Strength of Materials

Topics: Tensile strength, Elasticity, Yield Pages: 5 (879 words) Published: November 28, 2011
STRENGTH OF MATERIAL
TENSILE TESTING OF METALS
STRENGTH OF MATERIAL
TENSILE TESTING OF METALS

OBJECTIVE :

Tension test is carried out; to obtain the stress-strain diagram, to determine the tensile properties and hence to get valuable information about the mechanical behavior and the engineering performance of the material…

INTRODUCTION:

A tensile test, also known as a tension test, tests a material’s strength. It's a mechanical test where a pulling force is applied to a material from both sides until the sample changes its shape or breaks. It's is a common and important test that provides a variety of information about the material being tested, including the elongation, yield point, tensile strength, and ultimate strength of the material. Our experiment was performed on (Mild Steel and Brass) also have to prove that it is Mild Steel by *Young Modules Equation*.

Also, it’s a sample of material describes how it reacts when tension is applied to it. By measuring the changes in the material as tension is applied, engineers can determine a variety of things about the material, which is helpful in determining whether the material is a suitable choice for the application they have in mind. Tensile testing systems use a number of different units of measurements. The SI (International Systems of Units), recommends the use of either (Pa) Pascal or Newton’s per square meter for describing tensile strength.

THEORY:

A tensile load is applied to the specimen until it fractures. During the test, the load required to make a certain elongation on the material is recorded. A load elongation curve is plotted by an x-y recorder, so that the tensile behavior of the material can be obtained. An engineering stress-strain curve can be constructed from this load-elongation curve by making the required calculations. Then the mechanical parameters that we search for can be found by studying on this curve. Engineering Stress is obtained by dividing the load by the original area of the cross section of the specimen.

* Stress(σ)
σ=FA

Where:
F= Tensile force acted over the rod
A= Cross-sectional area of the inner rod

* Strain(ε)
ε=∆LL

Where:
∆L = Change in length
L = Length

* Ultimate Tensile Strength(UTS)
Ultimate Tensile Strength=Maximum Tensile ForceOrignal Cross-sectional Area

UTS=FmaxA0

Where:
Fmax = Maximum Tensile force
A0= Original length

Ultimate tensile strength (UTS), is the maximum stress that a material can withstand while being stretched or pulled before necking, which is when the specimen's cross-section starts to significantly contract

* Ductility
Ductility=Final gauge length-Initial gauge lengthInitial gauge length x 100

D=Lx-L0L0 x 100
Where:
Lx= Final Gauge length
L0= Original length

Ductility is generally measured in terms of percentage elongation in the specimen gauge length or the percentage reduction in cross sectional area of the specimen at the point of failure. Ductile metals do not have a well-defined yield point. The yield strength is typically defined by the "0.2% offset strain"

EQUIPMENTS:

COMPUTER SPECIMEN SAFETY GLASSES
GLOVES SAFETY SHOE SAFETY COAT
DIGITAL VERNIER CALLIPER HOUNSEFIELD TENSOMETER PROCEDURE:

* The Steel and Brass specimen were our work piece to start the experiment *
* The dimensions of both specimen were noted

* The diameter of the holder was adjusted so as to fit the specimen properly. One specimen was done at a...
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