A Lie groupoid, called second-order non-holonomic material Lie groupoid, is associated in a natural way to any Cosserat media. This groupoid is used to give a new definition of homogeneity which does not depend on a reference crystal. The corresponding Lie algebroid, called second-order non-holonomic material Lie algebroid, is used to characterize the homogeneity property of the material. We also relate these results with the previously ones in terms of non-holonomic second-order G-structures.
ContentsKey words and phrases. Groupoid, Lie algebroid, constitutive theory, Cosserat media, frame bundle, G−structure.This work has been partially supported by MINECO Grants MTM2013-42-870-P and the ICMAT Severo Ochoa projects SEV-2011-0087 and SEV-2015-0554. V.M. Jimnez wishes to thank MINECO for a FPI-PhD Position.