This document reports on the results of tensile and fatigue testing of steel specimens. Tensile testing was conducted on a specimen without a hole, with a 3mm diameter hole, and on a plain tension test specimen. The yield loads, ultimate tensile loads, and stresses were reported. Fatigue testing was also conducted where the specimen was bent with a known load and the resulting deflection and microstrain were measured. Equations were developed to relate bending stress to applied load and microstrain. Bending moment and stress values were calculated for different loads and deflections.

1. David Ramcharn
02743799
ME21A
FATIGUE LAB
TENSILE TESTING
Specimen without hole
Average
Area
Width (mm)
22.6
23
22.88
22.8266667
Thickness (inches)
0.131
0.129
0.127
0.129
Thickness (mm)
3.3274
3.2766
3.2258
3.2766
= Width * Thickness
= 22.83 * 3.28
= 74.88 mm2
Yield Load
Ultimate Tensile Load
= 5800 lbs
= 7900 lbs
= 2630.84 Kgs
= 3583.38 Kgs
Stress (σ)
= Force / Area
σyield
= 2630.84 * 9.81 / 74.88
= 344.654 N/mm2
σultimate
= 3583.38 * 9.81 / 74.88
= 469.45 N/mm2
Specimen with 3mm diameter hole
Average
Area
Yield Load
Ultimate Tensile Load
Width (mm)
22.52
22.56
22.64
22.57
Thickness (inches)
0.114
0.114
0.117
0.115
= (Width – hole diameter)* Thickness
= (22.57 – 3) * 2.921
= 57.164 mm2
= 4200 lbs
= 5700 lbs
σnominal
= 1905.1 * 9.81 / 57.164
= 326.89 N/mm2
σultimate
= 2585.48 * 9.81 / 57.164
= 443.622 N/mm2
Stress concentration Factor
= 1905.1 Kgs
= 2585.48 Kgs
Thickness (mm)
2.8956
2.8956
2.9718
2.921

2. David Ramcharn
02743799
K
ME21A
= σyield / σnominal
= 344.654 / 326.89
= 1.056
TENSION TEST
Average
Area
Width (mm)
27.4
27.5
26.9
27.2
27.25
= Width * Thickness
= 27.25 * 3.125
= 85.16 mm2
Yield Load
Ultimate Tensile Load
= 23190 N
= 32800 N
Stress (σ)
= Force / Area
σyield
= 23190 / 85.16
= 272.32 N/mm2
σultimate
= 32800 / 85.16
= 385.17 N/mm2
From work sheet P-yield
= 19110N
Area
= Width * Thickness
= (27.25 – 3) * 3.125
σnominal
= 19110 / 75.78
= 252.173 N/mm2
Therefore
K
= 272.32 / 252.173
= 1.08
Thickness (mm)
3.2
3.15
3.05
3.10
3.125

3. David Ramcharn
02743799
ME21A
FATIGUE TESTING
L = 62.5mm
b = 16.5mm
σbending
= (3PL)/ bt2
= (3*100*62.5)/16.5 * 42
= 71.023 N/mm2
Loaqd
(lbs)
0
2
4
6
8
Load
N)
0
8.900
17.799
26.699
35.598
microstrain
t = 4mm
P = 100N
Deflection (mm) microstrain
0
93
186
278
371
0
0.15
0.30
0.45
0.60
0
143
285
428
570
From Graph #1 of Load (N) vs Microstrain
Y
i.e Gradient of Graph
= 10.424x
…………………………………………….. 1
= 10.424 microstrain / N
From Graph # 2 of Deflection (mm) vs. microstrain
Y
i.e gradient of graph
= 950x ……………………………………………... 2
= 950 microstrain / mm
If specimen was subjected to a total deflection of 2.602mm then:Deflection
From eqn. 2.
Microstrain
= 2.602 / 2
= 1.301mm
= 1.301 * 950
= 1235.95 microstrain
Sub in eqn 1
1235.95
Load
= 10.424 * load
= 1235.95 / 10.424
= 118.57 N
Corresponding σbending = (3*118.57*62.5)/16.5 * 42
= 84.21 N/mm2
Bending Moments
= P * L/2

4. David Ramcharn
02743799
ME21A
= (3PL)/ bt2
σbending
For a given deflection and strain
P
= microstrain / 10.424
Load
= 143 / 10.424
= 13.72 N
Bending Moments
= 13.72 (62.5 / 2)
= 428.75 N mm
σbending
= (3*13.72*62.5)/(16.25*42)
= 9.89 N/mm2
Deflection (mm)
microstrain
Load N
0
0.15
0.30
0.45
0.60
0
143
285
428
570
0
13.72
27.34
41.06
54.68
Bending Moments
(N mm)
0
428.75
854.38
1283.13
1708.75
Bending Stress
(N/mm2)
0
9.89
19.72
29.61
39.43