Effect of heterogeneous interphase on the mechanical properties of unidirectional fiber composites studied by FFT-based method

Based on representative volume element (RVE) with interphase region between fiber and matrix, the microscopic mechanical behavior of transversely randomly distributed unidirectional (UD) carbon fiber reinforced polymer composites is studied by using fast Fourier transforms (FFT) simulation. The change of mechanical properties across interphase region can be described by an exponential function. By using FFT method, the effect of fiber volume fraction and interphase properties distribution on the effective material properties and the damage development mechanism of the composites are investigated. The effect of heterogeneous behaviors of carbon fiber with core/shell like behavior and interphase is also discussed. Compared to the traditional finite element model with zero-thickness interface, the stress-strain results obtained by the present computational approach are in good agreement with experimental data. This study can be helpful for interface design and manufacturing of fiber reinforced composites.