HIGH-STRAIN RATE COMPRESSION OF FIBER COMPOSITES

A model is presented for the dynamic compressive behavior of fiber com posites under prescribed axial strain rate. The model includes the eff ects of fiber misalignment and material nonlinearity. A couple stress is used to take into account the fiber bending resistance. An examinat ion of the dynamic axial stress-strain relation shows that the model i s consistent with experimental results. For a given strain rate, the a xial stress goes through a maximum associated with microbuckling (i.e. the formation of kink bands). The dependence of this dynamic compress ive strength on strain rate is also consistent with experiments. Final ly, the model is used to predict the kink band width as a function of the strain rate; at high axial strain rates, the kink band width is ab out one-half that for quasi-static loading. (C) 1997 Elsevier Science Ltd.