Ultra-thin ply composite laminates are the product of a novel manufacturing technology that produces laminates with higher longitudinal compressive and in situ strengths, higher resistance to delamination events and higher laminate tensile and compressive strengths. However, failure mechanisms in this novel material-type are not completely understood up to now, neither are the most appropriate analysis methods to represent these mechanisms.
For instance, the choice of the constituent materials (reinforcing fibres and matrix) and ply size effects become particularly important due to ply thinness, which can be as low as 0.015 mm (i.e. 2-3 fibre diameters). On the other hand, macro-mechanical homogenization is much easier to achieve in ultra-thin ply laminates due to a finer ply dispersion; hence, their mechanical behaviour is suitably represented by a homogenized quasi-brittle material model at the coupon and subcomponent levels.
The aim of this project is to understand the failure mechanisms and fully exploit the load bearing capacities of ultra-thin ply laminates by means of the development of novel numerical techniques integrating FFM and PF approach of fracture in the most efficient way.
These modeling strategies will be set up at different scales of analysis. Micro-mechanical analysis will provide more comprehensive understanding with regard to the potential sources of damage (matrix breakage, fibre-matrix decohesion, delamination, among others), as well as the prospective propagation paths, and allow the study of constituent and ply size effects.
Additionally, macro-mechanical modeling strategies will be employed to predict the macroscopic response of ultra-thin ply coupons and structures. Special attention will be devoted to investigating geometrical effects and loading states in specimens with stress concentrations and holes, which are of relevant practical importance in the aeronautical and aerospace industries