[1] Department of Mechanical Engineering, University of Coimbra, Polo II, Pinhal de Marrocos, P-3030 Coimbra, Portugal
[2] Lab. Microstructure Mecan. des Mat., LM3 UA CRNS 1219, ENSAM, 151 Bd de l'Hôpital, F-75013 Paris Cedex, France
[3] Dir. Rech. et Affaires Scientifiques, SAMM, PSA-Peugeot Citroen, Ch. Malmaison, F-91510 Bièvres, France