// exa 6.7 Pg 177 clc;clear;close; // Given Data Wmax=40;// kN Wmin=20;// kN L=500;// mm Se_dash=350;// MPa Sut=650;// MPa Syt=500;// MPa n=1.5;// factor of safety ka=0.9; // surface finish factor kb=0.85;// size factor ke=1;// load factor Kf=1;// fatigue strength factor Wm=1/2*(Wmax+Wmin);// N Wa=1/2*(Wmax-Wmin);// N Se=ka*kb*ke*Se_dash;//MPa Mm=Wm*L/1000/4;// kN.m Ma=Wa*L/1000/4;// kN.m //sigma_m=32*Mm/%pi/d**3; & sigma_a=32*Ma/%pi/d**3 //soderburg failure criteria - 1/n=sigma_m/Syt+Kf*sigma_a/Se //d=((32/%pi*n/1000)*(Mm/Syt+Kf*Ma/Se))*(1/3) d=((32/%pi/1000)*(Mm/Syt+Kf*Ma/Se)*n)**(1/3)*1000;// mm printf('shaft diameter = %.f mm.',d)