Structure-Property Relationship in Disordered Hyperuniform Materials: Microstructure Representation, Field Fluctuations and Effective Properties

Disordered hyperuniform (DHU) materials are an emerging class of exotic heterogeneous material systems characterized by a unique combination of disordered local structures and a hidden long-range order, which endow them with unusual physical properties. Here, we consider material systems possessing continuously varying local material properties $\mathcal{K}({\bf x})$ modeled via a random field. We devise quantitative microstructure representation of the material systems based on a class of analytical spectral density function ${\tilde \chi}_{_\mathcal{K}}({k})$ associated with $\mathcal{K}({\bf x})$, possessing a power-law small-$k$ scaling behavior ${\tilde \chi}_{_\mathcal{K}}({k}) \sim k^\alpha$. By controlling the exponent $\alpha$ and using a highly efficient forward generative model, we obtain realizations of a wide spectrum of distinct material microstructures spanning from hyperuniform ($\alpha>0$) to nonhyperuniform ($\alpha=0$) to antihyperuniform ($\alpha<0$) systems. We perform a comprehensive perturbation analysis to quantitatively connect the fluctuations of the local material property to the fluctuations of the resulting physical fields. In the weak-contrast limit, our first-order perturbation theory reveals that the physical fields associated with Class-I hyperuniform materials (characterized by $\alpha \ge 2$) are also hyperuniform, albeit with a lower hyperuniformity exponent ($\alpha-2$). As one moves away from this weak-contrast limit, the fluctuations of the physical field develop a diverging spectral density at the origin. We also establish an end-to-end mapping connecting the spectral density of the local material property to the overall effective conductivity of the material system via numerical homogenization.