Computational implementation and experimental validation of a micro-mechanics informed progressive damage Strain Invariant Failure Theory

The current paper deals with the failure modelling in continuously reinforced composite structures taking into account the material's inherent microstructure. The implementation of a constitutive model for transversely isotropic damage in fibre reinforced composites is presented. Damage initiation in the orthotropic linear elastically modelled composite is governed by the Strain Invariant Failure Theory (SIFT), utilising the first strain invariant and the second deviatoric strain invariant for damage initiation. To phenomenologically account for the material's microstructure, the homogenised macro strain is related to the micro strain by means of strain amplification factors determined from prior simulations of Repeating Unit Cells (RUCs) with different fibre arrangements utilising Periodic Boundary Conditions (PBCs). For validation of the numerically implemented model, experimental tests of composite laminates with varying layups are performed. The conducted experiments are simulated utilising the implemented models and the obtained results are validated with the experimental data.