a) A short hollow, cast iron cylinder with wall thickness of 10 mm is to carry compressive load of 100 kN. Compute the required outside diameter 'D', if the working stress in compression is 80 N/mm^2. (7 marks)
b) Differentiate between plastic deformation and elastic deformation. (4 marks)
c) Define Shear stress. (4 marks)
2. a) A 50-mm-diameter solid cast-iron post as shown in Fig. 1 is buried 600 mm in soil. Determine maximum shear stress in the post and angle of twist at its top. Assume torque about to turn the post, and soil exerts uniform torsional resistance of t N·mm/mm along its 600 mm buried length. G = 40(10^3) GPa. (9 marks)
b) A cylindrical boiler is subjected to an internal pressure, p. If the boiler has a mean radius, r and a wall thickness, t, derive expressions for the hoop and longitudinal stresses in its wall. If Poisson's ratio for the material is 0.30, find the ratio of the hoop strain to the longitudinal strain and compare it with the ratio of stresses. (6 marks)
3. a) Two forces applied to the bracket BCD as shown in Fig. 2.
i. Knowing that the control rod AB is to be made is a steel having an ultimate normal stress of 600 MPa, determine the diameter of the rod for which the factor of safety with respect to failure will be 3.3.
ii. The pin at C is to be made of a steel having an ultimate shearing stress of 350 MPa. Determine the diameter of the pin C for which the factor of safety with respect to shear will also be 3.3.
iii. Determine the required thickness of the bracket supports at C knowing that the allowable bearing stress of the steel used is 300 MPa. (11 marks)
b) Define Torsion. (4 marks)