A FAMILY OF QUADRILATERAL HYBRID-TREFFTZ P-ELEMENTS FOR THICK PLATE ANALYSIS

This paper presents a family of quadrilateral hybrid-Trefftz (HT) p-el ements based on Reissner-Mindlin theory of moderately thick plates. As compared with existing higher-order HT thick plate elements (J. Petro lito), which make use of an incomplete set of polynomial homogeneous s olutions for the internal displacement and rotation fields and of an a uxiliary conforming frame held involving independently interpolated bo undary distributions of displacements and rotations, the new elements differ essentially with respect to the following two points: (1) A T-c omplete set of homogeneous solutions including polynomial and nonpolyn omial functions has been derived and used to represent the intraelemen t displacement and rotations fields. (2) The displacement component of the auxiliary frame field has been linked with the tangential compone nt of the rotation so as to satisfy a particular constraint derived fr om equilibrium considerations. The practical efficiency of these modif ications has been assessed through a series of numerical examples whic h have shown that the new p-elements are robust, more accurate in term s of the number of unknowns and of the computational effort, and that they do not lock in the thin limit.