Keys and Coupling Many Types of Keys and couplings, however understand how Torque is transferred in between each, and forms shearing stresses

Shaft Coupling Sometimes, join 2 shafts together Flanged couplings Torque in Shaft  Torque in Couplings  Shear in bolts Similarly keys Bolt circle Flanged Couplings Bolt Shaft

TA < TR Design of Shaft Torque applied, TA = ∏ τ d3 / 16 Where, τ = shear stress in shaft d = shaft dia. Design of bolts Torque resisted, TR = Shear Stress Area x Radius of bolt circle TR = n . (∏/4) . db2 . τ b . (D/2) Where, τ b = shear stress in bolt db = bolt dia. D = Diameter of bolt circle n = number of bolts TA < TR

TA < Tk Design of Shaft Torque applied, TA = ∏ τ d3 / 16 Where, τ = shear stress in shaft d = shaft dia. Design of keys Torque resisted, Tk = Shear Stress Area x Radius of shaft Tk = l b τ k (D/2) Where, τ k = shear stress in key db = bolt dia. D = Diameter of bolt circle n = number of bolts TA < Tk .

Springs and Stiffness Stiffness of spring Load required to produce a unit deflection in spring. K = F/x x=unit deflection Under gravity, W = F

Springs Types of spring Bending / leaf / laminated spring Torsion / helical spring Close Coil helical spring Open Coil helical spring

Springs Uses of Springs Storing energy, used in watch Shock absorbers Seismic isolation Spring balance Cycle seats

Closed Coiled helical springs subjected to axial loads R = radius of the coil d = Spring wire diameter W= axial load on spring N = number of coils/turns δ = deflection τ, θ, G, Torque produced by axial load T = W R Also T = ∏ τ d3/16 Thus, ∏ τ d3/16 = W R

Length of wire = no. of coils x length of one coil Or, l = n 2∏R T = G θ J l θ = 64 WR2 n Gd4 δ = R. θ = 64 WR3 n Stiffness, s = W = Gd4 δ 64 R3 n Energy Stored in a spring, U = (1/2) W δ

Combined Bending and Torsion Find how Tanθ = 2 τ / f = T /M Where T = Torsion, M = Bending Moment τ = Shear Stress M = Bending Stress

Tutorial- 2 Sketch 5 examples of use of springs List differences between closed and open coil springs. Provide one sketch minimum Answer Q.1. from Rethalia’s exercise on Helical Springs. pp. 72 Answer Q.1. to Q.7 from Rethalia’s example exercise