Transcript Document

PAPER RIVER CHASM BRIDGE
ME104Q
Team Boomerang • Mechanical Engineering • University of Rochester
Executive Summary
1 inch on
inside after
bend
The premise of this experiment is built on the idea that all materials
have certain properties concerning stress and yield strength that
make virtual simulation of them both possible and very accurate.
This idea has revolutionized the manufacturing process, and has
given way to a new realm of efficiency.
A bridge made of aluminum must support a load with minimal
deformation. A loading deck holding two people is placed over the
center of the bridge. While supporting this load, a long piece of
paper must be pulled out from under the deck. The supported load
will be divided by the weight of the finished bridge. The highest
resulting quotient will receive the highest number of points. In our
case, a unique construction of a C-beam aluminum (6061-T651)
bridge was modeled and tested in ANSYS Workbench. Changes
were made, and the model was retested, until the bridge met our
specifications. These virtual models allowed us to simulate several
prototypes without actually having to build them. We kept the
model that best fit our needs, and drew the assembly and part
drawings to have it actually physically built. Holes were drilled into
the finished product at low stress areas to reduce weight. In both
construction, and amount of material, the safety factor was pushed
as far to the threshold of 1 as possible.
We then tested these prototypes with a slightly
higher than intended load. The prototype that
fares the best is kept, and tested further to
perfect its design. The colors show areas of
varying stress. This allowed us to know
where to put the holes without sacrificing
strength.
We modeled numerous prototypes in ANSYS
Workbench. This program allowed us to
specify size, material, design, and load.
Bridge
The People
We then turned the details of the accepted prototype into
assembly and part drawings. This allowed simple
manufacture and construction in the machine shop. We
specified all details.
Loading Bar
Table Top
Team Boomerang:
Steven Vollmer
Engineering Student
Max Sicherman
Engineering Student
Alexandra Wikstrom
Engineering Student
Patrick Ripp
Engineering Student
**All excess weight is put onto the wooden
plank
Working in collaboration with:
Dr. D.J. Quesnel
Mechanical Engineering
Professor
Paper River
Wooden
Plank
The University of Rochester
Machine Shop
This work was made possible with the gracious support of
the University of Rochester Department of Mechanical
Engineering, under the direction of Stephen J. Burns.
The following pictures represent the expected
performance of the bridge based on simulations done in
ANSYS Workbench. This view displays the Equivalent
Stress, or the stress the bridge will suffer.
8.5 inches
The final product will be tested with the loading deck shown
above. Two people will stand on the loading deck, and their
weight, along with the weight of the deck, provide the total
load. We will measure the resulting deformation.
Summary
•Our bridge was designed, modeled, and tested within ANSYS
Workbench.
Bridge Statistics:
Load Used for Simulation
315 lbs
Bridge Mass
0.27654 lbm
Material Used
6061-T651
Parts Attachment
Pop Rivets
•Our bridge was built, more or less, to our specifications in the
University of Rochester machine shop.
•The deformations and stresses that are observed in the ANSYS
calculations, although close to one, are satisfactory.
•The bridge, assuming the ANSYS calculations are correct and account
for environmental error, should perform as expected.
Figure of Merit = Mass Supported
Mass of Bridge
Figure of Merit = _______________
Pass_____
The finished product was then built to specifications. We
measured it and scrutinized every detail to insure
satisfaction. Obvious defects were reported and fixed.
Fail_____
•The bridge should support the expected load with less than the shown
deformation (the force in the simulations was overestimated).
ANSYS simulation of the Maximum
Shear Stress. This shows where the metal
is most likely to shear, and where it
suffers shear stress.
ANSYS Simulation of total deformation.
This was valuable in determining that this
prototype would work. The displacement
is small enough to be satisfactory.
ANSYS simulation of Safety Factor. We
pushed our safety factor as close to 1 as
possible. This was one of the important
concepts of the experiment.
Presentation:
December 13th, 2004
11:30 am – 12:30 pm