Aspects of the determination of residual stresses in ceramics by ultrasounds hole-drilling V. Goanţă, P.D. Barsănescu, B. Leiţoiu and C. Bîtcă EPJ Web of Conferences, 6 (2010) 44003 Published online: 10 June 2010 DOI: 10.1051/epjconf/20100644003