Analysis of the integration of cohesive elements in regard to utilization of coarse mesh in laminated composite materials

SUMMARYAn analysis of the solver convergence difficulties and erroneous results when large cohesive elements are utilized in delamination propagation simulations in laminated composites is presented. Special focus is given to the numerical integration of the cohesive element force vector and stiffness matrix. The magnitude and variation of the integration error are analyzed, and the results show that contrary to statements found elsewhere in the literature, the 2 × 2 point Newton‐Cotes quadrature, commonly used in commercial software, results in large errors and is one of the limiting factors for using larger elements. By reducing the integration error in the damage process zone of the interface, more accurate results can be obtained, and larger elements can be utilized with less iterations, thereby decreasing the computational cost. Copyright © 2014 John Wiley & Sons, Ltd.