Locking-free mixed hp finite element methods for curvilinear domains

Mixed hp finite element methods (FEMs) are robust with respect to Poisson ratio locking when straight-sided quadrilateral elements are used. For the p version, which uses Fixed and generally large elements. curved elements are necessary to represent curved domains accurately. We show that mixed hp curved quadrilateral elements retain the robustness of their straight-sided counterparts, provided degenerate elements are avoided. We also show that lip version triangles are robust. We use these concepts to develop a locking-Free FEM for geometrically-nonlinear elasticity. (C) 2001 Elsevier Science B.V. All rights reserved.