Characterization of Sheet Buckling Subjected to Controlled Boundary Constraints

A wedge strip test is designed to study the onset and post-buckling behavior of a sheet under various boundary constraints. The device can be easily incorporated into a conventional tensile test machine and material resistance to buckling is measured as the buckling height versus the in-plane strain state. The design yields different but consistent buckling modes with easy changes of boundary conditions (either clamped or freed) and sample geometry. Experimental results are then used to verify a hybrid approach to buckling prediction, i.e., the combination of the FEM analysis and an energy-based analytical wrinkling criterion. The FEM analysis is used to obtain the stress field and deformed geometry in a complex forming condition, while the analytical solution is to provide the predictions less sensitive to artificial numerical parameters. A good agreement between experimental data and numerical predictions is obtained.