A pressurized steel tank is constructed with a helical weld that makes an angle a = 55°

Question:

A pressurized steel tank is constructed with a helical weld that makes an angle a = 55° with the longitudinal axis (see figure). The tank has radius r = 0.6 m, wall thickness t = 18 mm, and internal pressure p = 2.8 MPa. Also, the steel has modulus of elasticity E = 200 GPa and Poisson's ratio v = 0.30.
Determine the following quantities for the cylindrical part of the tank.
(a) The circumferential and longitudinal stresses.
(b) The maximum in-plane and out-of-plane shear stresses.
(c) The circumferential and longitudinal strains.
(d) The normal and shear stresses acting on planes parallel and perpendicular to Probs. 8.3-12 and 8.3-13 the weld (show these stresses on a properly oriented stress element).