Vol.12, No1, 2012, pp.65–70
UDC  539.3

Transition theory has been used to derive the elastic-plastic and transitional stresses. Results obtained have been discussed numerically and depicted graphically. It is observed that the rotating disc made of incompressible material with inclusion requires higher angular speed to yield at the internal surface as compared to the disc made of compressible material. It is seen that the radial and circumferential stresses are maximum at the internal surface with and without edge load (for flat disc). With the increase in thickness parameter (k = 2, 4), the circumferential stress is maximum at the external surface while the radial stress is maximum at the internal surface. From the figures drawn the disc with exponentially varying thickness (k = 2), a high angular speed is required for initial yielding at the internal surface as compared to flat disc and exponentially varying thickness for k = 4 onwards. It is concluded that the disk made of isotropic compressible material is on the safer side of the design as compared to disk of isotropic incompressible material as it requires higher increase in an angular speed to become fully plastic from its initial yielding.

Keywords: elastic, plastic, compressibility, transitional stresses, isotropic, rotating disk