1.0 Objectives
- To obtain a general understanding of how different materials and cross sections behave under uniaxial tensile loading.
- To determine the stress-strain relationship and compare mechanical/material properties of various materials and cross sections.
- To obtain the mechanical properties: the modulus of elasticity, the yield stress, the ultimate stress, the fracture stress and the ductility ratio.
2.0 Introduction
The tensile test is the most commonly performed and simplest among all mechanical tests. In this experiment, a specimen is subjected to a gradually increasing uniaxial load until failure occurs. The typical testing procedure is to deform or stretch the material at a constant speed.
Circular and rectangular cross-section specimens made of steel, copper/aluminum, and plastic (polypropylene) will be tested. The load-deformation data is recorded during the experiment so this data can be plotted once the procedure is complete.
Students will learn how to properly conduct a tensile test and obtain the relevant material properties from the results. Further, students will discover how different materials as well as different cross sections (strip versus dog-bone per ASTM E8/E8M) behave under similar loading conditions.
Background
Mechanical testing plays an important role in evaluating fundamental properties of engineering materials (modulus of elasticity, Poisson's ratio, ultimate strength, yield strength, fracture strength, resilience, toughness, % reduction in area, and % elongation) as well as in developing new materials and controlling the quality of materials for use in design and construction.
Ductile vs. Brittle Failure
Ductile materials will neck down through the plastic range before rupture. Brittle materials do not neck down significantly — instead they fail sharply and abruptly at the maximum load because they do not exhibit much plasticity.
3.0 Theory and Equations
Tensile testing applies an axial pulling force to a standard specimen until failure occurs. The key properties derived from this test include yield strength, ultimate tensile strength (UTS), and elastic modulus (E).
Stress is a measure of the intensity of an internal force, defined as the force P per unit area A. Strain is a measure of the deformation, defined as the change in length divided by the original length.
Universal Testing Machine (UTM) Schematic
Figure: Schematic diagram of a Universal Testing Machine showing the main components including load cell, grips, specimen, extensometer, and hydraulic actuator.
Mechanics Solver (Hover to animate)
1. Stress (Engineering)
2. Strain (Engineering)
3. Young's Modulus
4. Percent Elongation
5. Percent Reduction of Area
6. Ductility Ratio
Key Definitions
Proportional Limit: Stress at which the straight-line portion of the stress-strain curve ends.
Elastic Limit: Maximum stress for which stress is directly proportional to strain (material deforms plastically beyond this).
Yield Point: Point after which significant increase in strain occurs with little or no increase in stress.
Ultimate Strength: Highest value of apparent stress on the stress-strain curve (UTS).
Fracture Strength: Value of stress at the point of final fracture.
Nominal Fracture Stress: Breaking load / Initial cross-sectional area.
Actual Fracture Stress: Breaking load / Final cross-sectional area.
Material Response During Loading
Original
L₀, A₀
Elastic
Recoverable
Plastic
Permanent
Necking
Localized
Fracture
Failure
4.0 Apparatus
The following equipment and materials are required for the tensile test experiment:
Universal Testing Machine (UTM)
Vernier Caliper
Steel Ruler
Test Specimens
(Steel, Copper/Aluminum, Plastic/PP)
Note: Ensure you compare strip and dog-bone sample geometry (ASTM E8/E8M standard).
5.0 Brief Procedure
1. Measure the dimensions of each test specimen before and after the test and fill in Table 1. Mark the gauge length on the test specimen.
2. Ensure that you should be able to compare strip and dog-bone sample (ASTM E8/E8M standard).
3. Switch on the Universal Testing Machine (UTM).
4. Mount the test specimen in the grips of the machine.
5. Apply and record the load and the corresponding deformation.
6. Repeat steps (1) to (5) for various types of test specimen.
⚠️ Important: Step-by-step procedure to run the machine and experiments should follow the instructions as stated on the machine.
5.1 Safety Measures
The following safety precautions must be observed when conducting tensile testing to prevent injury and equipment damage.
1 Personal Protective Equipment (PPE)
- • Always wear safety glasses or goggles to protect eyes from flying fragments during specimen fracture.
- • Wear closed-toe shoes and avoid loose clothing that may get caught in the machine.
- • Use hearing protection if the machine generates loud noise during operation.
2 Machine Operation Safety
- • Never operate the UTM without proper training and supervision from the lab instructor.
- • Keep hands and fingers away from the grips and moving parts during testing.
- • Ensure the emergency stop button is accessible and know its location before starting.
3 Specimen Handling
- • Handle specimens carefully as metal edges may be sharp and cause cuts.
- • Ensure the specimen is properly aligned and securely gripped before applying load.
- • Stand clear of the specimen during testing as it may eject fragments upon fracture.
4 General Laboratory Safety
- • Keep the work area clean and free from obstructions.
- • Do not leave the machine unattended during operation.
- • Report any machine malfunction or unusual behavior immediately to the instructor.
- • Know the location of the first aid kit and fire extinguisher in the laboratory.
Important: Students who fail to follow safety procedures may be asked to leave the laboratory. Safety violations will be reported to the academic supervisor.
6.0 Result
Present your tensile test results in a clear and traceable format. All tables and figures must include units, labels, and proper numbering.
1. Tabulate measured specimen dimensions (d₀, L₀) and the calculated cross-sectional area (A₀).
2. Provide the raw load-extension data used to generate the stress-strain curve.
3. Convert the raw data into engineering stress-strain data and show at least one sample calculation with correct units.
4. Plot the engineering stress-strain curve and label key points including the proportional region, yield strength, UTS, necking onset, and fracture point.
5. Determine the elastic modulus (E) from the slope of the initial linear portion of the stress-strain curve.
6. Include a clear sketch or photo of the fractured specimen with the fracture appearance and necking location marked.
7.0 Discussion
Please login and complete all 7 discussion items below. Your responses will be included in your lab report.
7.1 Comparison and Discussion of Results in Table 4
Compare the results presented in Table 4 with the reference values. Discuss the potential reasons for any differences observed in the tested specimens.
7.2 Comparison of Mechanical/Material Properties
Compare and contrast the mechanical and material properties of the tested materials, highlighting both similarities and differences.
7.3 Yield Point vs. Yield Strength
Distinguish between the yield point and yield strength on a stress-strain curve. Identify which parameter provides a more accurate indication of a material's suitability for a specific tensile application.
7.4 Proportional Limit vs. Elastic Limit
Differentiate between the proportional limit and the elastic limit for each material. Determine which limit is a more critical indicator of a material's mechanical behavior.
7.5 Advantages of Stress-Strain Diagram
Discuss the advantages of using a stress-strain diagram over a load-deformation diagram for presenting test results.
7.6 Strip vs. Dog-bone Specimen Comparison
Compare between strip versus dog-bone specimens and discuss any differences or criteria needed to conduct the tensile test.
7.7 Graph Comparison of Strip vs. Dog-bone
Compute the graph comparison of strip versus dog-bone stress-strain diagrams and indicate the areas that could/may possibly show differences.
8.0 Tensile Test Worksheet
Record your experimental data below. Login to save and export your worksheet.
Table 1: Dimension of the tested specimen
Material: Steel/Copper/Aluminum | Type: Rectangular/Round
| Material | Initial (unit: mm) | Final (unit: mm) | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| L0 | A0 (mm²) | d0 | b0 | h0 | Lf | Af (mm²) | df | bf | hf | |
| Steel | ||||||||||
| Copper | ||||||||||
| Aluminum | ||||||||||
| Plastic/PP | ||||||||||
d = diameter; b = width; h = height/thickness; L = length; A = area
Table 2: Observation data for the tested specimen
| No | Force (N) | Elongation (mm) | Stress (Pa) | Strain |
|---|
Table 3: Observation load for the tested specimen
| Material | Load at Elastic Limit (N) | Load at Upper Yield Point (N) | Load at Lower Yield Point (N) | Ultimate Load (N) | Breaking Load (N) |
|---|---|---|---|---|---|
| Steel | |||||
| Copper | |||||
| Aluminum | |||||
| Plastic/PP |
Table 4: Properties for the tested specimen
| Material | Proportional Limit Stress (Pa) | Nominal Fracture Stress (Pa) | Actual Fracture Stress (Pa) | % Reduction in Area | Strain | % Elongation | Ductility |
|---|---|---|---|---|---|---|---|
| Steel | |||||||
| Copper | |||||||
| Aluminum | |||||||
| Plastic/PP |
Table 5: Percentage error of the tested specimen
| Material | Properties | Modulus of Elasticity (Pa) | 0.2% Offset Yield Stress (Pa) | Yield Stress (Pa) | Ultimate Stress (Pa) |
|---|---|---|---|---|---|
| Steel | Experimental | ||||
| Reference | |||||
| % Difference | |||||
| Copper | Experimental | ||||
| Reference | |||||
| % Difference | |||||
| Aluminum | Experimental | ||||
| Reference | |||||
| % Difference | |||||
| Plastic/PP | Experimental | ||||
| Reference | |||||
| % Difference |
Note: Yield stress = Yield load / initial cross-sectional area | Ultimate stress = Ultimate load / initial cross-sectional area | Nominal fracture stress = Breaking load / initial area | Actual fracture stress = Breaking load / final area
📷 Specimen Photo Documentation
Capture photos of your specimen before and after the tensile test. These images will be included in your lab report.
1 Before Test
2 After Test (Fractured)
📝 Important Note: The generated PDF serves as supporting documentation only. Students are required to prepare a formal lab report using Microsoft Word and attach the downloaded PDF as an appendix to their submission.
Virtual Tension Lab
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Tensile Test Quiz
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Lab Assessment Rubric
MEQ 491: Laboratory Report Rubric (March 2025)
| Item / Criteria | Excellent (9-10) | Good (7-8) | Satisfactory (5-6) | Poor (3-4) | Very Poor (0-2) |
|---|---|---|---|---|---|
| 1. Appearance, Organization, Front Page | All lab sections in correct order, well formatted, very readable, neat. Few spelling/grammar errors. Complete front-page info (title, names, date, signature). Tape/ring binding. Own self cover report with computer typing. Submit in single PDF format. | Sections in correct order, good formatting. Some spelling/grammar errors. Missing one piece of information except title and name. Tape/ring binding. Few improper format issues. | Sections in order, rough but readable formatting. Multiple spelling/grammar errors. Missing two pieces of information. Stapled without binding. Improper own self cover (no logo, no title, etc). | Sections out of order, sloppy formatting. Too many spelling/grammar errors. Missing more than two pieces of information. Stapled at the end. | Most of the 'poor' conditions are not met. (Score 0) |
| 2. Objective and Theory Information | All objectives clearly identified and stated in new sentences. Detailed paragraph of prior knowledge. Includes outside research. | All objectives identified but somewhat unclear. Some copied directly with some attempt at new sentences. Detailed prior knowledge paragraph. | Objectives partially identified and unclear. Mostly copied from lab manual. Theory mostly copied with some new sentences. | Objectives may not be identified and not clear. Some objectives missing. Very little prior knowledge described. | Most of the 'poor' conditions are not met. (Score 0) |
| 3. Apparatus and Procedures | All equipment and materials listed. Detailed, labeled diagrams. Clear step-by-step numbered procedures. Includes safety tips/guidelines. Safety report with pictures attached. | Vital items listed with maybe one omission. Includes diagram. Clear step-by-step procedures. Procedure mostly copied with some new sentences. Safety report attached but lacks picture. | Some items listed with many omissions. Necessary diagram missing. Procedures not clear, not enough, confusing. Procedure mostly copied from lab manual. | Most items not listed. Diagram missing. Procedure very incomplete and confusing. | Most of the 'poor' conditions are not met. (Score 0) |
| 4. Results — data, graphs, calculations (×2 weight) | Results correct, clearly recorded and organized with visible trends. All figures/graphs/tables correctly drawn, numbered with titles/captions and units/labels. All calculations shown. Example calculation with MS Word equation formula. | Results correct, clearly recorded but trends not obvious. Minor problems in figures/graphs/tables. Units/labels included. A few calculations missing. A few equations use formula. | Some results missing, unorganized and incorrect. Some figures/graphs/tables incomplete or sloppy. Some units/labels missing. Some calculations missing and wrong. | Most results missing, very unorganized and incorrect. Most figures/graphs/tables contain errors. Most units/labels missing. Most calculations missing and wrong. | Most of the 'poor' conditions are not met. (Score 0) |
| 5. Discussion (×2 weight) | Answer all questions correctly and clearly. All important trends and data comparisons interpreted correctly. Explains how results support/don't support theory. Errors, effects, and ways to reduce errors discussed. | Missing one question, others correct and clear. Almost all results interpreted correctly with minor improvements needed. Errors and possible effects discussed. | Missing two questions. Some results correctly interpreted with partial understanding. Experimental errors mentioned. | Missing more than two questions with incorrect answers. Incomplete/incorrect interpretation. Discussion of theory and objectives missing. No discussion of errors. | Most of the 'poor' conditions are not met. (Score 0) |
| 6. Conclusions | Summarizes essential data and results. States whether findings achieved all objectives. States validity including experimental error. Includes suggestion for improvement and what was learned. | One of the 'excellent' conditions is not met. | Two of the 'excellent' conditions are not met. | More than three of the 'excellent' conditions are not met. | No conclusion. (Score 0) |
| 7. References | Multiple sources (journal, book, magazine, internet etc.) — more than 9 references. Standard format as mentioned in lab manual. 30% references from previous 5 years. | Multiple sources (6–8 references). Written in standard format. | Only two sources (3–5 references). Not written in standard format. | Only one source (1–2 references). Not written in standard format. | No references listed. (Score 0) |
Attendance Note:
i. Absent: Score = 0%
ii. Doing an experiment but lab report is not submitted: Maximum score = 10%
Official Lab Record
Review your scores and generate a complete lab report. Your report will include game performance, quiz results, worksheet data, and discussion responses.
Game Score
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Quiz Score
0 / 5
Report will include:
0.00 MPa
(Game + Quiz x 10)
📝 Important: Students must refine their formal report using Microsoft Word and attach the generated PDF as supporting documentation in their final submission.