Teach lesson
Tensile Testing: strength and ductility from a real materials lab
Students use the Materials remote lab to observe a tensile test, interpret force-displacement evidence, identify elastic and plastic regions, and compare strength and ductility without inventing unsupported material data.
Learning Outcomes
Explain what a tensile test measures and what it does not measure by itself.
Identify elastic response, plastic deformation, maximum force, and fracture from lab evidence.
Distinguish strength from ductility using force-displacement or result-image evidence.
State the extra specimen information needed to convert force-displacement to engineering stress-strain.
Write a source-bounded interpretation of a real tensile result.
Student activity preview
Activity Content
Preview only. In a class session, students can fill in responses and submit their work to the teacher.
1. What a tensile test can tell you
15 min
A tensile test pulls a specimen until it deforms and eventually fractures. The machine records how much force is applied and may show crosshead travel, specimen extension, or both depending on the interface. From that evidence you can infer several material behaviors, but only if you keep the terms separate.
- Elastic behavior: the specimen returns toward its original length if the load is removed.
- Plastic behavior: permanent deformation remains after the load is removed.
- Strength: how much load or stress the specimen resists before yielding, reaching maximum load, or fracturing.
- Ductility: how much plastic deformation occurs before fracture.
- Test/specimen stiffness: how steep the early, approximately linear part of the force-displacement curve is for this setup. Do not call it Young's modulus unless specimen geometry and gauge strain are known.
Tensile test in Materials
The Materials lab uses recorded real tests. Treat the result as experimental evidence, not as an ideal textbook curve.
If specimen dimensions are known, force and extension can be converted into engineering stress and strain:
Engineering stress and strain
\sigma = \frac{F}{A_0}
\qquad
\varepsilon = \frac{\Delta L}{L_0}
In this activity, do not invent missing dimensions. Crosshead travel is not automatically the same as gauge-length extension measured by an extensometer. If the lab screen gives force and crosshead travel only, analyze the force-displacement curve and state what extra information would be needed for stress-strain or Young's modulus.
Explain the difference between strength, stiffness, and ductility in your own words. Use one sentence for each term.
When is it valid to calculate engineering stress from a tensile-force result?
2. Run and document a tensile test
25 min
Use the Materials lab route for Tensile test. Select one material/alloy/treatment route as directed by your instructor. If time allows, run a second treatment of the same alloy so the comparison is meaningful.
Example tensile result screen
Record the evidence that the student interface shows: video observations, result image, curve/table values, or exported data if the interface provides it.
Open Materials and run a tensile test
Open the Materials lab from this activity.
Choose Tensile test.
Select the material, alloy, and treatment assigned by your instructor. Recommended first route: aluminium / AW6060 / as delivered.
Observe the test video and result screen.
Record at least six points or features from the force-displacement evidence: start, early linear region, yield/transition if visible, maximum force, near-fracture, and final/fracture observation.
Repeat for a second treatment or material if your instructor asks for a comparison.
Tensile-test evidence
Use one row per point or feature. If the UI provides a CSV/table, use values from it. If it provides a graph/result image only, record readable coordinates or feature descriptions and label them as graph-read estimates.
| Material / alloy / treatment | Point or feature | Displacement / travel mm | Displacement source | Force kN | Area/gauge length known? | Visual/result observation | Evidence source |
|---|---|---|---|---|---|---|---|
Which two rows in your table are the strongest evidence for maximum load and ductility? Name the rows and explain why they are useful.
3. Interpret the tensile curve
25 min
Identify the region that is most likely elastic. What evidence from the force-displacement curve or result screen supports your choice?
Use your table to make one statement about strength and one statement about ductility for the specimen. Each statement must cite a row or value.
Suppose two specimens have the same maximum force, but one has twice the cross-sectional area. Would they have the same tensile strength as stress? Explain using the stress equation.
4. Write the lab interpretation
10 min
Write a concise tensile-test interpretation for your specimen. Include: the specimen route, the strongest evidence for strength, the strongest evidence for ductility, one limitation of the available data, and whether you are making a force-displacement or stress-strain claim.