Search for: All records

Cylinder buckling is notoriously sensitive to small geometric imperfections. This is an underlying motivation for the use of knock-down factors in the design process, especially in circumstances in which minimum weight is a key design goal, an approach well-established at NASA, for example. Not only does this provide challenges in the practical design of this commonly occurring structural load-bearing configuration, but also in the carefully controlled laboratory setting. The recent development of 3D-printing (additive manufacturing) provides an appealing experimental platform for conducting relatively high-fidelity experiments on the buckling of cylinders. However, in addition to geometric precision, there are a number of shortcomings with this approach, and this article seeks to describe the challenges and opportunities associated with the use of 3D-printing in cylinder buckling in general, and probing the robustness of equilibrium configurations in particular. This article is part of the theme issue ‘Probing and dynamics of shock sensitive shells’. 

This paper considers the load–deflection behavior of a pyramid-like, shallow lattice structure. It consists of four beams that join at a central apex and when subject to a lateral load, it exhibits a propensity to snap-through: a classical buckling phenomenon. Whether this structural inversion occurs, and the routes by which it happens, depends sensitively on geometry. Given the often sudden nature of the instability, the behavior is also examined within a dynamics context. The outcome of numerical simulations are favorably compared with experimental data extracted from the testing of three-dimensional (3D)-printed specimens. The key contributions of this paper are that despite the continuous nature of the physical system, its behavior (transient and equilibria) can be adequately described using a discrete model, and the paper also illustrates the utility of 3D-printing in an accessible research context. 

Abstract This paper describes a primarily experimental study in which a nonlinear structural component (a slender, mechanically buckled panel) is subject to probing. That is, equilibrium configurations are explored when a specific location on the panel is subject to the application of a (variable) displacement constraint and characterized by a corresponding probe force. This probe force (in this study located at the center of the rectangular panels) is measured using a load cell and the resulting shape(s), taken up by the panel, measured using digital image correlation (DIC). Although the probe is only applied at a single location, this arrangement supplies considerable information about the changing equilibrium landscape including revealing co-existing equilibrium configurations using large perturbations and associated hysteresis phenomena. In addition, monitoring the probing force, and specifically when it drops to zero, provides a window into “free” equilibria that would otherwise be unstable and unobservable. Finally, it is shown that the probed equilibrium configurations provide the “landscape” within which any dynamically induced trajectories evolve including snap-through oscillations.