An engineering solution for mesh size effects in the simulation of delamination using cohesive zone models

A new decohesion element with the capability of dealing with crack propagation under mixed-mode loading is proposed and demonstrated. The element is used at the interface between solid finite elements to model the initiation and non-self-similar growth of delaminations in composite materials. A single relative displacement-based damage parameter is applied in a softening law to track the damage state of the interface and to prevent the restoration of the cohesive state during unloading. The softening law is applied in the three-parameter Benzeggagh-Kenane mode interaction criterion to predict mixed-mode delamination propagation. To demonstrate the accuracy of the predictions, steady-state delamination growth is simulated for quasi-static loading of various single mode and mixed-mode delamination test specimens and the results are compared with experimental data.

Numerical simulation of mixed-mode progressive delamination in composite materials

Wave propagation and group velocity

A new decohesion element with mixed-mode capability is proposed and demonstrated. The element is used at the interface between solid finite elements to model the initiation and non-self-similar growth of delaminations. A single relative displacement-based damage parameter is applied in a softening law to track the damage state of the interface and to prevent the restoration of the cohesive state during unloading. The softening law for mixed-mode delamination propagation can be applied to any mode interaction criterion such as the two-parameter power law or the three-parameter Benzeggagh-Kenane criterion. To demonstrate the accuracy of the predictions and the irreversibility capability of the constitutive law, steady-state delamination growth is simulated for quasistatic loading-unloading cycles of various single mode and mixed-mode delamination test specimens.

/pdf/mixed-mode-decohesion-finite-elements-for-the-simulation-of-58v2hnt70u.pdf

Mixed-Mode Decohesion Finite Elements for the Simulation of Delamination in Composite Materials

https://ntrs.nasa.gov/api/citations/20080014292/downloads/20080014292.pdf

A damage model for the simulation of delamination in advanced composites under variable-mode loading

This article describes the application of interface elements to the prediction of progressive delamination in composite materials. The work has been implemented in two separate commercial finite-element computer packages, ABAQUS [1] and LUSAS [2]. In the former case, this has been achieved via a "user subroutine", while in the latter case the elements are embedded directly within the system, either in the standard "release version" of the code or in a research version, to which the authors have access and in which they have implemented various algorithms directly. Comparisons are made with a range of experimental results for composite material specimens. In addition to the finite-element solutions, closed-form results are also presented that are based on a corrected beam theory.

Predicting Progressive Delamination of Composite Material Specimens via Interface Elements

Nonlinear transient analysis of rectangular composite laminated plates

Prediction of delamination in braided composite T-piece specimens

An approach employing decohesive models with mixed damaged scale and using total fracture energy was developed to simulate the delamination process of a stiffened fibre-composite panel and a repaired composite sandwich panel. Two decohesive material models – a bilinear interfacial decohesive function and the other a cubic polynomial interfacial decohesive function – were developed by using total fracture energy Gc, and based on using interface elements. In comparison with traditional numerical methods in fracture mechanics, this approach automatically predicts the failure load, crack path and the residual stiffness in the fracture process. Applications in this article are delamination analysis of a stiffened fibre-composite panel under four-point bending conditions and a repaired composite sandwich panel under four-point bending test. Comparisons between modeling predictions and experimental observations show that these decohesive models perform well. This article compares the problem of numerical convergent failure between two decohesive material models.

Predicting Progressive Delamination of Stiffened Fibre-Composite Panel and Repaired Sandwich Panel by Decohesion Models:

Interfacial behaviour of the bone–cement interface has been studied under tensile, shear and mixed mode loading conditions. Bovine cancellous bone was used to bond with acrylic bone cement to form bone–cement interface samples, which were mechanically tested under selected tensile, shear and mixed mode loading conditions. The influence of the loading angle and the extent of the cement penetration on the interfacial behaviour were examined. The failure mechanisms with regard to loading mode were examined using micro-focus computed tomography. The measured tensile and shear responses were utilized in a cohesive zone constitutive model, from which the pre-yield linear and the post-yield exponential strain softening behaviour under mixed mode loading conditions was predicted. The implications of the work on the studies of cemented joint replacements are also discussed.

Jiye Chen

Papers

Predicting Progressive Delamination of Composite Material Specimens via Interface Elements

Nonlinear transient analysis of rectangular composite laminated plates

Prediction of delamination in braided composite T-piece specimens

Predicting Progressive Delamination of Stiffened Fibre-Composite Panel and Repaired Sandwich Panel by Decohesion Models:

Bone–cement interfacial behaviour under mixed mode loading conditions