Transverse mechanical behaviour of fiber reinforced composites — FE modelling with embedded cell models

Abstract

The composite limit flow stress for transverse loading of metal matrix composites reinforced with aligned continuous fibers is investigated by recently developed embedded cell models in conjunction with the finite element method. A circular fiber is surrounded by a metal matrix, which is again embedded in the composite material with the mechanical behaviour to be determined iteratively in a self-consistent manner. Stress-strain curves obtained by using the embedded cell model are compared with those of the corresponding Al/46 vol% B composite with random 2D fiber packing. The comparison shows good agreement between experiment and simulation. Systematic studies of the stress-strain curves with the embedded cell model for a circular fiber surrounded by a square, circular, elliptical or rectangular shaped metal matrix result in almost the same composite limit flow stress. Furthermore, these random 2D fiber arrangements are compared with regular 2D fiber arrangements. It is found that the strength of composites with randomly arranged fibers cannot be described by modelling regular fiber arrangements. The composite limit flow stress calculated from embedded cell models lies between that of the hexagonal arrangement and the square arrangement of fibers loaded transversely. Finally, a model is derived for describing composite strengthening for regular and random fiber arrangements in dependence of matrix hardening and fiber volume fraction.