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+// exa 7.9 Pg 209
+clc;clear;close;
+
+// Given Data
+d=36;// mm
+P=15;// kW
+N=720;// rpm
+//Tmax=1.25*Tm
+sigma_yt=245;// MPa (for C20 steel)
+n=3;// factor of safety
+sigma=82;// MPa (Design tensile stress)
+
+tau=0.577*sigma;// MPa (shear stress)
+sigma_u=200;// MPa (for FG 200 cast Iron)
+n2=5;// factor of safety (for FG 200 cast Iron)
+tau2=20;// MPa shear stress (for FG 200 cast Iron)
+
+// Max. torque transmitted
+//P=2*%pi*N*Tm/(60*10**3)
+Tm=P/(2*%pi*N/(60*10**3))*1000;// N.mm
+Tmax=1.25*Tm;// N.mm
+printf('\n Maximum transmitted torque = %.f N.mm',Tmax)
+
+// Hub diameter
+tau_h=20;// MPa (permissible shear stress in hub)
+//Tmax=(%pi/16)*(d1**4-d**4)/d1*tau_h   ...eqn(1)
+d1=2*d;//mm (empirically)
+tau_h=Tmax*1000/((%pi/16)*(d1**4-d**4)/d1);// MPa
+t1=(d1-d)/2;// mm (thickness of hub)
+printf('\n Hub diameter = %.f mm',d1)
+printf('\n Thickness of hub = %.f mm',t1)
+d4=d+t1;// mm
+printf('\n Diameter of recess in flanges = %.f mm',d4)
+d3=4*d;//mm
+printf('\n Outside diameter of protecting flange = %.f mm',d3)
+
+//Hub length
+b=d/4;// mm (width of key)
+l=1.5*d;// mm (length of key)
+printf('\n width of key = %.1f mm.',b)
+printf('\n length of key = %.f mm.',l) 
+t=b;// mm (thickness for square key)
+printf('\n thickness for square key = %.f mm',t)
+printf('\n Hub length = %.f mm',l)
+
+//Number of bolts
+n=ceil(4*d/150+3);// no. of bolts
+printf('\n Number of bolts = %.2f.',n)
+
+// Bolt diameter
+r2=1.5*d;// mm
+F=Tmax/r2/n;//N
+//(%pi/4)*db**2*tau_b=F
+db=sqrt(F/((%pi/4)*tau));// mm
+printf('\n Bolt diameter = %.2f mm. Use db=6 mm for design purpose',db)
+db=6;// mm (adopted for design)
+bolt_dia=db;//mm
+
+// Flange thickness
+t2=0.5*t1+6;// mm (empirically)
+printf('\n Flange thickness = %.1f mm. Use t=20 mm',t2)
+//F=n*db*t2*sigma_c
+sigma_ci=F/n/db/t2;// MPa
+//2*%pi*d1**2*tau*t2/4=Tmax
+tau=Tmax/(2*%pi*d1**2*t2/4);// MPa
+printf('\n permissible bearing stress in flange = %.2f MPa < 40 MPa',sigma_ci)
+printf('\n shearing of the flange at the junction with hub = %.2f MPa < 20 MPa.',tau)
+printf(' Values are acceptable.')
+
+// Check for crushing of bolt
+//n*db*t2*sigma_cb*d2/2=Tmax
+d2=d1+d;// mm
+db=bolt_dia;//mm
+sigma_cb=Tmax/(n*db*t2*d2/2);// MPa
+printf('\n permissible crushing strength of bolts = %.2f MPa < 82 MPa.',sigma_cb)
+printf(' Hence design is safe.')
+// Thickness of protecting flange
+t3=0.5*t2;// mm
+printf('\n Thickness of protecting flange = %.f mm', t3)
+// Hub overlap 
+ho=3;// mm (min)
+printf('\n Hub overlap = %.f mm (min)',ho)
+