Assessment of load transfer characteristics of a fiber-reinforced titanium-matrix composite

Abstract

The extent of stress transfer that occurs around broken fibers dictates the longitudinal strength as well as the reliability of the fiber-reinforced composites. The governing load transfer characteristics of a ~32-vol% SiC fiber reinforced Ti-6Al-4V matrix composite (TMC) were investigated by recourse to uniaxial tension and 4-point bend flexure tests. Measured strengths and the variability in them are compared with the predictions of different load sharing models. The experimental tensile stress-strain response indicates to localization in fiber failure and the local load sharing (LLS) model predicts the composite strength more closely than a global load sharing (GLS) model. The flexure strengths are significantly larger than those predicted using the analytical models but are similar to that obtained using simulations that incorporate stress gradients and LLS. Broader distribution in flexure strength is also in agreement with simulation results, indicating that the LLS governs the strength of the TMCs. Implications of this observation are discussed. The TMCs are compared and contrasted with the Al-matrix composites in terms of their strength variability and size-scaling.