21 st International Conference on Composite Materials Xi’an, 20-25 th August 2017 SIMULATION OF THE OPEN-HOLE TENSILE RESPONSE OF COMPOSITE LAMINATES USING A COMBINED DISCRETE AND CONTINUUM DAMAGE APPROACH Mina Shahbazi 1 , Reza Vaziri 1 1 Composites Research Network, The University of British Columbia, Vancouver, Canada mina@composites.ubc.ca, reza.vaziri@ubc.ca Keywords: Damage Progression, Open-Hole Tensile Test, Nonlocal Continuum Damage Model, Cohesive Zone Model, Explicit FEM ABSTRACT In this study, an efficient combination of continuum and discrete damage mechanics based approaches is used to model the interacting effect of delamination and intra-laminar damage modes in notched composite laminates subjected to tensile loading [1]. Delamination is the only mode of damage captured by a discrete approach while all intra-laminar forms of damage are modelled using a nonlocal continuum damage approach. A series of open-hole specimens that have been tested under tensile loading [2] are simulated using the proposed approach. The specimens are made of quasi-isotropic IM7/8552 carbon fibre/epoxy laminates with varying hole diameter, ply and laminate thickness while keeping the ratios of the hole diameter to specimen width and length constant. The current approach is shown to capture the dominant failure mechanisms as well as the overall behaviour, including the size and layup effect on the notched strength of the laminate. 1 INTRODUCTION Reliable prediction of the inelastic behaviour of laminated composite materials requires that the computational model be able to capture the interaction of several failure/damage mechanisms including matrix cracking, fibre breakage, splitting and delamination. The accurate prediction of the onset and propagation of certain discrete damage modes (e.g. splitting and delamination), is critical in predicting the progressive damage response of the laminate up to its ultimate failure. In a continuum approach, damage is considered to occur as a result of multiple damage modes with no single isolated crack that dominates the zone of damage. In such cases one may consider the effect of multiple micro-cracks smeared into a locally homogeneous continuum field. An example of this approach is the sub-laminate based material model that was first developed at UBC known as CODAM [3]. More recently, the second generation of this model (CODAM2) has been introduced [4] with a nonlocal regularization scheme to address both the mesh size and orientation dependencies of the numerical solution. A built-in form of this material model is available in the commercial finite element software package, LS-DYNA, as MAT219. A practical methodology for calibrating these models has also been developed [5]. The material constants required as input for this model are the initiation and saturation values of the equivalent strains that drive each mode of damage. This material model has been originally developed to represent the effective behaviour of a sublaminate where the initiation and saturation strain values are deduced from the experimentally characterized strain-softening curves and the fracture energy of the sublaminate rather than those of the individual plies [6]. This approach is applicable when the extent of delamination is relatively minor and the material building block can be considered to be a