03_v5_gpsfordesigner_ws_3_030402

WS3-1CAT509, Workshop 3, March 2002

WORKSHOP 3

BICYCLE PEDAL STATIC ANALYSIS



100 lbs

100 lbs

Elastic Modulus, E 29.0E6 psi

Poisson’s Ratio, 0.3

Density .284 lb/in3

Yield Strength 36,000 psi

WORKSHOP 3 – BICYCLE PEDAL STATIC ANALYSIS

Problem Description Your job will be to analyze various components of a mountain bicycle. We

will start with the pedal. Let’s assume a 200 lb person riding this bike is standing, balanced evenly

on each pedal. Material (Steel) properties as specified below. Use a rough analysis to determine where the high stress areas exist that will require additional mesh refinement.


Suggested Exercise Steps

1. Open the existing CATIA part in the Part Design workbench.

2. Apply steel material properties to the part.

3. Create a new CATIA analysis document (.CATAnalysis).

4. Pre-process initial finite element mesh.

5. Apply a clamp restraint.

6. Apply a distributed force.

7. Compute the analysis.

8. Visualize the analysis results.

9. Save the analysis document.

WORKSHOP 3 – BICYCLE PEDAL STATIC ANALYSIS


Open the CATIA part ws3pedal.CATPart in the Part Design workbench.

Steps:

1. Select File and Open… from the top pull-down menu.

2. Access the class workshop directory using the typical Windows interface.

3. Open the pedal by double-clicking.

By default, the pedal and all other CATPart documents are opened in the Part Design workbench.

Step 1. Open the existing CATIA part

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Step 2. Apply steel material properties to the part

Before every session you should verify your session units.

Steps:

1. Select Tools from the menu then Options.

2. Select the General category then Parameters.

3. Select “Units” tab, change all units to the English system.

Notice there are many variables accessed by a scroll bar, verify and edit until all units are consistent. You must change each one separately, select OK.

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Steps:

1. Select the Pedal “Part” representation in the features tree.

2. Click the Apply Material icon.

3. Activate the Metal tab in the Library window.

4. Select Steel.

5. Make sure Link to file is selected, then select OK.

6. Make certain material is applied properly in the features tree.

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Verify and edit structural material properties and activate material rendering.

Steps:

1. Right click Steel in the features tree.

2. Select Properties.

3. Select Analysis tab.

4. Verify and edit structural material properties here, select OK.

5. Click the Customized View Parameters icon to activate custom view material rendering.

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Step 3. Create a new CATIA analysis document

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Steps:

1. From the Start menu select the Analysis & Simulation then the Generative Structural Analysis workbench.

2. Select Static Analysis, select OK.

3. Your Static Analysis document gets automatically linked to the CATPart.

4. Note the Material Property 3D.1 previously specified in the CATPart document shows up here in your CATAnalysis document.

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Step 3. Create a new CATIA analysis document

Specify the External Storage directory locations.

Steps:

1. Select the Storage Location icon.

2. In the Current Storage Location modify the Results Data location and rename as shown.

3. In the Current Storage Location modify the Computation Data location and rename as shown, select OK.

4. Note the Links Manager in the features tree reflects the paths.

You can create specific directories for additional organization.

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Step 4. Pre-process initial finite element mesh

Define the global finite element mesh properties.

Steps:

1. Double Click the “OCTREE Tetrahedron Mesh.1:Pedal” representation in the features tree or the “Mesh” icon on the part.

2. Specify the recommended rough Global Size = .25”.

3. Specify the recommended Sag = 10% of Global Size.

4. Specify element type “Linear” (TE4, means 4 node tetrahedron) and is good for a rough analysis, select OK.

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Step 5. Apply a clamp restraint

Steps:

1. Select the Clamp Restraint icon.

2. Select the shaft that attaches to the crank.

3. Select OK.

4. Note the Clamp object added to the features tree.

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Step 6. Apply a distributed force

Steps:

1. Select the Force icon.

2. Select the 3 outside foot grip pads.

3. Enter -100 lbs in the Z-direction, select OK.

4. Note the Distributed Force object added to the features tree.

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Step 7. Compute the analysis

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Steps:

1. Select the Compute icon.

2. Compute All Objects defined, select OK.

3. Notice the estimated time, memory, disk requirement and Warning for decreasing computation time - select Yes to continue.

4. This symbol indicates computation required.

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Preview active


Step 8. Visualize the analysis results

Visualize the finite element mesh in the deformed state of the system as a result of loading.

Steps:

1. Select the Deformation Image Icon.

2. Note the Deformed Mesh Image added to the features tree.

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Visualize the Von Mises stress which is a combination of all primary and principal stresses.

Steps:

1. Select the Stress Von Mises icon.

2. Note the Image Deactivated symbol for the Deformed Mesh image.

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Visualize the displacement vectors.

Steps:

1. Select the Displacement icon.

2. Right mouse click Transl. displacement vector in the tree.

3. Select Definition.

4. Select Visu tab.

5. Note by default SYMBOL is selected, select OK.

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Visualize the displacement field patterns using the AVERAGE-ISO definition.

Steps:

1. Right click Translational displacement vector in the features tree.

2. Select Definition.

3. Select Visu tab.

4. Select AVERAGE-ISO, select OK.


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Add additional image smoothing options to the AVERAGE-ISO visualization definition.

Steps:

1. In the Image Edition window, select the Iso/Fringe button.

2. Select the box for ISO smooth.

3. Select OK.

4. Select OK.

Transitions between colors on the image display are blended.


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Visualize the computation error which represent scalar field quantities defined as the distribution of energy error norm estimates for a given computation.

Steps:

1. Select the Precision icon.

2. Double click on the Estimated local error color map palette.

3. Select Impose Max for the color map palette, select OK.

4. Select the Informations icon.

5. Then select in the features tree Estimated local error.

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Conclusions You now know where the “hot spots” are but the stress and displacement results are

questionable with a 43.5% Global Precision Error.

The next step is to refine the mesh in the critical areas. We will go over this in the next workshop #4.


.25” Linear Mesh

Max Von Mises 24.6 ksi

Translational Displacement .00407 inch

Error Estimate 8.65e-8

Global % Precision error

Local % Precision error

43.5 %

NA %

Recommendation

Error Estimate 1.00e-8 (zero)

Global % Precision error

Local % Precision error

20 %

10 %


Step 9. Save the analysis document

Steps:

1. From the File menu select Save Management.

2. Select document you want to save.

3. Select Save As to specify name and path, select OK.

The pedal.CATPart and .CATAnalysis should each be saved under a new name in the work directory.

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03_v5_gpsfordesigner_ws_3_030402