Existence and uniqueness for the linear Koiter model for shells with little regularity

We give a simple proof of existence and uniqueness of the solution of the K oiter model for linearly elastic thin shells whose midsurfaces can have cha rts with discontinuous second derivatives. The proof is based on new expres sions for the linearized strain and change of curvature tensors. It also ma kes use of a new version of the rigid displacement lemma under hypotheses o f regularity for the displacement and the midsurface of the shell that are weaker than those required by earlier proofs.