Tensorial Polar Decomposition of 2D fourth-order tensors

One studies the structure of 2D symmetric fourth-order tensors, i.e. having both minor and major indicial symmetries. Verchery polar decomposition is rewritten in a tensorial form entitled Tensorial Polar Decomposition. The main result is that any 2D symmetric fourth-order tensor can be written in terms of second-order tensors only in a decomposition that makes explicitly appear invariants and symmetry classes. The link with harmonic decomposition is made thanks to Kelvin decomposition of its harmonic term. (C) 2015 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.