DAMAGE EVOLUTION IN Ti-SiC UNIDIRECTIONAL FIBER COMPOSITES

摘要

Fiber fractures in metal-matrix composites often initiate damage zones that grow until therncomposite fails. To better understand the evolution of such damage from a micromechanics pointrnof view, a model Ti-matrix/SiC-fiber composite was studied for the first time. Using high energyrnX-rays and a small sampling volume, the damage zone around a broken fiber was investigated.rnThe growth of this zone was monitored in situ under applied tensile stress by measuring thernresponses of the fibers and the matrix. The diffraction data was compared to a modified shear lagrnmodel, which considers the elastic response of the matrix and the fibers. A comparison of thernmodel and data shows a correlation on the trend of the data, while the nature of the damage regionrnincurs discrepancies. Results indicate a need for further refinement of the model, revealing thernnecessity of incorporating such factors as residual stress in the system and plasticity in the matrix.