Microstructure generation of long fiber reinforced hybrid composites using the fused sequential addition and migration method

We present a fused sequential addition and migration (fSAM) algorithm to generate synthetic microstructures for long fiber reinforced hybrid composites. To incorporate the bending of long fibers, we model the fibers as polygonal chains and use an optimization framework to search for a non-overlapping fiber configuration with the desired properties. As microstructures of hybrid composites consist of materials with varying characteristics, e.g., different fiber orientation distributions or fiber volume fractions, the unit cell needs to be divided in subcells. Then, the objective function is required to account for the characteristics of the subcells individually. To ensure that the location of a fiber is restricted to its respective subcell, we apply box constraints during the optimization procedure. Depending on the materials and the manufacturing processes, the interfaces within hybrid composites show either strict separation or interlocking of the different materials. Hence, we enable selecting the box-constraint type to model the interface according to the desired composite. We provide a detailed discussion of the extensions of the original fSAM algorithm to generate hybrid composites, considering two alternative procedures to handle the box constraints during the optimization procedure. ... mehrAs the selection of the box-constraint type influences the synthetic microstructures, we investigate the shape of the interfacial areas and the computed effective stiffnesses. Last but not least, to validate the capability of the fSAM algorithm to generate representative microstructures, we compare the resulting mechanical behavior with experimental data.