A unified level set based methodology for fast generation of complex microstructural multi-phase RVEs

In the frame of the multi-scale computational analysis of complex materials, the generation of Representative Volume Elements (RVE) is often a crucial step. Various microstructure generation tools may be used, depending on the material to be considered, such as Discrete Element Methods (DEM), Random Sequential Addition (RSA) based methods for particulate media requiring important computation times; or Voronoï tessellation methods for polycrystalline materials. Besides being material specific, some of these methods may become unaffordable when considering complex microstructures, large inclusions numbers or high volume fractions. The present contribution presents a unified level set based methodology for complex, periodic (or not) and random RVE generations. The presented methodology allows RVE generation for particulate granular media, polycrystalline aggregates with large size distribution and arbitrary shapes, as well as for complex three-phase or poly-phase microstructures. A level set controlled Random Sequential Addition algorithm is used for particle distribution generation, allowing increasing the RSA algorithm efficiency, generating large and dense populations of arbitrary shaped inclusions with precise control on neighboring distances. Starting from this, several methods are presented to add specific realistic features to the generated RVEs. Modifications and densifications allow the distribution pattern to fit observed real samples or to present a specific spatial organization. The addition of one (or more) phase(s) obtained from the growth of the initial inclusions allows reproducing some typical microstructural patterns such as grain bridging in clayey soils, interfacial transition zones in concrete or hydrated gel in cement paste. The versatility of the proposed RVE generation method is illustrated by means of various examples, reproducing realistic microstructural arrangements of clayey soils, irregular masonry and polycrystalline aggregates with bimodal size distributions.