On the existence of the Airy function in Lipschitz domains. Application tothe traces of H-2

We prove the existence of the Airy function w corresponding to the stress t ensor S in a plane domain Omega connected, eventually not simply connected, with Lipschitz boundary Gamma. In order to understand the relations betwee n the boundary values of w and S . n, we study the tangential derivative fr om H-1/2(Gamma) into H-1/2(Gamma). With the help of these results we charac terize the traces of a function in H-2(Omega) extending the previous result s of Necas and Grisvard. (C) 2000 Academie des sciences/Editions scientifiq ues et medicales Elsevier SAS.