250+ TOP MCQs on Modes of Failure & Stresses and Answers

Machine Design Multiple Choice Questions on “Modes of Failure & Different kind of Stresses”.

1. A mechanical component may fail as a result of which of the following
a) elastic deflection
b) general yielding
c) fracture
d) each of the mentioned
Answer: a
Clarification: Failing simply means unable to perform its function satisfactorily.

2. Type of load affects factor of safety.
a) True
b) False
Answer: a
Clarification: Dynamic load has higher factor of safety as compared to static loading.

3. For cast iron components, which of the following strength are considered to be the failure criterion?
a) Ultimate tensile strength
b) Yield Strength
c) Endurance limit
d) None of the mentioned
Answer: a
Clarification: Ultimate tensile strength is the highest stress a component can undergo before failingand hence is used as a criterion.

4. For components made of ductile materials like steel, subjected to static loading which of the following strength is used as a failure of criterion?
a) Yield strength
b) Ultimate strength
c) Endurance limit
d) None of the mentioned
Answer: a
Clarification: In elastic material there is considerable plastic deformation at yielding point.

5. Pitting occurs on _____ of the component.
a) Surface
b) Inner body
c) Inside or on surface
Answer: a
Clarification: Pitting is a process in which small holes occur on a surface of component.

6. Buckling is elastic instability which leads to sudden large lateral deflection.
a) True
b) False
Answer: a
Clarification: Definition of buckling.

7. The critical buckling load depends upon which of the following parameters?
a) Yield strength
b) Modulus of elasticity
c) Radius of gyration
d) Each of the mentioned
Answer: d
Clarification: It depends on moment of inertia(which further depends on radius of gyration), elasticity and yield strength.

8. If there are residual stresses in the material, than lower factor of safety is used.
a) True
b) False
Answer: b
Clarification: Residual stress increases the chance of failure.

9. Which of the following relationship is true? (p=Poisson’s ratio)
a) E=2G (1+p)
b) E=G (2+p)
c) E= 2(G+ p)
d) No relation exist between E, G and p
Answer: a
Clarification: Formula.

10. Modulus of rigidity for carbon steels is greater than that of grey cast iron.
a) True
b) False
Answer: a
Clarification: Modulus of rigidity is double for carbon steels as compared to grey cast iron.

11. According to principal stress theory, which option represents the correct relation between yield strength in shear (YSS) and the yield strength in tension (YST)?
a) YSS=0.5YST
b) YSS=0.577YST
c) YST=0.5YSS
d) YST=0.577YSS
Answer: a
Clarification: Shear diagonal is at 45’ and by equation of shear stress theory, the required relation is obtained.

12 .A beam subjected to bending moment undergoes which of the following stresses?
a) Compressive
b) Tensile
c) Both compressive & tensile
d) None of the mentioned
Answer: c
Clarification: The portion above the neutral axis is under compression and the portion below it is under tensile stress.

13. The bending stress varies _______ with the distance from the neutral axis.
a) Linearly
b) Inversely
c) Squarely
d) Bending stress is independent of distance from the neutral axis
Answer: a
Clarification: Bending Stress= (Bending Moment x distance from neutral axis/ Moment of inertia).