A boundary-type meshless method called the scaled boundary node method(SBNM) is developed to directly evaluate mixed mode stress intensity factors(SIFs) without extra post-processing.The SBNM combines the scaled boundary equations with the moving Kriging(MK) interpolation to retain the dimensionality advantage of the former and the meshless attribute of the latter.As a result,the SBNM requires only a set of scattered nodes on the boundary,and the displacement field is approximated by using the MK interpolation technique,which possesses the δ function property.This makes the developed method efficient and straightforward in imposing the essential boundary conditions,and no special treatment techniques are required.Besides,the SBNM works by weakening the governing differential equations in the circumferential direction and then solving the weakened equations analytically in the radial direction.Therefore,the SBNM permits an accurate representation of the singularities in the radial direction when the scaling center is located at the crack tip.Numerical examples using the SBNM for computing the SIFs are presented.Good agreements with available results in the literature are obtained.
A meshless numerical model is developed for analyzing transient heat conductions in three-dimensional(3D) axisymmetric continuously nonhomogeneous functionally graded materials(FGMs). Axial symmetry of geometry and boundary conditions reduces the original 3D initial-boundary value problem into a two-dimensional(2D) problem. Local weak forms are derived for small polygonal sub-domains which surround nodal points distributed over the cross section. In order to simplify the treatment of the essential boundary conditions, spatial variations of the temperature and heat flux at discrete time instants are interpolated by the natural neighbor interpolation. Moreover, the using of three-node triangular finite element method(FEM) shape functions as test functions reduces the orders of integrands involved in domain integrals. The semi-discrete heat conduction equation is solved numerically with the traditional two-point difference technique in the time domain. Two numerical examples are investigated and excellent results are obtained, demonstrating the potential application of the proposed approach.
The scaled boundary finite element method(SBFEM)is a novel semi-analytical technique that combines the advantages of the finite element method and the boundary element method with unique properties of its own.This method has proven very efcient and accurate for determining the stress intensity factors(SIFs)for mode I and mode II two-dimensional crack problems.One main reason is that the SBFEM has a unique capacity of analytically representing the stress singularities at the crack tip.In this paper the SBFEM is developed for mode III(out of plane deformation)two-dimensional fracture analysis.In addition,cubic B-spline functions are employed in this paper for constructing the shape functions in the circumferential direction so that higher continuity between elements is obtained.Numerical examples are presented at the end to demonstrate the simplicity and accuracy of the present approach for mode III two-dimensional fracture analysis.
