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WORLD UNIVERSITY OF BANGLADESH
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Assignment
Prepared By:
Submitted
To
Name:
MOHAMMED ABDUR RAZZAK Name: JAHANGIR ALAM
Roll
No: 3326
Designation:
Lecturer
Registration
No: WUB/10/13/60/3326
Batch
No: 60/C Semester No: Four
Year:
second Date of Submit ion:
Introduction
:
In tension and
compression test, attempt is made to apply an axial load to a test specimen so
that uniform tress distribution can be ensured over the critical section. In
such tests the specimen is subjected to a gradually increasing ( i.e static )
uniaxial load until failure occurs. The static tension and compression tests
are the most commonly made and are among the simplest of all the mechanical
tests. These tests provide almost all the fundamental mechanical properties for
use in design. The use of the tension as against the compression test in all
probability is largely determined by the type of service to which a material is
to be subjected. Metals, for example, generally exhibit relatively high
tenacity and are therefore better suited to and are more efficient are
resisting tensile loads than material of relatively low tensile strength. For
brittle materials such as mortar, concrete, brick and ceramic products, whose
tensile strengths are low compared with their compressive strengths, and which
are principally employed to resist compressive forces, the compression test is
more significant and finds greater use.
Stress :
Stress ( Ó ) is defined as
the intensity of the internal distributed forces or components of forces that
resist a change in the form of a body. Stress is measured in terms of force per
unit area (P/A), e. g. psi, kg/cm², N/mm² etc.
Strain :
Strain is defined
as the change per unit of length in a linear dimension of a body. It is
a ratio, or dimensionless number, and is therefore the same weather measured in
inches per inch of length or length or centimeters per centimeter, etc.
(Strictly, this definition of strain is limited and is applicable to axial
strain only. However, this definition is provided for easy conceptualization by
the students; a more general definition is that strain is the intensity of the
definition- whatever be the nature of deformation.)
01.
OBJECTIVES:
i.
To
test a Timber specimen under compressing loading parallel to the grain.
ii.
To
draw strain-strain diagram.
iii.
To
study the failure characteristics of the timber specimen.
iv.
To
determine the following properties of the timber specimen.
02.
APPARATUS:
i.
Compresometer ii. Steel
scale iii. Slide calipers
03.
MACHINE:
i.
The
universal Testing machine.
04.
SPECIMEN:
47mmx47mmx153mm Wooden Block (ASTM D
143)
05.
PROCIDURE:
i.
Measure
the size of the specimen by a slide
calipers
ii.
Record
gage length and multiplication factor of the Compresometer.
iii.
Attach
Compresometer with the specimen and set the specimen in proper position of the
testing machine.
iv.
Adjust
the Compresometer dial to read zero.
v.
Apply
load continuously at a uniform speed until failure and read the Compresometer
10 KN intervals.
vi.
Take
off the Compresometer when breaking starts.
vii.
Record
the maximum load and the final length between the gauge marks.
viii.
Note
the characteristics of the fractured surfaces and draw the extended surfaces of
the failed specimen and show the failure pla
Data
sheet for Compression test for timber:
Gauge Length: 153 mm
Cross-sectional area of
the specimen: 2209 mm
Observation
No
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Load in KN
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Compresometer
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Load
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Deformation in mm
|
Stress KN/mm²
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Strain
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Remarks
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01
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0
|
0
|
0
|
0
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0
|
0
|
0
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02
|
10
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2
|
10
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.02
|
4.53x10ֿ ֿ³
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0.13x10ֿ ֿ³
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03
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20
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5
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20
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.05
|
9.05x10ֿ ֿ³
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0.33x10ֿ ֿ³
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04
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30
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8
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30
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.08
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13.58x10ֿ ֿ³
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0.52x10ֿ ֿ³
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05
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40
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9
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40
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.09
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18.11x10ֿ ֿ³
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0.59x10ֿ ֿ³
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06
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50
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15
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50
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.15
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22.63x10ֿ ֿ³
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0.98x10ֿ ֿ³
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07
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60
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18
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60
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.18
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27.16x10ֿ ֿ³
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1.18x10ֿ ֿ³
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08
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70
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22
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70
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.22
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31.69x10ֿ ֿ³
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1.44x10ֿ ֿ³
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|
09
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80
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26
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80
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.26
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36.22x10ֿ ֿ³
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1.70x10ֿ ֿ³
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|
10
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90
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30
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90
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.30
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40.74x10ֿ ֿ³
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1.96x10ֿ ֿ³
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11
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100
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60
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100
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.60
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45.27x10ֿ ֿ³
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3.92x10ֿ ֿ³
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12
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Average
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50
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0.18
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22.63x10ֿ ֿ³
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1.18x10ֿ ֿ³
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Sample
Calculations:
01.Proportional Limit = .60x 10ֿ ֿ³ KN/mm²
02.Modulus of elasticity = 19.18 KN/mm²
03.Modulus of resilience =
04.Young Strength of offset method = 0.05
05.Proof strength = 46.27x10ֿ ֿ³ KN/mm²
06.Ultimate Strength = 54.32x10ֿ ֿ³ KN/mm²
