Name of the College : Noorul Islam College of Engineering
University : Anna University
Degree : B.E
Department : Mechanical Engineering
Subject Code/Name : ME 1302 – Design of Machine Elements
Document Type : Question Bank
Website : niceindia.com
Download Model/Sample Question Paper :https://www.pdfquestion.in/uploads/niceindia.com/3035-ME1302_Design_of_Machine_Elements_.pdf
NICE Design of Machine Elements Question Paper
Unit I :
1. Define : Factor of safety
The ratio between maximum stresses to working stress is known as factor of safety.
Factor of safety = Maximum stress/ Working stress
Related : Turbomachinery Institute of Technology &Sciences IT1201 Signals & Systems B.E Question Bank : www.pdfquestion.in/3038.html
2. Define endurance limit :
Endurance limit is the maximum value of completely reversed stress that the standard specimen can sustain an infinite number (106) of cycles without failure.
3. What is impact load? :
If the time of load application is less than one third of the lowest natural period of vibration of the part, it is called an impact load.
4. What are the various phases of design process? :
i. Recognition of need.
ii. Definition of problem
iii. Synthesis
iv. Analysis and optimization
v. Evaluation
vi. Presentation
5. What are the different types of loads that can act on machine components?
a. Steady load.
b. Variable load.
c. Shock load
d. Impact load.
6. What are the factors affecting endurance strength :
Factors affecting endurance strength are
i. Load
ii. Surface finish
iii. Size
iv. Temperature
v. Impact
vi. Reliability
7. What are the types of variable stresses? :
a. Completely reversed or cyclic stresses
b. Fluctuating stresses
c. Repeated stresses
8. Differentiate between repeated stress and reversed stress :
Repeated stress refers to a stress varying from zero to a maximum value of same nature.
Reversed stress of cyclic stress varies from one value of tension to the same value of compression.
9. What are the types of fracture? :
a. Ductile fracture
b. Brittle fracture
10. Distinguish between brittle fracture and ductile fracture :
In brittle fracture, crack growth is up to a small depth of the material. In ductile fracture large amount of plastic deformation is present to a higher depth.
11. Define stress concentration and stress concentration factor.
Stress concentration is the increase in local stresses at points of rapid change in cross section or discontinuities. Stress concentration factor is the ratio of maximum stress at critical section to the nominal stress
12. Explain size factor in endurance strength :
Size factor is used to consider the effect of the size on endurance strength. A large size object will have more defects compared to a small one. So, endurance strength is reduced. If K is the size factor, Actual endurance strength = Theoretical endurance limit x K
13. Explain Griffith theory. (Or) State the condition for crack growth :
A crack can propagate if the energy release rate of crack is greater than crack resistance.
14. What are the modes of fracture? :
a. Mode I (Opening mode) – Displacement is normal to crack surface.
b. Mode II (Sliding mode) – Displacement is in the plane of the plate.
c. Mode III (Tearing mode) – Out of plane shear.
15. What are the factors to be considered in the selection of materials for a machine element? :
i. Required material properties
ii. Manufacturing ease
iii. Material availability
iv. Cost
16. What are various theories of failure? :
i. Maximum principal stress theory.
ii. Maximum shear stress theory.
iii. Maximum principal strain theory.
17 List out the factors involved in arriving at factor of safety :
i. material properties
ii. nature of loads
iii. presence of localized stresses
iv. mode of failures
18. Give some methods of reducing stress concentration :
i. Avoiding sharp corners.
ii. Providing fillets.
iii. Use of multiple holes instead of single hole
iv. Undercutting the shoulder parts.
19. Explain notch sensitivity. State the relation between stress concentration factor, fatigue stress concentration factor and notch sensitivity.
Notch sensitivity (q) is the degree to which the theoretical effect of stress concentration is actually reached. The relation is, Kf = 1 + q (Kt-1)
20. What are the factors that effect notch sensitivity? :
i. Material
ii. Notch radius
iii. Size of component
iv. Type of loading
v. Grain Structure