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					    Section I

Introduction about
 Machine Design I



                     1
Talking Points
   What is the meaning of design?
   Classifications of design
   Mechanical engineering design?
   Phases of design
   Design considerations
   Design factor of safety
   Examples of mechanical equipments
   Units
                                        2
      What is the Meaning of
      Design?

   The formulation of plan for the satisfaction
    of a human need. Sometime the particular
    need to be satisfied is well defined, and
    sometime it is not; thus, a lot of thought
    and effort is necessary to understand the
    particular need, clearly.


                                                   3
Classifications of Design
   Clothing design       Computer-aided design
   Interior design       Heating system design
   Highway design        Machine design
   Landscape design      Engineering design
   Building design       Process design
   Ship design           Etc…
   Bridge design


                                                   4
    Mechanical Engineering
    Design?
   The design of things and systems of a
    mechanical nature--machines, products,
    structures, devices, and instruments.
   Mechanical design utilizes mathematics,
    physics (kinematics, statics, dynamics),
    material science, and the engineering
    mechanics science.

                                               5
        Phases of Design
1.   The recognition of a need and a statement of this need in
     general terms. This defines the problem.
2.   The consideration of different schemes for solving the
     problem and the selection of one to be investigated in more
     detail. This phase includes a feasibility studies, backed up by
     special research if necessary.
3.   A preliminary design of the machine, structure, system, or
     process selected. This establishes broad overall features and
     makes it possible to write specifications for major
     components.
4.   Design of all components and preparation of all necessary
     drawings and detail specifications.
                                                                  6
Design Considerations
   Strength                Noise
   Reliability             Styling
   Thermal properties      Shape
   Corrosion               Size
   Wear                    Flexibility
   Friction                Control
   Processing              Stiffness
   Utility                 Surface finish
   Cost                    Lubrication
   Safety                  Maintenance
   Weight                  Volume
   Life
                                              7
     Design Factor of Safety
   The ratio of the component strength to the working or
    allowable stress.
                            strength
                   nd 
                        allowable stress
   The “strength” can be anything the designer chooses it to
    be. It should often be the yield strength, the ultimate
    strength, the fatigue strength…etc. It is a material
    property; while the working stress is the safe stress, which
    is allowed to be undertaken by the material in design.
   For structural steel work, nd is taken 2.0 to 2.5; but in case
    of cast iron, concrete, wood, nd is taken as 4.0 to 6.0.    8
Examples of Some Mechanical
Equipments




            Chainsaw
                              9
       Examples of Some Mechanical
       Equipments – Cont.



Tractor with front-end-loader attachment




                                           Aircraft landing gear   10
            Industrial crane
Examples of Some Mechanical
Equipments – Cont.




Reverse                Turbo Charger




              Engine
                                       11
Units




        12

				
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posted:6/8/2012
language:English
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