Experimental probing of the configuration space of circular, clamped panels

Abstract

A thin, post-buckled, circular plate is a classic exhibiter of bi-stability. That is, an elastic structural element that possesses more than a single (stable) equilibrium configuration. The key here is that the plate may be flat, or deflected in a given direction. In the latter case, this is a thoroughly nonlinear phenomenon that typically requires a relatively large perturbation (using a probing force) to deflect the system from one equilibrium configuration to the other, in which we can think of a structure exhibiting an initial configuration, but able to be pushed-through into an inverted, complementary stable configuration, or even into other shapes. The work described here is primarily experimental, exploiting the capabilities of digital image correlation. It points in the direction of identifying nonlinear, global features of the structural behavior, features that tend to have a strong influence on underlying behavior in an operational, dynamic environment. Some of the equilibrium configurations require a degree of interrogation to be revealed, i.e., they are not necessarily observed without some exploratory probing of the configuration space and we present results from a number of experimental studies of clamped, circular panels. The study is preceded by some experiments on initially flat panels, for which there is some access to analytic results and helps to set the stage for nonlinear environment in the post-buckled landscape.