This paper presents a method to estimate the stored energy during the tensile deformation of an aluminum multicrystal and polycrystal sheet sample. The method is based on thermo mechanical macroscopic fields analysis, like strains and temperature, obtained by a visible and an infrared cameras. Preliminary experimental results are presented. On an A1 multicrystal sheet, heterogeneous thermo mechanical fields associated to the localized movement of dislocations at a microscopic scale are presented. Furthermore, the energetic balance established during the tensile deformation of an A1 polycrystal show a decreasing ratio of stored energy on anelastic energy and a non constant fraction of total work converted into heat.