No abstract

A numerical procedure aimed at simulating the structural behavior of delaminated composite plates under compressive load, is developed and presented in this article. Although delamination buckling and growth have been widely studied in the literature, in this article the effect of fiber—matrix failure on the buckling behavior of a delaminated structure up to final failure is investigated in detail. A geometrically non linear finite element (FE) approach is adopted for elastic instability simulation, the modified virtual crack closure technique (MVCCT) is used for the energy release rate (ERR) evaluation at the delamination front and fracture mechanics based progressive damage approach is introduced for the simulation of fiber—matrix damage onset and evolution. Comparisons of numerical results with existing experimental data on composite panels with an embedded circular delamination under compressive load, are presented for preliminary validation purposes. Furthermore, the influence of the different failure mechanisms on the compressive behavior of delaminated composite plates is assessed, by comparing numerical results obtained with models characterized by different degrees of complexity. Finally, results of a limited sensitivity analysis are shown, pointing out the influence of some key parameters characteristics of the adopted numerical approach on the accuracy of numerical simulations.

To cite this version:Elisa Pietropaoli, Aniello Riccio. Formulation and assessment of an enhanced finite element procedure for the analysis of delamination growth phenomena in composite structures. Composites Science and Technology, Elsevier, 2011, 71 (6) This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.-1/35-

This paper addresses the prediction of intralaminar and interlaminar damage onset and evolution in composite structures through the use of a finite element based procedure. This procedure joins methodologies whose credibility has been already assessed in literature such as the Virtual Crack Closure Technique (for delamination) and the ply discount approach (for matrix/fiber failures). In order to establish the reliability of the procedure developed, comparisons with literature experimental results on a stiffened panel with an embedded delamination are illustrated. The methodology proposed, implemented in ANSYS © as post-processing routines, is combined with a finite element model of the panel, built by adopting both shell and solid elements within the frame of an embedded global/local approach to connect differently modelled substructures.

Composites are materials characterized by complex failure phenomena that onset and interact. Several approaches are available in literature to predict the behaviour of composite structures taking into account failure modes. However, most of them require the knowledge of experimental parameters, which generally are not provided by composite suppliers. Progressive failure techniques represent a valuable alternative to these methodologies because they rely on failure criteria and ply-discount techniques often based on the choice of a single degradation factor whose value is chosen by the analyst as small enough to prevent convergence problems in finite element analyses. The aim of this work is to analyze the behaviour of a composite structure taking into account the damage onset and evolution. The analysis is performed by using a constitutive material model (USERMAT) developed and implemented in the Finite element software ANSYS©. The accuracy of the procedure proposed is assessed by comparing numerical results and experimental data taken from literature.