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+// exa 7.2 Pg 200
+clc;clear;close;
+
+// Given Data
+P=30;// kW
+N=750;// rpm
+//Tmax=1.2*Tm;// MPa
+tau_s=35;// MPa
+tau_b=35;// MPa
+tau_k=35;// MPa
+sigma_cs=70;// MPa
+sigma_ck=70;// MPa
+sigma_cb=70;// MPa
+tau_ci=15;// MPa
+pb=0.8;// MPa
+
+//sigma_cs=2*tau_s;// MPa
+
+//Tmax=1.5*Tm
+mu=0.15;// coefficient of friction
+
+//SHAFT DIAMETER
+// P= 2*%pi*N*Tm/60/1000 
+Tm=P/(2*%pi*N/60/1000);// N.m
+Tmax=1.2*Tm;// N.m
+// %pi*d**3*tau_s/16= Tmax
+d=(Tmax/(%pi*tau_s/16)*1000)**(1/3);// mm
+printf('shaft diameter = %.2f mm. Use d = 42 mm.',d)
+d=42;// mm
+
+// HUB DIAMETER
+// Tmax=%pi/16*((d1**4-d**4)/d1)*tau_h
+tau_h=tau_ci;// MPa
+//d1*(Tmax/(%pi/16)/tau_h)-d1**4=d**4 -- eqn(1)
+Tmax=Tmax*1000;// N.mm
+p=[1 0 0 -Tmax/(%pi*tau_h/16) -d**4] ;// polynomial coefficients from eqn(1)
+d1=roots(p);// roots of poly 
+d1=d1(1);// mm (taking +ve value)
+d1=2*d;// mm (empirically adopted) 
+t1=(d1-d)/2;// mm (thickness of hub)
+printf('\n thickness of hub = %.f mm',t1)
+//d4=d+t1;// mm (diameter of recess in flanges)
+//printf('\n diameter of recess in flanges = %.f mm',d4)
+d3=4*d;// mm (outside diameter of protecting flange)
+printf('\n outside diameter of protecting flange = %.f mm. Use 170 mm',d3)
+d3=170;// mm (adopted)
+
+//Key size & Hub length
+b=d/4;// mm (width of key)
+l=1.5*d;// mm (length of key)
+printf('\n width of key = %.1f mm. Use b = 12 mm',b)
+b=12;// mm
+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=(0.04*d+3);// no. of bolts
+printf('\n Number of bolts = %.2f. Use n=6',n)
+n=6;// adopted
+
+// Bolt diameter
+db=0.5*d/sqrt(n);// mm
+printf('\n Bolt diameter = %.2f mm. Use db=20 mm for design purpose',db)
+db=20;//mm (adopted)
+bolt_dia=db;//mm
+dsb=24;// mm(shank diameter of bolt for design)
+
+// Outer diameter of rubber bush
+trb=2;// mm (thickness of rubber bush)
+tbb=6;// mm (thickness of brass bush)
+d3=dsb+2*trb+2*tbb;// mm 
+d2=d1+d3+2*tbb;// mm (pitch circle diameter of bolts)
+printf('\n pitch circle diameter of bolts = %.f mm ',d2)
+
+// Check of shear in bolt
+F=2*Tmax/n/d2;// N
+//%pi/4*db*2*tau=F
+tau=F/(%pi/4*db**2);//MPa
+printf('\n Permissible shear stress in bolts = %.2f MPa < 35 MPa. Hence design is safe.', tau)
+
+// Length of brush
+pb=0.8;// MPa(bearing pressure of brush)
+//F=l2*d3*pb;
+l2=F/d3/pb;// mm
+printf('\n length of bush = %.f mm',l2)
+
+// Check for pin in bending
+c=5;// mm (clearance between two flanges)
+l3=(l2-c)/2+c;//mm
+//M=%pi/32*db**3*sigma_b & M=F*l3
+sigma_b = F*l3/(%pi/32*db**3);// MPa
+printf('\n Bending stress in pin = %.1f MPa',sigma_b)
+
+// Maximum shear stress in pin
+tau_max=sqrt((sigma_b/2)**2+tau**2);//MPa
+printf('\n Maximum shear stress in pin = %.2f MPa < 35 MPa. Hence design is safe.',tau_max)
+
+// Flange thickness
+t2=0.5*t1+6;// mm (empirically)
+printf('\n Flange thickness = %.1f mm. Use t=18 mm',t2)
+t2=18;// mm (adopted)
+tau=Tmax/(2*%pi*d1**2*t2/4);// MPa
+printf('\n shearing of the flange at the junction with hub = %.2f MPa < 15 MPa.',tau)
+printf(' Values are acceptable.')
+
+//Note - Answer in llast part is calculated wrong in the textbook(error in calculation).