Tensile Testing
Essay by Liezel Henwood • June 26, 2017 • Lab Report • 1,388 Words (6 Pages) • 1,218 Views
Tensile test
This laboratory report rotates around a test which was carried on a rod of material in order to determine the tensile strength of the material. During the experiment, different parameters, which include the diameters and length of the materials, were noted down. In addition, the loading on the rod was carried and this led to the elongation of the material. This process was carried out with the determination of the increasing elongation length due to the increased loading. It has to be noted that the tensile strength of the material is the final strength on which the material is able to withstand a certain load. This means that the loading has to be done until the fracture level of the material is reached. After the experiment, several parameters were noted down in order to help in the analysis, which would lead to the determination of the tensile strength. The key parameters include the elongation length and the loading, which was applied. The parameters were also key in the determination of the yield strength and the percentage elongation.
First, the diameter of the rod, which is the specimen, was taken out by the use of the Vernier caliper. The diameter was key in the determination of the area of the specimen. The specimen was then placed on the machine for the test to be carried out. The threads were tightened on the chucks to ensure that the specimen was tightly helped to ensure that the process was accurate. In addition, the nuts were tightened with hands to ensure that they were firm on the specimen. The machine was then connected to a switch on the interface. The process started and the elongation was measure. The jack handle was used to apply the required load and ensure that the loading was increased accordingly each moment and the respective elongation was noted out. The loading was slowly applied, the load applied, and elongations achieved were noted out respectively. On each occasion a load was increased, the elongation achieved was noted down. After that, the load vs. elongation achieved graph was plotted out. This was used in order to identify the elastic limit, upper yield point and lower yield point.
The specimen used had an original diameter of 6 millimeter and original length of 65.57 millimeters.
Results
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | |
Load KN | 1KN | 6KN | 13KN | 17KN | 17KN | 17KN | 16KN | 16KN | 14KN | 13KN | 13KN fracture |
Cumulative load, KN | 1 | 7 | 20 | 37 | 54 | 71 | 87 | 103 | 117 | 130 | 143KN |
Elongation mm | 00.18 | 00.34 | 00.55 | 00.96 | 1.52 | 2.10 | 2.70 | 3.31 | 3.95 | 4. 62 | 7.09 |
Stress values
The stress values which is also referred to as the direct stress is based on the force which is applied, and the cross sectional area of the specimen. The direct stress is found through the division of the force applied on each case by the correctional area of the specimen, which is constant. The following values of direct stress were attained after the experiment was carried out.
Stress 1 = 35,373 Mpa
Stress 2 = 212,239 Mpa
Stress 3 = 459,851 Mpa
Stress 4 = 601,344 Mpa
Stress 5 = 601,344 Mpa
Stress 6 = 601,344 Mpa
Stress 7 = 565,971 Mpa
Stress 8 = 565,971 Mpa
Stress 9 = 495,225 Mpa
Stress 10 = 459,851 Mpa
Stress 11 = 459,851 Mpa, = 0 due to fracture point
From the analysis of the stress values, the increase in force applied in able to lead to a higher stress value. In each value, an increase in loading results to a higher stress value from the initial value. Nevertheless, since each loading case is taken independently, some of the higher values are initial than the previous ones. This is because the specimen has already undergone some elongation and stress value and therefore is applied to another case of straining. For instance, the stress 6 is higher than the stress 7. This is because the loading, which is applied on stress 7, is lower than the loading in stress 6. The loading on the case 7 is done after the effect of the of the case 6 loading has taken the effect and this is the main reason the case 11 is able to be considered as a fracture point although the stress value is lower than others in the loading cases.
The other calculation is based on looking for the strain values of the experiment. The strain calculation is based on the change on length and the original length of the specimen. The direct strain is found through the division of the elongation and the original length of the specimen rod. The following results were achieved after the analysis of the results which were arrived after carrying out the experiment;
Stain 1 = 0.002745
Stain 2 = 0.005185
Stain 3 = 0.008387
Stain 4 = 0.0146
Stain 5 = 0.0232
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