Abstract : Bending of plates refers to internal states of stress such that the membrane stress resultants vanish. From the kinematic point of view, it means that the in-plane displacements of the material points of the plate are null. In other words, the degrees of freedom of plates in bending are the out-of-plane displacement (thick and thin plates), together with the two material rotations (thick plates only) – see article “Direct Derivation of Plate Theories”