A drawn, thin -walled tube has plastic (orthotropic) anisotropy. The axial direction of the tube is similar to the rolling direction of anisotropic sheet metal. The tube diameter is 3 inches and the wall thickness is 0.040 inch. The strain ratios were measured from tensile tests in the axial and hoop directions, R0 = R = 2.5, R90 = P = 0.8. The yield strength in the axial direction is 40,000 psi.
a. If the tube is capped at both ends and pressurized, determine the pressure at which the cylindrical tube wall will yield.
b. Will the length of the tube increase, decrease or stay the same. (Hint: determine E axial/ E hoop.)