| A new finite element method for fourth-order elliptic partial differential equations is presented and applied to thin bending theory problems in structural mechanics and to a strain gradient theory problem. The new method combines concepts from the continuous Galerkin method, the discontinuous Galerkin method and stabilization techniques.; A brief review of the continuous Galerkin method, the discontinuous Galerkin method and stabilization techniques highlights the advantages and disadvantages of these methods and suggests a new approach for the solution of fourth-order elliptic problems. A new continuous/discontinuous Galerkin (C/DG) method is proposed which uses low-order C0-continuous interpolation functions and is formulated in the primary variable only. The advantage of this formulation over a more traditional mixed approach is that the introduction of additional unknowns and a related difficulties can be entirely avoided. In the context of thin bending theory, the C/DG method leads to a formulation where displacements are the only degrees of freedom, and no rotational degrees of freedom need to be considered.; The main feature of the C/DG method is the weak enforcement of continuity of first and higher-order derivatives through stabilizing terms on interior boundaries. Consistency, stability and convergence of the method are shown analytically. Numerical experiments verify the theoretical results, and applications are presented for Bernoulli-Euler beam bending, Poisson-Kirchhoff plate bending and a Toupin-Mindlin shear layer. |
