Dynamic Biaxial Plastic Buckling of Circular Shells

Of particular interest is the experimental study of the complex dynamic plastic buckling of circular metallic shells and their energy absorption capacity. Initially proposed by Baleh and Abdul-Latif (2006), “Quasi-Stalic Biaxial Plastic Buckling of Tubular Structures used as an Energy Absorber,” ASME J. Appl. Mech., 74, pp. 638–635, the novel idea, which aims to enhance the strength properties of materials, is extended for studying the biaxial plastic dynamic buckling behavior of circular shells. It can be assumed that changes in local deformation mechanisms, which reflect this enhancement in the strength properties, are mainly governed by the loading path complexity. The question of whether the performance of dynamic axially crushed tubes could be further improved by using the developed device (the absorption par compression-torsion plastique (ACTP)) generating a biaxial loading path (combined compression and torsion) from a uniaxial loading. A key point emerging from this study is that the structure impact response (i.e., the plastic flow mechanism and the absorbed energy) is influenced by the loading rate coupled with the biaxial loading complexity. In this study, three different metallic circular shells made from copper, aluminum, and mild steel, having distinct geometrical parameters, are extensively investigated. The obtained results show that the higher the biaxial loading complexity provided by the ACTP applied, the greater the energy absorbed by the copper, aluminum, and mild-steel structures. Thus, it is easy to demonstrate that the enhancement in the energy absorption, notably in the case of aluminum, is higher than 150%, in favor of the most complicated loading path (i.e., biaxial $45deg$ case) compared to the classical uniaxial case. Moreover, the deformation mode for the tested materials is slightly sensitive to the torsion amplitude in dynamic loading, contrary to the quasistatic one.