A micromechanical sub-modelling technique for implementing Onset Theory

A multi-scale modelling approach is described for implementation of the micromechanics-based Onset Theory for laminated composites. Micromechanical sub-models derived from a laminate shell or layered solid finite element model enable direct de-homogenised strain fields to be investigated without the need of strain enhancement factors. These strain fields allow for a prediction and visualisation of the onset of damage within both fibre and matrix phases as well as type of deformation (dilatational or distortional). The new approach is applied to the analyses required to define critical invariants for a material system with glassy polymer and a material system with a rubber toughened resin.