New Stress Formulation in X-FEM Based on Numerical Integration of Restoring Forces Using Equivalent Polynomial Functions

Document Type : Article

Authors

D‌e‌p‌t. o‌f C‌i‌v‌i‌l E‌n‌g‌i‌n‌e‌e‌r‌i‌n‌g K. N. T‌o‌o‌s‌i U‌n‌i‌v‌e‌r‌s‌i‌t‌y o‌f T‌e‌c‌h‌n‌o‌l‌o‌g‌y

Abstract

In this study, stress formulas in the extended finite element method are investigated. The stress components for the enriched DOFs are developed and conventional stress components of the standard DOFs are modified. The modified stresses for the standard DOFs have a unique value for the whole domain of the cracked element, whereas the stress components for the enriched DOFs have different values at each side of the crack faces. New formulations are obtained by investigating the restoring forces equations. To do so, new polynomial functions are developed by eliminating the element partitioning when the shifted Heaviside function is utilized. The proposed stress formulas are verified by the force convergence criterion. It is shown that the proposed formulations for the standard DOFs are more compatible with the characteristics of the crack propagation within the cracked body and the stress components for the enriched DOFs represent the tractions at the crack faces, although properties of material nonlinear behavior are not considered. It is proven that the internal forces calculated utilizing the proposed formulation are in equilibrium with the external loads.

Keywords


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