FLEXURAL AND AXIAL COMPRESSIVE FAILURES OF THREE-DIMENSIONALLY BRAIDED COMPOSITE I-BEAMS.

Three-dimensionally braided composite I-beams have been loaded in four-point flexure and under axial compression. Linear stress/strain behavior up to the point of initial failure was observed in the flexure tests. Both tests provided consistent data for compressive moduli as well as good resolution for the characterization of damage initiation and propagation. The absence of delamination observed in the three material/geometry combinations for the composite I-beams compared with conventional laminated composites demonstrated the inherent through-the-thickness reinforcement of the three-dimensionally braided composites.