15.1 INTRODUCTION

Rotating structural elements are very common in many of the moving structures such as wheels of a cycle, bike, and shafts in transmitting the power. The stresses induced in the members owing to rotation are referred as centrifugal stresses. Rotation induces centrifugal forces within the body of the rotating object. These centrifugal forces are dependent on the mass of the objects. Thus, it is assumed that the mass of the structural element is uniform and mass density is constant throughout the body.

15.2 STRESSES IN ROTATING THIN DISC

Rotating discs are grouped in two categories such as thin rings and solid discs.

Analysis of Thin Rings

Consider a thin ring rotating about its center of gravity at O as shown in Figure 15.1.

Consider an elemental strip, which makes an angle δθ at the center and its position is defi ned by θ as shown in Figure 15.1.

The radial acceleration on the elemental strip considered is rω2.

The radial force acting on the element

‘b’ is the dimension perpendicular to the width of the ring.

Component of the radial force F acting in the Y direction is

Taking th e equilibrium equation that sum of vertical forces is equal to zero.