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Winner Discover Sensors Award
Waterford Inst. Of Tech. 2010
Dungarvan CBS
Philip Coffey, Gary Hurley, Joseph FoleyTeacher
Mr. Eanna McGrath
Look at what forces can do to a bridge.
What Is a Newton?
A Newton is the unit of measurement for a
Force
What Is One Newton?
1 apple=
1 Newton
Joseph shows that
Forces in Pairs
Newton’s Third Law
Newton’s third law states that every
action has an equal and opposite reaction
Philip demonstrates this law using
two force sensors to
measure the forces acting in
opposite directions upon an elastic band.
Now to our bridge
But First,What are many bridges built from?
I beams
But why I beamsWhy not Box section for example?
I beams are used because they are strong and can resist tension, compression and torsion forces. However they are lighter and cheaper than box
section.
And that’s why I beams are used
We are investigating the forces acting on various
parts of our bridge as a car travels across it
To do this we use four load cells on the bridge connected to a laptop.
Load Cells
Typical forces on the bridge.
What can affect the forces acting on the bridge?
What about a pothole?
To demonstrate how a pothole can affect the forces on a bridge.
A force plate is used. Gary applies a force by jumping on it.
As you can see by the spike the force acting on the force plate is almost quadrupled when Gary crashes
back down.
Now we must simulate a pothole on our bridge.
We use an elastic band over the road to simulate this
situation.
Typical forces on the bridge with a
pothole
Now look at the difference between the two graphs
Without the pothole
With the pothole
WithWithout
Comparing the graphs without and with a pothole.
Large Spike Caused By Pothole
Imagine the advantages sensor technology offers to engineers in building bridge prototypes and
testing new designs.
This enables them to research and anticipate forces on a bridge.
Avoiding potholes in the world of
construction...
...is just as important as avoiding
bunkers in the world of golf.
As Gary says “The stresses involved in both are often the
same”.