Interview Questions: Design of Machine Elements

Define Ductility.
It is the property of the material enabling it to be drawn into wire, with the application of tensile force. It must be both strong and plastic. It is usually measured in terms of percentage elongation and reduction in area, (e.g.) Ni, Al, and Cu.

Define fatigue.
When a material is subjected to repeated stress, it fails at stresses below the yield point stress; such type of failure of the material is called fatigue.

Define the factor of safety.
The ratio between maximum stresses to working stress is known as a factor of safety.
Factor of safety = Maximum stress /Working stress

Define the 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.

What is the 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.

What are the various phases of the design process?
The various phases of the design process are:
  • Recognition of need.
  • Definition of problem
  • Synthesis
  • Analysis and optimization
  • Evaluation
  • Presentation
What is the use of Goodman & Soderberg diagrams?
They are used to solve the problems of variable stresses.

What are the factors affecting endurance strength?
Factors affecting endurance strength are
  • Load
  • Surface finish
  • Size
  • Temperature
  • Impact
  • Reliability
What are the types of variable stresses? 
Types of variable stresses are:
  • Completely reversed or cyclic stresses
  • Fluctuating stresses
  • Repeated stresses
Differentiate between repeated stress and reversed stress.
Repeated stress refers to stress varying from zero to a maximum value of the same nature.
Reversed stress of cyclic stress varies from one value of tension to the same value of compression.



Popular posts from this blog

Electrical Machines (Three Phase Transformers)

Thermodynamics (Compressible Flow)

Electrical Machines (Special Machines)