MULTISCALE MODELLING OF COMPOSITES WITH DIRECT FE2

Abstract

Compared to traditional multiscale modelling approaches, Direct FE2 stands out for its ease of implementation and computational efficiency. As such, this thesis seeks to further improve the computational efficiency of Direct FE2 and apply it to efficiently model composite structures. Firstly, a Direct FE2 framework based on the shear-flexible Timoshenko-Ehrenfest beam element is developed. Such a framework would allow composite beam structures to be modelled efficiently and can be readily extended to a corresponding Mindlin-Reissner plate. Next, the framework is modified based on layerwise theories to allow the accurate and efficient modelling of sandwich structures, another commonly used composite. Finally, a simple and efficient adaptive framework is developed for Direct FE2. By selectively including RVEs only in regions of nonlinearity, the computational cost of multiscale modelling can be reduced significantly, allowing large heterogeneous structures to be modelled efficiently.