CIVE 265 - Lab 2 - Tensile Testing of Me
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Transcript of CIVE 265 - Lab 2 - Tensile Testing of Me
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CIVE 265Structure and Properties of Materials
Lab #2 – Tensile Testing of Metals
The mechanical properties of metals under tensile loading are studied in this lab. Two material types,
Steel and Aluminum, are tested to understand the behaviour of metals under tensile loading. Using an
axial tension testing machine, tensile loads are applied to each specimen until failure, and plots of load
vs. displacement are obtained. From these plots, stress vs. strain curves will be generated and the test
results will be analyzed and discussed. Procedure:
The lab was carried out by the course TAs (K. Ghahremani, R. Coughlin) and Lab Technician (R.
Morrison) using the MTS testing frame in the UW Structures Lab.
The employed MTS 810 Material Testing System is an
integrated testing package with loading capacity of 100 KN,
equipped with hydraulic control, hydraulic power, and
hydraulic actuated grips (see Figure 1).
The specimen geometry and specification and loading rates are
based on [ASTM E8-03, “Standard Test Methods for Tension
Testing of Metallic Materials”].
Each specimen was carefully inspected and the required
dimensions, i.e. width, thickness, and gauge length, were
measured at three different points in its reduced section before
each test. Then the specimen was put in the frame and the ends
clamped between two grips, one fixed to the movable
crosshead on top and other fixed to the immobile grip on the
bottom. Each specimen was then loaded beyond yield,
unloaded and reloaded to failure using the MultiPurposeTestware with a prescribed loading rate. This software records
force and displacement, in N and mm respectively, during
testing. After failure (fracture into two pieces), the final cross
section dimensions and elongation were measured.
Figure 1: MTS 810 testing frame.
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Test specimen:
Test Specimens were made according to ASTM E8-03 (see Figure 2). Three types of specimens were
tested: Type 1 (S 1,2,3,4,5) made of Steel 350W, Type 2 (Al 1,2,3) made of Aluminum 6061, and Type
3 (Al-A 1,2) made of annealed Aluminum 6061. Type 3 uses the same base material as Type 2 but
underwent a heat treatment which simulates the effect of welding. The procedure outlined in ASTMB918/B918M-09 was used and describes standard practices for the heat treatment of wrought
aluminum alloys. Annealing 6061 grade aluminum requires the metal to be heated to 765 °F (407 °C)
and maintained at this temperature for 2 to 3 hours. To obtain full annealing, the specimen must then
be cooled at a rate of 50 °F/h (28 °C/h) to 500 °F (260 °C).
Figure 2: Rectangular tension test specimen geometry [ASTM E8-03].
The specimens dimensions before and after testing and loading rates at each stage, i.e. loading,
unloading, and reloading, are summarized in Table 1.
Figure 3. Measuring specimen cross section dimensions and length after failure
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Table 1: Specimen description and loading details.
Dimensions before testing
(mm)
Dimensions after failure
(mm)
Loading rates
(mm per minute)
Symbol MaterialAverageWidth
(W0)
AverageThickness
(T0)
GaugeLength
(L0)
Width
(Wf )
Thickness
(Tf )
Length
(Lf )
Loading Unloading Reloading
S 1 Steel 12.75 9.64 50.80 8.92 6.57 67.33 0.5 1 1-5
S 2 Steel 12.76 9.65 50.80 8.93 6.46 67.72 0.5 1 1-5
S 3 Steel 12.76 9.61 50.80 9.10 6.64 67.53 0.5 1 1-5
S 4 Steel 12.80 9.36 50.80 8.53 6.36 66.54 1.5 3 3-15
S 5 Steel 12.75 9.42 50.80 9.18 6.75 67.00 1.5 3 3-15
Al 1 Aluminum 12.72 9.75 50.80 10.50 6.96 61.00 1.5 3 3-15
Al 2 Aluminum 12.73 9.68 50.80 10.61 6.95 59.82 1.5 3 3-15
Al 3 Aluminum 12.72 9.78 50.80 10.65 6.44 60.94 1.5 3 3-15
Al-A 1 Annealed
Aluminum 12.72 9.76 50.80 9.82 5.81 69.18 1.5 3 3-15
Al-A 2 Annealed
Aluminum 12.71 9.75 50.80 9.30 5.32 70.35 1.5 3 3-15
Three specimens, one of each type, were filmed during testing and the compiled video file, together
with the real time load – displacement histories, is uploaded to UW-ACE.
*Note that the program takes the displacement values from an “extensometer”. The gauge length for
the extensometer is 50.70 mm, i.e. to calculate engineering strain at each point using given histories,
displacement values should be divided by 50.70.
Each group is required to watch the video, set an appointment with one of the TAs to see the fractured
specimens, and write a lab report. The report itself should include the following elements:
1. INTRODUCTION
Introduce the subject in the report and briefly state the purpose and usefulness of the study.
2. DATA ANALYSIS
The purpose of this analysis is to calculate various mechanical properties for the three different metals,
namely: the modulus of elasticity, yield stress, ultimate stress, resilience, toughness, failure strain, and
percent area reduction.
Details of Specimens
Briefly describe the test specimens used for this experiment as summarized in Table 2.
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Table 2: Specimen description and loading details.
Specimen Symbol Loading
Aluminum
Annealed Al - A 1,2Load beyond yield, unload
and reload to failure
As received Al 1,2,3 Load beyond yield, unloadand reload to failure
Steel As received S 1,2,3,4,5Load beyond yield, unload
and reload to failure
Specimen Geometry
Describe the geometry of the specimens using Figure 3 and Table 1.
Figure 3: Typical specimen.
Table 3: Specimen geometry (mm).
Specimen Width (W 0 ) Thickness (T 0 )Gauge Length
(L0 )Area (A0 )
S 1,2,3,4,5
Al 1,2,3
Al-A 1,2
Details of Testing Equipment
Describe the testing machine (briefly). Note the units of measurement used by the machine.
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Measured Data
Generate load vs. displacement curves for each specimen using the data uploaded to UW-ACE.
Describe these curves and note any observed trends. Describe the failure surface for each specimen
type (as mentioned earlier, you can come to TAs’ office in CPH 3654 to see the fractured specimens).
Table 4: Specimen dimensions after testing (mm).
Specimen Width (W f ) Thickness (T f )Gauge Length
(Lf )Area (Af )
S 1,2,3,4,5
Al 1,2,3
Al-A 1,2
Table 5: Description of load-displacement curves.
Specimen Yield Load (kN) Yield Disp. (mm) Max. Load (kN)Failure Disp.
(mm)
S 1,2,3,4,5
Al 1,2,3
Al-A 1,2
Calculated Data
Do the following:
• Plot engineering stress vs. strain curves for Specimens S 1, Al 1, and Al-A 1 in one figure.
Discuss the different properties of the various metals.
• Plot engineering stress vs. strain curves including all the specimens for each metal. Discuss the
variability between the specimens for each metal.
• Plot individual engineering and true stress vs. strain curves for each of the specimens
(engineering and true stress vs. strain on the same plot).
• Study and explain the significance of each plot. Discuss the practical value of each plot.
Note: Make sure that the plots originate at zero stress and zero strain. Stress units should be in MPa.
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Mechanical Properties
Do the following:
• Calculate the material properties in Table 6 for each of the specimens.
• Explain the practical importance of each material property.
Table 6: Mechanical properties.
SpecimenElastic
Modulus,E (MPa)
YieldStress, f y
(MPa)
UltimateStress, f u
(MPa)
Ductility%EL
Ductility%RA
ResilienceModulus,U r (J/m3)
Toughness(J/m3)
S 1,2,3,4,5
Al 1,2,3
Al-A 1,2
3. DATA INTERPRETATION
This section can be used to discuss the differences in the observed material behaviour of the steel and
aluminum materials tested, and the effect of annealing on the behaviour of aluminum.
Sources of Error
Describe the various possible sources of error in this lab.
4. CONCLUDING REMARKS
Summarize the findings.
5. REFERENCES
Document the references considered for preparing the report.
6. APPENDICES
Categorize the appendices and label each of them. The appendix can include the required plots (or they
can be placed in the main body), extra pictures, or any important information. Sample calculations must
also be included in the appendix.