Construction of a new class of quadrilateral spline elements based on the scaled boundary coordinates.

The scaled boundary finite element method (SBFEM) is a semi-analytical numerical approach based on the scaled boundary coordinates. Recently, the method which uses interpolations in both the circumferential and radial directions has also been developed based on the scaled boundary representation. However, the stress fields are always discontinuous within the S-elements by both the original SBFEM and the latter method. In this paper, a new class of quadrilateral elements with interior smoothness is constructed by extending the B-net method based on the area coordinates into the S-net method based on the scaled boundary coordinates. In the S-net method, the Bernstein bases are separately applied to discretize both circumferential and radial directions in each sub-triangle of an S-element (or quadrilateral element), and the smoothness conditions between adjacent triangles can be simply represented in the form of linear equations. Then, by using the S-net method, we obtain a new class of quadrilateral elements with interior smoothness and high-order completeness. The shape functions or interpolation bases can be obtained explicitly and determined by the same interpolation nodes of the S-element as the original SBFEM. Some numerical tests also show that the proposed elements can obtain good results. • A new class of quadrilateral FEM elements is constructed in the scaled boundary coordinates with interior C 1 continuity. • The B-net method based on the area coordinates is extended into the S-net method based on the scaled boundary coordinates. • The new elements overcome the stress singularity at the scaling centre and stress discontinuity inside the S-element. • The high-order completeness of the new elements is proved theoretically and thus the convergence is guaranteed. • The extended S-net method can construct new polygonal elements with high-order continuity. [ABSTRACT FROM AUTHOR]