Extension of quasi-static damage meso-modelling of composite laminates to dynamic failure and erosion

Impact tests on structures are destructive, costly and difficult to analyze. This is particularly true for composite structures, whose properties and failure mechanisms are highly dependent on the chosen stacking architecture. As a result, virtual testing is of paramount importance for the design of composite structures subjected to impact ... but difficult. Because of the practical importance of laminated composites, and thanks to fifty or more years of intensive research, the response to static failure is now well understood. At the meso level, this involves microcracking, fiber breakage, delamination and their interaction. Since the damage mechanisms typical of laminated composites with continuous long fibers are the same in both static and dynamic conditions, we can hope to extend the static meso-modeling of laminated composites to the dynamic. Another aspect is that, in today's industrial environment, due to the lack of robustness of the local constitutive model, important numerical parameters such as mesh density are fixed in order to calibrate the model against a reference test. This process is tedious, and only allows the safe analysis of variations around well-controlled situations. The most widespread approach to overcoming the lack of consistency of the material model with regard to fracture is that of non-local spatial approaches, including phase-field approaches. In the case of composites, where numerous scales and mechanisms need to be addressed, these methods have yet to be developed and validated. We therefore tried another possibility, that of regularization using a time-dependent model, which is quite natural in dynamics. It appears that using a usual rate-dependent model is not sufficient to circumvent all the problems associated with spurious damage localization in the dynamics. This is why we have proposed and developed the concept bounded rate damage model. A consequence of the model is that a minimum critical time is required to completely damage the material. The coupling between time and space seems to prevent parasitic localization, at least in our experience to date. The presentation will cover these aspects, the basis for meso-modeling laminate damage and the limited damage rate model, as well as some applications and adaptations to dynamic delamination and damage, fracture and erosion of laminates subjected to high-speed impact.