Breakage Model Research Articles

Accelerating charge estimation in molecular dynamics simulations using physics-informed neural networks: corrosion applications

Molecular Dynamics (MD) simulations are used to understand the effects of corrosion on metallic materials in salt brine. Reactive force fields in classical MD enable accurate modeling of bond formation and breakage in the aqueous medium and at the metal-electrolyte interface, while also facilitating dynamic partial charge equilibration. However, MD simulations are computationally intensive and unsuitable for modeling the long time scales characteristic of corrosive phenomena. To address this, we develop reduced-order machine learning models that provide accurate and efficient predictions of charge density in corrosive environments. Specifically, we use Long Short-Term Memory (LSTM) networks to forecast charge density evolution based on atomic environments represented by Smooth Overlap of Atomic Positions (SOAP) descriptors. A physics-informed loss function enforces charge neutrality and electronegativity equivalence. The atomic charges predicted by the deep learning model trained on this work were obtained two orders of magnitude faster than those from molecular dynamics (MD) simulations, with an error of less than 3% compared to the MD-obtained charges, even in extrapolative scenarios, while adhering to physical constraints. This demonstrates the excellent accuracy, computational efficiency, and validity of the developed model. Lastly, even though developed for corrosion, these protocols are formulated in a phenomenon-agnostic manner, allowing application to various variable-charge interatomic potentials and related fields.

Analytical modeling of energy-based matrix crack growth and fiber breakage in unidirectional ceramic matrix composites under static tensile behavior in the longitudinal direction

An analytical model was developed to characterize the material behavior of ceramic matrix composites (CMCs). The model incorporates energy-based matrix crack growth, accounting for thermal residual and debonding stresses. Matrix crack growth was analyzed using the Monte Carlo method to represent the random nature of crack growth, which considers the distribution of defects within the material. Additionally, a periodic matrix crack growth model was examined. The results from the model, enhanced with correction factors, showed strong agreement with those obtained from Monte Carlo simulations. Furthermore, the global load sharing (GLS) model that includes the probability of matrix cracks propagating into the fibers was proposed and integrated with the periodic matrix crack growth model. This combined model accurately expressed the stress–strain and crack density–stress relationships up to the point of fiber breakage. The study also examined the propagation of matrix cracks into the fibers in relation to debonding stress and energy, leading to the successful validation of the proposed model.

Effects of Thickness of the Corn Seed Coat on the Strength of Processed Biological Materials.

The strength and energy of processed biological materials depend, among others, on their properties. Despite the numerous studies available, the relationship between the internal structure of corn grains and their mechanical properties has not yet been explained. Hence, the aim of the work is to explore the relationship between the internal composition of maize kernels and its mechanical properties by studying the impact of the maize seed coat thickness on its breakage susceptibility. To achieve the assumed goal, selected physical properties (length, width, and thickness) of corn grains were distinguished, and a static compression test was carried out on the Insight 50 kN testing machine (MTS Systems Corporation, Eden Prairie, MN, USA) with a test system for experimental verification of the compression behavior of biological materials. Furthermore, after the compression test, the thickness of the seed coat was measured using a laboratory microscope. It was found that there is a correlation between the thickness of the maize seed coat and force, deformation, and mass-specific energy at the bioyield point. The presented data constitute a foundation for the development of a mechanistic breakage model considering the variable strength properties of the seed coat and endosperm as the structural elements of kernels. Further research should be focused on the determination of the strength properties under dynamic conditions and revealing the relationship between the loading rate, strength properties, and internal structure for several maize varieties, which better reflect the ranges of variability in the real nature of mechanical processing.

Mechanical characteristics of roll crushing of ore materials based on discrete element method

The application of high-pressure grinding rolls (HPGR) for ore crushing is considered to be one of the effective ways to save energy and reduce emissions in the ore processing industry. The crushing effect is directly determined by the forces of ore material during roll crushing. However, the mechanical state of ore material in roll crushing and the effect of roll structure, process parameters, feed particle size, on the force during the crushing of ore material needs to be expanded. Therefore, this paper intends to use the discrete element method to study the mechanical characteristics of roll crushing of ore materials. Firstly, the iron ore breakage model parameters are calibrated according to compression and impact crushing tests. Then, considering different roll structures, process parameters, and feed particle sizes of high-pressure grinding rolls, a simulation of the industry high-pressure grinding roll crushing process is developed. The particle velocity is innovatively used to study the force of particles in different regions of the compression zone. Considering the force and wear of ore particles, rollers, and cheek plates, the breakage process of HPGR is analyzed comprehensively. The results show that the material in the roll-crushing process is mainly subject to the normal force. The forces on particles at different locations in the compression zone are related to average velocity. To improve the crushing effect of HPGR, the crushing process of the ore should be combined with the wear of the roller and cheek plates. The vulnerable zone between the roller and cheek plates is indicated, and the extrusion pressure of the roller is slightly lower than the shear force between the particles.

Mechanism and Evolution Model of Particle Breakage of Construction Waste Recycled Aggregates: Implications for a Permeable Base

Mechanism and Evolution Model of Particle Breakage of Construction Waste Recycled Aggregates: Implications for a Permeable Base

Effects of aggregate crushing and strain rate on fracture in compressive concrete with a DEM-based breakage model

This study looked at how breakable aggregates affected the mesoscopic dynamic behavior of concrete in the uniaxial compression condition. In-depth dynamic two-dimensional (2D) studies were conducted to examine the impact of aggregate crushing and strain rate on concrete’s dynamic strength and fracture patterns. Using a DEM-based breakage model, concrete was simulated as a four-phase material consisting of aggregate, mortar, ITZs, and macropores. The concrete mesostructure was obtained from laboratory micro-CT tests. Collections of spherical particles were used to imitate aggregate breakage of different sizes and shapes by enabling intra-granular fracturing between them. The mortar was described in terms of unbreakable spheres with different diameters. Compared to the mortar, the aggregate strength was always stronger. A qualitative consistency was achieved between the DEM results and the available experimental data. Concrete’s dynamic compressive strength rose significantly with strain rate and just somewhat with aggregate strength. The fracture process was impacted considerably by aggregate crushing and strain rate. The number of broken contacts grew with an increase in strain rate and a decrease in aggregate strength.

Simulating breakage by compression of iron ore pellets using the discrete breakage model

Simulating breakage by compression of iron ore pellets using the discrete breakage model

DEM simulation of an impact crusher using the fast-cutting breakage model

DEM simulation of an impact crusher using the fast-cutting breakage model

Critical length prediction for fiber breaking in injection molded of long-fiber reinforced thin-walled products

Fiber length is one of the vital factors in determining the properties of long fiber reinforced thermoplastics (LFRT). However, many factors may generate fiber breakage in the injection molding process of LFRT, such as friction, melt shear, injection rate, etc. Especially for thin-walled products, owing to the relatively narrow mold cavity and frozen layer near the mold wall, it’s usually difficult for the fibers to move freely with the melt, leading to fiber breakage under the shear stress of the flow field eventually. In such a situation, the existing buckling breakage model based on the assumption fibers immersed in the flow field being in an unconstrained state is no longer applicable. In this paper, a new model for calculating the critical length of constrained fiber in thin-walled injection molded products is developed. A typical long glass fiber reinforced polypropylene thin-walled product was employed to verify the reliability of the model. The high-precision fiber length analyzer was used to calculate the fiber length distribution at different distances from the injection port. At the same time, the length distribution at the corresponding position was predicted via the model. The average prediction accuracy in the three sampling sections is 87.8%, 91.4% and 83.6%, respectively. The results show that the proposed model can effectively predict the fiber length distribution of injection molded thin-walled products. This conclusion provides important support for further accurate calculation of the mechanical properties of products.

Real Case Study of 600 m3 Bubble Column Fermentations: Spatially Resolved Simulations Unveil Optimization Potentials for l-Phenylalanine Production With Escherichia coli.

Large-scale fermentations (»100 m³) often encounter concentration gradients which may significantly affect microbial activities and production performance. Reliably investigating such scenarios in silico would allow to optimize bioproduction. But related simulations are very rare in particular for large bubble columns. Here, we pioneer the spatially resolved investigation of a 600 m³ bubble column operating for Escherichia coli based l-phenylalanine fed-batch production. Microbial kinetics are derived from experimental data. Advanced Euler-Lagrange (EL) computational fluid dynamics (CFD) simulations are applied to track individual bubble dynamics that result from a recently developed bubble breakage model. Thereon, the complex nonlinear characteristics of hydrodynamics, mass transfer, and microbial activities are simulated for large scale and compared with real data. As a key characteristic, zones for upriser, downcomer, and circulation cells were identified that dominate mixing and mass transfer. This results in complex gradients of glucose, dissolved oxygen, and microbial rates dividing the bioreactor into sections. Consequently, alternate feed designs are evaluated splitting real feed rates in two feeds at different locations. The opposite reversed installation of feed spots and spargers improved the product synthesis by 6.24% while alternate scenarios increased the growth rate by 11.05%. The results demonstrate how sophisticated, spatially resolved simulations of hydrodynamics, mass transfer, and microbial kinetics help to optimize bioreactors in silico.

Fractal Analysis of Particle Size and Morphology in Single-Particle Breakage Based on 3D Images

The accurate modeling of single-particle breakage based on three-dimensional (3D) images is crucial for understanding the particle-level mechanics of granular materials. This study aims to propose a systematic framework incorporating single-particle breakage experiments and numerical simulations based on a novel 3D particle reconstruction technique for fractal analysis of particle size and morphology in single-particle breakage. First, the vision foundation model is used to generate accurate particles from 3D images. The numerical approach is validated by simulating the single-particle breakage test with multiple Fujian sand particles. Then, the breakage processes of reconstructed sand particles under axial compression are numerically modeled. The relationship between 3D fractal dimensions and particle size, particle crushing strength, and morphology is meticulously investigated. Furthermore, the implications of these relationships on the particle breakage processes are thoroughly discussed, shedding light on the underlying mechanisms that govern particle breakage. The framework offers an effective way to investigate the breakage behavior of single sand particles, which will enhance understanding of the mechanism of the whole particle breakage process.

Human Mastication Analysis-A DEM Based Numerical Approach.

Mastication is an essential and preliminary step of the digestion process involving fragmentation and mixing of food. Controlled muscle movement of jaws with teeth executes crushing, leading towards fragmentation of food particles. Understanding various parameters involved with the process is essential to solve any biomedical complication in the area of interest. However, exploring and analyzing such process flow through an experimental route is challenging and inefficient. Computational techniques such as discrete element numerical modeling can effectively address such problems. The current work employs the Discrete Element Method (DEM) as a numerical modeling technique to simulate the human mastication process. Tavares and Ab-T10 breakage models coupled with Gaudin Schumann and Incomplete Beta fragment distribution models have been implemented to analyze the fragmental distribution of food particles. The effect of particle shape (spherical, polyhedron, and faceted cylinder), size (aspect ratio), and orientation (vertical and horizontal) on breakage and fragment distribution is analyzed. To account for the elastic-plastic behavior and moisture content in food particles, modifications has been made in breakage models by incorporating numerical softening factor and adhesion force. The study demonstrates how numerical modeling techniques can be utilized to analyze the mastication process involving multiple process parameters.

Modelling breakage of steelmaking materials for simulation of mechanical degradation during handling

Modelling breakage of steelmaking materials for simulation of mechanical degradation during handling

A stepped vibrating screening device with a crushing function based on the difference in tuber-soil aggregate breakage behaviour

A stepped vibrating screening device with a crushing function based on the difference in tuber-soil aggregate breakage behaviour

Breakage Patterns of High-Level Thick Weakly Cemented Overburden for Coal Safe and Sustainable Mining

The breakage of massive thick weakly cemented rock layer is likely to cause strong mine earthquakes, which threatens the safe and sustainable production of the mine. In order to reveal the breakage law of high-level giant-thickness weakly cemented overburden rock and prevent the occurrence of mine earthquakes, we took the 2201 and 2202 working faces of Yingpanhao Coal Mine as the research object, established the mechanical calculation model of breakage of the high-level giant-thickness weakly cemented overburden, and used the methods of medium-thickness plate and short-beam function to solve the breakage law of high-level giant-thickness weakly cemented overburden rock. The findings indicate that during initial mining operations of high-level giant-thickness weakly cemented overburden rock, the applied force remains well below its bearing capacity. This condition ensures the stability of the overburden, effectively suppressing energy release events and minimizing surface subsidence. However, as mining progresses and approaches its operational limits, the overburden experiences both tensile and shear failures. This results in substantial increases in surface subsidence and the occurrence of frequent high-energy events. Finally, the model is verified against the surface-measured data and microseismic data of Yingpanhao Coal Mine, which proves the reliability of the model. The research results have important practical significance for mine earthquake prevention and safe and sustainable mining in similar geological conditions.

New critical state constitutive model considering particle breakage implicitly for uncemented carbonate sands

One of the main problems of carbonate sands is the fragile nature of particles and their susceptibility to breakage. Carbonate sands are affected by volumetric strain even at low stress levels, which is not the case with silicate sands. By defining a simple breakage model, the current study develops an elastoplastic critical state constitutive model that considers the impact of particle breakage on the mechanical behavior of carbonate sands. The particle breakage model depends on mean effective stress and critical breakage stress, which is assumed to correspond with the precompression pressure of soil in the oedometer test. In the proposed model, critical state line movement with the breakage parameter (α) considers the particle breakage effect. Based on the unified clay and sand model (CASM), a novel dynamic yield surface with a shape parameter affected by particle breaking has been created. Certain modifications are made to the modified Cam-Clay stress dilatancy to predict the behavior of carbonate sand. The current model has only ten parameters that simulate the carbonate sands’ behavior even at high-stress levels without any breakage test. Experimental data with different soil densities, loading stress paths, and stress levels were compared with the model, and the results demonstrated satisfactory conformance.

Discrete Element Modeling of the Breakage of Single Polyhedral Particles in the Rotary Offset Crusher

Innovation in comminution is expected to continue unabated to address the inefficiencies that are inherent in comminution circuits. The rotary offset crusher (ROC) is a new comminution device with a promising performance potential in terms of throughput due to the enhanced speed of transportation induced by the centrifugal force of the discs. However, the processes driving the comminution of particles trapped in the conical space between the two discs of the crusher are not fully understood. To gain a better insight into the comminution process in this device, discrete element modeling (DEM) simulations were conducted to study the breakage of a single particle for the crusher operated under two different dynamic conditions, i.e., (1) a stationary top disc and (2) both discs rotating at the same speed. For both scenarios, the speed of the discs was varied between 550 and 2350 rpm. Experimental testwork was also conducted with the laboratory prototype to generate the data that were used to calibrate the breakage parameters of the Ab × t10 breakage model. Simulations were performed using polyhedral UG2 ore particles that were generated with the in-built particle generator in the DEM simulator. The simulated ROC, which is operated with both discs rotating, outperformed the ROC with a stationary top disc in terms of the specific input energy and throughput. The crusher with a stationary top disc is characterized by high shear forces (suggesting a higher wear rate), specific input energies greater than 1 kWh/t, and low throughputs (<50 kg/h). The ROC operated with a stationary disc is not recommended for hard rock applications due to expected excessive wear of crushing surfaces and higher energy consumption. The freewheeling discs are recommended, but there is scope to optimize the crusher performance in terms of the power draw, size reduction, and throughput by manipulating the difference between the speeds of the discs. There is also scope to optimize the crusher performance when it is simulated with many particles. Once the full performance potential of the ROC is established, it will then be important to benchmark it against the existing crushers in the minerals industry as well as other industries where crushers are used.

Simulation of rice grain breakage process based on Tavares UFRJ model

Simulation of rice grain breakage process based on Tavares UFRJ model

Exploring the Regimes of Particle Behavior upon Impact via the Discrete Element Method.

Discrete element method simulations are conducted to probe the various regimes of post-impact behavior of particles with solid surfaces. The impacting particles are described as spherical agglomerates consisting of smaller constituent (or primary) particles held together via surface adhesion. Under the influence of a wide range of impact velocities and particle surface energies, five distinct behavioral regimes-rebounding, vibration, fragmentation, pancaking, and shattering-are identified, and force transmission patterns are linked to post-impact behavior. In the rebounding regime, the coefficient of restitution decreases linearly as impact velocity increases and the particle agglomerate experiences compaction. In the fragmentation regime, rebound velocity generally decreases with increasing fragment size. The rebound velocity of fragments decreases with time except for the smallest fragments, which can increase in velocity due to collisions with other fragments of high velocity. Particle breakage in the pancaking regime does not follow common mechanistic models of breakage.

Stochastic model for migration and breakage of detrital and authigenic fines

Mobilisation of attached particles during flow in rocks occurs in geo-energy processes. Particle mobilisation, their migration through rocks and pore plugging yield significant decline in permeability and well injectivity and productivity. While much is currently known about the underlying mechanisms governing the detachment of detrital particles against attracting electrostatic forces, a critical gap exists in the theoretical understanding of detachment by breakage of widely spread authigenic particles, which naturally grow on rock grains during geological times. Previous works derived micro-scale mechanical equilibrium equations for both detrital and authigenic particles, and the upscaling procedure from particle to pore and core scales for detrital fines. In this paper, for the first time we derive a stochastic model for migration and breakage of authigenic fines and authigenic–detrital mixtures. This allows for core-scale transport modelling based on the particle-scale torque balance. We introduce a novel framework for predictive stochastic detachment modelling by particle–rock bond breakage that integrates the beam theory of elastic particle deformation, strength failure criteria and viscous flow around the attached particle. The analytical expressions for stress maxima and stress diagrams for a single particle allow determining the critical failure stresses, breakage points of the beam and breakage flow velocity. The mathematical model describing lab coreflood includes the maximum retention function for both authigenic and detrital fines. The matching laboratory coreflood data under increasing velocity at micro- and core-scales achieved high matching of the experimental data by the model. High matching validates the upscaling and downscaling procedures derived.