Influence Of Low-frequency Vibrations Research Articles

The influence of low-frequency vibration on the restoration of the range of knee motion in laboratory animals after immobilization (experimental study)

Background. The term “joint contractures” is used to describe the loss of passive range of motion of diarthrosis joints, the most common and mobile type of a joint. Measuring passive or active range of motion in a joint with contracture is key to assessing the severity of joint contractures. The purpose of the study: to determine the impact of immobilization on the development of movement limitation in the knee joint of laboratory animals (rats) and to evaluate the possibility of restoring mobility in case of using low-frequency vibration during and after immobilization. Materials and methods. The experimental study was conducted on 30 non-linear white male rats aged 6 months. Immobilization of the pelvic limb was performed at an angle of 140° in the knee joint. The animals were randomly divided into 3 groups: I — immobilization and free restraint after immobilization, II — immobilization and vibration development of the joint after immobilization, III — immobilization and vibration development of the joint during and after immobilization. Vibration development of the immobilized knee joint was performed daily in the mode of 20 Hz with an amplitude of 1.5 mm and a duration of 10 minutes. The range of motion and real contracture were determined as the difference between the measured range of motion and the range of motion before the start of the experiment for each animal individually. Results. It was found that a rapid increase in movement limitation occurs starting from the 2nd week of immobilization. A decrease in the range of motion in rats of the groups I and II under conditions of immobilization occurred the same way. After the end of immobilization, a slow increase in the range of motion was observed in the group I; in the group II, the growth was almost linear and after 4 weeks, the indicator was close to the norm. In the group III, the limitation of the range of motion after immobilization was significantly less; therefore, accordingly, recovery took place already 2 weeks after the removal of the immobilization bandage. Immobilization of the knee joint in rats of groups I and II caused a contracture of 60°, while in the group III, the restrictions did not exceed 25°. And, accordingly, the recovery in the groups with vibration development was rapid; in the group III, a full recovery was achieved, in the group II — a recovery of up to 5° of the residual contracture. In the group I, we observe a residual contracture of almost 35°, which is more than the formed immobilization contracture in the group III. Conclusions. Low-frequency vibration allows reducing the impact of immobilization and significantly accelerate the recovery of mobi-lity (range of motion) of the joint after its completion. If it is impossible to carry out vibrotherapy during the period of immobilization, it should be started as early as possible after immobilization. To date, there are few studies considering the effect of low-frequency vibration on the development of immobilization contractures and their treatment. The obtained data require further research with longer periods of immobilization and those examining immobilization options and modes of vibration impact on the joints.

A New Permeability Model Under the Influence of Low-Frequency Vibration on Coal: Development and Verification

A New Permeability Model Under the Influence of Low-Frequency Vibration on Coal: Development and Verification

Influence of low-frequency vibration on friction coefficient of contact interface in bend-stretch forming

Low-frequency vibration assisted bend-stretch forming has a good friction reduction effect due to the “surface effect” and enhances the forming ability of materials compared to traditional bend-stretch forming. In order to further improve the friction state of the forming contact interface, the contact interface friction between AL6005A aluminum alloy and Q345B steel under low-frequency vibration was analyzed by using the elastic-plastic contact theory. The formula for calculating the sliding friction coefficient of contact pressure and low-frequency vibration parameters was established. The influence of forming contact pressure and vibration frequency on the contact stress, friction force, and friction coefficient of asperity at the contact interface is obtained through the simulation analysis of low-frequency vibration sliding friction of double rough contact surface. The results show that the application of low-frequency vibration can weaken the influence of contact pressure on the friction coefficient and reduce the friction coefficient between AL6005A aluminum alloy and Q345B steel. Within a specific range of contact force, the sliding friction coefficient decreases first and then increases with the increase of vibration frequency. There is a critical vibration frequency to minimize the sliding friction coefficient of the contact interface.

Influence of Photon Beam and Motor Vibrations on At-Wavelength X-Ray Speckle Scanning Metrology

Speckle scanning metrology is an effective tool to determine the X-ray wave front error in synchrotron radiation. By measuring wave front radii of curvature, X-ray optics can be high-precision aligned and adaptive optics can be used for compensating these wave front errors to pursue an aberration-free wave front. Photon beam and motor vibrations are the major limitations in characterizing the beam performances. An analytical model is presented in this article to reveal the influences of photon beams and motor vibrations on the measurements of the wave front radii of curvature. It is worth noting that the influence of low-frequency vibration is oscillatory and thus the selection of sampling frequency is strongly related. The experimental results verify the model and reveal the main dependency of the experimental deviations on the amplitude and frequency of vibrations.

Influence of low-frequency vibrations on mass transfer in pores

The work is devoted to the numerical investigation of mass transfer in a narrow extended channel at small low-frequency fluid vibrations. These questions are of interest for technological processes associated with impregnation and filtration. Three different series of mass transfer problems are considered. In the first series a low velocity flow with some diffusing component was supplied through the initial section of a long thin rectangular channel. In the second series the speed fluctuation near the zero point was considered, i.e. there was no stationary component of the fluid velocity in the channel. In the third series of calculations the mass transfer was determined for the case when the dissolving substance was absorbed on the opposite wall of the channel. Calculations of mass transfer in capillary channels showed that with longitudinal oscillations of the flow in the channel, the amplitude of the velocity oscillations has the main influence while the frequencies play practically no role.

Influence of low-frequency vibration in Die Sinking EDM: a review

Electric discharge machining (EDM) is a thermal-based machining process where material removal in the form of melting and vaporization occurs due to repeated electrical sparks between electrode and workpiece. EDM process finds wide applications in the manufacturing, automobile, aerospace, and biomedical industries due to its remarkable feature of producing complex geometrical shapes like molds, tools, and dies. Irrespective of materials hardness. In this review, the paper author has given details about a new advancement made in the EDM process, which is low-frequency vibration-assisted Die Sinking EDM. There is also a brief introduction of vibration setups that can be used to generate low-frequency vibration. There is also some discussion about various optimization techniques (e.g., TOPSIS, MOORA, GRA) used to optimize the process parameters that are current, frequency, pulse on time, and pulse off time to get better response parameters ( MRR, TWR, and SR). Besides, there is extensive discussion about the effect of current, pulse on time, pulse off time and frequency on MRR, SR, and TWR. In the end, some discussion on the effect of low-frequency vibration on surface topography is also discussed.

Numerical and Experimental Study on the Influence of Low Frequency Vibration on Strains of Single Point Incremental Forming

Single point incremental forming (SPIF) is a decent potential procedure appropriate for small batch production. In addition to that, the formability of the material is expanded compared to the other sheet metal forming processes. Meanwhile, the more advanced SPIF process requires perfect comprehension of the material deformation technique. In this paper, the equipment of vibration - sheet metal forming was designed. Finite element model was used to demonstrate and analyze the effect of different frequencies of vibration on the strain distribution in single point incremental forming process. The results show that specific vibration parameters can decrease strain. Moreover, an experimental vibration system using single point incremental forming was designed. The numerical model is primarily supported by test results conclusions from a simple cone of Al1050 aluminum alloy.

Investigations on the machinability of titanium alloy using low frequency vibration assisted turning under minimum quantity lubrication

Titanium alloy found major applications in aerospace, automobile and chemical factories due to its large strength at elevated temperature, good corrosion resistance, low thermal conductivity and light weight. Because of its superior qualities, this alloy found difficult to machine. The machinability of titanium alloy can be improved by adding low frequency vibrations (less than 1000 cycles per second) to the cutting tool. An enhancement in the machining performance can be attained by applying minimum quantity lubrication (MQL) in the cutting zone. In this study an attempt has been made to enhance the machinability of Ti6Al4V alloy by using MQL technique during low frequency vibration assisted turning (LFVAT). Experiments were conducted and the influence of low frequency vibrations plus MQL on the turning process was estimated by measuring the average surface roughness, main cutting force and tool wear. The performance of LFVAT, LFVAT + MQL, conventional turning (CT) and CT+MQL compared in terms of the aforesaid output parameters.

Mechanical coating formed under conditions of vibration exposure

The study results of the zinc coating obtained on the surface of metals in the process of mechanochemical synthesis, implemented in the conditions of vibrowave systems, are presented. The features of coating formation mechanism, an activating role in its formation of free-moving, under the influence of low-frequency vibrations, indenters, are disclosed. The advantages of applying zinc coatings method in comparison with traditional methods are shown.

The Influence of Low-Frequency Vibrations on the Lipid Profile in Women

Introduction: The aim of this dissertation is an evaluation of the effect of low frequency vibration on serum lipid profiling women. Materials and Methods: A group of females aged 28-64 years old were assessed twice, before and after 19 days of exposure to low frequency vibration. The parameters of the vibration used (frequency and amplitude) and the short exposition time were selected in order to comply with standards established to safeguard human health; mechanical stimulus safe for human health according to the Polish Standard PN EN ISO 2631-1:1997. The parameters used were as follows: frequency 3.5Hz, amplitude 4 mm and duration time 20 min. The main exclusion criteria for this study were: neoplasm, history of myocardial infarction, history of stroke, history of bone fracture within the two years prior to the study. To assess the effect of low frequency vibration with the parameters as specified above the following physiological and biochemical variables were used: total cholesterol serum level, high density lipoprotein (HDL) cholesterol serum level, low density lipoprotein (LDL) cholesterol serum level, triglycerides (TGD) serum level. Biochemical blood parameters were assessed before and after the trial. Friedawald’s formula was used for the assessment of LDL cholesterol serum level. Upon completion of the study and the subsequent analysis of the results obtained the following conclusions were formulated. Results: A statistically significant lowering of total serum cholesterol and LDL serum cholesterol was observed. Conclusions: The use of the vibration platform with the operational parameters specified had a beneficial effect on the variables measured.

Experimental thermal energy assessment of a liquid metal eutectic in a microchannel heat exchanger equipped with a (10 Hz/50 Hz) resonator

In the present work, an experimental investigation was conducted on the fluid flow and heat transfer characteristics of gallium-indium eutectic flowing in the microchannel passages. The overall heat transfer coefficient, pressure drop, friction factor and the thermo-hydraulic performance of the microchannel was experimentally quantified for various compositions of indium in the eutectic mixture. Influence of low-frequency vibration at two frequencies and amplitudes on the overall heat transfer coefficient and thermo-hydraulic performance of the microchannel was also studied and discussed. Results showed that the eutectic mixture has a higher thermal performance in comparison with gallium (78% enhancement in thermo-hydraulic performance). Also, the vibration increased the heat transfer coefficient of the microchannel such that at a frequency of 50 Hz and an amplitude of 10 m/s2, the highest heat transfer coefficient and thermal performance of the microchannel was registered. However, the effect of the frequency was more tangible for the eutectic mixtures with lower viscosities such as 95%Ga-5%In and pure gallium. Also, neither the frequency nor the amplitude changed the pressure drop value of the system. Interestingly, the presence of the indium in the eutectic mixture enhanced the heat transfer coefficient, which was attributed to the enhancement in the thermal conductivity of the eutectic mixture. The augmentation in the value of the pressure drop was also compensated with the anomalous increase in the heat transfer coefficient. This study revealed the plausible application of Ga-In mixture in high heat flux cooling systems inside the microchannel heat exchangers.

Influence of low-frequency vibrations on the compression behavior and microstructure of T2 copper

In this study, the influence of low-frequency vibrations on the room-temperature compression behavior of T2 copper was experimentally investigated. Upon superposing a low-frequency vibration, the forming load noticeably reduced. Among the three vibration parameters investigated, viz. frequency, amplitude, and feeding rate, vibration amplitude plays the most important role in load reduction. The superposition of stress waves can explain the mechanism of forming load reduction at low-frequency vibrations. Due to an increase in the internal stress caused by the superposition of stress waves, the required forming load reduced. The influence of the vibrations on the microstructures of compressed specimens was also discussed. Under low-frequency vibration conditions, cyclic impact loading leads to an increase in the density of dislocations and the formation of dislocation cells, which gradually evolve into new grain boundaries, causing grain refinement.

Relationship Between Psychomotor Efficiency and Sensation Seeking of People Exposed to Noise and Low Frequency Vibration Stimuli

At the workplace of the machine operator, low frequency whole body and hand- arm vibrations are observed. They occur together with noise. Whole body vibration in the range of 3-25 Hz are detrimental to the human body due to the location of the resonant frequency of large organs of the human body in this range. It can be assumed that for this reason people working every day in such conditions can have reduced working efficiency. The influence of low frequency vibration and noise on the human body leads to both physiological and functional changes. The result of the impact of noise and vibration stimuli depends largely on the specific characteristics of the objects, which include among other personality traits, temperament and emotional factor. The pilot study conducted in the laboratory was attended by 30 young men. The aim of the study was to look for correlations between the need for stimulation of the objects and their psychomotor efficiency in case of vibration exposure and vibration together with noise exposure in variable conditions task. The need for stimulation of the objects as defined in the study is based on theoretical assumptions of one dimensional model of temperament developed by Marvin Zuckerman. This theory defines the need for stimulation as the search for different, new, complex and intense sensations, as well as the willingness to take risks. The aim of research was to verify if from four factors such as: the search for adventure and horror, sensation seeking, disinhibition and susceptibility to boredom, we can choose the ones that in conjunction with varying operating conditions, may significantly determine the efficiency of the task situation. The objects performed the test evaluation of their motor skills which consisted in keeping the cursor controlled by a joystick through the path. The number of exceeds of the cursor beyond the path and its maximum deviation was recorded. The collected data were used to determine the correlation between the working efficiency and the need for stimulation of the objects under the influence of vibroacoustic factors. The analysis of the results allowed to define a set of criteria that make up the arduous working conditions. The obtained results indicate the need for the continuation of the research.

Influence of low-frequency vibrations on the structure of amorphous Ti40.7Hf9.5Ni44.8Cu5 alloy

The amorphous Ti40.7Hf9.5Ni44.8Cu5 melt-span ribbon samples were subjected to low-frequency vibrations (20Hz) with an amplitude of 1 or 4μm at room temperature to study the influence of the vibrations on the structural relaxation and the crystallization of amorphous alloy. The results obtained showed that the samples retained the amorphous structure after low-frequency vibrations but the resistivity decreased due to some structural relaxation. It was found that the low-frequency vibrations with an amplitude of 4μm led to the formation of nanoclusters with ordered atomic position in the amorphous structure, but it hardly affected the crystallization temperatures.

Influence of Low-Frequency Vibration and Modification on Solidification and Mechanical Properties of Al-Si Casting Alloy.

One of the major aims of the modern materials foundry industry is the achievement of advanced mechanical properties of metals, especially of light non-ferrous alloys such as aluminum. Usually an alloying process is applied to obtain the required properties of aluminum alloys. However, the presented work describes an alternative approach through the application of vibration treatment, modification by ultrafine powder and a combination of these two methods. Microstructural studies followed by image analysis revealed the refinement of α-Al grains with an increase in the Si network area around them. As evidence, the improvement of the mechanical properties of Al casting alloy was detected. It was found that the alloys subjected to the vibration treatment displayed an increase in tensile and yield strengths by 20% and 10%, respectively.

Influence of low-frequency vibrations on blood flow improvement in human's limbs.

The fundamental cause of diabetic limbs' problem is insufficient blood supply. The aim of the current work was to experimentally and numerically investigate the blood flow velocity and pressure changes in the channel during vibrational excitation. The micro-scale Particle Image Velocimetry (μPIV) technique as well as corresponding numerical channel model in COMSOL Multiphysics software were used to investigate the influence of external vibrations. Momentum upstream flow were noted on the fluid that was influenced by vibrations. Furthermore, momentum flow velocity increased by more than 3 times in both experimentally and theoretically. These results show that suggested novel low-frequency vibrational excitation method should be investigated in clinical studies in case of improvement of blood circulation in human limbs.

Influence of low-frequency vibrations on the chemical reaction rate in the liquid phase for reagent association

A bistable state of a reaction system was theoretically shown to be possible for a multistage chemical reaction in the case of reagent association. The conditions for the bistability origin with a possible substantial change in the rate of reaction product formation were determined. The conditions for the appearance of oscillations of intermediate concentrations and the possibility for the origination of the corresponding acoustic frequencies were studied. The action of external vibrations with the frequency coinciding with that of intrinsic intermediate concentration oscillations can increase the reaction rate of reaction product formation.

Longwave Marangoni instability in a binary mixture under the action of vibration: Influence of the heat transfer on a free surface

We study the influence of low-frequency vibration on a longwave Marangoni convection in a layer of a binary mixture with the Soret effect. Heat loss at a free surface is taken into consideration. Linear stability analysis is performed numerically by means of the Floquet theory. It is shown that with the increase in the Biot number B, the system is stabilized. For heating from below, a crossover is found in a narrow interval of the Soret number: the stability domain decreases stepwise for arbitrary small B.

Phase-sensitive and fast-scanning laser probe system for diagnosis of high frequency acoustic wave devices

This paper describes a phase-sensitive and fast-scanning laser probe developed by the authors’ group for the diagnosis of acoustic wave devices used as a platform of highly sensitive sensors. Surface vibration is detected by the Sagnac interferometer, which is insensitive to low frequency vibration. From this feature, we can maximize the scanning speed without influence of low frequency vibration and sacrificing the signal-to-noise ratio of the measurement. It is demonstrated that high quality twodimensional (2D) image of acoustic wave field patterns can be captured in minutes order. Currently the maximum applicable frequency is 2.5 GHz. Because of the phase sensitivity, the measured field in the space domain is readily converted into the wavenumber domain by the 2D Fourier Transform. It is also demonstrated how effective the wavenumber domain analysis is for the purpose.

Influence of low-frequency vibration on the structure and properties of cast iron

Influence of low-frequency vibration on the structure and properties of cast iron