Failure Theories: Master the Art of Predicting Machine Component Failure

Question 1

Fatigue failure theory accounts for the influence of:

Accepted Answer

Cyclic loading

Answer

Steady loading

Answer

Temperature variations

Answer

Corrosion

Question 2

Which of the following is NOT a significant factor when choosing an appropriate failure theory?

Accepted Answer

Designer's preference

Answer

Material characteristics

Answer

Loading conditions

Answer

Component geometry

Question 3

The Von Mises criterion is a:

Accepted Answer

Failure theory based on energy

Answer

Failure theory based on stress

Answer

Failure theory based on strain

Answer

Failure theory based on time-dependence

Question 4

The Tresca criterion predicts failure when the:

Accepted Answer

Maximum shear stress surpasses the material's shear strength

Answer

Maximum principal stress surpasses the material's tensile strength

Answer

Maximum strain energy density exceeds the material's yield strength

Answer

Minimum principal stress falls below the material's compressive strength

Question 5

Which failure theory predicts failure when the maximum principal stress in a material reaches its ultimate tensile strength?

Accepted Answer

Maximum stress theory

Answer

Maximum strain theory

Answer

Fatigue failure theory

Answer

Shear failure theory

Question 6

The maximum strain theory is based on the assumption that failure occurs when the maximum elastic strain in a material exceeds its yield strain.

Accepted Answer

True

Answer

False

Question 7

Which of the following is a key assumption of the Tresca failure theory?

Accepted Answer

Failure occurs when the maximum shear stress exceeds the ultimate shear strength

Answer

Failure occurs when the maximum principal stress exceeds the ultimate tensile strength

Answer

Failure occurs when the maximum strain energy exceeds the ultimate strain energy

Answer

Failure occurs when the maximum strain energy density exceeds the ultimate strain energy density

Question 8

The Von Mises failure theory is also known as the:

Accepted Answer

Maximum distortion energy theory

Answer

Maximum shear stress theory

Answer

Maximum principal stress theory

Answer

Mohr-Coulomb failure theory

Question 9

Which failure theory is most suitable for materials that exhibit a significant amount of plastic deformation?

Accepted Answer

Distortion energy theory

Answer

Maximum principal stress theory

Answer

Maximum shear stress theory

Answer

Mohr-Coulomb failure theory

Question 10

The Mohr-Coulomb failure theory is commonly used to analyze the failure of:

Accepted Answer

Concrete

Answer

Metals

Answer

Polymers

Answer

Composites

Question 11

The safety factor is a ratio used to ensure that a component can withstand a load safely.

Accepted Answer

True

Answer

False

Question 12

To design a machine component that can withstand a wide range of loading conditions, it is advisable to:

Accepted Answer

Use a combination of failure theories

Answer

Use a single failure theory

Answer

Use a theory that is overly conservative

Answer

Use a theory that is too optimistic

Question 13

Which failure theory states that failure occurs when the maximum principal stress in a material exceeds its ultimate tensile strength?

Accepted Answer

Maximum stress theory

Answer

Maximum strain theory

Answer

Fatigue failure theory

Answer

Shear stress theory

Question 14

Which failure theory considers the cumulative effect of fluctuating stresses over time, leading to eventual failure?

Accepted Answer

Fatigue failure theory

Answer

Maximum stress theory

Answer

Maximum strain theory

Answer

Shear stress theory

Question 15

Which of the following materials is most likely to exhibit brittle failure under uniaxial tensile loading?

Accepted Answer

Concrete

Answer

Ductile iron

Answer

Steel

Answer

Aluminum

Question 16

Which of the following factors does NOT influence the failure strength of a material?

Accepted Answer

Poisson's ratio

Answer

Temperature

Answer

Strain rate

Answer

Surface finish

Question 17

In the context of failure theories, what is the significance of the yield strength of a material?

Accepted Answer

It represents the stress level at which the material begins to deform plastically

Answer

It is the maximum stress that a material can withstand without failing

Answer

It has no relevance to failure theories

Answer

It is the stress level at which the material becomes brittle

Question 18

According to the maximum stress theory, failure occurs when:

Accepted Answer

The maximum principal stress exceeds the material's ultimate tensile strength.

Answer

The maximum shear stress exceeds the material's yield strength.

Answer

The cumulative effect of repeated loading exceeds the material's fatigue strength.

Answer

The maximum strain exceeds the material's ultimate strain.

Question 19

Which failure theory takes into account the cumulative effect of repeated loading over time?

Accepted Answer

Fatigue failure theory

Answer

Shear stress theory

Answer

Mohr-Coulomb failure theory

Answer

Maximum stress theory

Question 20

A component is subjected to a tensile stress of 150 MPa and a shear stress of 80 MPa. If the ultimate tensile strength of the material is 200 MPa, what is the safety factor according to the maximum stress theory?

Accepted Answer

1.33

Answer

1.50

Answer

2.00

Answer

1.00

Question 21

For a rotating shaft subjected to a bending moment, which failure theory is most appropriate to predict the fatigue life of the shaft?

Accepted Answer

Fatigue failure theory

Answer

Tresca failure theory

Answer

Maximum stress theory

Answer

Shear stress theory

Question 22

Which failure theory is most suitable for predicting the failure of a composite material?

Accepted Answer

Tsai-Wu failure criterion

Answer

Shear stress theory

Answer

Maximum stress theory

Answer

Maximum strain theory

Question 23

A thin-walled pressure vessel is subjected to an internal pressure. Which failure theory is most likely to predict the failure mode of the vessel?

Accepted Answer

Maximum hoop stress theory

Answer

Tresca failure theory

Answer

Fatigue failure theory

Answer

Maximum stress theory