Development of a multi-scale methodology for composite structural modelling and validation of modelling procedure by mechanical testing - Final Report

Objectives of the work are to develop a multiscale methodology for composite structural modelling and to validate the modelling procedure by mechanical testing. In the field of the computational material science the multiscale methodology plays an important role. It is based on the hierarchical concept which recognises that there is a strong interconnection between phenomena which happen to different scales of length and time. In the field of the composite material the approach consists in the description of the ply by knowing the behaviour of the constituents, i.e. fibre and matrix. In this work was developed a constitutive model for a balanced plain weave fabric. This model, starting from geometrical parameters and mechanical parameters of the single constituents (fibre and matrix), determines the effective moduli of the representative unit cell (RUC). This model was implemented into a general purpose finite element program ABAQUS, building a specific user subroutine. The last part of this job was to determine a material failure mechanism theory for the balanced plain weave architecture that was implemented in the same specific user subroutine. The prediction of the failure at each increment of the load was obtained by using a quadratic failure criterion, applied to the strains with stiffness and strength reduction scheme to account for damage within the yarns. This standard user subroutine is an augmentation for any commercial finite element code giving the possibility to deal with any composite material made with balanced plain weave fabric, knowing the mechanical properties of the single constituents and the specific failure mechanism.