Section A
Q1.
(a)
What are the functions of cement mortar in brick masonry work ?
What are the purposes of making frog in bricks during moulding? Explain with the help of neat sketches.
(b)
A rectangular plate in biaxial stress is subjected to normal stress σ_x = 65 MPa and σ_y = -20 MPa. The plate (b × h × t) has dimensions 200 × 300 × 15 and is made of aluminium with E = 75 GPa and v = 0.33. All dimensions are in mm. Determine
(i) the maximum in-plane shear strain (γ_{\textmax}) in the plate,
(ii) the change in the thickness of the plate (\Delta t), and
(iii) the change in volume of the plate (\Delta V).
(c) The electric motor exerts a torque of 800 N on the steel shaft ABCD when it is rotating at constant speed. Design specifications require that the diameter of the shaft be uniform from A to D and that the angle of twist between A and D not exceed 1.5°. Knowing that \tau_{\textmax} ≤ 60 MPa and G = 77 GPa, determine the diameter of the shaft that may be used.
