UNIVERSIDAD

TECNOLOGICA
DE DURANGO
T.S.U EN MECATRONICA AREA DE MANUFACTURA FLEXIBLE

Class: Teacher
Mechanics of materials Serrato Pedrosa Jesus Alejandro

Students:

-Aguado Ruiz Erick Daniel

-Leyva Razo Adriel Salvador Group and Grade: 5B BIS

-Mejia Quiroga Angel Jesus

-Quiroga Enríquez Aaron

Practice #1: "Tensile testing"

Unit II date: Friday March 03rd 2025

I.Abstract

This report presents an experimental analysis of II.Keywords

the tensile stress behavior of different samples
under controlled conditions. The study aims to Tensile test: A test to measure a
material's resistance to being pulled
determine the mechanical properties, including
apart.
yield strength, and the Young’s modulus, by
Yield strength:The stress at which a
subjecting samples to uniaxial tensile testing.
material begins permanent
Results indicate significant variations in tensile
deformation.
properties among the samples, with the metal
Elastic limit:The maximum stress a
showing a higher tensile strength and stiffness
material can withstand without
compared to the wood, as like how the permanent deformation.
concetration of the material as its shape and Ultimate tensile
tensile zone aplication affect the reaction to the strength(resistance): The maximum
uniaxial stress. stress a material can withstand before
breaking when pulled.
Elongation: The amount a material
stretches under tensile stress.
Young’s modulus:A measure of a
material's stiffness.

III. Introduction
Tensile stress test is a fundamental technique in material engineering and science to evaluate the
mechanical properties of a wide range of materials under stress. It is crucial to understand how
materials react under tensile stresses for usage from structural engineering to manufacturing. The
tensile test provides vital parameters such as ultimate tensile strength, yield strength, and Young's
modulus, which engineers utilize to determine whether the material is appropriate for a specific usage
or not.

By analyzing the stress-strain curves obtained from the tests, important mechanical properties can
be determined and compared. The results will offer a good view into how the materials deform under
stress.

IV. Materials and methods

Corn stick
Aluminum wire
Wood Tongue Depressor
Tensile test machine
Analog Vernier Caliper
Marker

Process:

Preparation of the Sample

The first step involved measuring the length and diameter of each sample. For the wooden tongue
depressor, measurements were taken at the zone where tensile stress would be applied, specifically
in the transverse cross-sectional area. After obtaining these dimensions, markings were made at both
ends of each specimen to indicate the gripping zones for the tensile testing machine. Ensuring
uniform grip placement was essential for an even distribution of tensile force.

Placement in the Machine

The grips of the tensile testing machine were initially opened. Using the control panel, the distance
between the grips was adjusted to correctly position each sample within the machine. Once properly
aligned with the marked gripping zones, the grips were securely tightened to prevent slippage during
testing.

Execution of the Test

Each tensile test was conducted using the HOYTOM software, which controlled the machine’s
operation. The test proceeded until the first signs of fracture appeared in the sample, at which point
data collection was completed.

Data Analysis and Results

After testing, the stress and strain values for each sample were recorded. The HOYTOM software
generated stress-strain diagrams, providing a visual representation of each material’s mechanical
response under tensile loading. These plots were analyzed to determine key properties such as yield
strength or elastic limit, ultimate tensile strength, and Young’s modulus.

Process evidence
V. Results
The results of our test samples were as follows:
First, we have the corn stick, which was analyzed for its structural properties and potential
applications.

Max Force 1.057 kN

Resistance 37.4 MPa

Elastic Limit 36.9 MPa

Elongation 3.3%

This test specimen broke at one end, far from the center, indicating a non-uniform
stress distribution. This suggests that the material may have had weak points or
irregularities affecting its mechanical behavior.
E=F/A/∆L/Lo=0.7kN(aprox)/3.14mm^2/5.6mm(aprox)/298mm≈1317MPa=1.317GPa

F=force

A=Area

∆L=change in longitude

Lo=initial longitude

The second test specimen was a piece of wire, which was analyzed for its tensile strength and
deformation characteristics under applied stress.
 Max force 1.151 kn

Resistance 366.2 MPa

Elastic Limit 343.9 MPa

Elongation 3.1%

Just like our previous specimen, this one also broke near the edge and, once again,
far from the center. This pattern suggests that the material experiences higher
stress concentrations at the extremities, possibly due to structural inconsistencies
or external factors influencing the fracture location.

E=F/A/∆L/Lo=0.65kN(aprox)/3.14mm^2/2.8mm/196mm≈14490MPa=14.49GPa

And our third test specimen was a wooden tongue depressor, which was examined for its
bending resistance and fracture behavior under applied force.
 Max force 2.347 kn

Resistance 747.1 MPa

Elastic Limit 667.1 MPa

Elongation 2.4%

In this third specimen, despite having higher values in all evaluated aspects, the
final result did not change. Although it produced a cleaner sound when breaking, it
fractured without following any specific pattern. This suggests that the material's
internal structure may have influenced the way it failed, highlighting its brittleness
and lack of predictable fracture behavior.

E=F/A/∆L/Lo=1.35kN(aprox)/3.14mm^2/1.6mm/142mm≈38157MPa=38.157GPa

And here are the specimens after undergoing the entire testing process. Their final condition
provides valuable insight into how each material responded to the applied forces, helping us
analyze their mechanical properties and failure characteristics.
Final results
Materi Max Resist Elastic Elonga Young's Modulus (GPa)
al Force ance Limit tion
(kN) (MPa) (MPa) (%)

Corn 1.057 37.4 36.9 3.3 1.317

stick

Alumi 1.151 366.2 343.9 3.1 14.49

num
Wire

Wood 2.347 747.1 667.1 2.4 38.157

Tongu
e
Depre
ssor
VI. Discussion
Corn stick: This sample showed the lowest tensile strength and stiffness, as demostrated by
its low resistance and Young's modulus values. The fracture at one end, away from the center,
suggests potential weak points or irregular zones within the material.

The tensile strength of wood typically ranges from 50 to 150 MPa, depending on the type of
wood. The experimental result of 37.4 MPa is lower than the end of this range, which could
indicate that the wood used for the stick is of a softer type or has imperfections (like knots,
cracks, or high moisture content).

The Young's modulus of wood is generally in the range of 10 to 15 GPa, which is significantly
higher than the experimental value of 1.317 GPa. This discrepancy could be a possible error
in the calculation of the cross-sectional area, elongation, or applied force during the
experiment.

The elongation at break (3.3%) is consistent with the brittle nature of wood, which typically
shows a low ductility.

Aluminum wire: As expected, the aluminum wire showed significantly higher tensile strength
and stiffness compared to the corn stick. However, the fracture pattern was similar, occurring
near the edge, indicating possible stress concentrations at the extremities.

The tensile strength of pure aluminum typically ranges from 90 to 120 MPa, while aluminum
alloys can have tensile strengths up to 600 MPa or more. The experimental result of 366.2
MPa suggests that the wire tested may have been an alloy.

The Young's modulus of aluminum is generally around 69 GPa, which is considerably higher
than the experimental value of 14.49 GPa. This diference could be due to experimental
errors, such as incorrect measurements of the cross-sectional area or elongation, or the use
of a more brittle aluminum alloy.

Wood tongue depressor: This sample demonstrated the highest tensile strength and
stiffness among the three samples. However, its fracture behavior was unpredictable,
suggesting brittleness and a lack of uniform internal structure.

Wood is an anisotropic material, that means its mechanical properties vary depending on the
direction of the grain. The tensile strength of wood parallel to the grain typically ranges from
50 to 150 MPa, which is highly lower than the experimental result of 747.1 MPa. This
suggests a possible mistake in the calculation or measure realized during the experiment.

The Young's modulus of wood parallel to the grain is generally in the range of 10 to 15 GPa,
which is much lower than the calculated value of 38.157 GPa. This difference could be due to
the same measurement errors mentioned before.
VII. Conclusion
The results for the aluminum wire ,wooden tongue depressor and corn stick show significant
discrepancies. These differences could be asigned due to experimental errors, material
inconsistencies, or issues with the testing while preparating the samples. This highlight the
necesity to improve the accuracy, where the future experiments should give more precise
measurements of sample dimensions, with a proper alignment of the grips, and verification of
material properties.

VIII. References

MatWeb - the online materials information resource. (n.d.). Matweb.com. Retrieved March 4,
2025, from https://www.matweb.com/search/DataSheet.aspx?
MatGUID=0cd1edf33ac145ee93a0aa6fc666c0e0&ckck=1

(N.d.-a). Usda.gov. Retrieved March 4, 2025, from

https://www.fpl.fs.usda.gov/documnts/fplgtr/fpl_gtr190.pdf
(N.d.-b). Instron.com. Retrieved March 4, 2025, from https://www.instron.com/en-
us/resources/test-types/tensile-test