Property Modeling across Transition Temperatures in PMC's: Part III. Bending Fatigue

Parts I 1] and II 2] of the present paper introduced systematic models for the computation of thermal effects on strength and stiffness of unidirectional polymer matrix composites (PMC's) as well as the life prediction of these materials in end-loaded bending at elevated temperatures. The last step of this study was the possibility of introducing such models in durability codes such as MRLife 3]. A recent method was developed for the experimental characterization of end-loaded bending fatigue behavior of composites at elevated temperatures. The literature dealing with the durability of composite materials in bending focuses mainly on 3 and 4 point bending 4–6]. A limited set of data as well as the basis for theoretical modeling for fatigue end-loaded bending is available in the literature 7]. However, the life prediction scheme required elevated temperature experiments. New experiments in fatigue bending were performed in order to complete the available data. Microscopic observations revealed new information for the understanding of the damage process of unidirectional AS4/PPS composites in end-loaded fatigue bending. Finally, the models developed in Parts I and II were integrated into the MRLife integral enabling the life prediction of unidirectional PMC's under combined mechanical and thermal loads from room temperature experimental data.