Multiscale modeling of continuous crushing of granular media: the role of grain microstructure
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Multiscale modeling of continuous crushing of granular media: the role of grain microstructure Fan Zhu1
· Jidong Zhao1
Received: 20 November 2019 / Revised: 24 June 2020 / Accepted: 26 August 2020 © OWZ 2020
Abstract Natural granular materials such as sands often possess complex microstructural features including cleavage and minerals interfaces. Those features bring apparent mechanical anisotropy to particles and are known to have pronounced influence on particle crushing characteristics. This paper presents a multiscale simulation of continuous crushing of granular sand under onedimensional compression in consideration of particle-scale anisotropy through modeling planes of weakness inside individual particles, with reference to granular materials rich in minerals and containing cleavages. The multiscale modeling is based on a coupled peridynamics and non-smooth contact dynamics method where peridynamics is used to model crushing of individual particles and non-smooth contact dynamics is employed to simulate discrete granular system. Weak microstructural planes are simulated by breaking a fraction of peridynamic bonds as an initial condition. Simulation results show that anisotropic particles containing weak planes result in larger number of fragments and exhibit relatively higher fractal dimension with respect to particle size. Particle shape is found to approach a steady state profile with continuous crushing. Anisotropic particles generally bear smaller sphericity, aspect ratio, elongation and flatness than those isotropic particles. The anisotropy in particles seems to mitigate shape effect on particle strength and crushing energy. Macromechanical yield stress of the sample is related to single particle strength monotonically, but the relationship appears to be nonlinear when different microstructural features are involved. Keywords Weak plane · Particle crushing · Particle shape · Strength · Multiscale modeling
1 Introduction Particle crushing is a fundamental physical process underlying many macromechanical behaviors of granular materials. It has great relevance to many fields including geotechnical, mining, pharmaceutical and chemical industries where crushable granular materials are routinely handled. Large efforts have been devoted to developing advanced numerical tools for realistic simulation of particle crushing and understanding the underlying physics. Particle crushing in granular media by its nature involves complex, multiscale physics. On a mesoscale or representative elementary volume scale, the material can be characterized as a discrete granular system, whereas on particle scale, the material is
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Fan Zhu [email protected] Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong, SAR, China
usually of continuum nature where various microstructural features may be present and affect fracturing process. Granular materials, and particularly natural sands and rocks, often possess complex microstructural features such as cleavage a
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