Novel methods are described for removing the strong singularities arising in the domain integrals of elastoplasticity, and for solving the non-linear equation set. The former employs a new transformation from domain integrals to (cell) boundary integrals. The number of system equations is minimised by using the plastic multiplier as the primary unknown and an incremental variable stiffness iterative algorithm is developed for solving these equations. Excellent convergence is achieved and some numerical examples demonstrate the algorithm's effectiveness.

In this paper, an approach is presented for the numerical evaluation of weakly, strongly, hyper- and super-singular boundary integrals which exist in the Cauchy principal value sense in two-dimensional problems. In this approach, the singularities involved in integration kernels are analytically removed by expressing the nonsingular parts of the integration kernels as polynomials of the distance r. A self-contained Fortran code is listed and described for implementation of the proposed approach. The attached code is also able to evaluate general regular integrals using Gaussian quadrature, which enables the code to evaluate any two-dimensional boundary integral. Some examples are provided to verify the correctness of the presented formulations and the included code.

A nonlinear elastic boundary element method (NBEM) approach is developed as an innovative deforming mesh generator for computational aeroelastic simulation. The computational fluid dynamics (CFD) mesh is assumed to be embedded in an in finite nonlinear elastic medium of a hardening material, leading to the formulation of apseudononlinear elastostatic problem. Whereas the CFD surface mesh is treated as a boundary element model and the CFD flow field grid as domain sample points, the NBEM approach solves Navier’s equations using a particular solution scheme that removes the requirement of the domain integral in the conventional NBEM formulation. The NBEM approach has a unified feature that is applicable to all mesh systems, including unstructured, multiblock structured, and overset grids. An optimization strategy is employed to determine the optimum hardening material properties by minimizing the mesh distortion in the viscous region where grid orthogonality must be preserved. Three test cases are performed to demonstrate the robustness and effectiveness of the NBEM approach for deforming mesh generation.

In this paper, a simple and robust method, called the radial integration method, is presented for transforming domain integrals into equivalent boundary integrals. Any two- or three-dimensional domain integral can be evaluated in a unified way without the need to discretize the domain into internal cells. Domain integrals consisting of known functions can be directly and accurately transformed to the boundary, while for domain integrals including unknown variables, the transformation is accomplished by approximating these variables using radial basis functions. In the proposed method, weak singularities involved in the domain integrals are also explicitly transformed to the boundary integrals, so no singularities exist at internal points. Some analytical and numerical examples are presented to verify the validity of this method. q 2002 Elsevier Science Ltd. All rights reserved.

A novel set of auxiliary equations, which supplement the fundamental boundary integral equations, for the treatment of corners and edges arising in discontinuous traction problems and at zonal intersections is derived. Based on these equations, an efficient linear 3D multi-region BEM algorithm is presented which can deal with arbitrarily many regions. Numerical examples demonstrate the effectiveness of this algorithm.

In this paper, a set of internal stress integral equations is derived for solving thermoelastic problems.A jump term and a strongly singular domain integral associated with the temperature of the material are produced in these equations. The strongly singular domain integral is then regularizedusing a semi-analytical technique. To avoid the requirement of discretizing the domain into internal cells,domain integrals included in both displacement and internal stress integral equations are transformedinto equivalent boundary integrals using the radial integration method (RIM). Two numerical examples for 2D and 3D, respectively, are presented to verify the derived formulations.

In this paper, a new and simple boundary element method without internal cells is presented for the analysis of elastoplastic problems, based on an effective transformation technique from domain integrals to boundary integrals. The strong singularities appearing in internal stress integral equations are removed by transforming the domain integrals to the boundary. Other weakly singular domain integrals are transformed to the boundary by approximating the initial stresses with radial basis functions combined with polynomials in global coordinates. Three numerical examples are presented to demonstrate the validity and effectiveness of the proposed method.

This paper describes a robust and efficient elasto-plastic boundary element method (BEM) intended for complex problems in geomechanics. Some novel techniques are employed to evaluate the singular integral equations accurately and efficiently. In particular, the strong singularities arising in the domain integrals of the stress integral equations are removed by transforming them from domain integrals to (cell) boundary integrals. Adaptive integration schemes are used throughout to optimize the integration process. The system equations are condensed by recasting them in terms of the plastic multiplier, and a novel Newton–Raphson algorithm delivers greatly improved solution times. Some examples demonstrate the scope and power of the method.

In this paper, explicit boundary-domain integral equations for evaluating velocity gradients are derived from the basic velocity integral equations. A free term is produced in the new strongly singular integral equation, which is not included in recent formulations using the complex variable differentiation method (CVDM) to compute velocity gradients (Int. J. Numer Meth. Fluids 2004; 45:463-484; Int. J. Numer Meth. Fluids 2005; 47:19-43). The strongly singular domain integrals involved in the new integral equations are accurately evaluated using the radial integration method (RIM). Considerable computational time for evaluating integrals of velocity gradients can be saved by using present formulation than using CVDM. The formulation derived in this paper together with those presented in reference (Int. J. Numer. Meth. Fluids 2004; 45:463-484) for 2D and in (Int. J. Numer Meth. Fluids 2005; 47:19-43) for 3D problems constitutes a complete boundary-domain integral equation system for solving full Navier-Stokes equations using primitive variables. Three numerical examples for steady incompressible viscous flow are given to validate the derived formulations. Copyright 2007 John Wiley & Sons, Ltd.

In this paper, a set of boundary integrals are derived based on a radial integration technique to accurately evaluate two dimensional (2D) and three dimensional (3D), regular and singular domain integrals. A self-contained Fortran code is listed and described for numerical implementation of these boundary integrals. The main feature of the theory is that only the boundary of the integration domain needs to be discretized into elements. This feature can not only save considerable efforts in discretizing the integration domain into internal cells (as in the conventional method), but also make computational results for singular domain integrals more accurate since the integrals have been regularized. Some examples are provided to verify the correctness of the presented formulations and the included code.