Question $1$

A Solid steel shaft running at $600$rpm is supported on bearings $600$mm apart. The shaft receives $40$ kW through a $400$ mm diameter pulley weighing $400$ N located $300$ mm to the right of left bearing by a vertical flat belt drive. The power is transmitted from the shaft through another pulley of diameter $600$ mm weighing $600$ N located $200$ mm to the right of right bearing. The belt drives are at right angles to each other and ratio of belt tensions is $3.$ Determine the size of the shaft necessary, if the allowable shear stress in the shaft material is $40$MPa and the loads are steady.

$(50$ Marks$)$

Question $2$

$($a$)$

With suitable example differentiate between low cycle and high cycle fatigue.

$(04$ Marks$)$

$($b$)$

Discuss the S$-$N curve for Steel and aluminium alloy with clearly differentiating the role endurance limit$.$

$(06$ Marks$)$

Question $3$

Design a rigid flange coupling to transmit a torque of $250N-m$ between two coaxial shafts. The shaft is made of alloy steel, flanges out of cast iron and bolts out of steel. Four bolts are used to couple the flanges. The shafts are keyed to the flange hub. The permissible stresses are given below:

$,$ Shear stress on shaft $=100$MPa

Bearing or crushing stress on shaft $=250$MPa

Shear stress on keys $=100$MPa

Bearing stress on keys $=250$MPa

$,$ Shearing stress on cast iron $=200$Mpa

Shear stress on bolts $=100$MPa

$(20$ Marks$)$

Question $4$

Design a cotter joint to support a axial load of $100$ kN $.$ Carbon steel material selected which has Tensile stress $=100$MPa Compressive stress $=150$MPa; Shear stress $=60$MPa $(20$ Marks$)$