An Irreversible Constitutive Law for Modeling the Delamination Process Using Interface Elements

Abstract

An irreversible constitutive law is postulated for the formulation of interface elements to predict initiation and progression of delamination in composite structures. An exponential function is used for the constitutive law such that it satisfies a multi-axial stress criterion for the onset of delamination, and satisfies a mixed mode fracture criterion for the progression of delamination. A damage parameter is included to prevent the restoration of the previous cohesive state between the interfacial surfaces. To demonstrate the irreversibility capability of the constitutive law, steady-state crack growth is simulated for quasi-static loading-unloading cycle of various fracture test specimens.

Analysis Methodology for Assessing Delaminations in Composite Overwrapped Pressure Vessels

“…Solution of Equation (11) in conjunction with Equations (4) through (11) yields the optimum contour for a planar winding pattern. In the pre-processor, these equations are solved numerically by the fourth-order Runge-Kutta method with an adaptive stepsize control scheme.…”

“…While different techniques may be used to model this type of damage growth, using cohesive elements with embedded fracture mechanics properties offers a particular advantage. Since the path of delamination growth can be established a priori, cohesive elements and progressive failure analysis [8][9][10][11][12] can be used to predict growth along these well-defined failure lines.…”

Mesh Generation for solving Complex Structural Problems using Finite Element Methods

“…These methods can be used to calculate the components of the energy release rate. Cohesive zone modeling using de-cohesion elements have been presented in the work of Shahwan et al and Goyal et al [27], [28]. Cohesive interface elements have been applied to problems where the crack paths are not known a priori.…”

Modelling impact damage in marine composite panels

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