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CT Failure Modeling
Experiment Data
Pt. 2Mary Catherine Whitney3 June 2013
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Method Summary
Velocity Test
Configure bow to launchrod at 50mph
Shoot rod verticallydown into tube against arock
Used brass rods/tubes
Steel tubes could not be
found Compare brass rods to
brass tubes to see if thereis a difference
Gradual Displacement Test
Apply force to contained
rod until it is displaced a
set amount of inches
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Method
Gradual Displacement Test
Reduced Friction
Apply force to contained
rod until it is displaced a
set amount of inches Every half inch hit the
tube to reduce force of
friction
Gradual Displacement Test-Springback
When rod has been
displaced set amount of
inches, remove oneclosed off side
Measure movement
(springback)
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Materials Description
Rods/Tubes
Steel Rod
D: 0.125 in
L: 48 in
Brass Rod
D: 0.125 in
L: 36 in
Brass Tube OD: 0.125 in
ID: 0.0118 in
L: 36 in
Guide Tube
Plexiglass
OD: 4.75 in
ID: 4.25 in
L: 5 ft
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Results Summary
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Strain from Gradual
Displacement test
Total Length: 48 in
Compression 3in
Axial Strain
Compressed 3 in
3/48 = 0.0625
6.25%
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Velocity Tests 1 4 (brass)
Vertical Velocity TestGuide Tube ID: 4.25 in
Pull Length: 20 in
Tubes and rods buckled before hitting the
ground due to force of bowtest failure
Bottom of rod7
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Grad Test 5
Gradual Displacement Test
Reduced Friction
Guide Tube ID: 4.25 in
Compression Length: 5 inches before
deformation
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Test 6
Gradual Displacement Test
Springback
Guide Tube ID: 4.25 in
Compression Length: 3 inches
Top removedside administering the force
Springback length: 3 in; back to initial position
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Test 6 - video
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Test 7
Gradual Displacement Test
Springback
Guide Tube ID: 4.25 in
Compression Length: 3 inches
Bottom removedside not administering the
force
Springback length: 2 in
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Conclusions
Velocity Test
Failure to achieve results
Gradual Displacement Test -Springback
Removed top
Rod that had been
displaced 3 in is slightlydeformed but returned to
initial starting position
Removed bottom
Rod jumped out of tube,
moving 2 inches down Top of rod slightly
deformed
Gradual Displacement Test
Reduced Friction
Rod could be displaced more
if force of friction is reduced
Prevents lockup
Rod only slightly deformed
while being displaced 5
inches
Axial strain: 5/48 = 0.104; 10%12
