A new approach for evaluation of the potential gradient in the 2D boundary element method is presented. Numerical tests show the high accuracy of the recovered value of the tangential derivative of the potential on smooth and non-smooth boundaries. A multiple branch crack problem for a circular torsion cylinder is studied in this paper.
All branches emanate from the centre of the section.
The relevant boundary problem belongs to the modified Dirichlet problem. The modified Dirichlet problem is converted into the solution of two Dirichlet problems of the Laplace equation for the doubly connected region. The finite difference method is suggested to solve the problem. Finally, the torsion rigidity coefficient can be evaluated. Numerical examples are given to demonstrate the use of the proposed method.