DEM simulation of anisotropic granular materials: elastic and inelastic behavior
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ORIGINAL PAPER
DEM simulation of anisotropic granular materials: elastic and inelastic behavior Giuseppina Recchia1 · Vanessa Magnanimo2 · Hongyang Cheng2 · Luigi La Ragione1 Received: 31 July 2019 © The Author(s) 2020
Abstract In this work, Discrete Elements Method simulations are carried out to investigate the effective stiffness of an assembly of frictional, elastic spheres under anisotropic loading. Strain probes, following both forward and backward paths, are performed at several anisotropic levels and the corresponding stress is measured. For very small strain perturbations, we retrieve the linear elastic regime where the same response is measured when incremental loading and unloading are applied. Differently, for a greater magnitude of the incremental strain a different stress is measured, depending on the direction of the perturbation. In the case of unloading probes, the behavior stays elastic until non-linearity is reached.Under forward perturbations, the aggregate shows an intermediate inelastic stiffness, in which the main contribution comes from the normal contact forces. That is, when forward incremental probes are applied the behavior of anisotropic aggregates is an incremental frictionless behavior. In this regime we show that contacts roll or slide so the incremental tangential contact forces are zero. Keywords Granular materials · Micromechanics · Discrete Element Method · Effective moduli
1 Introduction Granular media are complex systems widely present in civil engineering in the form of soils or granulates, in industry including chemical synthesis, food production, thermal insulation, additive manufacturing and other application consisting of granular beds. Understanding the mechanical response of granular materials is important to elucidate fundamental aspects of the behavior of these particulate systems [1, 2]. To this end, numerical simulations, laboratory experiments and theoretical models have been employed. In particular, an interesting activity regards the theoretical analysis, * Giuseppina Recchia [email protected] Vanessa Magnanimo [email protected] Hongyang Cheng [email protected] Luigi La Ragione [email protected] 1
Politecnico di Bari, Via Edoardo Orabona, 4, Bari 70126, BA, Italy
MSM, TFE, Mesa+, University of Twente, Enschede, P.O.Box 217, 7500, AE, Netherlands
2
developed in order to establish predictive models that should reproduce what seen in numerical simulations and/or laboratory experiments. There are models based upon a phenomenological approach and other based on micro-mechanics. The latter are more favorable when compared with Discrete Element Method (DEM) simulations [3] because it is possible to test not only the macroscopic response of the aggregate but also local features that characterize particle interactions. In this paper, we focus on a numerical analysis for a granular aggregate, referring to theoretical models already available in literature. In fact, it is not our goal to develop a new theory but to provide new insights
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