Micromechanical modeling of Ti/TiB composites: Effects of tib whisker orientational distribution on the overall properties

This paper is concerned with the effects of whisker orientation and particle aspect ratio on the overall elastic properties of a Ti/TiB composite for varying TiB volume content. To study this two methods are proposed. The first approach uses finite element based numerical homogenization of representative volume elements. Here, artificial composite microstructures are generated using developed algorithms for efficient packing of TiB whiskers. This process models whiskers prolate ellipses and ellipses permitting the creation of high-resolution microstructures with high packing fractions and particle counts efficiently using an event driven particle interaction model. This packing method includes prescribed orientational dependence through enforcement of an orientation distribution function. The second approach is micromechanics-based and includes rigorous variational and analytical bounds used to validate and compare to numerical models. Results of this study indicate that the effective composite elastic properties exhibit dependence on the orientation of the whiskers, with random distributions resulting in the lowest axial Young’s modulus and distribution functions approaching perfect alignment with the highest per volume fraction. Furthermore, this study indicates that whisker aspect ratios in the range of 1 to 15 have significant influence on the effective mechanical response of Ti/TiB composites with particles perfectly align along the loading axis. For ratios above 15 the effective properties tend to become asymptotic.