Engineering Homework Help

ME 220 Materials Lab
Lab 6 – Tensile Test

Objective
To determine the strength and several elastic and inelastic properties of various materials and to observe
the deformation and fracture behavior of materials under load.

Experimental Apparatus
Universal testing machine (UTM), aluminum/steel/cast iron rod, digital extensometer, digital caliper
Safety Requirements
Please wear safety glasses in the lab. You are not allowed to start the testing machine unsupervised.
Experimental Procedure

1. Measure cross sectional area of steel rod

2. Mark off 2-inch gage length

3. Place the rod in the load cell

4. Attach the extensometer to the specimen

5. Calibrate the load cell and the strain gage extensometer

6. Turn on the load cell

7. Record strain every 500-lbs until it fractures

8. Take off extensometer once necking forms and record using a ruler (For brittle materials, take off the
extensometer before estimated fracture around 12~15k-lbs)

9. Repeat steps 1-8 using the aluminum rod/cast iron rod
Virtual Lab Link
https://content.steeluniversity.org/simulators/ten…
You can use the above link to perform a simulated tensile test.
Exercises
1.Using the virtual tensile test data, calculate the upper yield stress, lower yield stress, tensile strength,
elastic modulus and elongation.
2. (a) Using experimental data for different materials (C1018 steel, 6061 Aluminum and cast iron),
compute instantaneous strain and stress during the tests. Report sample calculations.
(b) Plot the stress-strain relationship. Based on the graph, discuss whether it is brittle or ductile material
and whether the graph line meets your expectation. Explain the reason.
(c) Estimate Young’s modulus in the elastic region based on the graph.