Post on 01-Jun-2018
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Abstract
The Tensile Test is used to create a Stress-Strain curve from the
application of force on both ends of a sample of material. From the Stress-
Strain graph constructed several properties can be measured or concluded
about the data. For this particular experiment it was necessary to determine
Young’s Modulus yield strength ductility and brea!ing strength of "#$S
$lastic %rass and Steel samples. &ach material endured three trials to
obtain more accurate data. %efore hand it was necessary to measure the
dimensions of each sample before inducing stress upon it in order to have
initial values for ' &longation calculations. (fter conducting the experiment
collecting the data and exporting the data for analysis it was determined
that Steel has the largest Young’s Modulus followed by %rass and "#$S
$lastic respectively. #n regards to yield strength from highest to lowest it is
%rass Steel and "#$S $lastic. %rea!ing strength calculations returned the
same phenomenon as yield strength. )hen considering ductility *'
&longation+ Steel possessed the highest value followed by "#$S $lastic and
%rass respectively.
Introduction
The Tensile Test is well established experiment to measure several
properties of a material. They are such properties such as yield strength
tensile strength elastic properties and ductility. The results of such as test is
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had succumbed to the stress applied it was necessary to evaluate the
change in length and cross sectional area two values calculated by the
software. (fter the experiment analysis and conclusions could be drawn
about the behavior of the materials under tension.
Data
The following data show the measured dimensions of the coupons
using a caliper. These values will become necessary later when determining
factors such as elongation and ductility.
Sampl
e
"#$S
$lastic
2
"#$S
$lastic
3
%rass
2
%rass
3
%rass
4
Steel 2 Steel 3 Steel 4
5ength
*mm+
67.38 67.44 9:.66 9:.6; 9:.:8 67.72 67.7: 67.76
)idth
*mm+
8.78 8.7; 8.7 8.7 4.:6 8.72 8.73 8.7
"eight
*mm+
7.8 7.8 7.76 7.76 7.76 7.7: 7.7: 2.7
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The following data show the stress strain curve created from each trial of
each sample.
7.77&=77 2.77&-72 3.77&-72 4.77&-72 8.77&-727.77&=77
.77&=77
2.77&=72
2. 7&=72
3.77&=72
3. 7&=72
4.77&=72
4. 7&=72
f*x+ >?@ > 7 Tensile Test: Plastic Trial 1
5inear *+
Strain (mm/mm)
Stress(MPa)
Figure 1 HIPS Plastic Trial 1
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7.77&=77 .77&-73 2.77&-72 2. 7&-727.77&=77
.77&=77
2.77&=72
2. 7&=72
3.77&=72
3. 7&=72
4.77&=72
4. 7&=72
f*x+ >?@ > 7 Tensile Test: Plastic Trial
5inear *+
Strain (mm/mm)
Stress(MPa)
Figure HIPS Plastic Trial
7.77&=77 2.77&-73 3.77&-73 4.77&-737.77&=77
.77&=72
2.77&=73
2. 7&=73
3.77&=73
3. 7&=73
f*x+ >?@ > 7 Tensile Test: !rass Trial 1
5inear *+
Strain (mm/mm)
Stress (MPa)
Figure " !rass Trial 1
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7.77&=77 2.77&-72 3.77&-72 4.77&-727.77&=77
.77&=72
2.77&=73
2. 7&=73
3.77&=73
3. 7&=73
f*x+ >?@ > 7 Tensile Test: Steel Trial 1
5inear *+
Strain (mm/mm)
Stress (MPa)
Figure % Steel Trial 1
7.77&=77 3.77&-72 8.77&-727.77&=77
.77&=72
2.77&=73
2. 7&=73
3.77&=73
f*x+ >?@ > 7 Tensile Test: Steel Trial
5inear *+
Strain (mm/mm)
Stress (MPa)
Figure & Steel Trial
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#t should be noted that the Young’s Modulus was ta!en directly from
the calculated slopes of the Stress-Strain graphs created in &xcel. Therefore
there are no calculations performed. "owever the values were averaged
together before being entered into Table #.
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0.2 x MaximumStrainValue = Yield Strenth
0.2 x0.300581 (mmmm)= 0.602 (mm/mm)
From the new strain rate of 7.;73 *mmBmm+ a new trendline can be
drawn parallel to the elastic region. The new line intersects the Stress-Strain
curve at 34.4 M$a.
,uctility will also be computed using data from the stress strain curve.
,uctility is the measure of how much stress a material can withstand once it
has reached plastic deformation. Since ductility can be calculated using
length elongation the measurements for "#$S $lastic %rass and Steel are
37.33' 27.8;' and 47.34' respectively. The previous values were
computed using the following eCuation.
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%rea!ing strength was also a value ta!en directly from the graph so no
calculations were needed. "owever the values were averaged together
before being entered into Table ##.
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Strength. This is not surprising when comparing the strength capabilities of
plastic to metals.
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#n conclusion it should be noted that the tensile test is a very eDective
means of material properties analysis. The experiment was conducted and
data was collected concerning the Young’s Modulus yield strength ductility
and brea!ing strength of three types of materials. &ach material was tested
three times to satisfy scienti1c criteria of accuracy of the results. Several
conclusions could be drawn about the behavior of the materials under stress
some being counter intuitive.