The two polymers that were tested gave the results of the first was 200mm per minute with a maximum load of 1066kN and the second 20mm per minute with a maximum load of 927kN.
Colour
Polymer
Mass
Density
Load
Failure
Tensile Strength
(g)
(Kg/m�)
(ken)
(N/mm�)
Red
HD Polyethythene
9.47
868.807
0.84
Very ductile
21
Yellow
LD Polyethythene
9.45
866.972
0.43
Very ductile
10.75
Black
Nylon 66 Glass
14.73
1351.376
5.27
Brittle
131.75
Amber
Acrylic
12.55
1151.376
2.75
Very Brittle
68.75
Clear
Polystyrene
11.13
1021.101
1.64
Very Brittle
41
White
Nylon 66
12.19
1118.349
2.55
Ductile
63.75
Blue
Tough Polystyrene
11.08
1016.514
0.8
Tough
20
Green
Polycarbonate
13.13
1204.587
2.59
Tough
64.75
Brown
Polypropylene
9.33
855.963
1.5
Brittle
37.5
Conclusion
In conclusion the polymer that can with stand the most load is the nylon 66 glass which took a load of 5.27kN whilst the LD Polyethythene took the smallest load with a result of 0.43kN. The nylon 66 glass had a high load but gave a brittle failure where as the LD Polyethythene was very ductile which gave a result of the polymer stretching. The effect that the rate of extension has on the polymer depends on the rate, if the rate is of a large rate such as 200mm per minute then the amount that the polymers amount of stretch will decrease. The lower the rate the more the stretch will be, for example in the Lloyds machine test the machine reached its maximum and the polymer had still not broke it just stretched to the full length of the machine.
Tensile testing of metals
Objective
The aim of this is to show the relationship between the load and extension of metals. We are going to test two samples of reinforcement. One shall be the plain R-bar and the other shall be a high strength T-bar. The samples must be in accordance with BS EN 10002-1:1990 using the Denison Tensile Test Machine.
We shall also test eight different metal bars of the same size using the Hounsfield Machine
Method
First we tested the reinforcement bars. The measurements of the diameter and the length of the bars are taken and recorded. The bar is loaded onto the Denison Test Machine and loaded until the bar fails. The maximum load is recorded and the bar removed. You have to measure the diameter and length so the Elongation and Reduction can be calculated. Then the other reinforcement bar is tested in exactly the same way.
Secondly we tested the Hounsfield tests using 8 different types of metal of the same size bars. The metals are carbon steels, Alloy steel, Aluminium alloy, copper, 70/30 Brass and 60/40 brass. They all have the same area of 20mm� apart from the Alloy steel which has an area of 10mm�. The metal is loaded on to the Hounsfield and load till failure and the maximum load is recorded, then pieces are used to find the Elongation and Reduction of the metals. All data is added to the table and used to work out the maximum strength of the metal bars.
Reinforcement Bar Results
Mild Steel
High Carbon Steel
(R-bar)
(T-bar)
Initial Diameter (mm)
15.96
15.15
Final Diameter (mm)
5.73
10.76
Initial Gauge length (mm)
50
50
final Gauge length (mm)
75.44
65.25
Maximum load (kN)
83.6
134.5
Maximum strength (N/mm�)
0.000104762
0.000177558
Elongation %
50.88
30.5
Reduction in area %
45.831
7.315
Hounsfield Test Results
Sample
Maximum Load (kN)
Maximum Strength (N/mm�)
Elongation %
Reduction in Area %
0.1% Carbon Steel
7.9
395
39
62
0.4% Carbon Steel
15.52
776
21.5
44
0.8% Carbon Steel
19.6
980
12
27
Alloy Steel
15.27
1527
11
40
Aluminium Alloy
6.75
337.5
13
55
Copper
6.4
320
19
72
70/30 Brass
8.5
425
38
68
60/40 Brass
9.01
450.5
39
68
Conclusions
The Elongation of the R-bar was of 50% of the original bar and the reduction was of 45% of the bar stretched which caused a cup and cone failure which is common in mild steel. In the T-bar the Elongation was of 30% and the Reduction of the bar was of 7% which caused the bar to snap instead of stretch. The difference between the yield and the maximum load is that the yield is what the bar can safely take without failing; the maximum loading is the point when then bar fails.
The diameter of the R is 15.96 and has two marked lines; the initial length is 50mm. This is very ductile, it’s not strong therefore is not used as much.
The T-bar s ribbed and has two marks on it which means the test should be quicker, and the failure was angled and there was a reduction in area. This is used as a main reinforcement and has more steel/carbon.
In the Hounsfield tests show the Elongation of the different metals show that the Alloy steel didn’t stretch as much as the 0.1% carbon and the 60/40 brass whilst the Reduction in area is greater in both the brass the less is in the alloy steel. The hardness of metals can be tested using Rockwell hardness test.
Brass is good in terms of corrosion and hardness. You would have to perform these tests in a wide range to be accurate. Brass has a composition of more than one material it is built up of 70copper x 30 brass. That’s why copper pipes are used for electrical / plumbing needs. They don’t use polymers as they are heavy. Copper is not very strong or expensive.
