Error! No text of specified style in document.
Laboratory Experiment # 1
1
Objectives:
The purpose of the experiment to determine the tensile properties (Yield strength,
Ultimate strength and Modulus of Elasticity) of materials.
Introduction:
The composite are those materials that are prepared by mixing the two constituent materials.
The composite are used so that we can combine the two materials having two different
special qualities to get a material having the properties of both. They can serve such function
that is totally unique due to their unique properties. As we do it in Reinforce Concrete case,
concrete is a material having good compression strength and the steel has good tensile
strength. We combine them the concrete that is called Reinforce concrete that has equally
good compression strength as well as good tensile strength. The mechanism of failure
between fiber and plastic reinforced structure subjected to tension are following:
Developments of cracks in matrix.
Individual fibers lead to failure.
Fiber failure
Major damage leading to failure.
The objective of this test is to subject a composite to a tensile load and the purpose of this test
is to check that to how much extent the composite materials can withstand load when they are
subjected to tensile loads.
Theory:
Tensile Testing
1.1 What is tensile testing?
There many types of mechanical tests, most basic type of test is tensile test which is also
called tension test. These types of tests are cheap in cost, simple and follow the standard.
When we apply the tensile load during this test, we can check the behavior of material very
quickly. In this way we can judge the strength of materials also.
1.2 Why tensile testing?
We can obtain the deep understanding regarding materials behavior in this test. When we
apply the tensile load, the materials go to elongation, after crossing the plastic region meet to
2
the rupture point. These types of test give complete profile in form of curve of material
behavior. Rapture point is also known as "Ultimate Strength" or UTS.
Figure 1 Stress-Strain Curve
2. Materials’ Properties:
Properties of materials are very helpful during the selection phase of the material for an
application. The performance and function of materials totally based on their properties.
There are long list of properties, few of important properties are categories in following
groups that are describes below:
Mechanical Properties, physical properties, chemical properties, manufacturing
properties.
3. Formulas:
( )=
∗
( )=
∗
( )=
∆ ∗ ∗
ℎ( )=
∗
3
Apparatus:
Tensile Testing Machine.
Vernier caliper.
Aluminum & Steel Specimen.
Glass Fiber Composites Specimen.
Figure2 Tensile Testing Machine
Figure 3 Vernier caliper
4
Figure 4 Steel Specimens after Fracture
Procedure:
First of all take the all specimen’s dimension like diameter and gage length. Unit of
these parameters in millimeter.
After this, aluminum specimen put into the tensile machine according to
recommended gage distance.
Applied the tensile load on this specimen.
As load applied the elongation in the specimen increased. The process of applying
force is continuing until specimen breaker.
After breakage, specimen divided into two pieces.
Plot the required graphs from the data that obtained from the tensile test machine
software with respect to applied load.
Calculated the materials properties that required in this experiment.
Repeated the same procedures for all specimens.
Data Analysis & Graphs:
Aluminum Specimen (Load Vs Deflection Curve and Stress Vs Strain Curve)
LOAD VS DEFLECTION CURVE
FOR ALUMINUM
5000
4000
3000
LOAD (N)
2000
1000
0
-0.001 0 0.001 0.002 0.003 0.004 0.005
-1000
DEFLECTION (M)
5
STRESS STRAIN CURVE FOR
ALUMINUM
500000000
400000000
STRESS (N/M2)
300000000
200000000
100000000
0
-0.02 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14
-1E+08
STRAIN (M/M)
Steel Specimen (Load Vs Deflection Curve and Stress Vs Strain Curve)
LOAD VS DEFLECTION CURVE FOR
1018 STEEL
5000
4500
4000
3500
3000
2500
LOAD (N)
2000
1500
1000
500
0
-1.00E-03 -500
0.00E+00 1.00E-03 2.00E-03 3.00E-03 4.00E-03 5.00E-03
DEFLECTION (M)
STRESS STRAIN CURVE FOR 1018
STEEL
600000000
400000000
STRESS (N/M2)
200000000
0
-0.02 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14
-2E+08
-4E+08
-6E+08
STRAIN (M/M)
6
Glass Fiber Composites (Load Vs Deflection Curve and Stress Vs Strain Curve)
LOAD VS DEFLECTION CURVE FOR
GLASS FIBER COMPOSITES
7000
6000
5000
4000
LOAD (N)
3000
2000
1000
0
-0.0001 -1000 0 0.0001 0.0002 0.0003 0.0004 0.0005
DEFLECTION (M)
STRESS STRAIN CURVE FOR
GLASS FIBER COMPOSITES
400000000
350000000
300000000
STRESS (N/M2)
250000000
200000000
150000000
100000000
50000000
0
-50000000 0
-0.02 0.02 0.04 0.06 0.08 0.1 0.12 0.14
STRAIN (M/M)
Experimental Outcomes:
Material Yield Strength % Tensile % Mod. of %
diff* Strength diff* Elasticity, E diff*
Meas. Expe Meas. Expect Meas. Expect
(MPa) ct. (MPa) . (GPa) .
(MPa (MPa) (GPa)
)
2024-T3 320 270 18.5% 420 400 5% 64 70 -8.5%
Aluminum
1018 Steel 270 250 8% 435 400 8.75% 145 200 -27.5%
Glass Fiber 480 500 4.16% 2500 3000 2% 75 70 -6.25%
Composites
7
Conclusion:
The original objective of this experiment was to find the relationship between normal stress
and strain for four metal coupons and compare experimental results with published values.
Based on the above results, the author determined that ductile materials gives a warning
(deformation) before breaking, thus making ductile materials safer to use as structural
materials. Different materials have different yield stresses, and ultimate stresses, hence
making the behavior of each material defers. Based on the graphs, Steel has the highest
strength and modulus of elasticity of all the four coupons, making it the sturdiest building
material. Aluminum has a much lighter weight and a lower ultimate stress that makes it
convenient enough for designing airplane frames.
References:
ASM Metals Reference Book, Third edition, Michael Bauccio, Ed. ASM International,
Materials Park, OH, 1993.
Metals Handbook, Vol.2 - Properties and Selection: Nonferrous Alloys and Special-Purpose
Materials, ASM International 10th Ed. 1990.
Structural Alloys Handbook, 1996 edition, John M. (Tim) Holt, Technical Ed; C. Y. Ho, Ed.,
CINDAS/Purdue University, West Lafayette, IN, 1996.
Mechanics of Materials: Bending – Normal Stress Mechanics of Slender Structures | Boston
University." Mechanics of Slender Structures RSS. N.p., n.d. Web. 18 June 2017.
<http://www.bu.edu/moss/mechanics-of-materials-bending-normal-stress/>.
