Autotuning of Isotropic Hardening Constitutive Models on Real Steel Buckling Data with Finite Element Based Multistart Global Optimisation on Parallel Computers

Figure 3

FE meshes of the specimen, showing on the left the buckling mesh before the application of the loading, with initial imperfection in the form of the 1st mode, calculated by the eigenvector/value analysis. The maximum deflection is 1 mm. On the right is the contour plot of the von Mises stress at 10 mm axial displacement. Note highly distorted elements in the regions adjacent to the constraints. Also note that the location of the maximum stress is on the side surface, closer to the outer region with positive curvature, while at the same time the stress is higher at the saddle point (inner) than at the outer point, with the maximum deflection. This fact has important implications for postbuckling fatigue and fracture behaviour of reinforcing bars [1, 2, 5].