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This work presents a
study of the influence on the macroscopic (homogenized) elastic properties of
polycrystalline materials induced by uncertainties in the material texture and
microstructure geometry. Since many microelectromechanical systems are made of
materials deposited as thin films with ⟨111⟩ fiber texture, we study the variance of
the homogenized elastic properties of the material around its nominal ⟨111⟩
texture. To perform this analysis, the perturbation stochastic finite element
method (PSFEM) is coupled to the mathematical theory of homogenization
leading to a second-order perturbation-based homogenization method. This
method is able to evaluate the mean and variance of a given homogenized
property as a function of the grain property uncertainty. The multiscale
formulation is implemented in a plane-stress linear elastic finite element framework
based on a multigrain periodic unit cell generated by Voronoi tessellation.
This perturbation-based homogenization method is verified against Monte
Carlo simulations, showing its effectiveness and limitations. Then, through
applications, it is evaluated how different levels of uncertainty in grains induce
uncertainty in the macroscopic elastic properties of the polycrystalline material.
In particular, the influence of the unit cell is studied. Finally, by coupling
the PSFEM with the Monte Carlo method, the effects on the macroscopic
properties of uncertainty of both the geometry and orientation of the grains is
estimated.
Keywords
perturbation stochastic finite element, homogenization,
Monte Carlo method, polycrystalline material