Section A
Q1.
(a) A circular bar ABC, 4 m long, is rigidly fixed at its ends A and C. The portion AB is 2.8 m long and of 50 mm diameter whereas BC is 1.2 m long and of 25 mm diameter. If the twisting moment of 700 Nm is applied at B, determine the values of the resisting moments at A and C and the maximum stress in each section of the shaft. For the material of the shaft G = 80 GN/m^2.
(b) What are supporting forces for the frame ? Neglect all weights except the 10 kN weight.
(c) An electronic instrument is to be isolated from a panel that vibrates at frequencies ranging from 25 Hz to 35 Hz. It is estimated that at least 80% vibration isolation must be achieved to prevent damage to the instrument. If the instrument weighs 85 N, find the necessary static deflection of the isolator.
(d) Describe all the inversions of a slider-crank mechanism.
(e) A structure is composed of circular members of diameter d. At a certain position along one member the loading is found to consist of a shear force of 10 kN along with an axial tensile load of 20 kN. If the elastic limit in tension of the material of the members is 300 MN/m^2 and there is to be a factor of safety of 3, estimate the magnitude of d required according to the maximum shear strain energy per unit volume theory. Poisson's ratio v = 0.3.
