Tensile Test Lab Report

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  • Topic: Carbon steel, Steel, Carbon
  • Pages : 7 (2204 words )
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  • Published : April 6, 2013
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Introduction
The construction materials course is an essential part of civil engineering as the strength of all structures and constructions depends on the material used. The tension test is one of the laboratories which help students develop their knowledge in this course by practice. During the laboratory a Tinius Olsen Tension Test equipment was used, and the test samples were from low and high carbon steel and timber with grains parallel and perpendicular to the load. Test equipment and materials

The test equipment used during the laboratory is one of the Benchtop Materials Testing Machines made by Tinius Olsen. This machine can test different types of materials and it is provided with software which gives the opportunity to users to fully control the system. Machine two different types of attachments: the first is to fix the metal samples, and second is to hold timber samples. The rate of loading can be controlled by the software. The materials used are trammel to measure the dimensions of samples, the felt pen, 4 samples of timber with grains parallel to the load and 2 samples of timber with grains perpendicular to the load, high-carbon steel, low-carbon steel and aluminium specimens. Results

Tables
| Low-carbon steel| High-carbon steel| Aluminium|
Dimensions, mm| 23.2| 26.6| 23.0|
Cross-sectional area, mm2| 19.7| 20.0| 20.0|
Load at elastic limit, kN| 14.5| 12.5| 5.13|
Maximum load, kN| 15.2| 19.2| 5.90|
Failure load, kN| 10.8| 16.5| 3.88|
Reduction in area, %| 0.57| 0.123| |
Area of failure, mm2| 8.50| 14.7| |
Elongation at failure, %| 13.3| 10.9| |
Table 1 Tension Tests: Results for metals
| Load parallel to grain| Load perpendicular to grain|
Specimen #| 1| 4| 10| 11| j| g|
Dimensions, mm| 90.9| 91.4| 91.1| 91.5| 86.1| 86.5|
Cross-sectional area, mm2| 168| 135| 121| 109| 170| 157| Load at elastic limit, kN| 0.700| 0.400| 0.250| 0.300| 0.105| 0.200| Maximum load, kN| 4.84| 3.13| 5.49| 4.73| 0.400| 0.323| Failure load, kN| 4.84| 3.13| 5.49| 4.73| 0.398| 0.221| Table 2 Tension Tests: Results for timber

| Low carbon steel| High carbon steel| Aluminium|
Elastic limit (or yield stress), MPa| 736| 624| 257|
Maximum stress, MPa| 772| 959| 295|
Nominal failure stress, MPa| 548| 824| 194|
True failure stress, MPa| 1271| 1122| |
Table 3 Tension Tests: Calculated Material Properties for metals | Load parallel to grain| Load perpendicular to grain|
Specimen #| 1| 4| 10| 11| j| g|
Elastic limit stress, MPa| 4.17| 2.96| 2.07| 2.75| 0.618| 1.27| Maximum stress, MPa| 28.8| 23.2| 45.4| 43.4| 2.35| 2.06| Nominal failure stress, MPa| 28.8| 23.2| 45.4| 43.4| 2.34| 1.41| Table 4 Tension Test: Calculated Material Properties for Timber The formulas used are:

Reduction in area=Initial area-Final areaInitial area×100% 1 Elongation at failure=Final length-Initial lengthInitial length×100% (2) Elastic limit=Load at elastic limitInitial area 3
Maximum stress=Maximum loadInitial area (4)
Nominal failure stress=Failure loadInitial area 5
True failure stress=Failure loadArea after it breaks (6)
Brief comments on differences and similarities in each property for the set of materials From the tables above it can be seen that:
* Low-carbon steel has the largest load and stress at elastic limit among all materials * High-carbon steel has the largest maximum load and stress among all materials * High-carbon steel has the largest failure load and nominal failure stress among all materials * Low-carbon steel has the largest true failure load among all materials * All properties is larger for timber with grains parallel to the grain rather than for timber with perpendicular to the grain

Graphs
Stress-strain or load-extension graphs have a different form depending on the structure of material and of these graphs can be divided to...
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