Question

2. Answer the following True or False Questions. a. “If the most conservative fatigue criterion as shown in the figure below were used for infinite life design, the first cycle yield failure check is not needed.” True___ or False _ b. It is easier to find the asymptotic value of fatigue strength as the endurance limit on the S-N curve for the CZ3000 alloy than that of endurance limit on the S-N curve for the 1045 steel. True_ or False _ c. “Through the notch sensitivity approach, you obtain a fatigue stress concentration factor higher than the stress concentration factor under static loading condition.” True_ or False _ d. Since the contact stress and load relation is not linear in rolling, the Hertzian endurance strength should increase nonlinearly with the hardness of the contact material. True_ or False _ e. Refer to the figure below. Even though the cyclic loading accidentally caused the stresses to exceed the levels at point A slightly (as marked by the red arrow), the machine part may not break instantly according to the Modified Goodman fatigue failure criterion. True_ or False ___ Sy Yield (Langer) line Alternating stress ?a Se Gerber line Load line, slope r = Sa/Sm Modified Goodman line Sa ASME-elliptic line Soderberg line 0 0 Sm Sy Sut Midrange stress ?m

          2. Answer the following True or False Questions.

a. “If the most conservative fatigue criterion as shown in the figure below were used for infinite life design, the first cycle yield failure check is not needed.” True_______ or False _______

b. It is easier to find the asymptotic value of fatigue strength as the endurance limit on the S-N curve for the CZ3000 alloy than that of endurance limit on the S-N curve for the 1045 steel. True_______ or False _______

c. “Through the notch sensitivity approach, you obtain a fatigue stress concentration factor higher than the stress concentration factor under static loading condition.” True_______ or False _______

d. Since the contact stress and load relation is not linear in rolling, the Hertzian endurance strength should increase nonlinearly with the hardness of the contact material. True_______ or False _______

e. Refer to the figure below. Even though the cyclic loading accidentally caused the stresses to exceed the levels at point A slightly (as marked by the red arrow), the machine part may not break instantly according to the Modified Goodman fatigue failure criterion. True_______ or False _______

Sy
Yield (Langer) line
Alternating stress ?a
Se
Gerber line
Load line, slope r = Sa/Sm
Modified Goodman line
Sa
ASME-elliptic line
Soderberg line
0
0
Sm
Sy
Sut
Midrange stress ?m

2. Answer the following True or False Questions.

a. “If the most conservative fatigue criterion as shown in the figure below were used for infinite life design, the first cycle yield failure check is not needed.” True or False

b. It is easier to find the asymptotic value of fatigue strength as the endurance limit on the S-N curve for the CZ3000 alloy than that of endurance limit on the S-N curve for the 1045 steel. True or False

c. “Through the notch sensitivity approach, you obtain a fatigue stress concentration factor higher than the stress concentration factor under static loading condition.” True or False

d. Since the contact stress and load relation is not linear in rolling, the Hertzian endurance strength should increase nonlinearly with the hardness of the contact material. True or False

e. Refer to the figure below. Even though the cyclic loading accidentally caused the stresses to exceed the levels at point A slightly (as marked by the red arrow), the machine part may not break instantly according to the Modified Goodman fatigue failure criterion. True or False

Sy
Yield (Langer) line
Alternating stress ?a
Se
Gerber line
Load line, slope r = Sa/Sm
Modified Goodman line
Sa
ASME-elliptic line
Soderberg line
0
0
Sm
Sy
Sut
Midrange stress ?m

Added by Mark M.

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