# Essay on ME1.1

Submitted By joemac1990
Words: 931
Pages: 4

ME1.1

Department of Engineering
University of Hull
3rd December 2013

Abstract / Summary

This experiment is to determine the Young’s modulus of elasticity for a sample of brass, aluminium and mild steel. Also determine other material properties by testing the samples to failure. The report will include all calculations from the experiment along with results in graph and numerical forms. The experiment was a success but did have some abnormal results such as brass having higher than expected results and mild steel having lower than expected results.

Contents

Abstract 2 Theory 4 Equipment/ materials 5 Procedures 5 Results 6 Discussion 16 Conclusion 16

Theory

The theory required for this experiment can be simplified to the followed equations.

E=Stress/Strain= σ/ϵ= Fl/Ax
E = Young’s modulus
F= Force
X = extension
L = gauge length
X = CSA (Cross sectional area)

Yield Point=F/CSA
F= force at point which plastic deformation stars

UTS=F/CSA
F = maximum force applied

Equipment/ materials

Description Quantity
Experiment equipment Marker Pen 1
Experiment equipment Hounsfield 50 KN tensile tester 1
Experiment equipment Rule 1
Experiment equipment Extensometer 1
Experiment equipment Vernier Calliper
Consumables Aluminium Sample 3
Consumables Brass Sample 3
Consumables Mild steel Sample 3

Procedures

Mark two 50mm gauge lengths on opposite faces of each sample with the marker pen (Example fig 1). Ensure that the gauge lengths overlap. By doing this the extension to fail results can be taken no matter where the material fails. Measure the cross sectional area of each sample.

Fig 1

Each sample should be clamped in the testing machine with the extensometer attached. Tensile load will be applied to the sample in increments of approximately 500N up to approximately 5000N. Record the elastic extension produced by each load. With the extensometer removed, the sample will be loaded until it fails. A graph of load and extension will be produced by the testing machine. Measure the cross sectional area of each sample at the fracture. Measure the final length of each sample by reassembling the pieces and measuring between the gauge marks. Consideration should be taken to the accuracy of these measurements.

Results
Mild Steel
Measurements before experiment Mild Steel (mm) Sample Dimensions Width Thickness width thickness area (m²) 12.76 3.97 12.69 4.03 0.01273 0.0040 0.0000508776 12.74 3.99
Mean 12.73 4.00
STD Deviation 0.04 0.03 Original length (m) 0.05
Measurements with extensimeter
(N) (mm) (m)
510 0.001875 0.0000018750
1017.5 0.005 0.0000050000
1502.5 0.0075 0.0000075000
2012.5 0.010625 0.0000106250
2520 0.013125 0.0000131250
3015 0.015 0.0000150000
3520 0.0175 0.0000175000
4062.5 0.020625 0.0000206250
4512.5 0.0225 0.0000225000
5010 0.025 0.0000250000

Young’s modulus
E=Stress/Strain= σ/ϵ= Fl/Ax

E=(5010 x 0.05)/(0.0000508776 x 0.000025)=196943381071.03N

Yield Point
Yield Point=F/CSA

Yield Point=16150/0.0000508776 = 317428703N

Ultimate Tensile Strength
UTS=F/CSA
UTS=22500/0.0000508776 = 442238131.1N

Young modulas Yield strength Ultimate Tensile Strength
(N) (Gpa) (N) (Mpa) (N) (Mpa) 196943381071.03 196.94 317428703 317.43 442238131.1 442.24

Brass
Measurements before experiment Brass (mm) Sample Dimensions Width Thickness width thickness area (m²) 12.77 4.06 12.74 4.03 0.01276 0.00404 0.0000514944 12.76 4.02
Mean 12.76 4.04
STD Deviation 0.02 0.02 Original length (m) 0.05

Measurements with…