2 - Mechanical Fatigue

Question 1

Fatigue cracking is a mechanical form of degradation that occurs when a component is exposed to
,,,,,,, for an extended period,

Answer 1

cyclical stresses

Question 2

Mechanical Fatigue cracking, often resulting in ,,,,

Answer 2

sudden, unexpected failure

Question 3

stresses causing Mechanical Fatigue cracking, can

be typically well below the ,,,,

Answer 3

yield strength of the material.

Question 4

Factors of Mechanical Fatigue cracking are:

Answer 4

Geometry,
Stress level,
Number of cycles, and
Material properties

Question 5

Materials like austenitic stainless steels and

aluminum that do not have an ,,,,,

Answer 5

endurance limit

Question 6

Materials like austenitic stainless steels and aluminum that do not have an endurance limit will have a fatigue limit defined by ,,,,

Answer 6

the number of

cycles at a given stress amplitude.

Question 7

For alloys with endurance limits, The ratio of endurance

limit over UTS is typically between ,,,,,,

Answer 7

0.4 and 0.5

Question 8

Heat treatments such as ,,,,,,, can improve fatigue resistance of carbon and low alloy steels

Answer 8

quenching and tempering

Question 9

300 Series SS, 400 Series SS, aluminum and most other non-ferrous alloys,,,,

Answer 9

does not exhibit an endurance limit

Question 10

For materials(300 Series SS, 400 Series SS, aluminum) without endurance limit, stress necessary to cause
fracture to the desired number of cycles necessary in a component’s lifetime. This is typically ,,,,,,, cycles.

Answer 10

106 to 107

Question 11

The signature mark of a fatigue failure is a ,,,,,,,,,,,,type fingerprint that has concentric rings called ,,,,emanating from the crack initiation site

Answer 11

“clam shell”

“beach marks”