Exploring Nonlinearities in Buckling of Solids

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When compressed sufficiently, a straight beam deforms by bulging to one of its sides, or buckling. For thousands of years of human civilization, we were trying to avoid this type of instability, most notably in construction of building. However, there is a paradigm shift in how we think about the buckling problems - we now embrace this phenomenon as a means of changing material functionality. A perfect example is the role buckling has in designing mechanical metamaterials, such as holey beams (beams with a regular line of holes), which, once buckled, show auxetic behaviours (they contract instead of expanding like regular beam of solid material would). This particular property emerges as a consequence of geometry of the structure, but even more interesting properties arise when geometry of the deformation combines with constitutive nonlinearities. For example, holey beams made from metals soften post-buckling (although the corresponding metals do not have strain-softening behaviour). During this project we will explore the interplay between geometrical and constitutive nonlinearities during buckling using a handful of model systems, including the holey beams. These interactions will be studied by combining theoretical modelling with quantitative experiments.