Modelling of the failure of carbon-fibre laminates subjected to dynamic loads S. Sanchez-Saez, J. Lopez-Puente, E. Barbero and C. Navarro Department of Continuum Mechanics and Structural Analysis, University Carlos III of Madrid, 28911 Leganes, Madrid, Spain Abstract. In this study, the behaviour of carbon/epoxy tape laminates subjected to dynamic loads, using a numerical model based on a progressive failure criterion, was evaluated. In order to verify whether the model can reproduce the behaviour observed experimentally in more complex laminates than unidirectional ones, quasi-isotropic laminates [ ¡45/0/90] 2S were tested under dynamic con- ditions. The model accurately reproduced the failure stress and strain and the failure modes of the laminates. 1. INTRODUCTION The use of composite laminates has become very important in the manufacture of structural components, because they have excellent specific mechanical properties which make them very competitive compared to metallic materials. However, the study of the failure of a composite structure is more complex than the study of a component manufactured with an isotropic material, as the former present an anisotropic behaviour and exhibit different damage mechanisms (delamination, fibre breakage, matrix cracking, fibre/matrix pull-out, etc) that appear simulta- neously and that could interact with each other. These damage modes depend on a large number of parameters, such as the fibre and matrix properties, the reinforcement architecture, the fibre/ matrix interface, the manufacture method, etc. Therefore, for the design of composite structures it is necessary to have models which will permit the prediction of the damage progression and the failure. Different failure criteria can be used to estimate the failure of laminates [1–4]. However, the most frequently used for static conditions, given their simplicity and their implementation in the majority of commercial structural design codes, are the Tsai-Hill and Tsai-Wu criteria, which consider the interaction between the different components of the stress tensor [5]. More complex criteria exist, both bidimensional and tridimensional, which takes into account the different failure mechanisms, such as matrix cracking, delamination or fibre breakage [6–8]. Although the study of failure criteria of composites under static load conditions has been widely studied, it cannot be considered a closed task [9, 10]. Of great interest is the “World Wide Failure Exercise,” headed by Hinton and Soden and involving the collaboration of a large number of researchers, which compares different failure criteria; it was published in the journal “Composite Science and Technology” (vol. 58, 62 and 64). The final conclusion was that there is not a valid criterion for all load conditions, materials and laminate configurations. In addition to those considerations, composite structures can be subjected to dynamic loads, either during their service life or during assemblage and maintenance operations. Several experimental works that analyze the behaviour of these structural elements under low velocity impact [11–13] and high velocity impact [14, 15] could be found in the bibliography. One of the most used criterion to predict the failure of laminates under dynamic conditions is the model developed by Chang-Chang [16], which considers four damage mechanisms: DYMAT 2009 (2009) 1807–1813 Ó EDP Sciences, 2009 DOI: 10.1051/dymat/2009254