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diff --git a/3681/CH8/EX8.4/Ex8_4.sce b/3681/CH8/EX8.4/Ex8_4.sce new file mode 100644 index 000000000..8ae86eb05 --- /dev/null +++ b/3681/CH8/EX8.4/Ex8_4.sce @@ -0,0 +1,21 @@ +// Calculating the tensile stress and factor of safety
+clc;
+disp('Example 8.4, Page No. = 8.12')
+// Given Data
+rpm = 3000;// Speed in r.p.m.
+Dr1 = 1.15;// Outer diameter of rotor (in meter)
+Nrs = 39;// Number of rotor slot
+Drs = 140;// Depth of rotor slot (in mm)
+Wrs = 45;// Width of rotor slot (in mm)
+gs = 7800;// Density of steel (in kg per meter cube)
+yield_stress = 520*10^(6);// Yield stress of rotor steel (in Newton per meter square)
+// Calculation of the tensile stress and factor of safety
+n = rpm/60;// Speed in r.p.s
+Dr2 = Dr1-2*Drs*10^(-3);// Diameter of rotor at the bottom of slots (in meter)
+t = (%pi*Dr2*10^(3)/Nrs)-Wrs;// Width of tooth at the bottom of slot (in mm)
+alpha = 360/Nrs;// Angle subtended by each slot (in degree)
+f = %pi^(3)/(3*t*10^(-3))*gs*n*n*(alpha/360)*(Dr1^(3)-Dr2^(3));// Tensile stress (in Newton per meter square)
+disp(f,'Tensile stress at the root of the teeth at normal operating speed (Newton per meter square)=');
+f_20 = 1.2^(2)*f;// Tensile stress at 20% over speed. Since centrifugal force is propartional of square of speed
+disp(yield_stress/f_20,'Factor of safety at 20% over speed =');
+//in book answers are 178 (Mega Newton per meter square) and 2.03 respectively. The answers vary due to round off error
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