Effect of fiber spatial arrangement on the transverse strength of titanium matrix composites

The transverse strength of titanium matrix composites (Ti-6Al-4V-SiC) with rectangular and hexagonal fiber arrangements was measured as a function of fiber volume fraction and cladding thickness. A net-section model was also developed to predict the strength as a function of fiber spatial arrangement. The model predictions are in good agreement with experimental results and recent finite element modeling (FEM) simulations. The data and model show that the transverse strength, for a fixed net fiber volume fraction, is strongly dependent on the cladding thickness, testing direction, and fiber spatial arrangement. The implications are particularly important for the design of rotating components such as rings or disks. For example, the transverse strength in the radial and axial directions can be tailored by using a rectangular fiber array and varying the cell aspect ratio. Another simple strategy for increasing the transverse strength, for an equivalent net fiber volume fraction, is to increase the cladding thickness. For some fiber arrangements, a locally high volume fraction composite surrounded by a thick cladding can be significantly stronger than a composite with a uniform fiber distribution.