2. Objectives
To integrate knowledge learned in the mechanics,
structures, materials, and manufacturing courses.
Systematically analyze an engineering problem
and obtain a suitable solution
Understand the concepts of factor of safety and
stress concentration
To obtain a working knowledge in the use of the
proper failure theories under steady and variable
loadings.
Design shafts and keys under various types of
loading.
Select standard V-belts.
Select standard anti friction bearings
Design mechanical joints, mainly; welded, riveted
and screw fastened joints.
3. Student Learning Outcome
1. Students will demonstrate ability to analyse
engineering problems and obtain possible
solutions [1,]
2. Students will demonstrate ability to write design
specifications for engineering systems. [1]
3. Student will demonstrate ability to design shafts
and keys under various types of loading [2,3,4,5]
4. Students will demonstrate ability to select
standard components: belts and bearings for
various applications. [3,6,7]
5. Students will demonstrate ability to design
different types of mechanical joints. [ 3, 8]
4. Mechanical design 1:
Design Process
Stress and factor of safety
Design of shafts
Selection of belts
Bearings
Welded joints
Riveted joints
Screw fasteners
5. Textbook and References
Mechanical Engineering Design, , Joseph E.
Shigley, Charles R. Mischke and Richard G.
Budyans McGraw Hill , International
editions, Seventh edition, 2004
Fundamentals of machine Component
Design, Robert C. Juvinall, Kurt M. Marshek,
John Wilely & Sons, Forth edition, 2005
Machinery’s Handbook, , Eric Oberg,
Franklin D. Jones and Holbrook L. Horton.
Industrial Press Inc., 27th edition, 2004
8. A product design must be:
Functional :
The product must perform to fill its intended need
Safe :
The product is not hazardous to users
Reliable :
The product will perform its intended function satisfactory at a given
age.
Manufacturable:
The product can be manufactured with the available technology with
required quantities
Marketable:
The product can be bought and service, repair, is available
Competitive : the product is contender, challenger, in its market
9. The Design Process
Recognition
of need
Definition
of problem
Presentation Synthesis
Evaluation Analysis and
optimisation
10. Synthesis :
• It is the methods of obtaining alternative
solution, Ideas
• It is sometimes called the invention of the
concept
• In this stage as many solutions or ideas as
possible are required
11. Factor which drives invention or creativity
Inherited qualities ,talent:
we cannot all inherit Leonardo's genes, but each
of us must have some talents qualities.
Thinking Methods:
you can employ proven techniques to increase
your inventive powers
Attitude:
you must be positive, you can invent!
Knowledge and experience:
your understanding of how related problems are
solved can be increased
Effort:
Edison (inventor of the light bulb) put more
effort to develop and improve his invention
12. Methods of obtaining alternative solution
Standard parts
Method of Inversion
Solution at stages
Black-box concept
Brain storming
13. Standard parts
Copy an existing solution
Change manual system into automatic one
Change the system from batch to
continuous production
If the required system is very large and only
part of it is available, use the available
parts and fill the gap with new design
Look for similar systems and modify to suit
the required one
14. Method of Inversion
Inversethe characteristics of the
system to get new ideas
Change shape: convex to concave etc.
Change motion: rotary to
linear, moving to stationary etc.
Change position: front to rear, top to
bottom, vertical to horizontal inside to
outside etc
15. Solution at stages
Divide the complex system into stages
Find
alternative solution for each
stage.
Combine the best and compatible
solution from each stage
16. Black-box concept
Consider the system as consisting of
black boxes
Do not investigate the details of each
box at this stage
17. Brain storming
Itis a free association of ideas where
each idea is recorded and actively
encouraged to initiate further ideas
A group of people with different
backgrounds
A leader
No criticism during ideation
Any idea which gives birth to other ideas
cannot be wholly daft,
18. General guidelines for writing design
specification
Title
Role of equipment
Inputs
Outputs
Environment and location
Measures of value
19. Title
The title should be very specific
Doesnot mix with other or previous
specifications.
Wordsshould give specific meaning
and can be easily translated to other
languages
20. Role of equipment
It describes broadly what the system is
supposed to do
It does not provide a solution to the problem
The role of equipment is very important for the
designer as well as the user.
Also it helps the manufacturer in
understanding the required specifications.
21. Inputs
It describes the characteristics of the
inputs to the system
– Nature (electric current, gas pressure, mechanical
movement)
– Quantity, (weight volume, distance speed etc.)
– The rate of change (kg/sec, m3/min..etc.)
– The shape of change (sine wave, constant, arbitrary)
22. Outputs
Similarly the output from the system
should be described
Without mentioning the relation
between the inputs and outputs
Unless the customer insists in a
certain way of transforming the inputs
to ouputs
23. Environment and location
Environment
all factors which may influence the design and has
not been mentioned in previously.
location is the relative position of the system to
other systems and equipment.
– Human
Equipment are in direct or indirect relation
with humans.
Man has a role in their
design, manufacture, assembly, use, or
maintenance.
Dimensions of human body
Natural abilities of human body Comfort.
– Auxiliary services
services needed for the system (compressed
air, water supply, electricity, hydraulic power )
24. Measures of value
Measure of value may includes:
Performance
Initial cost
Operation cost
Maintenance cost
EQUIPMENT RENT COST
Total life
Comfort and ease of use
Appearance
Safety
Training
Reliability