Tensile strength of titanium matrix composites: Direct numerical simulations and analytic models

A recently-developed model for the numerical simulation of tensile stress-strain behavior in fiber-reinforced composites is used to predict the tensile strength of a metal matrix composite consisting of a Ti-1100 matrix reinforced with SCS-6 SiC fibers. Data on the as-processed fiber strengths, interfacial strength, composite size, and fiber volume fraction From Gundel and Wawner are used as input. The predicted strengths agree very well with the sample-specific values measured by Gundel and Wawner, demonstrating the accuracy of the computational model. The effects of free surfaces ina thin ply lay-up geometry are simulated as well, and show a small and surprising increased tensile strength. A modified Batdorf-type analytic model is developed which yields predictions similar to the simulated strengths for the Ti-1100 materials. The ideas and predictions of the Batdorf-type model, which is essentially an approximation to the simulation model, are then compared in more detail to the simulation-based model to more generally assess the accuracy of the Batdorf model in predicting tensile strength and notch strength vs composite size and fiber Weibull modulus. The study shows the Batdorf model to be accurate for tensile strength at high Weibull moduli and to capture general trends well, but it is not quantitatively accurate over the full range of material parameters encountered in various fiber composite systems. (C) 1998 Elsevier Science Ltd. All rights reserved