We give a complete general answer to the problem, recurrent in continuum
mechanics, of determining of the number and type of symmetry classes of an
even-order tensor space. This kind of investigation was initiated for the space of
elasticity tensors, and since then different authors have solved this problem for other
kinds of physics, such as photoelectricity, piezoelectricity, flexoelectricity, and
strain-gradient elasticity. All these problems were treated using the same
computational method, which, though effective, has the drawback of not providing
general results. Furthermore, its complexity increases with the tensorial order. Here
we provide general theorems that directly give the desired results for any even-order
constitutive tensor. As an illustration of this method, and for the first time, the
symmetry classes of all even-order tensors of Mindlin second strain-gradient elasticity
are provided.
Laboratoire d’Analyse, Topologie,
Probabilités
Centre de Mathématiques et Informatique
CNRS, UMR 7353
Aix-Marseille Université, Technopôle Château-Gombert
39 rue F. Joliot-Curie
13453 Marseille
France