Mike Burgstrom • Jeff Cosgrove •
• Trevor DiMarco • Laura Wong
• Consider customer requirements
Load on any object
• Brainstorm ideas to create inexpensive
models from low cost materials
(i.e. cardboard, paper, etc.)
results in stress and
The purpose of the project was to
become familiar with bridge design
through computer-aided engineering
(CAE), specifically the ANSYS program.
possibly deformation.
Stress is an
accumulation of the
• Perform finite element analysis (FEA)
on design using computer simulation
tension and
compression within
an object.
ANSYS allows one to study the safety
factors and the results of deformation
and stress that are caused on a certain
object through load.
This picture shows the geometry of the bridge.
The bridge was constructed of two support legs
made from 6061-T0 aluminum, and the deck was
constructed from 6061-T651 aluminum. The structure
is held together with 8 1/8” pop rivets.
• Analyze results
This picture shows the total deformation of the
bridge. The maximum deformation is located beneath
the bridge, which is represented by the red area.
Deformation is the
• Alter design until satisfied with results
• Assemble the prototype
displacement of any
component within the
• Physically test the prototype
bridge, or more
generally any
alteration from the
original shape.
Fail
Fail
Pass
Design
Computer Test
Pass / Fail
This picture shows the amount of equivalent
von-Mises stress that is created when a
load of 565 pounds is placed onto the bridge.
Pass
Test Prototype
Build Prototype
Pass / Fail
Build
Today the design process follows a specific form that is
cheaper and less time consuming. One would first make a
design then simulate a test by using a computer program. If
the simulation passes then one can move on to building a
prototype. The prototype is then tested, if it passes then
production can begin.
10.65”
The 6061-T651 has higher yield
properties and was used for the deck of
the bridge. The 6061-T0 has lower yield
properties making it more appropriate for
bends, therefore it was used for the
multiple bended supports of the bridge.
.75”
.25”
Notes:
2”
1”
Material 6061-T651 sheet Aluminum
Drill holes when flat
This picture shows the safety factor associated with
the Equivalent von-Mises stress on the bridge.
Fold 90 degrees in two places along dotted lines to form parts
as shown in drawing FK-003. Both bent legs should be same
length
Break sharp edges
5”
Shear to size
All dimensions in Inch Units
Unless otherwise indicated, use default tolerances
x.x +/- .050”
x.xx +/- .010”
x.xxx +/- .005”
Angles +/- 2 degrees
2”
.0625
”
Fat Kids
Designed by
Fat Kids
6061-T651
Aluminum
The purpose of a safety factor is
to account for errors that occur in
the design or fabrication of the
bridge. When designing and
simulating the bridge, one should
seek a safety factor greater than
1.00 and less than 4.00 with a
goal between 2.00 and 3.00.
Drawing No.
FK-001
Quantity
1
Required
Descriptive Part Name
Bridge Deck
Drawing Type Drawing Size Scale as Drawn
Detail
This picture shows the amount of Maximum Sheer
Stress that is created when a load of 565 pounds is
placed onto the bridge.
A 8 x10
1:1, 1indrawing=1inpart
Safety Factor Results
Name
Safety Factor Safety Margin
Equivalent Stress
1.38
0.38
Sheer Stress
1.23
0.23
Scale as Printed
1:1 =100%
Checked by Engineer
M. E. Engineer
Drawing Issue Date
Date of This Revision
12/6/04
12/6/04
Engineer Phone #
1/8" Pop
Rivet
The safety factor based on the maximum sheer stress is lower
then the safety factor of the equivalent stress, which proves
that the maximum sheer stress is a more conservative theory.
6061-T0
Aluminum
This picture shows the safety factor associated with
the maximum sheer stress on the bridge.
Here is the original paper model next to
the aluminum prototype.
The simulation made it apparent that there
were two different types of stress that had
a major impact on the design. The
Maximum Sheer Stress proved to be the
more conservative theory. Accordingly,
the Safety factor associated with the
Maximum Sheer Stress was more
conservative than the Safety Factor
associated with the Equivalent Stress.
Due to the fact that the Maximum Sheer
Stress is more conservative, it was chosen
as the stress theory used to determine
whether the bridge was acceptable. The
results of the Maximum Sheer Stress were
used as a basis to determine the safety
factor of the designed bridge. Based on the
analysis and information acquired, the
bridge design used was implemented and
tested.