The objective of the experiment was to determine the existence of stress and strain concentrations on a cantilever beam, approximate the value of the stress concentration factor, K_n and compare to the published value of 1.2. The presence of any discontinuity such as holes, notches, or grooves, in a machine part of a structural member can alter the stress distribution in the vicinity of that discontinuity. Such discontinuities are called stress raisers, and the regions in which they occur are called areas of stress concentrations.^(1) The stress concentration factor, K_t, used to measure the ratio of the maximum stress at the stress-raiser to the nominal stress at the respective point.^(2) In this experiment, the discontinuity was a circular hole drilled through the depth of the beam on its centerline. Four strain readings were obtained one at a time using a strain indicator. A gage factor correction was made for the strain indicated by Gage 4, since it was different from gage factor of Gages 3, 2, and 1 using the equation:e\'_4.^(3) The result of this calculation was the nominal strain at the respective point. Then three coefficients, A, B, and C were determined from the measured strains using the equations: respectively.^(4) The summation of the A, B, and C equations yielded the maximum strain, epsilon_0, at the respective point. Finally, the stress concentration factor, K_t was obtained by dividing epsilon\'_0, over epsilon_7. The computations of the four strains, the gage factor correction (epsilon\'_7), the three coefficients (A, B, and C), the maximum strain (epsilon_0), and the measured stress concentration factor (K_t) were recorded and presented in Table 1. The experiment outcomes were 2242 mu epsilon, 1918 mu epsilon, 1821 mu epsilon, and 2000 mu epsilon for strain, 1967 mu epsilon for gage factor correction, 1377 mu epsilon, -518 mu epsilon, and 1868 mu epsilon for coefficients A, B, and C respectively. The maximum strain was found to be 2727 mu epsilon, and the stress concentration factor was found to be 1.386. Finally, the difference between the measured and the published stress concentration factor was -15.5%. I need to paraphrase it 1- Every single sentence. 2- using different words 3- must be typing thanks
Objective:
The main aim of the experiment is to find out the traces of strain and stress on a cantilever beam and the result is neared to the stress concentration factor value and then comparing it with the pre defined value i.e., 1.2.
Theory:
The stress distribution can be disturbed by the holes, grooves or notches in any structural member of the machine part. The areas in which these the discontinuities are formed are known as stress raisers and the effected area by these stress raisers are called area of stress concentrations.The stress concentration is measured by using the formula i.e., the ratio of maximum stress at the stress raisers to the nominal stress at that point. In this work, the discontinuity was on a beam which is hole drilled circularly on its centreline. By using the strain indicator, we measured four strain readings. Since the gage 4 was differing from the gage factors 3,2,1, a gage factor correction was made. Nominal strain at particular point is obtained as a result of this calculation. A,B, C were the three coefficients used to measure strains by some particular equations respectively. Maximum strain is yielded by summing A, B and C at respective point. By dividing maximum stress to the gage factor correction, stress concentration factor was obtained.
Result:
The results which were computed ad presented in Table 1 are as follows:
- Four strains
- Gage factor correction
- A, B and C coefficients
- Maximum strain
- Measured stress concentration factor
Conclusion:
The outcomes of this experiment were 2000, 2242, 1918 and 1821 for strain, 1967 for gage factor correction, A, B and C values were 1377, -518 and 1868. By doing this work, the stress concentration factor was found to be 1.386 and maximum strain was 2727. So, the final result is the difference between measured and published stress concentration and the factor was found to be -15.5%
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