Buckling and energy absorption behavior of shell structure with a compliant core.
Date of Issue2012
School of Mechanical and Aerospace Engineering
This dissertation presents the study on buckling and energy absorption behavior of a thin-walled cylindrical shell with complaint core under axial compression. Previous studies related to this subject focused on its behavior with a fully or fixed amount of infill. The principal aim of current work is to study the effect of partially filled foam core on its behavior in initial buckling, post-buckling and energy absorption. An energy-based technique is applied in initial buckling to obtain the theoretical solution of the critical buckling load, for an axisymmetric mode with partial infill. This solution has been verified by a subsequent finite element analysis. A comprehensive parametric study indicates that in practical design the filler's inner radius should not be more than 10% of the shell radius. A finite element analysis is then performed for the post-buckling behaviour. With an initial geometric imperfection applied, the previously observed large discrepancy between theory and experiment is quantitatively resolved. It reveals that the critical buckling load obtained in the experiments is closely located in the post-buckling region. Furthermore, the plateau load of such a structure with this specific imperfection is formulated. For a shell with thickness h, the post-buckling dimple requires a compressive force proportional to h2.5 in order to hold the dimple in place. For energy absorption, an analytical model is proposed to predict its axisymmetric crushing behavior with partial infill, by the energy balance method. This solution has been verified by a finite element analysis and experiments. Further axial crushing tests and corresponding finite element simulations are performed to study the non-axisymmetric behavior of shells with a diameter-to-thickness (D/h) ratio up to 660. The study suggests that the filler's inner radius should not be more than 50% of the shell radius in the design. The study is valuable in understanding the mechanisms and mechanics of the buckling and energy absorption behavior of thin-walled shells with foams. It provides guidelines for engineers in the design of such structures in order to achieve the optimal performance in terms of strength, energy absorption and weight.
DRNTU::Engineering::Mechanical engineering::Mechanics and dynamics