By Dr.S.G.A

1. MET 304
Mechanical Design 1
4
5
0
1
2
3
Dr. Salah Gasim Ahmed
ACX F92

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

6. Engineers Provide:
Engineering Products:
Washing machines, food
processors, trucks, weapons, tooth
brush, etc
Engineering services:
operation, maintenance, etc

7. Life of engineering product:
 Design
 Manufacture
 Test
 Develop

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

25. Thank You