Pneumatic Vibration Research Articles

A semi-active adaptive pneumatic vibration isolator based on frequency response analysis and nonlinear control

In this work, an adaptive nonlinear error feedback controller based on fuzzy state observer is proposed to a novel rubber pneumatic vibration isolator (PVI) system. First, a novel rubber PVI system is designed and developed. Harmonic balance method is applied to establish the dynamic model of the PVI system, so as to analyze the frequency response characteristics of the system. Second, to improve the PVI performance in low-frequency vibration, a nonlinear state error feedback control system based on fuzzy state observer is designed for the active PVI system. Furthermore, the experiment system is established. Finally, through the experimental comparison under 5 Hz, 7 Hz, 20 Hz, and 40 Hz, an adaptive PVI strategy is proposed. The experimental results demonstrate that the adaptive PVI shows better performance in vibration isolation.

Enhancing resource utilization: A novel method for effective separation of residual film and impurities in cotton fields

This study addresses the challenge of incomplete separation of mechanically recovered residual films and impurities in cotton fields, examining their impact on resource utilization and environmental pollution. It introduces an innovative screening method that combines pneumatic force and mechanical vibration for processing crushed film residue mixtures. A double-action screening device integrating pneumatic force and a key-type vibrating screen was developed. The working characteristics of this device were analyzed to explore the dynamic characteristics and kinematic laws of the materials using theoretical analysis methods. This led to the revelation of the screening laws of residual films and impurities. Screening tests were conducted using the Central Composite Design method, considering factors such as fan outlet, fan speed, vibration frequency of the screen, and feeding amount, with the impurity-rate-in-film (Q) and film-content-in-impurity (W) as evaluation indexes. The significant influence of each factor on the indexes was determined, regression models between the test factors and indexes were established, and the effect laws of key parameters and their significant interaction terms on the indexes were interpreted. The optimal combination of working parameters for the screening device was identified through multivariable optimization methods. Validation tests under this optimal parameters combination showed that the impurity-rate-in-film was 3.08% and the film-content-in-impurity was 1.94%, with average errors between the test values and the predicted values of 3.36% and 5.98%, respectively, demonstrating the effectiveness of the proposed method. This research provides a novel method and technical reference for achieving effective separation of residual film and impurities, thereby enhancing resource utilization.

A Compound Regulative Pneumatic Vibration Isolator With Quasi-Zero Stiffness Mechanism For Load Variable Instruments

A Compound Regulative Pneumatic Vibration Isolator With Quasi-Zero Stiffness Mechanism For Load Variable Instruments

OVERVIEW OF THE DESIGNS OF HINGED VIBRATION EXCITERS AND RESEARCH OF THEIR PARAMETERS AND THE FEASIBILITY OF THEIR USE ON VIBRATION PLATFORMS TO IMPROVE THE COMPACTING OF REINFORCED CONCRETE PRODUCTS

Construction of buildings using prefabricated technology is increasingly used in Ukraine. In parallel with this, the list of ready-made reinforced concrete products, which are used in monolithic-frame and monolithic-prefabricated technologies, is expanding. Because of this, it becomes necessary to increase the number of lines for the production of ready-made reinforced concrete products and to use equipment that will allow to quickly adjust the production process depending on the change in the type and size of the final products. At the same time, the most responsible process is the compaction and formation of the concrete mixture using volumetric compaction technology on vibrating platforms of block or frame construction. Such installations are designed for the compaction of concrete mixtures in forms standardized by size and which do not fully meet the requirements of universality when changing the production program, ensuring high quality of finished products, and are characterized by significant energy consumption. One of the directions for solving the mentioned shortcomings is the creation of a vibration installation with attached vibration exciters and a variable mode of operation. Such an idea is ensured by the use of a vibrating installation in which the frame with a plate welded on top is directly the pallet on which the compaction process takes place. The dimensions of the future product are limited by the installation of sides and partitions on the pallet, which are fixed using magnetic fasteners, thanks to which it is possible to easily rearrange the installation for other standard sizes of panels. The use of attached vibration exciters, which are evenly spaced over the area of the forming plate, aims to improve the distribution of amplitudes in the volume of the concrete mixture, improve quality and reduce the time for compaction of the product. The work includes an overview of the existing designs of mounted vibration exciters, an analysis of their disadvantages and advantages, as well as technical parameters. Ac-cording to the obtained results, it was determined that planetary pneumatic vibrators have advantages in the amount of disturbing force that they are able to generate per unit of their own mass, higher indicators of dyna-mism criteria compared to electric and hydraulic centrifugal analogues. Pneumoplanetary vibration exciters are simple in design, reliable and allow adjusting the frequency of oscillations within certain limits without the use of additional devices.

A novel parallel capillary-cavity model for the analysis of pneumatic hammer vibration in porous aerostatic bearings

Porous aerostatic bearings (PABs) are widely used in high-speed applications and ultra-precision machinery owing to their frictionless motion and remarkable stability. In this paper, a novel parallel capillary-cavity model based on the intricate pore structure characteristics is established to characterize air flow in PABs and analyze the pneumatic hammer vibration. An experimental setup is constructed to measure the pneumatic hammer vibration of PABs. The experimental results exhibit a strong agreement with the predictions. The effects of various factors, including different loads, air pressures and porosities on the pneumatic hammer vibration are thoroughly discussed. The results show that higher air supply pressures, larger loads, and increased porosity are more likely to trigger pneumatic hammer vibration in PABs.

Research on automatic metering and pneumatic vibration conveying technology of energetic powder materials

In view of the need to improve the automation and weighing accuracy of solid energetic materials in the weighing process, to reduce the process safety risk of the automatic conveying and loading process and improve the equipment safety control ability, a weight-loss pneumatic vibration conveying device is designed, which adopts the method of weight loss measurement. Through the weighing sensor installed on the weighing platform, the weight of the materials in the weighing hopper is fed back to the controller in real time, The controller obtains the weight reduction per unit time (i.e. the actual flow) through the internal algorithm. According to the difference between the actual flow and the set flow, the controller outputs the speed signal to control the motor speed to achieve the purpose of accurate feeding. A linear pneumatic vibrating conveying chute is designed to continuously convey materials at a certain speed. The linear pneumatic vibrating chute has good linear control through the adjustment of leaf spring, amplitude and frequency, and can realize the automatic and safe measurement and transportation of solid energetic materials.

Optimized directionality in acoustically coupled, dual motor, uniphase, moving coil microphones

In uniphase, moving coil microphones, pneumatic vibration cancellation is an effective means to minimize structural excitation. However, pneumatic vibration cancellation requires precise control of the transfer function between the capsule and the microphone body, and the internal volumes are large. Therefore, the uniphase, moving coil capsule with pneumatic vibration cancellation is not well suited as a portable platform in applications that require a compact size. The addition of a secondary transduction mechanism is commonly used to mitigate a variety of unwanted signal sources in microphones, and is an effective alternative to the pneumatic vibration cancellation. Because the secondary transduction mechanism is integral to the capsule, precise control of the capsule/body transfer function is not needed, resulting in a more portable solution. However, the current strategy for vibration cancellation is to isolate the secondary transduction mechanism from the acoustical excitation, which does not minimize the internal volume and is not compact. A new strategy proposes an alternative architecture where the two transduction mechanisms share an internal volume. When certain constraints are met, acoustically coupling the motors results both a minimized internal volume and an optimized microphone directionality at low frequencies. Simulated and measured results are shown to illustrate the implementation.

Research on the Pressure Regulator Effect on a Pneumatic Vibration Isolation System

The pneumatic vibration isolator (PVI) plays an increasingly important role in precision manufacturing. In this paper, aiming to detect the performance of the pressure regulator in the PVI system, a PVI testing system with a pressure regulator is designed and developed. Firstly, the structure of the pneumatic spring is presented and analyzed, and the nonlinear stiffness is obtained based on the ideal gas model and material mechanics. Then, according to the working principle and continuity equations of ideal airflow, a dynamic model of the PVI system with a pressure regulator is established. Through the simulation analysis, the vibration isolation performance is improved with the efficient and precise pressure regulator. The average values of both the vibration velocity and transmission rate decrease when the vibration is set to 4, 10, 20 and 40 Hz, respectively. The experiments demonstrate the reliability and effectiveness of the pressure regulator. This achievement will become an important basis for future research concerning precision manufacturing.

Highly damped single-chamber pneumatic vibration isolator using effects of thermal conductivity in the air volume

State-of-the-art pneumatic isolators have a two-chamber design with metered orifices between the chambers. This arrangement produces energy dissipation necessary to avoid excessive resonance vibration [1]. However, this leads to reduced isolation performance at high frequencies compared to a single-chamber isolator of equivalent total volume. Analysis shows that, while the dynamic process of the air compression in the pneumatic chamber is adiabatic for geometric parameters usually employed in vibration isolators, substantial dissipation of mechanical energy can be achieved by introducing certain thermally conductive features into the chamber. That makes practical a single-chamber design with sufficient damping. The paper presents the optimization of the geometry of thermally conductive features aimed at maximizing the loss factor at the resonance frequency of the isolation system. Experimental results illustrate the concept [2] and demonstrate the increased isolation effect. [1] V. M. Ryaboy, Vibration Control for Optomechanical Systems (World Scientific, 2022), p. 280. [2] Vibration isolation apparatus with thermally conductive pneumatic chamber, and method of manufacture, U.S. patent application No. 17/721834, USPTO, 2022.

Reliability of Gradient-Echo Magnetic Resonance Elastography of Lumbar Muscles: Phantom and Clinical Studies.

Magnetic resonance elastography (MRE) has been used to successfully characterize the mechanical behavior of healthy and diseased muscles, but no study has been performed to investigate the reliability of MRE on lumbar muscles. The objective of this work was to determine the reliability of MRE techniques on lumbar muscles in both ex vivo phantom and in vivo human studies. In this study, fresh porcine leg muscles were used in the phantom study, and 80 healthy adults (38.6 ± 11.2 years, 40 women) were recruited in the human study. Five repeated stiffness maps were obtained from both the phantom and human muscles by using a gradient-echo MRE sequence with a pneumatic vibration on a 1.5 T MR scanner. The technical failure rate, coefficient of variation (CV), and quality score were assessed to evaluate the reliability of MRE, respectively. Analysis of variance was performed to compare the stiffness between different lumbar muscles, and the difference was significant if p < 0.05 after Bonferroni correction. The results showed that the MRE achieved a zero technical failure rate and a low CV of stiffness (6.24 ± 1.41%) in the phantom muscles. However, in the human study, the MRE exhibited high CVs of stiffness (21.57%–25.24%) in the lumbar muscles, and the technical failure rate was higher in psoas muscles (60.0–66.3% in) than in paraspinal muscles (0.0–2.5%). Further, higher quality scores were noticed in paraspinal muscles (7.31–7.71) than those in psoas muscles (1.83–2.06). In conclusion, the MRE was a reliable technique to investigate the mechanical property of lumbar muscles, but it was less reliable to assess stiffness in psoas muscles than paraspinal muscles.

Nanoscale multiply charged focused ion beam platform for surface modification, implantation, and analysis.

The PELIICAEN (Platform for the Study of Ion Implantation Controlled and Analyzed at the Nanometric Scale) setup is a unique device, both for all of its in situ ultra-high vacuum equipment (focused ion beam column, secondary electron microscope, atomic force microscope, and scanning tunneling microscope) and for its nanostructuration performances on materials. The setup has been recently equipped with its own electron cyclotron resonance ion sources, a new position-controlled platform using pneumatic vibration insulators, and a fast pulsing device. Its performances were then deeply improved, providing access to a large choice of ions, an adjustable ion implantation depth up to a few hundred nanometers, an image resolution down to 25 nm, and an ion beam size on the sample down to 100 nm. With all this equipment, the PELIICAEN setup is in the international foreground to perform and analyze ion implantation and surface modification.

Dynamic Analysis of Quasi-Zero Stiffness Pneumatic Vibration Isolator

This paper focuses on analyzing the dynamic response of an innovated quasi-zero stiffness pneumatic vibration isolator (QZSPVI) using two mechanisms, including wedge and semicircle cam. Different from other studies relating quasi-zero stiffness isolation system, the pneumatic cylinder in this paper works as an air spring in order to easily adjust the dynamic stiffness of the proposed system according to the change of the isolated load through regulating the pressure. Firstly, the dynamic stiffness of the QZSPVI will be analyzed. Then, the condition for which the minimum dynamic stiffness is quasi-zero around the equilibrium position is also determined. The fundamental resonance response of the QZSPVI subjected to the externally harmonic force is analyzed through multi-scale method and the numerical simulations are verified. Secondly, due to exiting relative sliding frictional phenomenon between the cylinder and piston, instead of an experiment, another key content of this work is to identify the friction force model of the cylinder through virtual prototyping model. From this identified result, the complex dynamic response of the QZSPVI and coexistence of multiple solutions will be discovered by realizing the direct integration of the original dynamic equation through using the 5th-order Runge–Kutta algorithm. The analysis and simulation results clearly show the advantages of the proposed model against the equivalent pneumatic vibration isolator (EPVI), which only employs the wedge mechanism. This research will offer a useful insight into design and QZSPVI in practice.

Theoretical Study of Vibrocentrifugal Separation of Grain Mixtures on a Sieveless Seed-cleaning Machine

Abstract The article presents an analysis of known developments on creation of sieve-less pneumatic vibration centrifuges separating devices and processes of separating seed mixtures into fractions according to the complex of physical and mechanical properties of components. Mechanistic and mathematical models for studying the movement of particles over the sieve-free surface of pneumatic vibration separators were developed, theoretical studies of movement of seed mixture components were conducted and the most acceptable pneumatic vibration centrifugation process was determined by likeness to the process occurring on the separating surface of pneumatic sorting tables. To achieve the greatest separation of particles on the complex of their physical and mechanical properties (density, geometric dimensions, aerodynamic properties of seeds) is possible with the same direction of oscillatory motion and rotation of the separating surface performing the rotation in the direction from a larger radius to a smaller radius of the surface, in the “fluidization” mode, i. e. i.e. with periodic separation of the lower particles of the layer from the separating surface at simultaneous blowing of the layer by an air stream.

Improving the mechanical-mathematical model of pneumatic vibration centrifugal fractionation of grain materials based on their density

This paper has substantiated the mechanical-mathematical modeling of the process of fractionation of grain material into fractions. It has been established that this could optimize the process parameters and would make it possible to design new or improve existing working surfaces of centrifugal separators. A mechanical-mathematical model of the pneumatic vibratory centrifugal separation of grain material by density has been improved. This research is based on the method of hydrodynamics of multiphase media. The improved mechanical-mathematical model takes into consideration the interaction between the discrete and continuous phases of grain material by introducing conditions of interaction at the interface of these phases. In the hydrodynamic modeling of the movement of the circular layer of seeds, the coefficient of dynamic viscosity of discrete and continuous phases was taken into consideration. It was established that the pneumatic vibratory centrifugal separation process parameters are critically affected by the circular frequency of rotation of the cylindrical working surface, the frequency and amplitude of its oscillations. As well as such process characteristics as the airflow rate, dynamic viscosity coefficient, the average thickness of a grain material layer, and the mean density of its particles. Rational values for the technical parameters of the grain material pneumatic vibratory centrifugal fractionation process in terms of density have been determined by using the improved mechanical-mathematical model. The amplitude and oscillation frequency of the working surface are in the ranges A=(35…50)·10–5 m, ω=15.0...15.6 rad/s. The circular rotation frequency of the working surface, ω=24...25 rad/s. The airflow rate, V=2 m/s. It was established that using the improved mechanical-mathematical model of fractionation makes it possible to improve the performance of a pneumatic vibratory centrifugal separator by 9 %. At the same time, the effectiveness of grain material separation could reach 100 %.

Development of vibration system for decreasing of intensity of steel ladle outlet channel tightening

The problem of tightening of outlet channel of steel ladle still remains relevant at present. A review of scientific and technical studies, aimed at elaboration of methods to keep the channel flow section constant presented. An analysis of deposition forming mechanisms on walls of outlet channel of steel ladle was done. To prevent their formation it was proposed to apply a vibration impact on the ladle shutter. Using simulation studies and specially elaborated methodology, the degree of influence and frequency of amplitude oscillations, acting along the ladle channel, on increasing speed of layer thickness formation on its walls and number of tearing off hard particles was established. To evaluate intensity of elastic waves absorption by the refractories of ladle shutter during vibration impact on it, a natural experiment was done. As a result of the experiment an initial information was obtained for determining parameters of oscillation process to guarantee effective functioning of the proposed casting facility. A necessity was established to account tenfold decrease of vibration acceleration during propagation of elastic wave along the casting channel from the lower end of collector nuzzle to the upper end of the ladle casting nozzle. Results of the complex studies became base of technical solution at elaboration of design of the ladle shutter. The elaborated shutter is equipped by a system of exciting vertically-directed oscillations, promoting decreasing intensity of hard particles sticking on the walls of the outlet channel. The design of the perfected ladle shutter and general view of its test model shown, which is equipped with the vertically-directed oscillations exciting system. Depending on capacity of the steel ladles, which can be from 100 to 300 t, their shutters can be equipped with one or several pneumatic plunger vibrators. Each of the plunger having the mass of 0.8 kg, can develop an impact force up to 300 N when supplying into its working cavity compressed air of 0.2 MPa pressure at flow rate 150 l/min. Industrial tests of the modernized shutter in a foundry shop of Yasinovatsky machine-building plant were done.

Soft pneumatic gripper integrated with multi‐configuration and variable‐stiffness functionality

Soft grippers are compliant and self-adaptive, and can be highly compatible with the surrounding environment in grasping tasks. Currently, most soft pneumatic grippers are developed with a single grasping configuration, which leads to poor universality for different objects. Additionally, the oscillation caused by actuator's elastic bodies will result in poor stability during grasping and transportation, which can be improved by stiffness enhancement. A four-fingered soft pneumatic gripper is proposed by integrating multi-configuration and variable-stiffness functionality. The multi-configuration was realised by using the motion characteristics of a tangent mechanism. Meanwhile, a damping method based on electrorheological fluids was applied on a pneumatic actuator to improve the grasping stability. Besides, a machine vision technique was adopted to automatically adjust the grasping posture during manipulation. As a result, the proposed multi-configuration gripper can self-adaptively grasp different shapes of objects, especially two classical types, a pen canister as the flat cylinder and a cuboid box as the long cylinder. In addition, the electrorheological variable-stiffness method was manifested to be applicable for reducing pneumatic finger vibration. This research is expected to improve the versatility and grasping stability of soft pneumatic grippers.

Analytical study of a pneumatic vibration isolation platform featuring adjustable stiffness

This paper proposed a pneumatic vibration isolation platform (named VIP) with adjustable stiffness characteristics in which two opposite stiffness mechanisms are introduced. One with positive stiffness is formed by the wedge-roller mechanism used to support the load, which is named the load bearing mechanism (LBM), the other (called stiffness correction mechanism-SCM) generating negative stiffness in vertical direction, constructed by the cam-roller mechanism, is used for correction of the total stiffness of the VIP. Instead of using coil spring, the rubber air spring is employed, hence the stiffness of the VIP can be easily adjusted to adapt to the change of the isolated load as well as improve the isolation effectiveness in low frequency region. The force model of the rubber air spring generated by the compressed air, friction and viscoelastic is then built and identified via the experiment. Next, the dynamic stiffness model of the VIP will be established and analyzed. The primary resonant response of the proposed model subjected to harmonically excited base will be analyzed by employing the normal form technique. The effects of the configurative parameters on the amplitude-frequency curve are investigated. Furthermore, due to the nonlinear dynamical system, the complex dynamical analysis including coexistence solution, bifurcation and so on is necessary to explore in this work by using the numerical integration and Poincaré map. Finally, the isolation response of the VIP subjected to the random excitation is also evaluated and compared with that of the equivalent linear isolator (named ELI in which the SCM is removed). The result shows clearly the advantages of the VIP against the ELI. This work will furnish a useful insight into the design and manufacture of the low frequency vibration isolation systems.

Development and Preliminary Validation of a Pneumatic Focal Vibration System to the Mitigation of Post-Stroke Spasticity.

Some evidence has demonstrated that focal vibration (FV) plays an important role in the mitigation of spasticity. However, the research on developing the FV system to mitigate the spasticity effectively has been seldom reported. To relieve post-stroke spasticity, a new pneumatic FV system has been proposed in this paper. An image processing approach, in which the edge of vibration actuator was identified by the Canny edge detector, was utilized to quantify this system's parameters: the frequency ranging from 44 Hz to 128 Hz and the corresponding amplitude. Taking one FV protocol with the frequency of 87 Hz and the amplitude 0.28 mm of this system as an example, a clinical experiment was carried out. In the clinical experiment, FV was applied over the muscle belly of the antagonist of spastic muscle for twelve chronic spastic stroke patients. Spasticity was quantified by the muscle compliance and area under the curve for muscle (AUC_muscle). The result has demonstrated that, in the state of flexion of spastic muscle, the AUC_muscle and muscle compliance of the spastic muscle significantly increased immediately after FV compared with before-FV, illustrating the mitigation of the spasticity. This study will not only provide a potential tool to relieve post-stroke spasticity, but also contribute to improving the sensory and motor function of patients with other neurological diseases, e.g. spinal cord injury, multiple sclerosis, Parkinson and dystonia, etc.

Investigation of the process of pneumatic vibration separation of grain by density during one-dimensional movement of grain flow

Annotation Purpose. Formation of a mathematical description of the process of moving grains with different density in vibro-pneumatic liquefied grain medium under the action of pulsating air flow to determine the parameters of movement and the possibility of their separation into fractions. Methods. Theoretical determination of the dependences of the motion of grains with different densities in a vibro-pneumatic grain medium with pulsating air flow determines the mathematical method of research based on the addition and numerical solution of the equations of grain motion in a pneumatic vibrating separator. The mathematical model is formed as a result of drawing up the scheme of force interaction on grain in the vibro-pneumatic liquefied grain environment and the differential equations of movement of grains which are presented by a material point and indicators characterizing physical and mechanical properties of grain environment are received. Results. The motion of the center of mass of grains is considered as the motion of a certain particle, the coordinates of which coincide with the coordinates of the moving coordinate system (x, y), and the mass of a single grain m differs from the grains of the medium in density. The change of air flow velocity and the influence of pulsating air flow on the flow of grain material moving on a vibrating perforated surface are determined. The discrete-periodic change of the flow velocity, which is fed through the perforated support surface into the layer of grain material, is analytically described. The parameters of the grain motion process in an oscillating fluidized medium are determined, which are determined by the solution of a complex system of differential equations using computational methods using a PC. Conclusions. As a result of theoretical research, the possibility of increasing the efficiency of separation of grain materials by specific gravity of grains, by intensifying the process of separation of grain material provided the use of pulsating air flows to separate mixtures on vibrating surfaces and compared with existing separators using horizontal and inclined decks grain separation efficiency material increases by 35–42%. Keywords: pulsating air flow, grain, density, trajectory, fluidized medium, separation process, harmonic law of motion.

Study case about the production of masonry concrete blocks with CDW and kaolin mining waste

&lt;abstract&gt; &lt;p&gt;The worldwide generation of construction and demolition waste is about 30% to 35% of the total solid waste produced annually. In addition, the extraction of minerals leaves a high-grade environmental liability with tailings, such as kaolin clay, Brazil being one of the countries with the largest deposits and production of this mineral in the world. The kaolin clay extraction serves several industries such as ceramics, crockery, and paper, among others. The objective of this work is to insert these two wastes as raw material of construction elements, specifically masonry concrete blocks, thus giving an end to the residues, demonstrating their reutilization potential. Here, blocks were manufactured with replacement of natural aggregates, stone powder, and sand, by construction and demolition waste and of kaolin clay waste. The replacement percentages were up to 34% and 16%, respectively. The blocks made with pneumatic vibration compacting procedure presented strength beyond than what is established by norm, thus giving a favorable perspective of use for these residues as building elements.&lt;/p&gt; &lt;/abstract&gt;