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Topics: Shear stress, Tensile strength, Force Pages: 60 (6148 words) Published: December 5, 2013
UNIVERSITI TUN HUSSEIN ONN MALAYSIA
Faculty of Mechanical and Manufacturing Engineering
__________________________________________________________________ COURSE INFORMATION
COURSE TITLE: ENGINEERING LABORATORY III (BDA 27101)
TOPIC 1: TENSILE TEST

1.

INTRODUCTION

The tensile experiment is the most common mechanical test that reveals several important mechanical properties, such as: modulus of elasticity, yield strength, ultimate tensile strength, ductility, and toughness. The material to be tested is formed into a shape suitable for gripping in the testing machine, and then pulled at constant rate until it fractures. The tensile instrument elongates the specimen at a constant rate and has devices to continuously measure and record the applied load and elongation of the specimen. During the stretching of the specimen, changes occur in its physical dimensions and its mechanical properties. The ability to predict the loads that will cause a part to fail depends upon both material properties and the part geometry. This experiment involves testing to determine the relative properties.

2.

OBJECTIVES
1. To understand the principles of tensile testing machine.
2. To observe the stress-strain relationship for several standard materials by performing a tensile test.
3. To obtain approximate values from stress-stain curve such as percentage of elongation, Yield Strength; Tensile Strength and Modulus of Elasticity, E.

3.

LEARNING OUTCOMES

At the end of this experiment, students should be able to:
1. Conduct experiment and identify the dependent and independent variables. 2. Record, tabulate and analyze the raw data.
3. Indicate the important parameters such as yield strength, elastic, plastic region, maximum load, failure load and explain each parameter. 4. Determine the modulus of elasticity for each specimen.

5. Understand the stress-strain relationship for several standard materials by performing a tensile test and tensile properties from a stress strain curve.

UNIVERSITI TUN HUSSEIN ONN MALAYSIA
Faculty of Mechanical and Manufacturing Engineering
__________________________________________________________________ 4.

THEORY

A tensile test, also known as tension test, is probably the most fundamental type of mechanical test that can be performed on material. Tensile tests are simple, relatively inexpensive, and fully standardized. By pulling on something, you will very quickly determine how the material will react to forces being applied in tension. As the material is being pulled, you will find its strength along with how much it will elongate.

You can learn a lot about a material from tensile testing. As you continue to pull on the material until it breaks, a good, complete tensile profile will be obtained. A curve showing how it reacted to the forces being applied is produced. The point of failure is typically called its "Ultimate Strength" or UTS on the chart.

For most tensile testing of materials, you will notice that in the initial portion of the test, the relationship between the applied force, and load, and the elongation the specimen exhibits is linear. In this linear region, the line obeys the relationship defined as "Hooke's Law" where the ratio of stress to strain is a constant, or E = δ/ε. E is the slope of the line in this region where stress (σ) is proportional to strain (ε) and is called the "Modulus of Elasticity" or "Young's Modulus".

BDA27101-Edition III/2011

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UNIVERSITI TUN HUSSEIN ONN MALAYSIA
Faculty of Mechanical and Manufacturing Engineering
__________________________________________________________________ 5.

ADDITIONAL THEORY

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