Micro failure analysis of fiber metal laminates

In the failure analysis of composite materials, the damage of fiber and matrix is always noticed rather than the debonding of interface which is responsible for transferring the load between matrix and fiber. The stress amplification factors of fiber, matrix, and interface were extracted by establishing representative volume element model with interface and the strength of corresponding constituent is calculated in our work. Micro mechanics of failure served as the initial failure criterion of material components, and user-material subroutine (UMAT) was applied to realize progressive damage analysis of fiber metal laminate (FML) under different loading angles. The analysis results show that it is not strictly correct to directly use the stress on the matrix to calculate interface stress, and the damage trend of interface is consistent with that of fiber. The strain hardening phenomenon of FML decreases with larger loading angle, and the mechanical response of FML is about 45° symmetric due to its structure symmetry. The simulation results are in good agreement with the experiment results.