Part 1 - temperature set at 325, weight = 1232.9 g Part 2 - temperature set at 3

Question

Part 1 - temperature set at 325, weight = 1232.9 g

Part 2 - temperature set at 325, weight = 1428.9 g

Part 3 - temperature set at 345, weight = 1232.9 g

Label on the graphs

-primary(if observed), secondary and tertiary creep

-Steady state creep rate (where it starts and ends)

Explain how the variation in load (and thus stress) changes the creep rate.

Comment on the influence that increasing temperature has on creep.

If the experiment was repeated using steel or copper, how would the results compare with those for Aluminium? (mention melting point)

Explanation / Answer

1. Since, I didn't have a spreadsheet I am finding difficulty in labelling the measurements In part 1, 2 and 3.

2. Creep is a time-dependent Phenomena which occurs under constant Loading. The deformations in the structure increase as time go on increases, As the present case represents an Aluminium Material, we can illustrate from the Graph of part 1 and 3, an increase in temperature of 20 degrees Celcius, the strain rate will increase by 900%.

This is calculated as below,

From Part 1 graph, it is very clear that, strain rate = (0.02/600) = 0.00003333

Part 3 graph, the strain rate = (0.02/60) = 0.000333333

Therefore, increase in strain rate = (0.00033333-0.0000033333)/(0.000033333) = 9 = 900 %

3. variation in Load = increase in load by 15.9 % will increase the strain rate by (-0.0000333333+(0.01/85))/(0.00003333333) = 252.94 %.

Note that, (0.01/85) is a strain rate of part 2 when load = 1428.9 g.

4. As the coefficient of Thermal Expansion of Aluminium is 23.1 E-06 and for copper is 17.1 E-06 and for Steel is 7.2 E-06.

Thus, an Increase in Temperature in the copper by (20/325)=6.15 % will increase the strain rate by (900/(23.1/17.1)) = 666.24 % and an Increase in stress in the steel by 6.15 % will increase the strain rate by (900/(23.1/7.2)) = 280.52 %

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