This lab report summarizes a compression test experiment conducted to determine the mechanical properties of a metal alloy sample. The experiment involved compressing the sample between two plates using a universal testing machine while measuring stress and strain. The results showed the stress-strain curve for the material and identified its maximum compression strength. The objective was to learn how materials behave under compressive loads and determine properties like elastic modulus, yield point, and ultimate strength.
1. 1
Lab report
Engineering material lab
Lab No. 5: Compression test
Name: ahmad sarbast amin
Supervisor: M.Sc. Ahmed Taifor Azeez
Lab date: 23/12/2021
Department of Manufacturing & Industrial Engineering
Faculty of Engineering
Koya University
Kurdistan Region of Iraq
2021
3. 3
Introduction
A compression test is any test in which material experiences the opposing
forces inward upon the specimen from opposing side or otherwise
compressed, crushed, and flattened. The specimen is generally placed
between two plates which are the compression test fixture; the load is
distributed among the test sample surfaces and is compressed byapplying
force using the universal test machine. The test material while then
experiences shortening in the applied forces direction and expanding in the
perpendicular direction toward the applied force. The goals of compression
test in this experiment are to learn the applications of universal test machine
and strain gauge to obtain the stress-strain curves and identify the metal alloy.
Compression test also allow the determination of the behavior of the metal
alloy when it experiences the compressive load by measuring the variables
such as stress and strain. In this experiment, uni-axial tension-compression
test is used to determine the mechanical properties of the metal alloy and
Mechanical properties are of interest to engineers utilizing materials in any
application where forces are applied, dimensions are critical, or failure is
undesirable. Three fundamental mechanical properties of metals are the
elastic modulus (E), the yield point (σ y), and the ultimate strength (σ ult)
whish also known as the maximum compressionstrength. This reportcontains
the results of a compression testing lab experiment, which determined the
maximum compression strength while increasing load. The material was
tested at ambient temperature that remained constant. By definition, the
compressive strength of a material is that value of uniaxial compressive stress
reached when the material fails completely. The compressive strength is
usually obtained experimentally by means of a compressive test. During the
last lab test we explored creep testing. One of the differences between creep
testing and compression is rather than applying a uniaxial tensile load, a
uniaxial compressive load is applied. As can be imagined, the specimen is
shortened as well as spread laterally. The decrease in length and difference in
diameter was not measured after testing. We increased the load until the
material failed during the test.
4. 4
Objective
The aim of this thesis is to investigate the behavior of timber loaded
perpendicular to the fiber direction. In the study different calculation models
for bearing strength from the literature will be compared with the results from
an experimental study. The bearing strength will be studied experimentally
and the deformations will be studied with both LVDT (Linear variable
differential transformer) gauges and with the non-contact system ARAMIS
which will give the total strain field under the load. Different loading lengths
and different distances to the edge of the loaded member will be investigated.
The results from the experimental study will be compared with results
calculated using different models found in the literature. The study will show
which of the models fits best with the experimental results. The study will
only investigate fully supported beams of Norway spruce with compression
loads from a stud. Three different distances from the edge to the loaded point
will be studied as well as two different loading areas.
5. 5
Methodology
True stress- strain
If the fracture initiates in the tension surface within the middle third of the
span length,
calculate the modulus of rupture as follows:
R = PL / bd2
where:
R = modulus of rupture, psior MPa,
P = maximum applied load indicated by the testing machine, lbf or N,
L = span length, inch or mm,
b = average width of specimen, inch or mm, at the fracture, and
d = average depth of specimen, inch or mm, at the fracture.
Sample description
The sample is made of WOOD with dimensions shown in the table below
Gauge length
(𝑙0)
Initial width Initial thickness Final
length
Final width Final
thickness
6. 6
Experimental procedure
1) Measure the cross section and length of the samples to 0.1mm
2) Weigh each specimen to the nearest 0.1 gram
3) Determine the annual growth (rings/inch) and %Early and %Late wood.
4) Place a specimen on the center of the UTM platens.
5) Apply the load continuously and plot load-vs-deformation
6) Repeat these steps with the other wood sample
Results
The results from the ARAMIS-3D optical measurement system are presented
for oneboard loaded with a loading plate with the length l = 90 mm. The result
presented shows the strain field in the y-direction (vertical) at two loading
stages, approximately 20 kN and 40 kN. The lower load is taken in the linear
part of the load-deformation curve and the higher load is the maximum
compression force.
8. 8
Discussion
Compressive strength or compressionstrength is the capacity of a material or
structure to withstand loads tending to reduce size, as opposed to tensile
strength, which withstands loads tending to elongate. In other words,
compressive strength resists compression (being pushed together), whereas
tensile strength resists tension (being pulled apart). In the study of strength of
materials, tensile strength, compressive strength, and shear strength can be
analyzed independently. In this experiment, we are tasked to get the
compressive strength of a cement sample that we made. Testing the
compressive strength of the concrete is essential because we should know
what strength shake we use in a certain construction. Using the same mortar
that we used in the previous experiment, we put the mortar into a cube mold.
After setting, the sample is cured for seven days then it will be tested in the
universal testing machine to determine its compressive strength. The
compressive strength is the ratio of the load applied and the cross-sectional
area of the sample. We got 12pa as the compressive strength. The differences
between the compressive strength between the sample is due to the tamping
of the sample into the mold and the little holes in the surface of the sample.
Recommendation and Conclusion This experiment sought to determine the
compressive strength of the hydraulic cement. I conclude that, the
compressive strength of a hydraulic cement can be determine by using a
mortar cube specimen with the help of the universal testing machine. The
universal testing machine will you the maximum load applied to the specimen
which is necessary to determine the compressive strength. In order to get the
maximum compressive strength, you must use a mortar with a correct
watercement-sand ratio. It should not be too pasty. It must be workable and
has the right consistency. The water, cement, and sand must be measured
accurately for best results.
9. 9
Conclusion
Based ona literature review and from the specimens tested in this study, it can
be concluded that the compression perpendicular to the grain in timber is an
important property for structural design. It is dependent on the loading
situation, the loading area and the type of specimen. The case studied in this
case is the loading from a stud on a continuously supported rail. In this thesis
especially the effect of loading area and loading position was investigated.
Two loading areas were tested (45x 95) mm and (90 x 95) mm as well as three
distances from the end of the specimen 0 mm, 10 mm and in the middle of a
long specimen. The results showthat there is a great influence of loading area.
The compressioncapacity is about 65-70% higher for the casewith a doubled
loading area. There is also an effect of the distance from the end of the rail.
Loading in the middle of the long specimen increased the capacity with
approximately 25%. Moving the loading point only 10 mm from the edge
increased the capacity by 10% compared to loading at the edge. The capacity
of the compressionforce was calculated according to six different codes. The
codes were two versions of Eurocode 5, the Italian code the German code
(DIN 1052:2004) and two versions of the Swedish code (BKR). The results
showed that in all cases the experimental results were lower than the capacity
calculated accordingto the code. Themain explanation to this is probablythat
the loading was done with a steel stud with relatively sharp edges. Compared
to a timber stud this loading is much harder. The codethat gave results closest
to the experimental results was the new version of Eurocode 5. The results
from the code showed results that were 10-25% higher than the results from
the experiments. The results also show that Eurocode is farther from the
experimental results for the 45 mm wide specimens than for the 90 mm wide
specimens. The results from Eurocode show a result that is approximately
25% higher for loading in the middle of the specimen than at the edge, which
agrees well with the experimental results. The effect of loading 10 mm from
the edge is also approximately 10% higher than loading at the edge which also
agrees well with the code. This shows that Eurocode at least takes the loading
area and distance from the edge into accountin a reasonable way at least when
compared with these tests. The experimental results still show to low strength
compared to the codes. A further study using another material in the loading
stud should be done.
10. 10
References
Burkes DE, R Prabhakaran, T Hartmann, JF Jue, and FJ Rice. 2010a.
“Properties of DU–10 wt% Mo
alloys subjected to various post-rolling heat treatments,” Nuclear
Engineering and Design 240:1332–1339.
Snelgrove JL, GL Hofman, MK Meyer, CL Trybus, and TC Wiencek.
1997. “Development of veryhigh-density low-enriched-uranium fuels,”
Nuclear Engineering and Design 178:119–126.
