Comparison of the accumulation of fibre breaks occurring in a unidirectional carbon/epoxy composite identified in a multi-scale micro-mechanical model with that of experimental observations using high resolution computed tomography

National audienceA model to predict fibre break accumulation that takes into account all physical phenomena at the origin of the fibre break (i.e. the random nature, stress transfer due to breaks, fibre debonding and viscosity of the matrix) shows clearly that the failure of a unidirectional composite structure results in the formation of random fibre breaks which at higher loads coalesce into clusters of broken fibres. The object of the study is to experimentally confirm this scenario. Many techniques exist to detect the failure of carbon fibre composites, however none of them offer a resolution that allows this goal to be achieved in a non-destructive manner and in three dimensions. High resolution computed tomography has been used to confirm the scenario modelled. A sample was tested and observed in-situ at the European Synchrotron Research Facilities, ESRF, Grenoble. All fibre breaks arising in the vicinity of the final rupture of a unidirectional composite have been detected and the formation of clusters can be observed