Title: Towards micro-mechanic improved design of granular composites

Abstract

In composites, macro properties depend on micro-level morphology such as grains and matrix. Advances in 3D printing, combined with strain measurements by Digital-Image-Correlation (DIC) systems, offer manufacturing “tailor-made” morphologies and measuring the strain fields of entire regions. Analytical tools have been developed, such as Functional-Perturbation-Method (FPM) to account for micro-morphologies and their effect on the macro-level properties. For strength predictions, one can use the FPM and Green’s Functions (GF) to obtain deformation fields as a functional of the heterogenous moduli. Specifically, the heterogeneous strain fields can be approximated using FPM by developing the displacement fields as a Fréchet series about the average homogenous modulus: (0.1) 2D eroded Voronoi morphologies were 3D printed as specimens using PolyJetTM technology. The heterogenous moduli field of each specimen was processed into FPM performed with a GF for the case of a uniaxial tensile load. The 2D generalization of [3] for the first two terms of the Fréchet series for the displacements in yields: (0.2) Experiments revealed that local material morphology has significant impact on marco-level strength. The strain fields calculated by the FPM and GF were compared to ones obtained from DIC in the uniaxial tension tests, as seen in [Fig.1]. “Hotspots” locations were found to be identical to the ones observed experimentally with one of them being the actual fracture initiation location.