TEMPLATE LINK FOR TEACHERS TO CONTRIBUTE:



SolidWorks Lesson Template for Teachers to Contribute

Cover Sheet for Exemplary Lessons/Units Project

Faculty Member Name: Dr. Jeff Brown Date: 17 August, 2006

School District: Olympic College

Teacher’s School email address: jjbrown@olympic.edu

Title of Lesson/Unit: Cantilever Beam Design

Science, Technology, Engineering and Math) STEM Concepts Addressed:

1. Design a cantilevered I-beam to carry a distributed load of 30 kN.

2. Conduct a stress analysis of the original beam. The original cross section is shown to the right.

3. Optimize the beam by determining the lowest cross sectional area subject to two design criteria: the lowest factor of safety can be 5 and the maximum deflection of the beam can be 75 mm. The student may vary the flange width and/or height. However, the width and depth of the upper and lower flanges MUST be equal in each design. The student may also vary the web width and/or height.

4. The student will also develop a PowerPoint presentation of the results.

Length of instruction period: 50 min

How many periods needed to implement lesson unit:

1. ½ period - (optional) lecture activity on stress, stress calculations, factor of safety, ultimate stress, failure mechanisms.

2. 1 period - develop the model of the I-beam and conduct the stress analysis

3. 1 period – optimize the design

4. 1 period – prepare 5 minute presentations

5. 1 period – present 5 minute presentations

Grade Level(s) for use: All

Objectives:

1. Create a SolidWorks model of an I-beam.

2. Conduct a stress and deflection analysis using COSMOSXpress.

3. Optimize the design to obtain the smallest cross section subject to two design constraints.

4. Prepare a 5 minute oral presentation of results.

Materials:

SolidWorks software with COSMOSXpress, calculator, PowerPoint software for the presentation.

Procedures:

Step 1—model baseline I-beam

1. Open New Part

2. Sketch – Front Plane

3. Line – sketch the object around the origin making sure that all horizontal and vertical lines are constrained as you sketch them.

4. Add Relations – make the upper and lower edges equal in length. Also make the upper flange height equal to the lower flange height.

5. Smart Dimension all lines as shown at the right. Set dimension between edges and the origin first—simply set dimensions, you will add equations in the next step. Set the edge dimensions second—make these dimensions equal to those shown in the figure.

6. Add equations – open the equation editor. Add equations to make the dimensions between the left edges of the upper and lower flanges equal to ½ the flange width. Then make the dimension between the left hand edge of the web and the origin equal to ½ of the flange width. Finally make the dimension between the upper edge of the lower flange and the origin equal to the dimension between the lower edge of the upper flange and the origin. This will maintain the design intent when the cross section is modified in step 3.

7. (optional) discuss alternate ways to maintain the design intent.

8. Feature: Extruded Boss/Base – extrude the cross section 6 meters (6000 mm).

9. Save the Part as Baseline I Beam.

Step 2—Cosmos Stress analysis

1. Open COSMOSXpress.

2. In the welcome window, click Options.

3. Confirm that SI units is selected and browse to the folder in which you wish to keep the results. Click Next> to choose the material.

4. Choose Alloy Steel for the material. Click Next> to set restraints.

5. Click Next> again. Then click on the forward face section as shown. Click Next> twice to define the loads.

6. Click Next> again. Confirm that force is selected. Click Next>.

7. Chose the upper face to define where the force will act. Click Next>. [pic]

8. Confirm that Normal to each selected face is selected and input the magnitude of the force. Click Next> twice.

[pic]

9. Confirm that Yes is selected. (You may experiment with No and changing parameters but it will probably only confuse the students.) Click Next>.

10. Click Run—the first piece of information returned is the factor of safety. If you skipped the optional discussion on factor of safety, you should discuss it here. To get the picture shown, I entered 11 in the box and clicked Show me to determine where the lowest FOS is located. Click Next>.

11. Click on Show me the displacement distribution in the model. Click Next>.

12. The displacement distribution is shown.

13. You now know the FOS and maximum displacement.

Step 3—Optimize the Design

The students will now work in teams of two to modify the geometry to obtain the I-beam with the smallest cross sectional area that meets the design criteria. The students are free to modify the flange width and/or height. They are also free to modify the flange height and/or width. The design must have a minimum FOS greater than 5 and a maximum deflection less than 75 mm. NOTE: it is unlikely that a design will exactly meet either criterion. In other words, if the design has a FOS of exactly 5, then the maximum deflection will be less than 75 mm—it will not, in general, be possible to find a design with FOS exactly equal to 5 and deflection exactly equal to 75 mm.

Step 4—the teams prepare an oral presentation using PowerPoint.

Assessment:

o Students will demonstrate skill in creating solid model

o Students will demonstrate skill in conducting stress analysis

o Students will optimize an engineering design subject to two constraints

Resources Used:

None

Copyrighted Materials:

None

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