impact experiment.pdf

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Impact Experiment

Prepared for: Eng. Bilal El-Emour

Prepared by: Ahmed Al-Maghlouth

Due Date : April 2, 2012

ID#: 210014879

King Faisal University - College of Engineering


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Table of Contents

Objective ....................................................................... 3

Apparatus .................................................................. 4

Theory ........................................................................... 5

Procedure ...................................................................... 6

Analysis and Results .................................................... 7-9

Conclusion .................................................................... 10

References ..................................................................... 11

Impact Experiment Report

King Faisal University


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Executive Summary

Objective

To determine the behavior of metals under impact stresses.

To measure the energy absorbing capacity of the material subjected to sudden

loading.

To evaluate the toughness and notch sensitivity of engineering metals.




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Apparatus

A Pendulum Impact Tester That Consists of The Following:

A dial.

Reading Pointer.

Charpy release levers.

Brake Levers.

Stand.

Base.

Pendulum Hammer.

Pendulum Shaft.

Anvil block with supports for both Chapy and Izod specimen.




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Theory

Impact Testing

involves the sudden and dynamic application of the load. Parts such as

shafts, bolts, anvils and dies are examples of items subjected to impact loading.

Impact test

is defined as the resistance of a material to rapidly sudden applied loads.

Toughness

is a property, which is capacity of a material to resist fracture, (crack

propagation), when subjected to impact.

The machine measures the amount of energy absorbed by the specimen for the

rapture in joules unit.

The amount of energy absorbed can give an indication of the toughness of a

material.

It can classify the different types of materials into either brittle or ductile

materials.




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Two basic types of impact testing:

Charpy impact test

The specimen is supported as a simple beam with the load applied at the

center.

The position of latching tube is set to 140

The specimen is supported horizontally from two sides

The Izod test

The specimen is supported as a cantilever beam.

The position of latching tube is set to 90

The specimen is supported Vertically from one side




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Procedure

Fit Izod striker into appropriate position.

The Anvil for the Izod test should be securely fastened on the base.

Check the release mechanism.

Set the the pointer at 150j on the dial scale and contact with carrier .

Raise the pendulum into its release position and ensure its securely latched.

Release the pendulum by pressing down the lever, and measure energy loss

due to friction.

Wait until the pendulum has completed its initial swing.

Place the specimen in the support.

Repeat the same steps.




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Analysis and Results

The Following table contains the results of Izod test for different treated steel

rods :

Energy loss due to friction = 2J

Material Notch Energy Absorbed

Zc 1010

Zc 1040

Zc 1070

V 104

V 19

V 78

We can notice that ductile materials has a high absorbing energy, on the other hand

the low absorbing energy refer to the brittle materials.

A higher toughness material will absorb more energy.

Specimen with lowest absorbed energy means its brittle and has least toughness.

Specimen with Highest absorbed energy means its ductile and has highesttoughness.




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Why we use the notch in the specimen ?

to study fatigue crack initiation in specimen, and to see the The stress concentra-tion created by a flaw.

For The same conditions where would be the absorbed energy grater at V-

notch or U-notch ? and Why ?

Of course it would be the U-notch, because as we know from the normal stress

equation that the stress is grater when the cross sectional area is smaller, and here in

the V-notch we have a smaller cross sectional area.

What are the uses and applications of impact energy ?

Simply we can say that its applications are the natural disasters in general, such as :

Hurricanes Tides

What are the factors that effects the impact energy ?

Velocity of the hammer.

Specimen Material.

Temperature.




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Conclusion & Discussion

Regarding to what we have done in the experiment, we can clearly see that :

A higher toughness material will absorb more energy upon impact and will

therefore result in a low height to which the pendulum arm will swing to

following impact.

The more energy absorbed by the specimen, the more toughness the material

will be




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References

Strength Of Materials Lab. Manual, By Omar Alosta.

Mechanics of Materials, R.C.Hibbeler .



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