# Basic Concepts | Machine Design | Questions Answer For Interview

In this post we will see important questions regarding Machine Design ,Design Engineers Interview Questions – Basic Concepts . This questions with answers are helpful for interview ,viva , oral examination regarding Mechanical Machine Design  subject or field.

1. What are the different types of loads that can act on machine components?

2.  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

Read in details : Steps In Engineering Design Process -Engineering Design

3. What do you mean by 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.

4.  What are the types of variable stresses?
a. Completely reversed or cyclic stresses
b. Fluctuating stresses
c. Repeated stresses

5.  What are the types of fracture?
a. Ductile fracture
b. Brittle fracture

6.  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

7.  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

8.  What are various theories of failure?
i. Maximum principal stress theory.
ii. Maximum shear stress theory.
iii. Maximum principal strain theory

9.  List out the factors involved in arriving at factor of safety
i. material properties
iii. presence of localized stresses
iv. mode of failures

10. 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.

11. What is  the bending equation.
M/I = E/R = Fs/Y.
M – Bending moment
I – Moment of intertia
E – Youngs modulus
R – Radius of the shaft
Fs – Shear stress
Y – Distance from neutral axis

12. what is the torsion equation.
T/J = CØ/L = Fs/R
T – Torque
J – Polar moment of intertia
C- Rigidity modulus
Ø – Angle of twist
L – Length of the shaft
Fs – Shear stress
R – Radius of the shaft

13. 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.

14. What is key?
A key is device, which is used for connecting two machine parts for preventing relative motion of rotation with respect to each other.

15.  What are the types of keys?
ii. Tangent key
iii. Sunk key
iv. Round key and taper pins

Read in details :Types Of Mechanical Keys- Design Of Keys.

16.  How is a bolt designated ?
A bolt is designated by a letter M followed by nominal diameter and pitch in mm.

17. Define pitch.
Pitch is defined as the distance from appoint on one thread to the corresponding on the adjacent thread in the same axis plane.