Vibration Force Field Research Articles

Study on particle size and density segregation law in the separating process of poor quality coal with high gangue content under the action of composite force field

ABSTRACT Thin-seam mining frequently captures a significant proportion of gangue and interbedded coal in surface coal mines. Consequently, raw coal has a broad range of particle size distributions and a high percentage of components with intermediate densities, which are complex and challenging to separate. This study aims to determine the method of product division and the segregation law of particle size and density of raw coal during the separation process using a vibration and airflow composite force field. A difference in the particle size segregation of the coal particles was evident. Particle-size segregation primarily occurs in the separation area. Large-particle-size coal has a wide distribution range, spreading over the entire bed and fully utilizing the bed to achieve separation. The material becomes increasingly displaced into the separation area as its particle size decreases, thereby weakening the separation effect. Large coal particles can undergo density segregation in the vertical direction, with low-density material placed in the upper layer. This ensures that low-density material is incorporated into the refined coal product. Regardless of density, the coal tended to tilt more toward the bottom layer as the particle size decreased. This results in a poor density stratification effect with refined coal products mixed with gangue and an increase in the mismatch content. The extent of fine coal discharge was determined to be two-fifths of the entire length of the discharge side. This ensures that the majority of refined coal is recovered and that there is no excessive gangue mixing with the refined coal output. Achieving a 55.54% yield, refined coal lowers its ash content by 16%, increases its calorific value by 1400 kcal/kg, and effectively separates coal with a high gangue concentration.

Numerical Simulation and Experiment on Pill Coating of Red Clover Seeds under the Action of Vibrating Force Field

In order to solve the problem of the low qualification rate of the pilling and coating of small-grain forage seeds, a vibration force field is introduced to the traditional vertical disk coating machine to promote the mixing of materials and improve the qualification rate of the pilling. Using the typical small-grain forage seed red clover as an example, we used the vibration force field after adding seed powder particles to a coating pot for the theoretical analysis of the force situation, using the discrete element software EDEM to construct a red clover seed simulation model with the coefficient of discretization as the evaluation index. We studied the effects of the rotational speed of the coating pot, the vibration frequency of the pot, the amplitude of the vibration of the pot, and the other operating parameters of the pot on the uniformity of the seed powder mixing, with the pelletization of the pass rate as the physical evaluation standard, using a one-way test to study the effect of operating parameters on the pelletization pass rate. We used the qualified rate as the physical evaluation standard, through a single-factor test, to study the influence of the working parameters on the qualification rate of the pilling. The results show that the simulation test evaluation index of the discrete coefficient and the physical test evaluation index of the pilling qualification rate with the change rule of the working parameters is consistent with the discrete coefficient, and can be used as an indirect evaluation index of the quality of pilling. To further determine the optimal combination of working parameters, a quadratic regression orthogonal design test was conducted with the discrete coefficients as the evaluation index, and the second-order regression equations of the red clover seeds were established and analyzed by ANOVA using Design-Expert software. The study shows that, when the rotational speed of the coating pot is 307.204 rpm, the vibration frequency is 2.526 Hz, and the vibration amplitude of the coating pot is 5.843 mm, the predicted coefficient of dispersion at this time is 8.1%. Simulation using the best combination of parameters to obtain the average value of the dispersion coefficient of 8.4%, relative to the predicted value of 3.7%, indicated that the optimization of the experimental regression model is accurate, and the results obtained for the vibration of small seeds under the conditions of the design of the pellet granulation coating machine and the optimization of the pelletization coating process parameters have a certain degree of reference significance.

An integrated assessment of microfluidic microbial fuel cell subjected to vibration excitation

Microfluidic microbial fuel cell is considered as a new development direction of green and sustainable energy systems. Compared with other microbial electrochemical reactors, microfluidic microbial fuel cells have lower cost and higher energy efficiency. In practice, vibration is a non-negligible factor affecting the performance of microfluidic microbial fuel cell. However, numerical studies in this area are lacking. In the current work, a two-dimensional transient model for microfluidic microbial fuel cell is established by coupling the vibration force field with hydrodynamics, mass transfer, whole-cell electrochemical reaction kinetics and microbial growth. The correctness of the model is guaranteed by comparing the experimental data with simulation results. After model validation, an integrated assessment of the vibration effect on microfluidic microbial fuel cell is obtained. Major conclusions show that vibration excitation can inhibit the growth of electricigens inside the anode, thus reducing the output performance of microfluidic microbial fuel cell. Increasing the vibration intensity and frequency will exacerbate this effect. However, appropriate vibration excitation is beneficial to the substrate removal of microfluidic microbial fuel cell. Vibration will destroy the laminar flow pattern in the microchannel and increase the bacteria concentration inside the cathode. Additionally, the increment of feed flow rate is conductive to enhancing the anti-vibration ability of the cell

Experimental study on stress transfer of alfalfa during vibration compression

To reveal the mechanistic role of vibration in the compression of alfalfa stalk, the stress transfer of alfalfa compression process under the action of vibration force field was evaluated with a self-developed vibration compression test system. The internal stress in the upper layer of the compressed material was gradually transmitted to the lower layer. The stress transfer rate between the upper and lower material varied with the vibration frequency. Within the experimental vibration frequency range, when the frequency was 15 Hz, the stress transfer rate was the smallest. Compared with ordinary compression, the stress transfer rate and maximum pressure during vibration compression were small, but the relaxation density was high, indicating that vibration is beneficial to alfalfa compression. Comprehensive analysis of stress transfer, maximum pressure and relaxation density, when the vibration with vibration amplitude of 0.5 mm and frequency of 15 Hz was introduced, a denser alfalfa block was obtained with less pressure.

NUMERICAL SIMULATION AND EXPERIMENT OF VIBRATION PELLETIZER BASED ON EDEM

In order to quantitatively describe the influence between the mixing process and the pelleting quality of the vibration pelletizer, this paper uses EDEM to conduct a numerical simulation study on the uniformity of the seeds and powder mixing of the pelleting machine under vibration force field. Meanwhile, a single factor test was established to verify the feasibility of numerical simulation. The results show that the coefficient of variation CV is the smallest and the mixing uniformity between the seeds and powder is the highest when the vibration frequency is 20Hz, the rotation speed is 45r/min, the tilt angle is 40° during numerical simulation. The pelleting qualified rate J and single seed rate P as the test index of the mixing uniformity of seed pelleting shows the optimum value in the single factor test, EDEM can be used to analyse the mixing uniformity and pelleting quality in pelletizer. The results of orthogonal experiment indicated that the best combination of parameters was obtained as follows: vibration frequency of 20Hz, rotation speed of 45r/min and tilt angle of 40°, the mixing uniformity of seeds and powder and the pelleting quality of Agropyron seeds are the highest. This study can effectively provide reference for design of pelleting machine of small seeds under vibration force field.

Simultaneously achieving self-toughening and self-reinforcing of polyethylene on an industrial scale using volume-pulsation injection molding

It is critical and difficult for production of large polymer parts using injection molding method to simultaneously achieve both good flowability and mechanical properties. Volume-Pulsation Injection Molding (VPIM) technology, exerting a high-amplitude vibration force field during the entire injection molding process, can be exploited to address this challenge, on an industrial scale. Through orientation of macromolecules with vibration forces during injection molding, mechanical properties of polymers can be improved at low cost without sacrificing flowability. In this study, employing VPIM technology, self-toughening and self-reinforcing of high-density polyethylene (HDPE) were realized while maintaining satisfactory flowability. Comparing with those of the convention injection molding (CIM) samples @ 210 °C, impact and yield strengths of the VPIM samples @ 0.7 Hz-210 °C were increased by 782.93% and 14.25%, respectively. According to crystal morphologies, shish-kebabs were formed in intermediate layer, leading to a remarkable enhancement in mechanical properties. Injection temperature and processing frequency had an influence on the shish-kebab structure and the intermediate layer thickness, thereby determining mechanical properties. These analysis results were supported by the evidence from impact-fractured surface morphology, 2D-SAXS, 2D-WAXD, and DSC. The response law of crystal structure and morphology to the vibration flow field was proposed to uncover the influence of processing conditions on material properties.

Simultaneously toughening and reinforcing high-density polyethylene via an industrial volume-pulsatile injection molding machine and Poly(ethylene terephthalate)

It is difficult for polymeric materials to avoid the conflict between the mechanical properties and flowability in manufacturing large-sized injection-molded products. To solve the issue, this paper develops an industrial volume-pulsatile injection molding (VPIM) machine to introduce a high-amplitude vibration force field into the entire injection molding process. As a one-step morphology control, the vibration force field can drive the dispersed Poly(ethylene terephthalate) (PET) droplets to form the stiff microfibrils to improve the mechanical properties of the high-density polyethylene (HDPE) with high melt flow index (MFI). HDPE matrix is toughened and reinforced simultaneously under the synergistic effect of VPIM and PET. The impact and yield strengths of the HDPE/PET composite sample prepared by VPIM are increased by 696% and 28.5%, respectively, compared with that of the pure HDPE sample prepared by conventional injection molding (CIM). The optimal process frequency is found to be 0.5Hz for the mechanical properties of HDPE/PET composite. The phase and impact-fractured surface morphologies indicate that the dramatic improvement of the mechanical properties should be attributed to the in-situ formation of PET submicron-fibrils and hybrid shish-kebabs in the intermediate region. The morphological analysis results are verified by DSC, DMA, 2D-WAXD, and 2D-SAXD tests. From a multi-physics perspective, the influencing mechanism of the vibration flow field on the morphology is put forward to reveal why the mechanical properties of HDPE/PET composite are the best at 0.5Hz.

Separation Process of Fine Coals by Ultrasonic Vibration Gas-Solid Fluidized Bed.

Ultrasonic vibration gas-solid fluidized bed was proposed and introduced to separate fine coals (0.5–0.125 mm fraction). Several technological methods such as XRF, XRD, XPS, and EPMA were used to study the composition of heavy products to evaluate the separation effect. Results show that the ultrasonic vibration force field strengthens the particle separation process based on density when the vibration frequency is 35 kHz and the fluidization number is 1.8. The ash difference between the light and heavy products and the recovery of combustible material obtain the maximum values of 47.30% and 89.59%, respectively. The sulfur content of the heavy product reaches the maximum value of 6.78%. Chemical state analysis of sulfur shows that organic sulfur (-C-S-), sulfate-sulfur (-SO4), and pyrite-sulfur (-S2) are confirmed in the original coal and heavy product. Organic sulfur (-C-S-) is mainly concentrated in the light product, and pyrite-sulfur (-S2) is significantly enriched in the heavy product. The element composition, phase composition, backscatter imagery, and surface distribution of elements for heavy product show concentration of high-density minerals including pyrite, quartz, and kaolinite. Some harmful elements such as F, Pb, and As are also concentrated in the heavy product.

Study on Slow Crack Growth Resistance of High-Density Polyethylene Pipes Prepared by Vibration Extrusion

The slow crack growth resistance is one of the key factors to improve the service life of the plastic pipes. The high-density polyethylene (HDPE) pipes were prepared using a self-made electromagnetic dynamic plasticating extruder, which applied a vibration force field to the entire plasticating and extrusion process by the axial vibration of the screw. The slow crack growth resistance of HDPE pipes prepared by static extrusion and vibration extrusion was investigated. The effects of the vibration force field on the slow crack growth resistance of HDPE pipes were studied by DSC and WAXD analysis. The results showed that HDPE pipes prepared by vibration extrusion had higher melting temperature, higher crystallinity, larger crystal sizes, thicker lamellas and more perfect crystals. At the same time, the quasi net structure of the HDPE pipes chains can be obtained. All these are favorable for the improvement of the slow crack growth resistance property HDPE pipes.

The Study on Open-Celled Morphology of Polymer Blends in Vibration

The purpose of this research is to analysis on cell morphology of polymer blends foam in different vibration parameters. In this study, foamed was produced using a dynamic simulation foaming setup designed by ourselves. The addition of the vibration force field improved the cell nucleation. At the same time, the vibration reduce the polymer viscosity and increase the dissolution of CO2, which improve the content of open-celled microcellular foam.

Development and Application of Die Swell Data Gathering System Based on Multi-Function and all-Electric Rheometer

A real-time die swell data gathering system was developed based on laser diameter gauge in order to measure the die swell of the viscoelastic materials. Software of the system is compiled by C language. Data gathering, date display, data saving and date analysis were realized. Experimental procedures were established, by which the die swell can be acquired. The laser gauge is put 5cm under the die of self-developed multi-function and all-electric rheometer (MAR) to measure the diameter of the extrudate. The rheological behaviors of the PP/PS blends are tested. The change laws of the melt die swell ratio in the condition of different frequency and amplitude were obtained. Compared with the steady-state extrusion, after introducing vibration force field, the melt die swell ratio decreases obviously. The die swell ratio of the blends decrease in fluctuation state with the increase of the frequency; while decreases gradually with the increase of the amplitude. In addition, with the die length-diameter ratio increases, die swell ratio of the blends decreases gradually.

Vibration-assisted melt compounding of polypropylene/carbon black composites: Processability, filler dispersion and mechanical properties

Composites of polypropylene and carbon black were melt compounded by a vibration-assisted process. For comparison, conventional extrusion was also used for preparation of the same composites. A throughput of the vibration-assisted process was established to be higher than that of conventional extrusion. Microscopic images of the extrudates demonstrated better dispersion of the fillers when the vibration force field was applied. The mechanical properties and viscoelastic behavior of the composites were studied and the results were discussed in the context of the reinforcing action of the fillers and the higher level of polypropylene chain scission accompanying the vibration-assisted process.

Hysteresis Heat Build-up and Low Temperature Processing of Polymer under the Vibration Force Field

By using dynamic capillary and multi-dimensional vibration experiment desktop, isotactic polypropylene ( iPP ) is selected for the objective material to investigate the effect of the vibration parameters on the viscoelastic properties of polymer and its molding process. And a series conclusions can be draw that: The phase angle of polymer tends to decrease after a increase with vibration frequency increasing. The phase angle reach maximum value of 90° when the vibration frequency equals to the material natural frequency. Which polymer experience as pure viscous materials, also hysteresis heat build-up rate goes up to the peak. The plasticizing rate of polymer increase as the vibration amplitude, but the higher requirement for the equipment leveled up as well. The polymer plasticizing rate display the same law with that of phase angle against vibration frequency. When the vibration frequency equals to the material natural frequency, the plasticizing rate reach maximum. The investigation of this study will offers valuable theoretical references for polymer processing and novel equipment design in low-temperature.

Measurement and Analysis on Dynamics Cold Crystallization Parameter of High-Density Polyethylene (HDPE) Sheet by Vibration Force Field

Physics mechanics properties of polymer materials don’t only depend on their chemical constitution, molecular weight and distribution of molecular weight, but also depend on their agglomerate configuration. The effect of vibration on the microstructure and mechanical properties of high-density polyethylene (HDPE) sheets, obtained through vibration plasticating extruder in low temperature, were studied systematically. Crystalline polymer is analyzed by differential scanning calorimetry(DSC), wide angle X ray diffraction(WAXD). The test result which represents parameters of crystalline structure is helped to judge the outside factors for crystalline structure, such as melting point, crystallinity and heat of fusion by DSC and crystallinity, crystal plane distance and grain size by WAXD, and canning electron microcopy (SEM). The results indicate that the vibration extrudate in low temperature has higher crystallinity, perfect crystallite, and strong inter-spherulite ties.

Effects of Vibration Force Field on Extensional Stress of Polymer Melt in Contraction Die

Electromagnetic dynamic plasticating extrusion, as one of main novel forming methods, has many important benefits to the forming process and the properties of its products. Here a visualization technique of flow induced birefringence was used to study the effects of the vibration parameters of screw on the extensional stress in contraction die. It is shown that , the extensional stress vibrate with the screw vibration at the same frequency; the amplitude of the extensional stress increases with the amplitude of the screw increasing; the average extensional stress at dynamic extrusion is less than that without vibration force, and it decreases with the screw vibration frequency or amplitude increasing.

Lower Temperature Plasticizing and Extrusion of Polymer in Spherical Screw Extruder under Vibration Force Field

Abstract Physical and mathematical model for polymer plasticizing in proposed electromagnetic dynamic spherical screw extruder were developed to explore polymer plasticizing and molding mechanism at lower temperature under vibration force field. Polymer plasticizing mechanism was studied by deriving the mathematical expressions of energy consumed and the polymer flow. The energy consumed in polymer plasticizing was depicted in terms of vibrating dissipation, polymer deformation, shear and friction energy. LDPE was used as an objective material and extruded by the extruder with the electromagnetic excitation and spherical screw. The experimental results show the good agreement with theoretical calculations. Both of them show that: Polymer processing temperature and energy consumption decrease significantly while the plasticizing rate is increased over 60% by introducing the vibration force field. The research offers experimental and theoretical references as well as the evaluation method for optimizing the polymer processing parameters and designing the vibration induced equipment.

Rheological Properties of Neat and Calcium Carbonate Particles Filled Polypropylene Blends under Axial Vibration Force Field

Abstract Structures, working mechanism, data collecting and processing methods of the self-made multifunctional all-electronic rheometer for polymer composites were introduced in detail. The validity of this equipment was proved by deriving the apparent shear viscosity expression under axial vibration condition and comparing the results obtained from both this self-made rheometer and Rosand Rh7D capillary rheometer at steady state. With this equipment, the effects of calcium carbonate weight fraction, particle size and vibration parameters on apparent shear viscosity of calcium carbonate filled propylene composites were investigated. The results show that: the apparent shear viscosity of the composites increases with the filled particle concentration. However, it is seldom affected by particle size within certain a range of shear rate. While the apparent shear viscosity increases with the decrease of particle size at moderate shear rate. Besides, the apparent shear viscosity declines rapidly with the increasing vibration amplitude. However it exhibits a cosinoidal or sinusoidal trend as vibration frequency increases and peaks at the resonant frequency of the composites.

Theoretical and experimental study of the melting process of high‐density polyethylene for multidimensional vibration equipment

AbstractA model for investigating the melting process under a vibration force field is presented. The key parameters of this model are as follows: the rotation of the screw and heat are supplied by the vibration force field for the material phase conversion. A multidimensional vibration desk (DWZD‐500) and low‐density polyethylene material were used to investigate the effect of the vibration parameters on the melting process. A comparison of the derived model and experimental results revealed that increasing the vibration parameters increased the melting mass. This study will serve as the theoretical basis to optimize the parameters of vibration extruders' processing polymers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

The study on the creep of calcium carbonate-filled polypropylene (PP/CaCO3) prepared at different vibration condition

A vibration force field had been introduced during the polymer injection processing in the article, which caused some physical properties of the articles were significantly improved. The creep behavior of calcium carbonate-filled polypropylene (PP/CaCO3) prepared at different vibration condition was studied in order to reveal the influence of vibration conditions on the creep behavior. First, the tensile creep behavior of the PP/CaCO3 prepared at different vibration conditions has been investigated with a tensile creep apparatus, and it had been observed that with the vibration frequency increasing, the tensile strain would be maximum value at 0.72 Hz. While the tensile strain of the PP/CaCO3 prepared at different vibration pressure would be decreasing with the vibration pressure increasing. Then the wide-angle X diffraction (WAXD) and the differential scanning calorimeter (DSC) were used to explore the microstructure of the PP/CaCO3 article prepared at different vibration condition. According to the WAXD and DSC data, the number of the crystal grain may play an important role on the change of the creep behaviors of PP/CaCO3 article prepared at different vibration conditions. Finally, the inner reason why the different vibration condition would cause different creep behavior could be found that if the number of the crystal grain is larger, then there would be stronger physical cross-linking structure, which causes stronger anti-creep ability.

Improved mechanical properties and structure of polypropylene pipe prepared under vibration force field

AbstractThe polypropylene (PP) pipes were prepared using a self‐made electromagnetic dynamic plasticating extruder, which introduced a vibration force field into the whole plasticating and extrusion process by the axial vibration of the screw. The effects of the vibration frequency and the vibration amplitude on the mechanical properties and microstructure of PP pipes were investigated using bursting pressure testing, tensile testing, impact testing, differential scanning calorimetry (DSC), and wide‐angle X‐ray diffraction (WAXD). The mechanical properties testing showed that the circumferential strength of PP pipes increased significantly, and the biaxial self‐reinforcement pipes could be obtained. Also, the impact strength was improved. When compared with the conventional static extruded specimens, the maximum increase of bursting pressure, tensile yield strength, and impact strength were 27.03%, 7.3%, and 16.2%, respectively. DSC and WAXD analysis showed that the PP pipes obtained by vibration plasticating extrusion (VPE) had higher crystallinity, higher melting temperature, more perfect crystals, and smaller crystal sizes, but no new polymeric crystalline peak appeared. The improvement of mechanical properties of the PP pipes prepared by VPE was attributed to the higher crystallinity and the improvement of the molecular orientation and of the crystalline morphology under the action of the vibration force field. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009