The document discusses machine design and provides examples. It defines machine design as the process of selecting materials, shapes, sizes, and arrangements of mechanical elements so a machine can perform its intended task. As an example, it describes the process of designing a belt drive, which involves selecting elements like pulleys and belts, their shapes and materials, and their sizes. It also mentions classification and considerations in machine design processes, and provides a simple example of designing an L-shaped bracket.

1. Prepared by : Dinesh Gupta, G. L Bajaj Group of Institutions,
Mathura

2. Machine Design is the process of
selection of the materials, shapes,
sizes and arrangements of
mechanical elements so that the
resultant machine will perform the
prescribed task
What is Machine Design?

3. For example, the process of design of a belt drive
consists of :
1. Selection of arrangement of mechanical
elements like : pulleys, belt, shafts, keys,
bearings, etc;
2. Selection of shapes of these mechanical
elements;
3. Selection of materials for these mechanical
elements; and
4. Selection of sizes of these mechanical elements.

4. Belt drive design arrangement in a
Centrifugal Blower

5. Classification of Machine Design

6. Design Process

7. Design Considerations
 Design considerations are the characteristics
which influence the design of the element or,
perhaps, the entire system. Normally, a number of
such characteristics have to be considered in any
design problem.
 In a given design problem, the design engineer
should identify the various design considerations
and incorporate them in the design process in
their order of importance.
 For example, in the design of a spring, two most
significant design considerations are : strength
and stiffness.

9. Simple Design Problem
 Let’s talk about design of a simple “L" shaped
bracket, one side of it is clamped and at the other
side it is carrying some amount of load.

10.  For initial design we have started with 5 mm thick plate.
 The following steps need to be followed for finding out the actual
thickness needed for the bracket:
1. Calculating maximum bending moment: To find out the section
where the maximum bending stress occurs So, the maximum
bending moment M=750 kg-mm
2. The area moment of inertia for this section = (bd^3)/12
= 1041.667 mm4
3. Calculating bending stress: The classic formula for determining
the bending stress in a member is:
f/y=M/ I
f = M.y/ I
= 750 X 2.5/1041.667 kg/mm2
= 1.8 kg/mm2
If we consider a steel with yield strength is 25 kg/mm2, then we can
see that stress generated in the clip is substantially low , so we have
the chance to further reduce the thickness of the clip.

11. The HAL Tejas is an Indian single-
seat, single-jet engine, multi-role light
fighter designed by the Aeronautical
Development Agency and Hindustan
Aeronautics Limited.