A Perspective on the Revival of Structural (In)Stability With Novel Opportunities for Function: From Buckliphobia to Buckliphilia

Abstract

Buckling of slender structures is traditionally regarded as a first route toward failure. Here, we provide an alternative perspective on a burgeoning movement where mechanical instabilities are exploited to devise new classes of functional mechanisms that make use of the geometrically nonlinear behavior of their postbuckling regimes. Selected examples are highlighted across length-scales to illustrate some of the exciting opportunities that lie ahead. [DOI: 10.1115/1.4031456] IntroductionSlender structural elements (e.g., rods, plates and shells) under compression are ubiquitously subjected to mechanical instabilities. In 1744, Euler [1] laid the foundation for the formal analysis of structural stability; a field that has matured to become paramount in engineering design and one of the pillars in the history of mechanics [2]. A modern and detailed perspective on the stability of structures is found in the seminal book by Ba zant and Cedolin [3]. Across length-scales, buckling has traditionally been regarded as a first route toward failure and can lead to catastrophic collapse [4]; an approach that can be succinctly referred to as Buckliphobia. By contrast, Buckliphilia is a more recent and burgeoning trend that is changing the above paradigm. Mechanical instabilities of slender structures are therefore envisioned as opportunities for novel modes of functionality that are to be predictively understood in order to then be exploited.In these efforts of adopting Buckliphilia, there is a need to rationalize the complex configurations that arise in the postbuckling regime, far-from-threshold. The large displacements and rotations permissible by slender structures can yield nontrivial and nonnegligible geometric nonlinearities, even if their material properties remain linear. Furthermore, this strong rooting of the postbuckling behavior on geometry results in general and universal modes of deformation; albeit with threshold or onsets that are scale-or material-dependent. To avoid overstatement, it is important to note that viscoelasticity, plasticity, fracture, and other phenomena can introduce additional time-and length-scales that may compromise the geometric universality of the buckling modes. In many problems involving the large deformation of thin structures, however, the strains at the material level are small enough, such that these effects are secondary and a linear elastic constitutive description suffices.Qualifying a structure as slender is a statement on aspect ratio rather than length-scale, which added to the fact that elasticity is a scale-free theory, ensures that functional mechanisms based on the instability of slender structures can be instantiated over a wide range of length-scales. In Fig. 1, we represent three representative examples that illustrate this scale invariance. First, the crumpling of paper [5] (Fig. 1(a)) has been regarded by the nonlinear physics community as a canonical problem, at the centimeter scale, for Precision desktop experiment to study the buckling of a thin rod injected int...

HCI meets Material Science

“…A pattern of circular voids exists on the shell so that when the internal pressure falls below a critical value, the narrow pieces of material between the voids collapse inwards causing buckling of the ball. In [193] the author discusses in more detail how buckling of slender structures can be exploited to develop functional mechanisms for smart morphable surfaces. As another example, Daynes et al [44] developed a bistable, elastomeric origami morphing structure, made from silicone, with locally reinforced regions of acrylonitrile butadiene styrene (ABS).…”

The Geometric Role of Precisely Engineered Imperfections on the Critical Buckling Load of Spherical Elastic Shells

“…6(c), provides a design guideline for the shape that a defect should have in order for a shell to buckle at the lowest possible pressure. Whereas traditional applications in structural mechanics would typically seek to maximize j d , these findings could be useful for the more recent movement of utilizing buckling as a mechanism for functionality [37,38].…”

Exploiting Microstructural Instabilities in Solids and Structures: From Metamaterials to Structural Transitions

“…Especially at the macroscopic level, structural instability and the associated large deformation of soft matter have produced many multifunctional devices that exploit buckling, snapping, and creazing to result in beneficial acoustic or mechanical performance, see Ref. [43] for a recent survey. Like in structures, instability at the material level stems from non-(quasi)-convex energy landscapes [44,45]; here, however, instability is not tied to multiple stable or metastable structural deformation modes but involves multiple stable microstructural configurations such as those in phase transitions and phase transformations [46], domain switching and domain patterning [47][48][49], deformation twinning [50,51], or strain localization, shear banding, and patterning in plasticity [52].…”