A pinboard by
Gourab Ghosh

PhD Student, Civil and Environmental Engineering Department, Vanderbilt University


we propose a stabilized finite element method for alleviating the artificial compliance issue

Composites are now-a-days widely used in aerospace, naval and mechanical industries to build airplanes and cars. Researchers are concerned about predicting their failure mechanisms, prediction of crack propagation and crack growth issues as their uses are growing day by day. To increase the cost effectiveness and efficiency of this process, we do numerical simulation building a computer model of the actual structure. It has been found that delamination is one of the major failure modes in composites. Delamination of composite materials is commonly modeled using intrinsic cohesive zone models (CZMs), which are generally incorporated into the standard finite element (FE) method through a zero-thickness interface (cohesive) element; however, intrinsic CZMs exhibit numerical instabilities when the cohesive stiffness parameters are assumed to be large relative to the elastic stiffness of the composite material. To address this numerical instability issue, we propose a stabilized finite element method by combining the traditional penalty method with the Nitsche’s method that is equally effective for any specified initial stiffness of the cohesive (traction-separation) law. The key advantage of the proposed method is that it generalizes the Nitsche’s method to any traction-separation law with arbitrary large values of initial stiffness and provides a unified way to treat cohesive fracture problems in a variationally consistent and stable manner. We implemented the stabilized method in the commercial finite element software Abaqus via the user element subroutine and simulated benchmark tests for mode I and mixed-mode delamination in isotropic materials to establish the viability of the approach.