A research study on folded, V-shaped, shells and rocks opens new perspectives for the production of origami-inspired materials, that is materials that can change shape and size to fit a certain purpose.
The study is the work of a team of Solids and Structures Mechanics led by Davide Bigoni of the Department of Civil, Environmental and Mechanical Engineering at the University of Trento.
It made it to the cover of the March issue of the Proceedings of the Royal Society A, a journal dedicated to mathematical, physical and engineering sciences, featuring a picture of a cockscomb oyster.
Origami-like materials – explains professor Bigoni, can change shape and size in order to adapt to a specific situation. Imagine for instance a house of cards structure that can be flattened without breaking to let a car drive on it, and then can be expanded again to perform other functions, to become an antenna, for example. Origami-like materials have multiple applications, even in architecture, where a facade might be designed to continuously change its shape to be constantly exposed to sunlight.
The researchers started with the observation of V-shaped folded rocks and cockscomb oysters and later identified common mechanisms at the basis of their bending.
We have formulated a theory – says Bigoni, to explain the process through which a layered rock formation can bend spontaneously, like a book, creating the so-called “Chevron Folds”. Chevron folds near Millook Haven, in Cornwall, are very famous, but similar geological phenomena can be found near Acqualagna, in the Italian region of Marche.
A similar process occurs – continues Bigoni, in the growth phase of the Lopha Cristagalli, a bivalve seashell commonly known as “cockscomb oyster”, which has a shell with clear folding. The reason of the folding lies in an instability process. When a layered material is stressed, it can become instable and bend because of an event that may even be of secondary importance.
As professor Bigoni explains,
A similar process occurs upon shell growth of bivalve oyster Lopha Cristagalli, commonly known as “cockscomb” oyster, presenting folds very evident. The explanation of the formation of folds are in a runaway process, in which a layered material subject to stress may become unstable or bending due to an event of importance also apparently secondary.
The article entitled “Folding and faulting of an elastic continuum“, signed by Davide Bigoni and Panos A. Gourgiotis, University of Trento, is available from the RSPA site.