Strain Test for Metals-Lab Report

Lab report on the strain Rates of Copper and Aluminum

Strain rate is the rate at which materials are deformed with time. It measures the deformation of materials within the distance of the parcels adjacent to it. The ratio comprises of the rate at which the materials are expanding or shrinking at different temperatures. The ratio can also be used to represent the shear rate of the material without changing the volume of the material (Raju, 2009).

In this experiment the strain rates of aluminium and copper was measured at room temperatures and the results obtained were given in a sheet of paper. The experiment involved the use of eight attempted experiment each of which gave a different result.

The strain rate of a metal is predicted to be directly proportional to the melting point, boiling point and the ionization energy of the specific metal. In this specific experiment, it is expected that the metal with the highest ionization energy and also the highest boiling point and the melting point will have the highest strain rate (Raju, 2009).

The results were then analyzed and a line graph plotted to show the same

Generalized procedure

The materials are put under flash point temperature to measure the tendency of the mixture to be deformed or to form a flammable mixture under controlled lab conditions. The experiment used the shrinking property of copper and aluminum at different conditions.

This test method is used to measure and describe the properties, product and the assembly of materials. The materials are put in a source of heat and the ignition source under controlled condition is used to control the experiment. The controller of the experiment should be very careful to ensure that fire hazards are maintained and controlled during the experiment.

The flash point procedure should be done at temperatures between room temperatures to 250 degree Celsius. The materials under test should then be subjected to these conditions and the energy at which they are deformed is then recorded and the results obtained written in tabular form.

The results are then discussed and analysis of the same is done. The materials are then compared and necessary conclusions are made

Experimental hypothesis

The main hypothesis of the experiment is;

1. The strain rate of different materials increase with the increase in temperature
2. The strain rate of aluminium is lower than that of copper.

Aims of the experiment

The main aim of the experiment is to;

1. Determine the strain rate of aluminium and copper and different temperatures
2. To compare the strain rate of aluminium and that of copper

Materials

The following materials are required in conducting the experiment

1. Extensometer
2. Thermometer

• Calorimetric apparatus

1. Sample of copper
2. Sample of copper
3. Record book

• Boiling water
• Water bath

1. Control experiment

Sample experiment

The above experiment is used to measure the deformations of copper and aluminium at different temperatures (Raju, 2009).

The following was used as the sample result

The sample result was the sample of copper used as the control experiment and done the deformation which is then used to test and compare the deformation of aluminium and the blister copper

 

1.    Load cell capacity	50 kN
2.    Jig	50 k N non Shift
3.    Tested speed	50m/s
4.    Test temperature	Room temperature
5.    Equipment used	Extensometer

 

The sample rates

Copper strain rate	0.0025m/s
Aluminium strain rate	0.0035m/s

Procedure

The samples of copper and aluminium were put in the extensometer shown above and the time taken for their deformation to occur was recorded.

The experiment was done first using copper at room temperature and then using aluminium at the same room temperature.

The same procedure was then repeated nine times to obtain the results as shown in the table below

Results obtained

 

Experiment no	Copper (energy in kJ)	Aluminium ( energy in kJ)
1	388	388
2		2.293
3		2.563
4	20.45
5	17.55
6		2.210
7		2.453
8	17.21
9	15.30

Graphs

The following data can be represented using line graphs as shown below

Line graph showing the strain rate for copper

 

 

 

Discussion

The strain rate for copper is seen to higher to higher than that of aluminium. This can be attributed to the fact that the tensile strain for aluniminum is less than that of copper

The results are not in agreement with the hypothesis of the project as copper is seen to have a higher strain rate as compared to aluminium. The density of aluminium is higher than that of copper and so its strain is expected to be higher than that of copper. However, the results obtained from the experiments done, show otherwise

The melting point for copper is 1083 while the melting point of aluminium is 659 (Allen, Bayles,, Gile,  & Jesser, 2002).From the experimental results obtained, it is evident that the melting point of a substance is directly proportional to its strain rate. Similarly, the first ionization energy for aluminium is 578 kilo Joules per mole while that of copper is 745.5 kilo Joules per mole (Casida, Jamorski, Casida, & Salahub, 2008). It therefore, implies that the higher the ionization energy the higher the strain rate as the experiment depicts.

 

 

Reference

Allen, G. L., Bayles, R. A., Gile, W. W., & Jesser, W. A. (2002). Small particle melting of pure metals. Thin solid films, 144(2), 297-308.

Casida, M. E., Jamorski, C., Casida, K. C., & Salahub, D. R. (2008). Molecular excitation energies to high-lying bound states from time-dependent density-functional response theory: Characterization and correction of the time-dependent local density approximation ionization threshold. The Journal of chemical physics, 108(11), 4439-4449.

Raju, I. S. (2009). Calculation of strain-energy release rates with higher order and singular finite elements. Engineering Fracture Mechanics, 28(3), 251-274.