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2019 Research Highlight: Modeling the Transition to Granular Phase and Subsequent Granular Flow in High Comminuted Ceramics

Modeling the Transition to Granular Phase and Subsequent Granular Flow in High Comminuted Ceramics

CMEDE Researchers
Professor Lori Graham-Brady
Johns Hopkins University
Professor Ryan Hurley
Johns Hopkins University
Dr. Andrew Tonge
CCDC Army Research Laboratory
Dr. Joel Clemmer
Johns Hopkins University
Professor KT Ramesh
Johns Hopkins University
Professor Mark Robbins
Johns Hopkins University
Mr. Alex (Xiangyu) Sun
Johns Hopkins University
Dr. Qinglei Zeng
Johns Hopkins University

Under impact loading, highly comminuted ceramics transition to a granular phase and undergo granular flow. Characterizing the post peak strength transition to rapid fragmentation and subsequent granular flow is difficult to capture experimentally. Our current work attempts to address the competitive crack coalescence leading to fragmentation and uses a continuum breakage mechanics model for the subsequent mobility of fragments and tracking the evolving fragment size distribution.

Crack size statistics obtained at each instant from flaw size statistics using a wing crack growth-based damage model has been used to model three dimensional elliptical cracks. Using different nearest crack models, crack coalescence has been addressed, enabling prediction of fragment size/shape distributions using a connected region-based algorithm. This model also provides insights regarding the criterion for transition from damaged solid to granular medium. The predicted fragment statistics serve as an input to a breakage mechanics-based continuum granular flow model. A micro-mechanics based damage model, the granular transition model, and breakage mechanics model all form the framework of the Ceramics CMRG’s integrative model (built on the Tonge-Ramesh constitutive code), which helps understand the dynamic response of brittle ceramics including evolving fragmentation and post peak softening response.