Breakage Conditions Research Articles

Investigating the Influence of Medium Size and Ratio on Grinding Characteristics

This study explores the effect of steel ball size and proportion on mineral grinding characteristics using Discrete Element Method (DEM) simulations. Based on batch grinding kinetics, this paper analyzes the contact behavior during grinding, discussing particle breakage conditions and critical breakage energy. The results indicate that while increasing the size of the steel balls leads to higher collision energy, the collision probability decreases significantly; the opposite is true for smaller steel balls. Simulation results with different ball size combinations show that increasing the proportion of smaller balls does not significantly change the collision energy but greatly increases the collision probability, providing a basis for optimizing ball size distribution to improve grinding performance. Furthermore, appropriately increasing the proportion of smaller balls can reduce fluctuations in grinding energy consumption, thereby enhancing collision energy and collision probability while reducing energy costs. Liner wear results demonstrate that larger ball sizes increase liner wear, but different ball size combinations can effectively distribute the forces on the liner, reducing wear.

Global Dynamic Responses and Progressive Failure of Submerged Floating Tunnel Under Cable Breakage Conditions

Global Dynamic Responses and Progressive Failure of Submerged Floating Tunnel Under Cable Breakage Conditions

Rock fines breakage by flow-induced stresses against drag: geo-energy applications

The paper presents a strength-failure mechanism for colloidal detachment by breakage and permeability decline in reservoir rocks. The current theory for permeability decline due to colloidal detachment, including microscale mobilisation mechanisms, mathematical and laboratory modelling, and upscaling to natural reservoirs, is developed only for detrital particles with detachment that occurs against electrostatic attraction. We establish a theory for detachment of widely spread authigenic particles due to breakage of the particle-rock bonds, by integrating beam theory of particle deformation, failure criteria, and creeping flow. Explicit expressions for stress maxima in the beam yield a graphical technique to determine the failure regime. The core-scale model for fines detachment by breakage has a form of maximum retention concentration of the fines, expressing rock capacity to produce breakable fines. This closes the governing system for authigenic fines transport in rocks. Matching of the lab coreflood data by the analytical model for 1D flow exhibits two-population particle behaviour, attributed to simultaneous detachment and migration of authigenic and detrital fines. High agreement between the laboratory and modelling data for 16 corefloods validates the theory. The work is concluded by geo-energy applications to (i) clay breakage in geological faults, (ii) typical reservoir conditions for kaolinite breakage, (iii) well productivity damage due to authigenic fines migration, and (iv) feasibility of fines breakage in various geo-energy extraction technologies.

Numerical Analysis of Dynamic Response in Large Caissons during Wet-towing after Cable Breakage

Variable and complex marine environmental loads combined with wave resistance and the insufficient controllability of large caisson structures pose serious challenges during maritime towing. Cable breakage events are common, and improper behaviors could give rise to a variety of accidents. This work explored the dynamic responses of large caisson structures following towing cable breakage under irregular waves combined with harsh currents. Two types of cable breakage, i.e., main bridle and towing bridle breakage, were taken into account. Four potential wave–current combinations were assumed for each situation according to direction. The obtained results show that drag rope breakage could give rise to lateral shifts in the structure, which can become a serious condition when exposed to angled waves. Additionally, following breakage, significant force fluctuations took place in the remaining intact cables. For main cable breakage, both lateral and backward displacements were observed in the structure, which gradually entered a ‘flowing with the wave’ state. Furthermore, under the two abovementioned cable breakage conditions, the structure air gap consistently exceeded 2.3 m, ignoring the possibility of a wave slamming event.

Extraction of cadmium from aqueous solutions by emulsion liquid membrane (ELM) using three different carriers dissolved in a 70:30 ratio of sunflower oil to kerosene

This study explores the use of novel green emulation liquid membranes (GELMs) for the simultaneous extraction and stripping of Cd (II) from aqueous solutions. A solute is transported through the membrane due to the presence of the carrier and then concentrated in the internal phase. Soybean, sunflower, corn, and canola oils were used to form green substitutes to petroleum-based organic diluents for use as GELMs. Bis-(2-ethylhexyl) phosphate (D2EHPA), tri-butyl- phosphate (TBP), and trioctylamine (TOA) were the extractants, span 80 was the emulsifier, and HCl or H2SO4 was used as the stripping agent. The best conditions for maximum extraction efficiency (98.68%), stripping efficiency (97.14%), and lowest membrane breakage (0.9%) were achieved using a mixture of sunflower oil and kerosene in the ratio of 70:30. The other optimum values of the variables were: 2% (v/v) Span 80, 10 min emulsification time, 12700 rpm emulsification speed, 400 rpm of agitation speed, 5% (v/v) D2EHPA, an external phase pH was 3.5, an internal phase of 0.25 M HCl, and 5:1 of the treat ratio (external phase to emulsion) at 10 min contact time. The synthesized membrane was reused eight times, with approximately the same efficiency and no significant breakage during the first seven cycles.

Fault diagnosis method of dissolved oxygen sensor electrolyte loss based on impedance measurement

Dissolved oxygen affects the growth and survival of aquatic organisms and considers as an important indicator of aquaculture water quality. Moreover, the electrochemical dissolved oxygen sensor may become faulty due to flow shock or damage by organisms which destroys the dissolved oxygen permeable membrane and results in loss of electrolytes. In this paper, a method was developed for detecting electrolyte loss faults in polarographic dissolved oxygen sensors by directly measuring impedance of sensing electrodes without additional sensing elements or modifying the sensor. First, the factors interfering electrolyte concentration-impedance relationship and the requirement for temperature compensation was determined. Secondly, a fault diagnosis of internal electrolyte loss was achieved by using the difference between the theoretically calculated value and the impedance measurement value in combination with the electrode reaction law. Finally, the impedance detection method was demonstrated using artificially simulated faults. The results showed that the developed method had accurate tracking of electrolyte consumption with a Pearson coefficient of 0.987. Three different levels of breakage failures were simulated and detected as 4.48 %, 21.07 % and 73.47 %, respectively. The mean absolute error of the normal state was about 1.67, which increased to 16.3 after a period of failure. The developed method meets the requirements of embedded development because it uses a simple fault detection device and easy data processing using a simple microprocessor. Furthermore, the diagnosis result has been demonstrated as an indicator of membrane health and breakage conditions of dissolved oxygen sensors.

Analysis of the Influence of Downhole Drill String Vibration on Wellbore Stability

Most studies related to aspects of wellbore stability, such as wellbore breakage, block dropping, and wellbore expansion, revolve around the physicochemical interaction between drilling fluid and surrounding rock, but relevant studies show that drill string vibration during drilling also has a crucial and even decisive influence on wellbore stability. In order to thoroughly explore the influence mechanism of drill string vibration on wellbore stability, our research group established a finite element flexible simulation model of drill string dynamics and used a storage downhole vibration measurement device to collect downhole real drilling vibration data to verify the correctness of the simulation model. Then, based on the critical conditions of wellbore breakage, a wellbore stability evaluation method was established, and the wellbore stability under different drilling parameters and drilling tool combination conditions was evaluated and analyzed. The research results play an important role in revealing the influence mechanism of drill string vibration on wellbore stability and can provide theoretical guidance for engineering problems such as wellbore instability risk assessment.

Effect of bottom unlatch and top breakage mooring lines on the dynamic behavior of a semisubmersible platform system

Mooring disconnections occur frequently in a floating production system (FPS), probably resulting in the instability of structures or even offshore accidents. Therefore, this paper investigates the influence of mooring disconnections on the response of a SEMI system under regular waves and irregular waves. Two failure modes were performed and compared according to the disconnected positions of mooring lines: the top breakage and bottom unlatch. A numerical model of a fully coupled hull/mooring/riser system was established through a self-developed program to obtain the detailed behavior of each component. The results indicated that the platform motion became a 4-period nonlinear response containing a super-harmonic motion when three moorings unlatched. The disconnected moorings produced a large deformation due to the sliding of anchor points. The riser tension exhibited robustness under mooring failure because of its low tension level and the robustness of platform heave. Compared with bottom unlatch conditions, the platform under top breakage conditions showed a larger-amplitude fluctuation and a slightly farther offset particularly three moorings all disconnected. The total mooring force under top breakage conditions would lose more fairlead tension at the failure time, thus inducing a lower mooring force for the platform.

Cell wall fracture mechanism in ultrasonic-assisted cutting of honeycomb materials

Revealing the ultrasonic cutting mechanism of honeycomb composite is important for determining the acoustic parameters of the ultrasonic system and selecting the parameters of the cutting process. Understanding more details of the stress on the cell wall from ultrasonic vibrating tool and the conditions for cell wall breakage is essential to study the machining mechanism. According to the evolution of contact state between the straight edge cutter and the honeycomb cell wall in a cycle, the cutting force acting on the cell wall is divided into three stages: transverse cutting load action, longitudinal cutting load action, and no cutting load action. The cell wall deflection and stress equations under transverse cutting load were established by applying elastic thin plate small deflection theory. The deformation and fracture characteristics of the honeycomb cell wall were analyzed by combining the analytical and the finite element model. The results showed that the ultrasonic vibration of the cutter greatly improved the stiffening effect of the cell wall and its fracture was caused by the deflection under the transverse cutting load, which exceeded the maximum allowable deformation after local stiffening. In addition, with only longitudinal cutting load, it was difficult to break the critical buckling state that leads to cell wall fracture.

Calculation of the Height of the Water-Conducting Fracture Zone Based on the Analysis of Critical Fracturing of Overlying Strata

Accurate division of the water-conducting fracturing zone (WCFZ) in the mining overburden serves as an important basis to evaluate the stability of coal mining under water bodies. Research on the WCFZ is conducive to controlling surface subsidence and realizing safe coal mining under water. Traditionally, the WCFZ is generally determined by field observation (liquid leakage method, borehole television, etc.) or empirical formula. Although these methods boast high accuracy, they are time-consuming and laborious and have some problems such as weak pertinence and a large value range. In this study, a mechanical model under the critical breakage condition of hard and soft strata was established on the basis of the specific geological and mining information of a mine. Besides, the stability condition for the broken strata to form the “masonry beam” structure and the deflection-based bending deformation formula of hard and soft strata were deduced, and the method of calculating the height of WCFZ based on the analysis of critical fracturing of soft and hard strata (hereafter referred to as the CFSHS-based height calculation method) was proposed. Furthermore, with reference to the results of specific engineering tests, the height of the WCFZ in the working face 15,101 of coal mine XJ was analyzed by means of theoretical analysis, numerical simulation and engineering verification, which verifies the rationality and practicability of the CFSHS-based height calculation method.

Investigation of Deep Shaft-Surrounding Rock Support Technology Based on a Post-Peak Strain-Softening Model of Rock Mass

To control the large deformation that occurs in deep shaft-surrounding rock, the post-peak strain-softening characteristics of deep jointed rock mass are discussed in detail. An equivalent post-peak strain-softening model of jointed rock mass is established based on continuum theory and the geological strength index surrounding rock grading system, and numerical simulations are performed using FLAC3D software. The convergence-constraint method is used to analyze the rock support structure interaction mechanism. A composiste support technique is proposed in combination with actual field breakage conditions. During the initial support stage, high-strength anchors are used to release the rock stress, and high-stiffness secondary support is provided by well rings and poured concrete. This support technology is applied in the accessory well of a coal mine in Niaoshan, Heilongjiang, China. The stability of the surrounding rock support structure is calculated and analyzed by comparing the ideal elastic-plastic model and equivalent jointed rock mass strain-softening model. The results show that a support structure designed based on the ideal elastic-plastic model cannot meet the stability requirements of the surrounding rock and that radial deformation of the surrounding rock reaches 300 mm. The support structure designed based on the equivalent joint strain-softening model has a convergence rate of surrounding rock deformation of less than 1 mm/d after 35 days of application. The surrounding rock deformation is finally controlled at 140 mm, indicating successful application of the support technology.

Study on pre-damage diagnosis and analysis of adhesively bonded smart PZT sensors using EMI technique

The electro-mechanical impedance technique (EMI) is one of the best methods for continuous structural health monitoring (SHM) by embedding a smart piezoelectric ceramic Lead Zirconate Titanate (PZT) sensor or pasting it over the surface of the structure. The smart PZT transducer is intensely affected by the adhesive bonding condition between the PZT patch and the host structure. The current paper studies the damage-diagnosis process of the coupled electro-mechanical behavior of an adhesively bonded smart PZT transducer. The inverse of impedance signatures is used for investigating pre-damage diagnosis and analysis of surface-mounted PZT transducer. A parametric study on the variation of adhesive property is carried out to overcome the shear lag effect. The novel contribution of this paper discusses a methodology for an early diagnosis of damage in the PZT transducer and adhesive bond layer during the SHM process. Firstly, the damage is introduced to the PZT patch and bonding layer, and the corresponding EMI signatures are obtained using numerical modeling and simulations. The damage detection using susceptance is discussed for lower frequencies from 0 to 20 kHz. It is observed that the change in susceptance signature is not large enough to detect adhesive debonding. Subsequently, the conductance signatures are utilized for the investigation. It is observed that damage in the adhesive layer and PZT patch cause upward or downward shift with no alteration along the horizontal direction. It helps to detect sensor breakage and adhesive debonding effectively. Secondly, the simulation results are verified using the theoretical analysis for the single piezo configuration by improved continuum-based impedance equations. A modified dual piezo configuration is investigated to validate the proposed method. Experimental investigation on PZT-bonded aluminum plate involving perfectly bonded, adhesive debonding, and sensor breakage conditions are conducted to verify the process. It is found that the real part of the admittance signature is reliable and critical in sensor diagnosis, and sensor faults of debonding and breakage can be identified and differentiated. It also validates the semi-analytical work results. Therefore, the proposed methodology for pre-diagnosing damage present in the smart PZT sensor and adhesive layer using the EMI technique can be utilized for effective SHM.

Effect of hydrodynamic breakage on floc evolution and turbidity reduction in flocculation and sedimentation processes

Abstract Coagulation and sedimentation process is one of the most popular processes in drinking water treatment. Hydrodynamic breakage has a significant impact on the evolution of floc characteristics and the efficiency of turbidity removal. In this work, the effects of hydrodynamic breakage on floc size, fractal dimension, and floc morphology were investigated with an in-situ recognition system. The experiments were conducted in a continuous flocculation and sedimentation reactor equipped with perforated plates to provide different hydrodynamic breakage conditions. The experimental results indicated that the hydrodynamic conditions significantly influenced the floc destabilization and restructuring processes. A low hydrodynamic shear force provided by P1 led to the increase of both bigger sized flocs but accompanied with small particles (0–10 μm). Excessive velocity gradient provided by P3 produced smaller and looser flocs. An appropriate velocity gradient (i.e., the flow velocity through the perforated plate P2 at 18.9 × 10−3m s−1) was conducive for the formation of larger and more compact structures, with higher average floc size and fractal dimension. This flocculation condition in turn resulted in effective improvements in the turbidity removal efficiency. Floc evolution models were described based on the mechanism of the breakage and restructuring process.

Stability of A-Jack concrete block armors protecting the riverbeds

Flip buckets are among one of the most common types of energy dissipaters, especially for dams. The scouring phenomenon occurs when falling jets hit the river bed, and A-Jack concrete block armors can be used as an effective way to control such a phenomenon. The main purpose of this study is to investigate the stability of sediment particles using A-Jack concrete block armors. In this regard, the general form of the incipient motion and incipient failure of A-Jack armor were extracted based on dimensional analysis and particle stability analysis. In these analyses, the dimensionless parameter of stability number denoted by SN is a function of other variables. The results of different physical models for different hydraulic conditions and sediment sizes are evaluated. Variability of SN related to each variable is considered, and linear and non-linear models for prediction of breakage conditions of the A-Jack block are derived. Using the experimental results, several empirical relations were developed to predict the incipient motion and incipient failure for different protection alternatives under different conditions of A-Jack block. By defining the bed scour as a criterion for the stability of A-Jack block, a design relation was also proposed to determine the required block size. Other topics investigated and discussed in this paper include effects of size and type of A-jacks as well as criteria for a gravel filter.

Method for calculating a two-drum mine winder

In the Republic of Belarus, on the base of JSC “Soligorsk Institute for Resources Saving Problems with Pilot Production”, the development and launch of import-substituting mass production of large-capacity double-drum mine winders with an increased diameter of winding drums up to 7 meters were fulfilled. Earlier, in the post-Soviet space, machines with similar technical characteristics were not produced. Accordingly, for the implementation of the project, a comprehensive study of all the scientific and technical aspects of the creation of this equipment was required, taking into account the material and technical capabilities of the enterprises of domestic mining engineering. One of the important results of this study was the development of an improved methodology for calculating the basic elements of a winder. The technique allows calculating the strength parameters of the winding drums, shaft, disengagement mechanism, drive elements (mating clutch), bearings together with their anchor fasteners, reduced to normal operating conditions and to conditions of emergency wire breakage. The methodology includes the calculation of the stress-strain state of the elements of the winding drums using the finite element method and allows using the obtained numerical data to simulate the stress-strain state of the main components of the hoisting machine to calculate its safety factors in normal operation and in emergency conditions. The developed methodology was successfully tested in the design and technological center of JSC “Soligorsk Institute for Resources Saving Problems with Pilot Production” during the development of double-drum mine winders with large diameter winding drums for skip hoisting units of the Petrikov mining and processing complex, as well as during the modernization of existing hoisting units at working mines of JSC “Belaruskali”.

H induced decohesion of an Al grain boundary investigated with first principles: General conditions for instant breakage and local delayed fracture

The uniaxial tensile test response of a H decorated Σ5 [1 0 0] twist grain boundary (GB) in face-centred-cubic Al has been examined with first principles. The impurity shows a strong tendency to relocate during loading. To capture these H movements, the standard model framework was extended to probe loading-unloading hysteresis. Due to the strong monotonic decrease in the H formation energy with rising GB elongation, the maximum tensile stress accepted by the H decorated GB in the slow fracture limit generally is reached before breakage becomes thermodynamically favourable. For any intact GB configuration visited upon exceeding this stress, the assumption of global chemical equilibrium is argued to be violated. Moreover, while breakage remains ensured from the slow fracture limit considerations, it may in practice require the influx of H to the GB vicinity. A quantitative analysis of GB destabilisation in this scenario requires multi-scale modelling even in the slow fracture limit.

Experimental approaches for identifying the impact of enhanced flotation technology using hollow microspheres

Hollow microspheres should be characterized in terms of physicochemical aspects to understand the flotation effect principle. There have been insufficient studies on the effect of hollow microspheres in water treatment in terms of flotation. In this study, various analytical and experimental approaches were utilized to identify the flotation characteristics and understand the effect of hollow microspheres on flotation. These approaches included analytical methods such as particle count and zeta potential measurements, scanning electron microscopy-energy dispersive X-ray spectroscopy analysis, X-ray photoelectron spectroscopy, a floc breakage experiment, and a collision efficiency model. The hollow microspheres were spherical shape with an average size of 50 μm. The microspheres were identified to have a higher negative charge (−69.1 mV) than microbubbles (−51.1 and −30.5 mV). The binding energy of Si–O from the hollow microspheres showed the highest peak at 103.18 eV and 61,503.7 counts/s. Si–O binding structure and the molecular structure of the SixOx series were considered to be a structure in which Si32− is bonded to oxygen ion. The optimum floc breakage condition was determined to be 15 min. The number of particles increased because the average particle size is increased with the concentration of hollow microspheres injection. The turbulent flocculation (TF) model was confirmed to be consentient to the experimental data in comparison with the white-water bubble blanket (WWBB) model. As a result, the hollow microspheres had the characteristic of increasing floc size so that flocs can be floated easily.

Effect of particle breakage conditions on child particle aspect ratio

In particulate processes, the goal is often to control the particle size and aspect ratio distributions. One common unit operation is solution crystallization in agitated vessels, where a rotating impeller can break newly formed crystals. This study used sodium chloride crystals in three sets of laboratory scale experiments to investigate the effects of agitation rate, parent particle size, and solids concentration on crystal breakage. The first set used agitation rates of 1000, 1250, 1750, and 2000 rpm; the second set used average parent particle lengths of 569, 656, 3350, and 4690 μm; and the third set used solids concentrations of 1, 5, 7, and 10 g crystals/100 ml liquid. As expected, increasing the agitation rate produced a higher number fraction of particles smaller than 50 μm. The resulting child particle aspect ratios were primarily a function of the child particle size under the conditions studied.

Flaws and cracks stability in strengthened glass by residual stress

ABSTRACTStrengthened glass is widely used in structural glazing applications in the building and transportation sectors. Surface flaws and cracks are the main glass strength limiting factors. In this theoretical study both thermally (TSG) and chemically (CSG) strengthened glass are considered. A general approach is proposed, based on the calculation of the stress intensity factor (KI) resulting from the superposition of externally applied stresses, both mechanical and thermal, and residual stress introduced in the strengthening processes. In order to represent a severe design condition, an externally applied stress with a maximum tensile component of 50 MPa is introduced. The analysis is performed for soda‐lime glass for immediate breakage condition by comparing the stress intensity factor with the critical factor (KIC) and for time delayed breakage activated by subcritical crack growth by comparing the stress intensity factor with the corresponding threshold value (KIth). The classical parabolic residual stress distribution is employed for thermally strengthened glass while a new approach is proposed for the evaluation of the residual stress profile of chemically strengthened glass. A crack growth stability analysis based on the concept of apparent fracture toughness is performed. The residual stress profiles analysed for thermally and chemically strengthened glass are the typical ones resulting from common technological processes. The crack growth stability for the analysed stress profiles do not match the criteria to be defined as flaws insensitive.

Generalized loading-unloading contact laws for elasto-plastic spheres with bonding strength

We present generalized loading-unloading contact laws for elasto-plastic spheres with bonding strength. The proposed mechanistic contact laws are continuous at the onset of unloading by means of a regularization term, in the spirit of a cohesive zone model, that introduces a small and controllable error in the conditions for interparticle breakage. This continuity property is in sharp contrast with the behavior of standard mechanistic loading and unloading contact theories, which exhibit a discontinuity at the onset of unloading when particles form solid bridges during plastic deformation. The formulation depends on five material properties, namely two elastic properties (Young’s modulus and Poisson’s ratio), two plastic properties (a plastic stiffness and a power-law hardening exponent) and one fracture mechanics property (fracture toughness), and its predictions are in agreement with detailed finite-element simulations. The numerical robustness and efficiency of the proposed formulation are borne out by performing three-dimensional particle mechanics static calculations of microstructure evolution during the three most important steps of powder die-compaction, namely during compaction, unloading, and ejection. These simulations reveal the evolution, up to relative densities close to one, of microstructural features, process variables and compact mechanical attributes which are quantitatively similar to those experimentally observed and in remarkable agreement with the (semi-)empirical formulae reported in the literature.