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Abaqus.mater_Hol - HOME BOOKMARKS SEARCH Progressive Damage...

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2003 ABAQUS Users° Conference 1 Progressive Damage Modelling of FML°s. Implementation in a UMAT subroutine Jan Hol and Valeria Antonelli Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS Delft, The Netherlands Abstract: The present paper presents the procedure used to write a user material subroutine UMAT for shell elements to include property degradation of the composite plies of a Fibre Metal Laminate (FML). The Hashim°s three-dimensional piecewise stress-based criteria for in-plane failure has been implemented in the subroutine. The type of failure and its extension in the pre- preg layers can be visualised in ABAQUS-CAE. Case study has been the blunt notch strength of a GLARE plate. The numerical results were in good agreement with the experimental ones. 1. Introduction Fibre Metal Laminates (FML°s) are hybrid laminates made of polymer matrix composite (PMC) plies interspersed with metal plies. The two materials are assembled by curing the PMC plies and metal foils to form a composite laminate (Figure 1 ). Figure 1. Example of a FML . The benefits of FML°s arise from the ability to tailor material properties so that the attractive aspects of the two constituent materials are utilised and their weaknesses are avoided. The metal
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2 2003 ABAQUS Users° Conference layers protect the PMC core from environmental effects such as moisture ingress as well as providing improved impact resistance and bearing properties. The composite core has higher strength and stiffness to weight ratio than monolithic metal and is known to be less sensitive to fatigue effects. The combination of the two materials as a hybrid composite could potentially outperform either of the two constituent materials. To be able to fully exploit the capabilities of FML in a design stage, it is necessary to model with accuracy the type of failure and its location within the laminate. To be able to predict with a better accuracy the blunt notch strength of FML, a user subroutine UMAT has been implemented 2. Material modelling As fibre metal laminates are normally used in aeronautical applications, to describe the material behaviour of FML structures, laminated shell elements are used in FE-analyses. Two materials are therefore defined to describe the FML: an isotropic metal layer and a 2D-orthotropic one for the composite layer. The isotropic layer is defined as an elastic plastic material using the standard keywords available in ABAQUS. In general, for the composite ply, the 2D orthotropic material definition is used. In addition to this, failure of the different layers can be verified during post processing with the classical failure criteria as Tsai-Hill, Tsai-Wu, etc. In the present case, the Hashin°s in-plane stress failure [1] has been implemented in a material subroutine.
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