Hongyang Cheng

University of Twente | UT · Faculty of Engineering Technology (CTW)

The nonlinear history-dependent macroscopic behavior of granular materials is rooted in the micromechanics at contacts and irreversible rearrangements of the microstructure. The discrete element method (DEM) can predict the evolution of the microstructure using contact laws, but the micromechanical parameters are generally unknown because of the di...

Biot theory predicts wave velocities in a saturated granular medium using the pore geometry, viscosity, densities, and elastic moduli of the solid skeleton and pore fluid, neglecting the interaction between constituent particles and local flow, which becomes essential as the wavelength decreases. Here, a hydro‐micromechanical model, for direct nume...

The finite element method (FEM) is commonly used for modeling continuum media, while particle simulation methods like the so-called discrete element method (DEM) are used for discrete systems. Coupling the discrete (DEM) and continuum (FEM) methods is conventionally achieved through a direct mapping between discrete particles and finite elements. C...

Vegetated soil plays an essential role in confronting climate change. It is the host material where inorganic carbon is stored and green infrastructures are built. The expected impacts of climate change, such as extreme wetting-drying cycles, pose an urgent need to understand the interplay between soil deformation, root growth, and water/solute upt...

Bio-mediated methods, such as microbially induced carbonate precipitation, are promising techniques for soil stabilisation. However, uncertainty about the spatial distribution of the minerals formed and the mechanical improvements impedes bio-mediated methods from being translated widely into practice. To bolster confidence in bio-treatment, non-de...

The hydro-mechanical properties of the vadose zone are strongly influenced by seasonal cycles. The hydraulic behavior of this zone is determined by the coupling of biotic and abiotic factors. The biotic factors are controlled by the physiology and anatomy of the vegetation growing in the area, while the abiotic factors depend on the local soil char...

Laser sintering is a widely used process for producing complex shapes from particulate materials. However, understanding the complex interaction between the laser and particles is a challenge. This investigation provides new insights into the sintering process by simulating the laser source and the neck growth of particle pairs. First, a multi-phys...

This research exploits biomimicry to engineer innovative solutions for soil exploration and tunnelling in complex environments where soil burrowing is the main challenge. Drawing inspiration from the effective burrowing mechanisms of earthworms, we focused on the development of a untethered bio-inspired earthworm- like robot that faithfully replica...

Granular materials exist in various sizes and shapes and are often subject to complex motions, ranging from quasi-static to free-flowing. Predicting the bulk behavior of granular materials is difficult because of the randomness in their microstructure and particle-scale properties. Although advanced laboratory testing is making observations of part...

The original version of this article is a preface and no graphical abstract included, but during uploading files to ftp server, a mistake figures-ams2022-903-Graphical Abstract been added. The graphical snap is deleted as below.

The interaction between granular materials and deformable structures is relevant to many industries, such as mining, construction, and powder processing. Surface coupling between the discrete (DEM) and the finite element method (FEM) is commonly used to numerically describe particle-continuum interactions. Using a recently developed “surface-coupli...

Granular matter is the second most handled materials after water in global industry. Their macroscopic behavior arises from the collisional to collective motion of grains at varying lengths and time scales. The fluid-like and solid-like behavior of granular materials and their transitions [8] are relevant to many industrial problems, such mining ex...

The finite element method (FEM) is commonly used for modeling continuum media, while particle simulation methods like the so-called discrete element method (DEM) are used for discrete systems. Coupling the discrete (DEM) and continuum (FEM) methods is conventionally achieved through a direct mapping between discrete particles and finite elements. C...

Calibration of Discrete Element Method (DEM) parameters is essential for modeling geotechnical applications. This task can, however, be extremely tedious or sometimes even impossible to undertake. This is largely due to two issues namely: (1) a large sample size of DEM simulations and number of sampling iterations are necessary to accurately infer...

The spatial configuration is a significant contributing factor to dry granular materials' shear strength and dilative properties. This paper studies the effects of the particle size distribution (PSD) and the initial void ratio of a meso-structure through the drained triaxial compression using DEM. A novel multi-threaded two-level optimization is a...

The paper describes a novel methodology of designing granular phononic crystals for acoustic wave manipulations. A discrete element method is utilized to model the dynamics of a pulse wave propagating through the densely packed assembly of elastic spherical particles with an embedded phononic crystal — the region consisting of a certain arrangement...

The paper describes a novel methodology of designing granular phononic crystals for acoustic wave manipulations. A discrete element method is utilized to model the dynamics of a pulse wave propagating through the densely packed assembly of elastic spherical particles with an embedded phononic crystal - the region consisting of a certain arrangement...

This work presents an efficient probabilistic framework for the Bayesian calibration of micro-mechanical parameters for Discrete Element Method (DEM) modelling. Firstly, the superior behaviour of the iterative Bayesian filter over the sequential Monte Carlo filter for calibrating micro-mechanical parameters is shown. The linear contact model with r...

This work provides a novel discrete element method (DEM) framework for modelling the visco-elastic sintering kinetics in virgin and aged polymer powders. The coalescence of particle pairs, over long times, is described by a combined three-stage model of the sintering process, where each stage is dominated by a different driving force: adhesive cont...

Uncertainty exists in geomaterials at contact, microstructural, and continuum scales. To develop predictive, robust multi-scale models for geotechnical problems, the new challenge is to allow for the propagation of model/parameter uncertainty (conditioned on laboratory/field measurements) between micro and macro scales. We aim to first quantify the...

We investigate localization in granular material with the support of numerical simulations based upon DEM (Distinct Element Method). Localization is associated with a discontinuity in a component of the incremental strain over a plane surface through the condition of the determinant of the acoustic tensor to be zero. DEM simulations are carried out...

To prevent texture defects in powder-based processes, the sintering time needs to be adjusted such that a certain amount of coalescence is achieved. However, predicting the required sintering time is extremely challenging to assess in materials such as polymers because the kinetics exhibit both elastic and viscous characteristics when undergoing de...

Discrete Elements Method simulations are carried out to investigate waves propagation in isotropic, frictional granular media. The focus is on the effects of confining pressure, microstructure and input frequency on both wave velocity and attenuation. The latter is described via the seismic quality factor Q and three different measurement approache...

Poroelasticity theory predicts wave velocities in a saturated porous medium through a coupling between the bulk deformation of the solid skeleton and porous fluid flow. The challenge emerges below the characteristic wavelengths at which hydrodynamic interactions between grains and pore fluid become important. We investigate the pressure and volume...

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 pertu...

A series of high-pressure compression tests with various stress paths under monotonic and cyclic loadings were performed to examine the compression and particle crushing characteristics of silica sand in a dense state. Different stress paths were particularly designated to individually investigate the influences of mean and shear stress on particle...

Determining the pressure dependence of dynamic moduli in unconsolidated sediments is still an open problem in applied geophysics. This is because several petrophysical parameters affect the elastic response of the granular medium during compression. Effective medium theories based on the Hertz–Mindlin contact law estimate the effective moduli from...

We introduce the open-source package MercuryDPM, which we have been developing over the last few years. MercuryDPM is a code for discrete particle simulations. It simulates the motion of particles by applying forces and torques that stem either from external body forces, (gravity, magnetic fields, etc.) or particle interactions. The code has been d...

We focus on the main new developments underway in MercuryDPM. New features include deformable clusters (agglomerates), experimental coarse-graining, melting particles, particle-solid interactions, multi-resolution particle-fluid coupling, pressure-controlled Lees-Edwards boundaries, better hybrid openMP-MPI parallelisation, and more advanced STL/ST...

Elastic wave propagation provides a noninvasive way to examine polydisperse, frictional granular materials. The discrete element method (DEM) allows for a micromechanical interpretation of the acoustic response. Using experimentally measured granular microstructures as input, after straining them to various cyclic, oedometric compression states, we...

Biot's theory predicts the wave velocities of a saturated poroelastic granular medium from the elastic properties, density and geometry of its dry solid matrix and the pore fluid, neglecting the interaction between constituent particles and local flow. However, when the frequencies become high and the wavelengths comparable with particle size, the...

Elastic wave propagation provides a noninvasive way to probe granular materials. The discrete element method using particle configuration as input, allows a micromechanical interpretation on the acoustic response of a given granular system. This paper compares static and dynamic numerical probing methods, from which wave velocities are either deduc...

Probabilistic calibration of discrete element simulations using the sequential quasi-Monte Carlo filter

The calibration of discrete element method (DEM) simulations is typically accomplished in a trial-and-error manner. It generally lacks objectivity and is filled with uncertainties. To deal with these issues, the sequential quasi-Monte Carlo (SQMC) filter is employed as a novel approach to calibrating the DEM models of granular materials. Within the...

Due to the heterogeneity and anisotropy caused by geosynthetic inclusions, the design of geosynthetic-reinforced geostructures has been largely empirically-based. The presence of geosynthetic reinforcement complicates the stress history and fabric characteristics of the reinforced soil, posing an obstacle to the development of constitutive models f...

The calibration of DEM models is typically accomplished by trail and error. However, the procedure lacks of objectivity and has several uncertainties. To deal with these issues, the particle filter is employed as a novel approach to calibrate DEM models of granular soils. The posterior probability distribution of the microparameters that give numer...

Geosynthetic-reinforced soils are heterogeneous and discontinuous geomaterials that can be designed with great flexibility. For environmental and economic reasons, the application of geosynthetic reinforcements in the construction of infrastructures is becoming prevalent, along with the increase of the diversity in reinforcement forms, e.g., discre...

This paper numerically investigates the performance of geosynthetic-wrapped and -layered soil commonly used for constructing retaining structures by the discrete element method. First, the geotextile and the soil that make up the reinforced soil are calibrated with tensile, shear box, and triaxial test results. The discretization of two reinforced...

Geosynthetic is gaining attraction in civil engineering. Wrapping soils in geotextile bags (soilbag) as earth reinforcement gives astonishing rise in bearing capacity. To understand the fundamental mechanism and facilitate the development of soilbag’s constitutive relation, the authors develop and validate a computational model for studying the mic...

Geosynthetic Reinforced Soil (GRS) is widely used in infrastructure projects such as retaining wall and road/railway subgrade for technical and economical reasons. Despite of the worldwide usage, the basic mechanism of such reinforcement remains obscure, owing to its discontinuous and heterogeneous nature. Instead of being layered by planar geosynt...

Laboratory tests are conducted to preliminarily study the static and dynamic properties of frictional type and sliding type soil-bag layers. These include uniaxial compression, cyclic shear under various loading histories and shaking table test. The regular cyclic shear test results are used to determine the parameters of constitutive models for ea...