cive 265 - lab 2 - tensile testing of me

8/6/2019 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.

cive 265 - lab 2 - tensile testing of me

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