Comparison of the μ(I) and HBP models for simulating granular media

2018 ◽  
Vol 29 (07) ◽  
pp. 1850050 ◽  
Author(s):  
Mehran Kheirkhahan ◽  
Khosrow Hosseini
Keyword(s):  
Friction Coefficient ◽  
Failure Mode ◽  
Granular Flow ◽  
Granular Media ◽  
State Equation ◽  
Dam Break ◽  
Harmonic Mean ◽  
Height Ratio ◽  
Viscoplastic Models ◽  
Applied Stresses

Application of Lagrangian meshless methods in modeling granular flow has been a major concern for researchers due to their particular nature. For modeling granular movement, it is assumed that the particles are continuous. The SPHysics code is developed for modeling the movement of Newtonian fluids in which the pressure is derived from the state equation. In this study, [Formula: see text] and Herschel–Bulkley–Papanastasiou (HBP) viscoplastic models are implemented in the SPHysics code to analyze the movement of grains induced by the applied stresses. In the first model, the movement of granular particles is based on the characteristics such as inertia and friction coefficient, and in the second model, the movement is related to the non-Newtonian viscoplastic behavior of fluids. The accuracy of the models is evaluated by simulating the experimental benchmarks for granular dam break. The effect of length-to-height ratio on the failure mode of dam break phenomenon is also investigated. The performance of the models is increased by introducing the gate removal speed and also the harmonic mean of the viscosity instead of the viscosity proper to each particle. This study shows that the models could capture the behavior of grains in the static and the dynamic parts of the mass body.

scholarly journals Thermo-mechanical behavior of a granular media in a rotating drum

2019 ◽  
Vol 20 (2) ◽  
pp. 203
Author(s):  
Soumia Teyar ◽  
Mathieu Renouf ◽  
Yves Berthier
Keyword(s):  
Free Surface ◽  
Velocity Field ◽  
Numerical Experiment ◽  
Granular Flow ◽  
Granular Media ◽  
Free Surface Flows ◽  
Rail Transport ◽  
Rotating Drum ◽  
Electrical Behavior ◽  
Surface Flows

In the complex granular flow, the shear and flow of particles lead to increase in temperature that can enchain behavioral modifications. However, their thermo-mechanical and electrical behavior is of great interest for applications such as rail transport, grinding, and granular material reproduction systems. To study these behaviors, a numerical experiment is carried out on a rotating drum model. This device makes it possible to generate continuous and controlled free surface flows. Relying on the NSCD approach, the location of the hottest zone and the evolution of the temperature are correlated with the evolution of the velocity field.

Material Instability in Rapid Granular Shear Flow

2000 ◽  
Vol 627 ◽  
Author(s):  
J. D. Goddard
Keyword(s):  
Shear Flow ◽  
Granular Flow ◽  
Granular Media ◽  
Constitutive Models ◽  
Theoretical Work ◽  
Temperature Fields ◽  
Viscous Liquids ◽  
Material Instability ◽  
Recent Theoretical Work ◽  
Gas Kinetic Theory

ABSTRACTThis is a survey of recent theoretical work on shear flow instabilities of dry granular media in the Bagnold or “grain-inertia” régime. Attention is devoted to steady homogeneous unbounded simple shear, with the goal of identifying material (constitutive) instabilities arising from the coupling of stress to granular concentration and temperature fields. Such instabilities, the dissipative analogs of thermodynamic phase transitions, are familiar in numerous branches of the mechanics of materials.The current interest is motivated in part by the “dissipative clustering” found in various particle-dynamics (“DEM”) simulations of granular systems. Since particle clustering may invalidate standard gas kinetic theory, it is pertinent to ask whether hydrodynamic models based on such theories may themselves exhibit clustering instability.The present article is based largely on a recent review (Goddard and Alam 1999), which provides a unified linear-stability treatment for rapid granular flow, as well for slow flow of mobile particles immersed in viscous liquids. The analysis is based on a “short-memory” response of various fluxes to perturbations on steady uniform states, a feature characteristic of the most popular constitutive models for granular flow. In the absence of gravity, previous theoretical analyses reveal transverse “layering” and spanwise “corrugations” as possible forms of material instability (Alam and Nott 1998)Based on current theoretical findings, further work is recommended, including the exploration of the effects of gravity and of stress relaxation, both of which are likely to be important in real granular flows.

Correlation of Barreling Effect with Boundary Friction Coefficient during Upsetting of Various Materials Workpieces under Processing Conditions

2020 ◽  
Vol 992 ◽  
pp. 751-756
Author(s):  
Volodymyr V. Kukhar ◽  
Eduard S. Klimov ◽  
S.M. Chernenko ◽  
E.Yu. Balalayeva
Keyword(s):  
Friction Coefficient ◽  
Boundary Surface ◽  
Functional Relation ◽  
Strain Range ◽  
Height Ratio ◽  
Qualitative And Quantitative ◽  
Linear Dimensions ◽  
Closed Die Forging ◽  
Structural Carbon ◽  
Structural Carbon Steel

The necessity of taking into account the barreling effect at the design of die cavities, and open die and closed die forging processes on the basis of pre-forming of billets by upsetting is shown. The division of ideas about the indices of “bulk” and “linear” barreling (barrel shape), which is determined by the ratio of the bulk and linear dimensions of the workpiece after upsetting by flat dies, was made. The functional relation (correlation) between these indices and the friction coefficient on the boundary surface between flat dies and the upsetted workpiece has been determined. The qualitative and quantitative effect of workpiece dimensions (diameter-to-height ratio), strain range, temperature (conditions of cold and hot processing) and type of forming material (structural carbon steel, some of Cu-grades and Al-grades) on the barreling effect and friction coefficient during upsetting was found. The developed method makes it possible to predict a change in the friction coefficient during the upsetting of various material workpiece under given conditions of forming and to monitor their effect to the final shape.

Analysis of Failure Mode and Ultimate Bearing Capacity of Steel Truss Coupling Beam

2012 ◽  
Vol 594-597 ◽  
pp. 824-827 ◽  
Author(s):  
Hu Qiang ◽  
Zhi Heng Deng ◽  
Lin Qian ◽  
Dong Xiao Xu
Keyword(s):  
Bearing Capacity ◽  
Failure Mode ◽  
Order Effect ◽  
Calculation Model ◽  
Ultimate Bearing Capacity ◽  
Coupling Beam ◽  
Ultimate Capacity ◽  
Height Ratio ◽  
Steel Truss ◽  
Reversed Loading

A calculation model about failure mode and ultimate bearing capacity of steel truss coupling beam is proposed based on compatible distortion and balance conditions, second-order effect, elastic-perfectly plasticity and strain state about eight specimens when these specimens fail under low cyclic reversed loading. And then this model is applied to analyzing influences of height, span and chord stiffness on bearing capacity of truss. Some valuable results are obtained such as advantageous range of span-to-height ratio and influence laws of chord stiffness on ultimate capacity.

Study on HVOF Sprayed Nickel Coated MoS2 Coatings

2012 ◽  
Vol 490-495 ◽  
pp. 3574-3577
Author(s):  
Bai Lin Zha ◽  
Xiao Jing Yuan ◽  
Li Jiang ◽  
Zhi Hong Zha
Keyword(s):  
Friction Coefficient ◽  
Abrasive Wear ◽  
Uniform Distribution ◽  
Failure Mode ◽  
Bonding Strength ◽  
Dry Friction ◽  
Tribological Performance ◽  
The Self ◽  
The Mean ◽  
Mos2 Coating

The self-lubricating coating which is dense in microstructure with low porosity and degradation is sprayed by HVOF and the spray powder is Nickel coated MoS2 with 22%wt of MoS2. The mean bonding strength and hardness of Ni-MoS2 coating is respectively about 13.68 MPa and HRB94.5. Tribological performance is evaluated by the test of dry friction coefficient, which fluctuates from 0.25 to 0.32, while the wear granule is symmetry with a uniform distribution in size, moreover, the experiment results indicate the main wear failure mode of coating is abrasive wear.

scholarly journals Continuum Modeling of Granular Media

2014 ◽  
Vol 66 (5) ◽  
Author(s):  
J. D. Goddard
Keyword(s):  
Granular Flow ◽  
Granular Media ◽  
Evolution Equations ◽  
Particle Migration ◽  
Internal Variables ◽  
Continuum Modeling ◽  
Material Instability ◽  
Rapid Flow ◽  
Internal Balance

This is a survey of the interesting phenomenology and the prominent regimes of granular flow, followed by a unified mathematical synthesis of continuum modeling. The unification is achieved by means of “parametric” viscoelasticity and hypoplasticity based on elastic and inelastic potentials. Fully nonlinear, anisotropic viscoelastoplastic models are achieved by expressing potentials as functions of the joint isotropic invariants of kinematic and structural tensors. These take on the role of evolutionary parameters or “internal variables,” whose evolution equations are derived from the internal balance of generalized forces. The resulting continuum models encompass most of the mechanical constitutive equations currently employed for granular media. Moreover, these models are readily modified to include Cosserat and other multipolar effects. Several outstanding questions are identified as to the contribution of parameter evolution to dissipation; the distinction between quasielastic and inelastic models of material instability; and the role of multipolar effects in material instability, dense rapid flow, and particle migration phenomena.

Modeling of Granular Flow and Combined Heat Transfer in Hoppers by the Discrete Element Method (DEM)

2005 ◽  
Vol 128 (3) ◽  
pp. 439-444 ◽  
Author(s):  
Harald Kruggel-Emden ◽  
Siegmar Wirtz ◽  
Erdem Simsek ◽  
Viktor Scherer
Keyword(s):  
Discrete Element Method ◽  
Heat Transport ◽  
Granular Flow ◽  
Granular Media ◽  
Element Model ◽  
Discrete Element ◽  
Waste Utilization ◽  
Discrete Element Modeling ◽  
Particle Assemblies ◽  
Element Method

The discrete element method can be used for modeling moving granular media in which heat and mass transport takes place. In this paper the concept of discrete element modeling with special emphasis on applicable force laws is introduced and the necessary equations for heat transport within particle assemblies are derived. Possible flow regimes in moving granular media are discussed. The developed discrete element model is applied to a new staged reforming process for biomass and waste utilization which employs a solid heat carrier. Results are presented for the flow regime and heat transport in substantial vessels of the process.

scholarly journals Effects of the size and friction coefficient of particles on a liquid-gas-particle mixture flow in dam break

AIP Advances ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 015208 ◽  
Author(s):  
Kyung Min Park ◽  
Min Il Kim ◽  
Hyun Sik Yoon
Keyword(s):  
Friction Coefficient ◽  
Dam Break ◽  
Mixture Flow ◽  
Particle Mixture

The Effect of Grain Size and Shape on Sliding Friction of Wet Granular Media

2020 ◽  
Vol 234 (1) ◽  
pp. 107-116 ◽  
Author(s):  
Mojgan Aliasgari ◽  
Nahid Maleki-Jirsaraei ◽  
Shahin Rouhani
Keyword(s):  
Grain Size ◽  
Friction Coefficient ◽  
Granular Media ◽  
Sliding Friction ◽  
Volume Fraction ◽  
Silicone Oil ◽  
Network Effect ◽  
Crossover Point ◽  
Interstitial Liquid ◽  
Capillary Bridges

AbstractThe wet granular material creates networks in which interstitial liquid provides capillary bridges needed to hold grains together. There is an optimal fraction of the interstitial liquid in which the bridges are formed and the friction coefficient is minimal. We found that the size of the grains affects the friction of wet granular media. Our observations demonstrates that the optimum volume fraction, in which the friction coefficient is minimized, increases with grain size, but for sand immersed in water, this minimum friction coefficient itself increases with size and for glass beads immersed in silicone oil it decreases, indicating that the shape of the grains also has an effect on this friction. It is also shown that there is a crossover point for grain size at which the network effect created by capillary bridges is dominated by wet granular media. This crossover point is found.

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