ArulmiguMeenakshi Amman College of Engineering
Vadamavandal-604410.
Important questions and answers
ME3591- DESIGN OF MACHINE ELEMENTS
Prepared by
V.Umapathy,
Prof. /Mech.
S.No Questions and answers
.
Unit-I
FUNDAMENTAL CONCEPTS IN DESIGN
2 – marks question and answers
1. Define design.
The processes of creation of new, better machine and improving the existing one is called design.
2. List the factors influencing machine design.
Several factors influence machine design, including functionality, size and space, cost and weight,
manufacturing, safety, durability, reliability, and maintenance. These factors are interconnected and
require careful consideration to create effective and functional machines.
3. What is preferred number in design?
Preferred numbers, also known as preferred sizes, are a system of numbers used in machine design and
other fields to standardize dimensions and reduce manufacturing complexity. They are based on a
, geometric series, meaning each number is a fixed multiple of the previous number, leading to a
logarithmic progression. This system helps to ensure compatibility between different designs and
reduces the number of distinct sizes that need to be manufactured or stocked.
4. Define factor of safety.
It's the ratio of a material's ultimate strength or yield strength to the applied stress or working stress. A
higher FOS indicates a more conservative design, while a lower FoS might be more economical but
carries a higher risk.
5. What is the stress concentration factor?
The stress concentration factor (Kt) is a dimensionless parameter that quantifies the amplification of
stress at a point of discontinuity or geometric feature in a material. It's defined as the ratio of the
maximum stress (σmax) at the point of discontinuity to the nominal stress (σnom), which is the stress
calculated based on the overall cross-sectional area.
6. What is the endurance limit in design?
In machine design, the endurance limit represents the maximum stress a material can withstand under
repeated or fluctuating loads without experiencing fatigue failure. It's essentially the stress level below
which a material can withstand an infinite number of cycles without failing.
7. Write the difference between straight beam and curved beam.
The primary difference between a straight beam and a curved beam lies in their geometry and the
resulting stress distribution. Straight beams have a straight profile, while curved beams have a curved
profile. This difference leads to variations in stress distribution and the need for different analytical
approaches.
8. State difference between tolerance and fit.
Tolerance and fits are related concepts in engineering and manufacturing, but they refer to different
aspects of how parts are designed and assembled. Tolerance is the allowable variation in a dimension,
while a fit describes the relationship between the sizes of mating parts during assembly.
9. What is an SN curve?
An S-N curve (also known as a fatigue curve or Wöhler curve) is a graph that illustrates the relationship
between stress and the number of cycles to failure in a material under cyclic loading. It's a fundamental
, tool in fatigue analysis, helping engineers understand how materials behave under repeated stress and
predict their lifespan.
10. Define design stress.
Design stress, also known as working stress, allowable stress, or safe stress, is the maximum stress a
material can withstand under a load without failure. It's essentially the stress limit set by engineers to
ensure a structure or component remains functional and safe under expected conditions.
13 and 15 marks question and answers
11. The dimensions of the mating parts, according to basic hole system are given as follows:
Hole : 25.00 mm Shaft : 24.97 mm
25.02 mm 24.95 mm
Find the hole tolerance, shaft tolerance and allowance.
,
Vadamavandal-604410.
Important questions and answers
ME3591- DESIGN OF MACHINE ELEMENTS
Prepared by
V.Umapathy,
Prof. /Mech.
S.No Questions and answers
.
Unit-I
FUNDAMENTAL CONCEPTS IN DESIGN
2 – marks question and answers
1. Define design.
The processes of creation of new, better machine and improving the existing one is called design.
2. List the factors influencing machine design.
Several factors influence machine design, including functionality, size and space, cost and weight,
manufacturing, safety, durability, reliability, and maintenance. These factors are interconnected and
require careful consideration to create effective and functional machines.
3. What is preferred number in design?
Preferred numbers, also known as preferred sizes, are a system of numbers used in machine design and
other fields to standardize dimensions and reduce manufacturing complexity. They are based on a
, geometric series, meaning each number is a fixed multiple of the previous number, leading to a
logarithmic progression. This system helps to ensure compatibility between different designs and
reduces the number of distinct sizes that need to be manufactured or stocked.
4. Define factor of safety.
It's the ratio of a material's ultimate strength or yield strength to the applied stress or working stress. A
higher FOS indicates a more conservative design, while a lower FoS might be more economical but
carries a higher risk.
5. What is the stress concentration factor?
The stress concentration factor (Kt) is a dimensionless parameter that quantifies the amplification of
stress at a point of discontinuity or geometric feature in a material. It's defined as the ratio of the
maximum stress (σmax) at the point of discontinuity to the nominal stress (σnom), which is the stress
calculated based on the overall cross-sectional area.
6. What is the endurance limit in design?
In machine design, the endurance limit represents the maximum stress a material can withstand under
repeated or fluctuating loads without experiencing fatigue failure. It's essentially the stress level below
which a material can withstand an infinite number of cycles without failing.
7. Write the difference between straight beam and curved beam.
The primary difference between a straight beam and a curved beam lies in their geometry and the
resulting stress distribution. Straight beams have a straight profile, while curved beams have a curved
profile. This difference leads to variations in stress distribution and the need for different analytical
approaches.
8. State difference between tolerance and fit.
Tolerance and fits are related concepts in engineering and manufacturing, but they refer to different
aspects of how parts are designed and assembled. Tolerance is the allowable variation in a dimension,
while a fit describes the relationship between the sizes of mating parts during assembly.
9. What is an SN curve?
An S-N curve (also known as a fatigue curve or Wöhler curve) is a graph that illustrates the relationship
between stress and the number of cycles to failure in a material under cyclic loading. It's a fundamental
, tool in fatigue analysis, helping engineers understand how materials behave under repeated stress and
predict their lifespan.
10. Define design stress.
Design stress, also known as working stress, allowable stress, or safe stress, is the maximum stress a
material can withstand under a load without failure. It's essentially the stress limit set by engineers to
ensure a structure or component remains functional and safe under expected conditions.
13 and 15 marks question and answers
11. The dimensions of the mating parts, according to basic hole system are given as follows:
Hole : 25.00 mm Shaft : 24.97 mm
25.02 mm 24.95 mm
Find the hole tolerance, shaft tolerance and allowance.
,
