The material used for ordinary shafts is mild steel. When high strength is required, an alloy steel such as nickel, nickel-chromium or chromium-vanadium steel is used. Shafts are generally formed by hot rolling and finished to size by cold drawing or turning and grinding
2. A shaft is a rotating machine element, usually circular in cross
section, which is used to transmit power from one part to another,
or from a machine which produces power to a machine which
absorbs power.
The material used for ordinary shafts is mild steel. When high
strength is required, an alloy steel such as nickel, nickel-
chromium or chromium-vanadium steel is used. Shafts are
generally formed by hot rolling and finished to size by cold
drawing or turning and grinding
3. • The material used for shafts should have the following properties :
• 1. It should have high strength.
• 2. It should have good machinability.
• 3. It should have low notch sensitivity factor.
• 4. It should have good heat treatment properties.
• 5. It should have high wear resistant properties.
• The material used for ordinary shafts is carbon steel of grades 40 C 8, 45 C 8, 50 C 4
• and 50 C 12.
• The mechanical properties of these grades of carbon steel are given in the following
table.
• When a shaft of high strength is required, then an alloy steel such as nickel, nickel-chromium or
• chrome-vanadium steel is used.
4. • The following stresses are induced in the shafts.
1.Shear stresses due to the transmission of torque (due to
torsional load).
2.Bending stresses (tensile or compressive) due to the forces
acting upon the machine elements like gears and pulleys as
well as the self weight of the shaft.
3.Stresses due to combined torsional and bending loads.
Design of shaft based on strength under static loading
• Simple torsion
• Simple bending moment
• Combined torque and bending moment
• Combined axial load, torsional moment and bending moment
8. Shear Modulus is defined as the ratio of shear stress to the
corresponding shear strain within a material’s proportional limit. Also
known as modulus of rigidity and rigidity modulus, the shear modulus
is denoted by “G” and can be experimentally determined from the
slope of shear stress (τ) vs shear strain (γ) curve. The more the value of
the shear modulus or modulus of rigidity, the more rigid the material is.
The shear modulus values of engineering materials are determined by
torsional tests.
The relationship of Shear Modulus (G) with Young’s modulus (E) and
Poisson’s ratio (μ) is given below:
E=2G(1+μ) or G = E/(2(1+μ)
