Modeling of random bimodal structures of composites (application to solid propellants): II. Estimation of effective elastic moduli

TL;DR

This paper develops a method to estimate the effective elastic properties of heterogeneous solid propellants with bimodal spherical inclusions, accounting for interactions and size effects, which are crucial for understanding failure mechanisms.

Contribution

It introduces the multiparticle effective field method (MEFM) for accurately modeling elastic moduli considering inclusion interactions and size distribution in bimodal composite structures.

Findings

Effective elastic moduli are sensitive to inclusion size and distribution.

Larger particles exhibit higher stress concentration factors.

The method captures the influence of multimodal inclusions on composite behavior.

Abstract

We consider a linearly elastic composite medium, which consists of a homogeneous matrix containing a statistically homogeneous set of multimodal spherical inclusions modeling the morphology of heterogeneous solid propellants (HSP). Estimates of effective elastic moduli are performed using the multiparticle effective field method (MEFM) directly taking into account the interaction of different inclusions. Because of this, the effective elastic moduli of the HSP evaluated by the MEFM are sensitive to both the relative size of the inclusions (i.e., their multimodal nature) and the RDFs estimated from experimental data, as well as from the ensembles generated by the method proposed. Moreover, the detected increased stress concentrator factors at the larger particles in comparison with smaller particles in bimodal structures is critical for any nonlinear localized phenomena such as onset of yielding, failure initiation, and damage accumulation.