The coupling method for torsion problem of the square cross-section bar with cracks

By coupling natural boundary element method (NBEM) with FEM based on domain decomposition, the torsion problem of the square cross-sections bar with c racks have been studied, the stresses of the nodes of the cross-sections an d the stress intensity factors have been calculated, and some distribution pictures of the stresses have been drawn. During computing, the effect of t he relaxed factors to the convergence speed of the iterative method has bee n discussed. The results of the computation have confirmed the advantages o f the NBEM and its coupling with the FEM.