DESIGN OF MACHINE ELEMENTS
Group A

Mechanical systems and elements, overall design considerations, safety, ecological and
societal considerations in design. Codes for design-Bureau of Indian Standards (BIS)-codes,
design data handbook. Load, stress and critical sections in machine parts.
Materials, stress-strain curves of ductile and brittle materials, cast iron, steel, non-ferrous
alloys and plastics, hardness and surface properties of materials, material strength, factor of
safety and allowable stress. Review of axial, bending, shear and torsional loading on machine
components, combined loading, two- and three dimensional Mohr's circle. Stresses in curved
beams, thick and thin shells under pressure.
Deflection and stability, beam deflection and column buckling. Euler's formula and Johnson's
formula. Failures theories-maximum normal stress theory, maximum shear stress theory, and
maximum distortion energy theory. Application to components made of brittle and ductile
materials, stress concentration factor.
Cyclic loading and fatigue failures: Reverse bending, axial and torsion loadings, effect of
stress concentration, fatigue life prediction-Miner's rule, effect of surface treatments (shotpeening,
surface hardening) on fatigue
life of components.
Design of threaded fasteners and power screws, thread forms and threaded fastener types and
materials, power screws, bolt tightening and initial tension, static and group of bolts.
Rivets and welding: Loading, bending, direct shear, axial and bending.




Group B

 

Design of springs: Spring materials, helical compression and extension springs, design for
fatigue, loading, leaf sprints. Design of sliding bearings, bearing materials, fluid viscosity,
hydrodynamic lubrication, Petroff's equation, Raimondi and Boyd chart. Heat
dissipation.
Rolling elements bearings: Types, catalogue information (Timken and SKF bearings),
bearing life radial and thrust loads. Selection of bearings. Spur, helical and worm gears, gear
tooth profile, gear geometry, module, contact ratio, gear train, gear tooth bending strength,
gear tooth surface fatigue analysis, gear material.
Design of shafts, keys, pins and splines, shaft couplings. Cotter and pin joints, pipe joints,
gaskets, seal and packing, cylinder joints, flanged joints.
Clutches and brakes: Single and multiple plate clutch, constant wear and constant pressure
theories for plate clutches, materials, shoe drum brakes, internal and external shoe brakes.
Power transmission elements: Belts and chain drives, design of flat and V-belts.

 

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