Tensile Testing and Material Property Analysis Lab
MAE 315: Mech/Aero Lab
The Background
In Syracuse University’s MAE 315 course, I conducted a tensile test to evaluate the mechanical properties of five materials: 6061 Aluminum, 1018 Carbon Steel, Carbon Fiber (45° and 90°), and ABS Plastic. Each dog-bone shaped specimen was subjected to a uniaxial tensile force using the MTS 858 Mini Bionix II testing machine. The machine measured both the applied force and displacement. For the steel specimen, a high-precision extensometer was also used to capture strain data in the elastic region.
As the test progressed, the machine increased the applied tensile load until each specimen failed. I used the measured force and displacement data to calculate the stress-strain curves, which allowed for the extraction of key mechanical properties. These included yield strength, ultimate tensile strength, rupture stress, true rupture stress, Young’s modulus, and energy absorption metrics such as toughness and resilience.
This hands-on evaluation of material behavior under load reinforced my understanding of how to select materials based on their mechanical performance — a critical skill for any mechanical design or structural application.
Image 1 & 2: MTS Tensile Test Machine & Example Test Specimen
The Analysis
After completing the tensile tests, I processed the raw force and displacement data using MATLAB. I began by calculating the following for each data point in the set and plotting it on a graph:
Engineering Stress: Dividing the instantaneous force by the specimen’s initial cross-sectional area
Engineering Strain: Dividing the instantaneous axial displacement by the specimen’s original length
True Stress and Strain: Calculated similarly to the engineering values, but now accounting for necking past the ultimate tensile strength of the specimen
To extract key mechanical properties from the stress-strain data, I wrote custom scripts to:
Fit a linear regression to the initial elastic region and determine Young’s modulus
Apply the 0.2% offset method to determine the Yield Strength of materials where a yield point is not clearly defined on the stress-strain curve
Identify the Ultimate Tensile Strength and Rupture Strength
Calculate True Rupture Strength using the final dimensions of each failed specimen
I also used numerical integration techniques to compute:
The Modulus of Toughness (total area under the stress-strain curve)
The Modulus of Resilience (area under the elastic portion of the stress-strain curve)
In addition, I measured pre- and post-test geometry to calculate:
Percent Elongation
Percent Area Reduction
Poisson’s Ratio, using changes in width and length
Finally, I performed a full Uncertainty Analysis to quantify the reliability of my results. This included propagating measurement uncertainties from all instruments—such as calipers, tape measures, and the MTS machine’s sensors—to the final material property values.
Image 3: Stress-Strain Curve of Various Materials
Image 4: CF Stress-Strain Curve (45 & 90 deg)
Image 5: Modulus of Resilience Calculation MATLAB Code
The Results
Each material displayed distinct mechanical characteristics that aligned with its typical engineering applications. Among the five tested, 1018 Carbon Steel emerged as the strongest and was able to take the largest amount of strain before rupture. Its ability to withstand high stress levels and to deform significantly before rupture makes it an excellent candidate for heavy-duty structural applications where strength and durability are essential.
6061 Aluminum, while not as strong as steel, offered a solid balance of strength and ductility with the added advantage of being lightweight. Its strength-to-weight ratio makes it suitable for aerospace and automotive components where reducing mass is a critical requirement.
The two Carbon Fiber specimens behaved very differently due to their fiber orientation. The 90° sample exhibited high stiffness and strength but failed suddenly and with little deformation, acting more like a brittle material. In contrast, the 45° sample showed greater ductility and energy absorption, demonstrating that fiber direction heavily influences performance.
Lastly, ABS Plastic showed the lowest strength and stiffness. Its performance was far below that of the metals and composites, but its lightweight nature and ease of forming make it ideal for prototyping or low-load consumer applications.
In short, the test highlighted how material selection is highly dependent on the balance of strength, ductility, stiffness, and weight — and how even subtle differences, like fiber orientation, can drastically affect performance in anisotropic materials.