Figure 1 shows the tubes to be analysed schematically. The outer dimensions of the square cross-section are 400 mm x 400 mm. The tube has a wall thickness of 8 mm and a length of 3m. The tube material has a Young's modulus E = 200 GPa, a Poisson's ratio = 0.3, and a von Mises yield stress oy = 235 MPa. 400 mm 400 mm 3m Figure 1: Schematic for the square cross-section tube to be analysed.