Wave propagation in the framework of strain gradient continua: the example of hexachiral materials

Overview & Synopsis

Chirality, which means handedness, is a general property of asymmetry that is of prior importance in many fields of modern physics and biology. An object, or a system, is said to be chiral if it is not identical to its mirror image. Many materials exhibit chirality at different scales. At the microscopic scale chirality can be observed, for example, in chemistry, biological molecules (amino acids, protein, sugar), crystals, liquid crystals. Chiral organization is also observed at larger scales in bones, fiber-reinforced composites, mechanical structures. Effect of chirality on optical wave propagation is known since the first half of the 19th century with the work on crystal optical activity by, among others, Arago, Biot and Pasteur. But contrary to electromagnetism, the classical theory of elasticity is not chiral sensitive, although mechanical evidence of its importance has been reported in numerous and various situations. As a consequence, during the last few decades, different attempts have been made to extend the classical framework of elasticity in order to make it chirality-dependent. As shown in [1] a continuum description of chirality can be achieved using generalized continua theories.