As the convergence, good numerical accuracy and high computing efficiency
of nonconforming elements cannot be achieved simultaneously using the
finite element method (FEM) or the current numerical manifold method
(NMM), the first-order NMM was developed to analyze the bending of thin
plates. The first-order Taylor expansion was selected to construct the local
displacement function, which endowed the generalized degrees of freedom
with physical meanings and decreased the rank deficiency. Additionally,
the new relations between the global and local rotation functions in the
first-order approximation were derived by adopting two sets of rotation functions,
and
.
Regular meshes were selected to improve the convergence performance. With the
penalized formulation fitted to the NMM for Kirchhoff’s thin plate problems, a
unified scheme was proposed to deal with irregular and regular boundaries of the
domain. The typical examples indicated that the numerical solutions achieved using
the first-order NMM rapidly converged to the analytical solutions, and the accuracy
of such numerical solutions was vastly superior to that achieved using the FEM and
the zero-order NMM.
Keywords
nonconforming element, convergence, numerical manifold
method, first-order Taylor expansion