A local PUFEM modeling of stress singularity in sliding contact with minimal enrichment for direct evaluation of generalized stress intensity factors

• Stress singularity parameters are calculated numerically in the pre-processing phase.
• Consistent enrichment functions in sliding frictional contact for PUFEM are derived.
• The number of additional DOFs is decreased substantially, and they now have the physical meaning of GSIF.
• By direct PUFEM, there is no need for a contour Integral formulation to derive GSIF.
• The proposed direct approach provides a significant improvement in the accuracy of GSIF.

The order of stress singularity around sharp corners is studied by solving the characteristic equation numerically. The corresponding displacement and stress fields around the sharp corners, which accurately satisfy the compatibility of deformation and stress states on the two sides of the slave corner, are derived for various contact configurations. The dominant mode of infinite asymptotic stress field for contact problems is then implemented with minimum enrichments (2 functions for each enriched node), for the first time, within the framework of partition of unity finite element. An increased rate of convergence is achieved and the generalized stress intensity factor can be obtained directly from the additional unknowns. Numerical examples demonstrate the superior accuracy of the present approach to capture the sliding contact stress singularities near sharp corners.