the solid property. Click OK.

Figure 3-5: ▶Setting the PLATE element type

Figure 3-6: ▶Setting the SOLID element type




3.4. Create the Beam Property to Represent the Bolts

1. Click Elem/Property Type and set the value to beam. Enter ID of 13 and title as “bolt”. Select material 13 for the beam property. Click shape to enter a standard shape as a circular bar with radius 4.5. Click OK.

3.5. Mesh the Base Bracket

The parts are now ready to be meshed. In the Model Info toolbox, activate the Base Bracket Geometry. Right-click on the checkbox and select Show Selected Only.

Figure 3-7: ▶Setting the BEAM element type. Set the shape to a circular bar of radius 4.5.




1. Use Mesh →→ Mesh Control →→ Size on Surface to set the Mesh Size. In the Select Surface dialog, click Method ^ and select “on Solid.” Select the base bracket.

2. Change the values and settings in the Automatic Mesh Sizing dialog to match those given below:

3. Use Mesh →→ Geometry →→ Surface to mesh the base bracket. In the Entity Selection dialog, change the Method ^ to “on Solid” and select the bracket.

4. In the Automesh Surfaces, change the Property to 11..base_bracket_3mm. Make sure the mesh is set to Quad and that Mapped Meshing Options is set to On.

Figure 3-8: ▶Selecting surface to define mesh size

Figure 3-9: ▶Automatic meshing dialog




Figure 3-10: ▶Setting the property and activating the mesh

5. Use the Meshing Toolbox to check the quality of the mesh. Use Tools →→ Meshing Toolbox if the box is not already open on the left. Expand the Surface Mesh Quality Menu. Change the Quality Type to Jacobian and Number of Quality Levels to 4. Toggle on the Quality button at the top of the toolbox.

Figure 3-11: ▶Set the quality options and toggle on the quality view

Figure 3-12: ▶The Jacobian quality of each element in the mesh is displayed




6. To turn on the display of mesh size, use View →→ Options or press F6 to open the View Options dialog. Select the option Curve – Mesh Size under the category Labels, Entities and Color. Check the Draw Entity checkbox. In the Show As prompt, select 3..Symbols and Count. Click OK.

Figure 3-13: ▶Turn on the display of mesh size count

Figure 3-14: ▶The mesh size on each curve is now visible




7. To adjust the mesh sizing, expand the Mesh Sizing menu in the Meshing Toolbox. Select Set To in the Operation option and expand the Operation options. Change the number of elements to 16. Toggle on the Select button to enable the selection of curves.

Select both curves around each hole to change the number of elements on each curve to 16.

Change the number of elements to 8. Select the each of the quarter arcs in the washers around the holes. Also select each of the outer arcs on the flanges on the bracket and the lines going across the bracket on the two slopes.

3.6. Mesh the Arm with Tetrahedral Elements

In the Model Info toolbox, activate the geometry containing the arm.

Figure 3-15: ▶Resizing the mesh

Figure 3-16: ▶The mesh after resizing




1. Right-click on the corresponding checkbox and select Show Selected Only to hide other geometries. Expand the Model →→ Properties icon. Uncheck 11..base_bracket_3mm to hide the mesh of the base bracket.

2. In the Model Info toolbox, right-click on the geometry containing the arm and select Mesh Size. Set the values to those given below. Make sure to select Tet Meshing and uncheck Suppress Short Edges.

3. Right-click on the geometry and select Tet Mesh. In the Automesh Solids dialog, set the property to Property 12. The result is shown below:

Figure 3-17: ▶Automatic meshing dialog for Tet elements

Figure 3-18: ▶The resulting arm with mesh




4. Change the colors of the meshes using their respective properties. In the Model Info toolbox, check all properties. Right-click the 11..base_bracket_3mm property and select Edit. Click Palette… and select a gray color. Click OK on all dialogs. Repeat the process with Property 12 and select a shade of blue.

5. Use View →→ Options… or press F6 to open the View Options dialog. Under the Labels, Entities and Color category, select Element. Then select 3..Property Colors under Color Mode. Click OK. Press Ctrl+G to refresh the graphics window.

Figure 3-19: ▶Changing the color of a property

Figure 3-20: ▶Setting the element color to the property color




3.7. Create the Bar Elements

In the Model Info toolbox, check the base bracket geometry item to display it in the graphics window.

1. Use Custom Tools →→ Add Tools… and select Hole To Hole Fastener Using Surfaces.BAS to add the Hole to Hole Fastener Using Surfaces tool.

Figure 3-21: ▶The recolored mesh

Figure 3-22: ▶Custom Tools menu and the added Hole to Hole Fastener Using Surfaces tool




2. Use Custom Tools →→ Hole to Hole Fastener Using Surfaces to create the bolt elements connecting the two parts together. In the Select One Arc on the START of the Hole dialog, select an arc around the hole on the arm.

3. In the Entity Selection dialog, select the two washer surfaces around the corresponding hole.

4. Repeat this process with the corresponding hole in the base bracket.

Figure 3-23: ▶Select an arc

Figure 3-24: ▶Select the surfaces

Figure 3-25: ▶The process is repeated on the base bracket hole




5. Repeat the command with the other hole.

6. Right-click a checkbox in the Model Info window and select Show All. Red lines around the arcs and a single blue line going through each the hole now appear, showing rigid elements and beam element respectively. (Turn off the display of the arm elements and the arm geometry to see the beam elements.) The completed finite element model should look like the figure below:

7. Expand the Model →→ Element →→ By Type items in the Model Info window. Right-click the Beam, Linear item and select edit. Change the Property to 13..Bolt. Repeat in the second dialog that appears for the second beam.

8. Select the two properties created by the Hole to Hole Fastener Using Surfaces command (1..Faster No. 1: dia=10 and 2..Faster No. 4: dia=10) and delete them.

9. Save the model.

Figure 3-26: ▶The completed finite element model

Figure 3-27: ▶Change the property of the BEAM elements to Bolt




4. Apply Loads and Constraints

4.1. Apply Constraints

1. Expand the Model item in the Model Info toolbox. Right-click on Constraints and select New. Set the ID to 11 and name the constraint Pinned Base Bracket.

2. Expand the new Pinned Base Bracket item. Right-click Constraint Definitions and select On Surface. Select the surfaces around the two bottom holes on the base bracket.

3. Set the title to Pinned Base Bracket and set the type to Pinned – No Translation. Click OK.

Figure 4-1: ▶Selecting surfaces to constrain

Figure 4-2: ▶Specify a pinned constraint




4. Right-click on Constraint Definitions and select On Surface. Select the unconstrained areas of the bottom on the base around the pinned holes.

5. Set the title to Sliding Base. Select Arbitrary in CSys. Select -1..Use Nodal Output Sys from the dropdown menu and check TZ. Click OK.

4.2. Apply Loads

1. Right-click on the Loads item in the Model Info Toolbox and select New. Set the ID to 11 and enter the title Arm Loads.

2. Expand the Load item and the new Arm Loads item. Right-Click Load Definitions and select On Surface. Select the inside surfaces of the hole through the clevis.

Figure 4-3: ▶Selecting surfaces for second constraint

Figure 4-4: ▶Defining no translation in the Z direction




3. Set the title to Total Bearing Force on Surface. Select Bearing Force from the list on the left. Set the magnitude to 500. Uncheck Normal to Surface and click OK.

4. Set the tip of the vector to the given values:

5. Save the model.

Figure 4-5: ▶Selecting the surface on which to apply the force

Figure 4-6: ▶Defining the load

Figure 4-7: ▶Defining the vector direction of the bearing force




5. Apply Connection Between Arm and Bracket

The arm will be connected to the base with an NX linear connection.

5.1. Create a Connection Property

1. Expand the Connections item in the Model Info toolbox. Right-click on Properties and select New. Set the title to Linear Contact. Click the Default button at the bottom of the dialog to set the values. Change the Max Contact Search Dist to 10.

5.2. Define the Regions of Contact

1. On the Entity Display toolbar, toggle off all entities except Curves , Surfaces , and Regions .

2. In the Model Info toolbox, right-click the checkbox next to the arm geometry and select Show Selected Only.

3. Expand the Connections item in the Model Info toolbox. Right-click on Regions and select New Connection Region.

4. In the Connection Region dialog, set the title to Arm Base and select Defined by Surfaces. Click Add Multiple… and select the surfaces on the bottom of the arm.

Figure 5-1: ▶Define the connection property




5. In the Model Info toolbox, right-click the checkbox next to the base bracket geometry and select Show Selected Only. Right-click on Regions and select New Connection Region.

6. In the Connection Region dialog, set the title to Bracket Top and select Defined by Surfaces. Click Add Multiple… and select the surfaces on the top of the bracket by holding Shift and dragging the selection box over the desired surfaces.

Figure 5-2: ▶Select the base of the arm part

Figure 5-3: ▶The Connection Region dialog

Figure 5-4: ▶Select the top of the bracket




7. Save the file.

5.3. Apply the Connection Between the Arm and the Base Bracket

1. In the Model Info toolbox, turn on the display of the arm geometry and the base bracket.

2. Right-click on the Connectors item in the Model Info window and select New.

3. Set the title to Region 1-2. Select the Linear Contact property. Set the master to Arm Base and set slave to Bracket Top.

4. In the Entity Display Toolbar, toggle on the view of Connectors, Elements, Constraints and Loads.

Figure 5-5: ▶The Connection Region dialog

Figure 5-6: ▶The Define Contact Connector dialog




6. Analysis

6.1. Run Analysis

1. Right-click on the Analyses item in the Model Info toolbox and select Manage. Click New. Name the analysis set Total Bearing Load and click OK.

2. Click Analyze. The analysis is finished when the date appears in the messages box.

3. Use the PostProcessing Toolbox to observe deformation and stress distribution. Use Tools →→ PostProcessing Toolbox to open the toolbox if it is not already open.

4. Expand the Deform option. Change the style to Deformed. Change the output vector to 1. Total Translation.

Figure 6-1: ▶Creating the analysis set

Figure 6-2: ▶Setting the output vector options for deformation in the PostProcessing Toolbox




5. Expand Scale under Options. Set scale to Actual Deformations. Set Scale Actual By to 100.

6. Expand the Contour menu. Set the style to Contour. Set the output vector to 1..Total Translation.

Figure 6-3: ▶Setting the deformation scale

Figure 6-4: ▶Setting the output vector for contour




7. Open the View Options dialog (View →→ Options… or F6). Show the thickness of the base bracket by changing the options of Element – Orientation/Shape. Set element shape to 3..Show Cross Section.

8. Turn off the mesh symbols by changing the options of Curve – Mesh Size. Uncheck Draw Entity.

Figure 6-5: ▶Display the thickness of PLATE elements

Figure 6-6: ▶Remove the display of the Mesh Size symbols




9. Change the color of the filled edges under the category Tools and View Style. Set the color mode to 1..Use View Color. Enter a View Color of 0 (Black).

10. In the Entity Display toolbar, toggle off display of Regions , Connectors , Constraints and Loads .

11. The deformation and contour plots should now be displayed on the model. The graphics window should look like the image below.

Figure 6-7: ▶Change the border color of the elements to black

Figure 6-7: ▶The model with deformation and contour plots

Copyright © ATA Engineering, Inc. 2015 www.ata-plmsoftware.com

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new femap tutorial bracket assembly - ata siemens solution … · 2015. 2. 6. · preceding...

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