# Estimate Fatigue Strength At 2 0x 10* And 6 0x10Quot; Cycles

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olgtltligtthis fatigue lab test in material science .can you send it as excel file pleaseSubmission Date: Next Lab
Experiment: Fatigue Test
Problem 1
The fatigue data for a brass alloy are given as follows (each question carry 1 marks):
Stress amp,
S(MPa)
170
148
130
114
97
80
74
Cycle to
failure (N]
3.7×104
1.0×105
3.0×105
1.0×105
1.0×10′
1.0×105
1.0x10quot;
a) Make an S-N plot of the data.
b) Plot in 5 vs /n N and report your observations. Determine the material constants A and B by
fitting this plot to the equation S- AN .
c) Determine the fatigue life for 120 MPa.
d) Determine the Endurance limit or Fatigue strength whichever is applicable for this metal.
Problem 2
The fatigue data for a steel alloy are given as follows.
Stress amp,
S(MPa)
470
440
390
350
300
290
290
290
Cycle to
failure (N)
1.0×10*
3.0×10
1.0×105
3.0×10
1.0×105
3.0×106
1.0×10
1.0×108
e) Make an S-N plot of the data.
f) Plot In 5 vs In N and report your observations. Determine the material constants A and B by
fitting this plot to the equation S=ANquot;. Is A and B the same as in problem 1? Why or why
not?
g) Determine the Endurance limit or Fatigue strength whichever is applicable for this metal.
h) Estimate fatigue strength at 2.0x 10* and 6.0x10quot; cycles.
If you run a component made of this steel alloy at stress amplitude of 470 MPa and such
that you stop using it at 1.0 x 10′ cycles, determines the factor of safety on life.
j) If you run a component made of this steel alloy for 1.0 x 10# cycles but at 250 MPa, what is
the safety factor on stress?Mechanical Engineering