Essay on Tensile Test Lab Report

2206 Words Mar 21st, 2013 9 Pages
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
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When the elasticity ends the plastic region begins. In plastic region strain can increase significantly whereas stress increases with smaller increment. If the unloading happens the curve will fall parallel to the elastic region.
The Stress-Strain graphs have the same shape as Load-Extension graphs. To prove that the stress-strain curves were sketched for three different types of metal: low-carbon steel, high-carbon steel and aluminium. The data used during plotting the stress-strain graphs is represented in Appendix.
The graphs for low-carbon (0.15%) steel (See Figure 1 & 2).

Figure 2. The stress-strain graph for low-carbon steel
It can be seen from the graphs that at the beginning the curve behaves linearly until it reaches approximately 14.5kN (See Figure 1). Therefore, this section of the graph can be called the elastic region. Then the plastic region begins, and the curve reaches its maximum point at 15.1kN. After that the load decreases gradually for the bigger increment of extension until the break occurs (at 10.8kN).
The graphs for High-carbon (0.4%) steel.

Figure 4. The Stress-Strain Graph for High-carbon steel
The graph for high-carbon steel is similar to the graph for the low-carbon steel. However, the maximum stress in the graph for high-carbon steel is more by 4kN, and equal to the 19.2kN. Also it can be seen that the

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