Use Of Mechanical Vibrations Research Articles

Mechanical Vibration - A quick and EfficienMethod of Removing Damaged Prosthesis from its Cemented Position

Implant replacement or revision surgery in thehuman body ranks among the most demanding surgeries that orthopedic surgeons encounter in modern medicine.The removal of the hardened bone cement which securesthe implant within the bone, is the cause of a lengthyoperation. Often the use of sharp surgical instruments,ultrasonic devices etc. are employed, however all thesemethods are time-consuming and present variouscomplications.This paper describes the use of mechanical vibrations at afrequency of 40 Hz, on samples of implants anchored inanimal (pig) bone cavities with bone cement. Using a rotaryhammer drill equipped with a specially designed adaptor, toengage the tip of the implant, good results were obtained.The implant with its cement mantle was removed in a shorttime not exceeding 22 seconds.The procedure appears to be safe and is accomplished ina short time, commensurate with what is required inrevision surgery.

Gravity-driven powder flow and the influence of external vibration on flow characteristics

The controlled and homogeneous flow of dry granular powders through hoppers is essential for applications, namely, packaging of food grains, fertilizers and additive manufacturing processes such as directed energy deposition for better product quality. One of the major issues encountered in the granular flows through hoppers is flow stagnation due to the well-known arching phenomenon. Vibration-assisted granular flow through hoppers is one of the mechanisms used for better mass flow control. In this work, the influence of external mechanical vibration on the powder flow is investigated experimentally and using discrete element simulations. First, the mass flow rate through the hopper increases with an increase in vibration amplitude and then decreases, signifying the existence of an optimal amplitude of vibration. The DEM simulations explained the underlying mechanisms for the existence of an optimal amplitude of vibration corresponding to the maximum mass flow rate. A range of vibration amplitudes from 0 mm to 3.5 mm is used to study the flow behaviour; the maximum flow of around 33 g/s to 35 g/s is observed for 0.75 mm to 1.25 mm vibration amplitude for the hopper-particle combination studied in this work. The work also reports the influence of vibration frequency, hopper, and particle dimension on the flow characteristics. The research facilitates the effective use of mechanical vibration to enhance powder flow that can further be extended to non-spherical and multi-material particles.

41757 Investigating Preferences in the Use of Mechanical Vibration as a Topical Anesthetic

41757 Investigating Preferences in the Use of Mechanical Vibration as a Topical Anesthetic

New investigation of Micro-fluidized bed: The effect of wall roughness and particle size on hydrodynamics regimes

This study presents a new design for Micro-fluidized beds (MFBs), together with a new approach to their hydrodynamic analysis. Two 4 mm MFB reactors were manufactured from glass and resin (constructed by stereo-lithographic 3D printing), to assess the influence of wall roughness on the hydrodynamic characteristics. The novel 3D printing scheme ensures air tightness and good transparency of the reactor. Four types of glass, SiC, Al2O3 and TiO2, belonging to groups B, A/C and C from Geldart's classification, were used to investigate the influence of particle size on their fluidization behavior in MFBs. Three grades of MFB wall roughness were tested. Mechanical vibration energy was applied to the MFBs to improve the quality of fluidization, and to overcome wall friction and cohesive forces. Their hydrodynamic properties were obtained by analyzing pressure fluctuations in the time and frequency domains. The results show that only an appropriate increase in wall roughness was helpful for the suppression of slugging fluidization. The use of mechanical vibrations was found to promote the attenuation or destruction of plug phenomena, thus improving the quality of fluidization of Group A/C and C particles. The feasibility of fluidizing group A/C and C particles has thus been verified in a 3D printed MFB reactors.

ВОЗДЕЙСТИЕ МЕХАНИЧЕСКИХ КОЛЕБАНИЙ НА ОБЛЕДЕНЕНИЕ ИСПАРИТЕЛЕЙ ВОЗДУШНОГО ТЕПЛОВОГО НАСОСА

The analysis of the reasons for the insignificant spread of air heat pumps in countries with a cold winter period is carried out. Problems arising in the heat exchanger of the outdoor unit of the heat pump during operation in heating mode are indicated. The existing methods of anti-icing of outdoor units are considered, and their effectiveness is demonstrated, taking into account the cost of electricity and the problem of utilizing condensate. The possibility of removing ice from evaporators of air heat pumps using the method of high-frequency mechanical vibrations has been investigated. Laboratory equipment has been designed and tested for experimental research of high-frequency oscillations in the structures of evaporators manufactured by an industrial method. The possibility of their use in heat pumps, where the fight against frostbite is carried out by the method of mechanical vibrations, is considered. Investigations of evaporators of air heat pumps with different types of coolant for removing ice by means of mechanical vibrations on the surface of the heat exchanger have been carried out. Methods of fastening piezoceramic emitters to evaporators of various designs are considered. A comparative analysis of the materials used in the design of evaporators, a comparison of their acoustic properties and thermal conductivity, and recommendations on the selection of material for further research to improve the efficiency of ice destruction from the surface of evaporators are given. Ways of increasing the degree of cleaning of evaporators from ice are identified, recommendations are given for further research on the use of mechanical vibrations to combat frostbite of heat exchangers in air heat pumps under conditions of operation at low ambient temperatures

Contributions Regarding the Use of Mechanical Vibrations in Order to Improve the Properties of Steels and Welded Joints Used in Metal Constructions

The paper presents aspects regarding the influence of vibrations on the mechanical properties of welded joints, made with basic materials of Spanish and Romanian origin. In this research is presented the practical way to make the necessary assemblies for the proposed tests. The tests show that vibrations have a significant contribution to the quality of welded joints. This is explained by the appearance of several crystallization centres which makes the structure finer. By using vibrations, the atoms are rearranged in the structure, ensuring a proper de-tensioning. The stresses induced in welded metals are significantly reduced by the use of vibration during welding process. The addition materials have a significant contribution to the emergence of stresses in welded joints as well. These stresses can contribute to the appearance of microstructural constituents with significant hardness. The welding equipment and technologies used also have a significant contribution to the emergence of the remaining stresses. For example, the submerged arc welding technology (SAF) can introduce very high internal stresses. By using vibrations during the welding process, it is achieved a fine structure and a significant reduction of remaining stresses in the welded joints.

Harvesting the vibration energy of α-MnO2 nanostructures for complete catalytic oxidation of carcinogenic airborne formaldehyde at ambient temperature

Vibration is one of the most prevalent energy sources in natural environment, which can also be harvested and utilized to drive chemical reaction. Herein, mechanical vibration is used for enhancing the catalytic decomposition of formaldehyde at ambient temperature with the assistance of four well-defined morphologies α-MnO2 (nanowire, nanotube, nanorod and nanoflower). In particular, α-MnO2 nanowire exhibits the best catalytic activity, which can completely mineralize formaldehyde into carbon dioxide at ambient temperature by harvesting the vibration energy. To the best of our knowledge, this may be the first report that α-MnO2, as a non-noble metal catalyst, can completely decompose formaldehyde to carbon dioxide at ambient temperature. The characterization results show that α-MnO2 nanowire has a much higher oxygen vacancy concentration than other three catalysts. In addition, thermal effect generated from friction between nanoparticles induced by ultrasonic vibration may enhance its catalytic activity. More importantly, it is the vibration that effectively promotes the activation of O2 adsorbed on the surface oxygen vacancy to produce more ▪, thus increasing the catalytic decomposition performance. The strategy presented herein demonstrates a new approach for efficient use of mechanical vibration to improve catalytic activity of traditional catalysts.

Rendering Strategy to Counter Mutual Masking Effect in Multiple Tactile Feedback

Recently, methods and devices that simultaneously utilize two or more tactile feedback types have been proposed for more immersive interaction with virtual objects. However, the masking effect, which makes us less sensitive to various stimuli presented at the same time, has scarcely been explored. In this study, we propose a novel tactile rendering algorithm that can eliminate the mutual masking effect at the user’s sensation level, when mechanical vibration and electrovibration are applied simultaneously. First, the masking functions of the two stimuli were investigated for various stimulus combinations. Based on these, a generalized form of the masking function was derived. We then tested and confirmed that the proposed algorithm, which calculates the required stimulus intensity to compensate for the mutual masking effect, could render the arbitrary stimulus intensity desired to be perceived by the users. The results of the user test revealed that the proposed rendering algorithm significantly improved the virtual object recognition rate by approximately 23% when geometry and texture were presented jointly. This finding suggests principal guidelines for the combined use of mechanical vibration and electrovibration, as well as for other combinations of different tactile feedback types.

UTILIZATION OF ADMIXTURES IN SELF-COMPACTING HIGH PERFORMANCE CONCRETE

Flow-able concrete or self-consolidating or self-compacting concrete (SCC) is a particularly flow-able, non-segregating concrete which flows, plugs form-work, and captures the utmost congested rebars with none use of mechanical vibration. When used with admixtures to enhance the performance of concrete, it is called as self-compacting high performance concrete. An extant literature survey was taken up to understand the utilization of waste polyethene, fly ash and micro-silica in SCC to make it a SCHPC. It has been seen that very less amount of research work is available on use of waste polythene in conventional concrete as well as SCC. A few studies have reported positive results towards the mechanical properties i.e. compressive strength and flexural strength of concrete while no literature is available taking into account its initial cost and the durability aspects of such concrete.

Macaw palm supply chain: Evaluation of a semi-mechanized fruit harvesting system

The macaw palm (Acrocomia aculeata) is native to Brazil and is a promising crop for oil extraction for biodiesel production. Production methods are still lacking, as well as the in-depth knowledge required for domestication and improved fruit harvesting. The use of mechanical vibrations, which is well established in crops such as coffee, may help to develop harvesting methods. Therefore, this study evaluated the operational performance of a semi-mechanized macaw palm fruit harvester prototype. The prototype was evaluated in field tests conducted in Araponga, Minas Gerais, with plants originating from accessions in Minas Gerais and Mato Grosso do Sul. The evaluations were based on data involving operational capacity, operational efficiency and damage to fruits. The prototype presented an average operational capacity of over 90 %, thus validating the use of mechanical vibrations for macaw palm fruit harvesting.

Normalized Modeling of Piezoelectric Energy Harvester Based on Equivalence Transformation and Unit-Less Parameters

Micro-electromechanical systems are ubiquitous in several energy harvesting solutions and can be used in applications such as bio-implantable devices and wireless micro-sensors. Piezoelectricity is an interesting key to perform the interface between environmental extracted energy and the power delivered to the load due to the use of mechanical vibration and resonance features. However, it is necessary for a detailed analysis in order to obtain an accurate understanding of the system. In this regard, some works deal with the normalization procedures to analyze the piezoelectric component behavior based on the mechanical resonance frequency. In order to enhance the system modeling, the electromechanical resonance frequency must also be analyzed. This paper deals with an approach to model the piezoelectric component that allows analyzing several unitless parameters that are critical to improve the performance of the system. In addition, a state-space model for the piezo-harvester based on the Class-E resonant rectifier is presented. Some experimental results are shown to validate the theoretical approach. [2019-0082]

Effects of vibration on pool boiling heat transfer from a vertically aligned array of heated tubes

In the present study, the use of mechanical vibration for the enhancement of pool boiling heat transfer is evaluated theoretically. For this purpose, a vertical array of vibrating circular tubes is considered. The array is submerged in a pool of water under atmospheric conditions and electrically heated for boiling to occur on the tube surfaces. To model this phase-change phenomenon, a two-fluid formulation is employed and accompanied by the Rensselaer Polytechnic Institute (RPI) model to estimate the boiling heat flux on a solid surface. A comprehensive parametric study is undertaken to investigate the effects of the amplitude and frequency of vibration, the magnitude of the heat flux, and the pitch-to-diameter ratio of the array on pool boiling heat transfer in the presence of mechanical vibration. An increase of up to 90% in the heat transfer rate is achieved within the simulated operating conditions.

Control of cell behaviour through nanovibrational stimulation: nanokicking.

Mechanical signals are ubiquitous in our everyday life and the process of converting these mechanical signals into a biological signalling response is known as mechanotransduction. Our understanding of mechanotransduction, and its contribution to vital cellular responses, is a rapidly expanding field of research involving complex processes that are still not clearly understood. The use of mechanical vibration as a stimulus of mechanotransduction, including variation of frequency and amplitude, allows an alternative method to control specific cell behaviour without chemical stimulation (e.g. growth factors). Chemical-independent control of cell behaviour could be highly advantageous for fields including drug discovery and clinical tissue engineering. In this review, a novel technique is described based on nanoscale sinusoidal vibration. Using finite-element analysis in conjunction with laser interferometry, techniques that are used within the field of gravitational wave detection, optimization of apparatus design and calibration of vibration application have been performed. We further discuss the application of nanovibrational stimulation, or ‘nanokicking’, to eukaryotic and prokaryotic cells including the differentiation of mesenchymal stem cells towards an osteoblast cell lineage. Mechanotransductive mechanisms are discussed including mediation through the Rho-A kinase signalling pathway. Optimization of this technique was first performed in two-dimensional culture using a simple vibration platform with an optimal frequency and amplitude of 1 kHz and 22 nm. A novel bioreactor was developed to scale up cell production, with recent research demonstrating that mesenchymal stem cell differentiation can be efficiently triggered in soft gel constructs. This important step provides first evidence that clinically relevant (three-dimensional) volumes of osteoblasts can be produced for the purpose of bone grafting, without complex scaffolds and/or chemical induction. Initial findings have shown that nanovibrational stimulation can also reduce biofilm formation in a number of clinically relevant bacteria. This demonstrates additional utility of the bioreactor to investigate mechanotransduction in other fields of research.This article is part of a discussion meeting issue ‘The promises of gravitational-wave astronomy’.

Video based Process Observations of the Pulse Electrochemical Machining Process at High Current Densities and Small Gaps

Pulse Electrochemical Machining (PECM), a nontraditional process, using pulse-lengths in the low millisecond range as well as feed overlaid mechanical vibration, allows more precise tolerances and geometric precision through narrowing the working gap compared to conventional sinking ECM. With small working gaps in ranges down to 10μm, the anodic shape evolution during machining is getting difficult to monitor. Therefore understanding the shaping phenomena during the PECM process is key factor in achieving precision during the manufacturing of dies and molds, as well as precision parts in e.g. automotive or aircraft industry. In this contribution an experimental approach towards visual in-process observations of the PECM shaping process during the use of mechanical vibrations up to 50Hz and high pulsed current densities will be presented. Recording the process with a precisely clocked high speed camera system allowing precise μs shutter times, visual observations are conducted and being used as input for detailed downstream data analysis. The experimental study incorporates one of the most widely used flushing conditions in PECM as well as an outlook into the comparison between recorded in-process data and a static FEM simulation based on the monitored shape are given. In all experiments stainless steel of type AISI 304 (X5CrNi18–10) is used as anode and cathode material and for all PECM experiments a commercially available PEMCenter8000 with sodium nitrate as electrolyte was used. The concept presented will help to better link experiment and modelling of the PECM process, by simultaneously providing process relevant electrochemical data as well as the directly corresponding geometric shaping information during experiments.

Three-dimensional modeling of system of vibrating spherical balls using discrete element method

The modeling of particulate systems has been an important focus of research worldwide, as these are fairly common in nature, such as rain drops in air, snowfall, and several industrial processes such as chemistry, agriculture, pharmaceutical, powder metallurgy, soil mechanics, casting, cement manufacturing, civil, and etc. In recent years, one of important aspects of the granular material physics in industries is controlling way of the granular flow. One of the best ways of controlling the flow is the use of mechanical vibrations to guide the particles in desirable way. In this paper the effect of horizontal harmonic vibration on the particles flow is theoretically and experimentally investigated. During the base vibration, the spherical particles collide with each other and with the walls as well, causing a global pattern of particle motion which is interpreted as flow. The motion of spherical particles and the interaction forces due to the vibration is obtained numerically via discrete element method (DEM). Finally, the presented numerical model is compared with the experimental one and a good agreement between them is noticed.

Efeito agudo dos extensores do joelho unilateral na cadeira extensora com e sem estímulos na plataforma vibratória

INTRODUÇÃO: Nos últimos anos muitos estudos foram feitos com o objetivo de avaliar a utilização da vibração mecânica como parte de treinamento para melhora do condicionamento físico. Entretanto, a maioria avaliou os efeitos dos exercícios em conjunto com o treinamento vibratório para determinar se havia melhora após o treinamento, sem avaliar os efeitos dos exercícios realizados na plataforma com e sem vibração. OBJETIVO: Avaliar o efeito agudo do exercício nos extensores do joelho, com e sem o estímulo da plataforma vibratória. MÉTODOS: Trinta indivíduos ativos, do sexo masculino, com idades entre 18 e 45 anos, realizaram, de forma randomizada, três protocolos: grupo plataforma ligada (GPL), grupo plataforma desligada (GPD) e grupo controle (GC). Cada protocolo começava com aquecimento de cinco minutos em bicicleta ergométrica, com carga entre 75 e 100 watts e 70 rotações por minuto, seguido por seis séries de 10 movimentos de agachamento unilateral com intervalo de um minuto entre elas, com ou sem vibração mecânica, e terminava com o Work Test, realizado apenas no membro inferior dominante para determinação das valências físicas: trabalho, força, potência e velocidade. O grupo controle realizou apenas o Work Test após o aquecimento. RESULTADOS: Apenas a variável velocidade apresentou diferença estatisticamente significante (p < 0,05) quando comparado o GPL ao GC. CONCLUSÃO: O estímulo na plataforma vibratória não exerceu influência nas variáveis trabalho e potência dos extensores do joelho unilateral, mas, na velocidade do movimento, exerceu influência negativa causando fadiga.

The Effect of a Rapid Heating Rate, Mechanical Vibration and Surfactant Chemistry on the Structure-Property Relationships of Epoxy/Clay Nanocomposites.

The role of processing conditions and intercalant chemistry in montmorillonite clays on the dispersion, morphology and mechanical properties of two epoxy/clay nanocomposite systems was investigated in this paper. This work highlights the importance of employing complementary techniques (X-ray diffraction, small angle X-ray scattering, optical microscopy and transmission electron microscopy) to correlate nanomorphology to macroscale properties. Materials were prepared using an out of autoclave manufacturing process equipped to generate rapid heating rates and mechanical vibration. The results suggested that the quaternary ammonium surfactant on C30B clay reacted with the epoxy during cure, while the primary ammonium surfactant (I.30E) catalysed the polymerisation reaction. These effects led to important differences in nanocomposite clay morphologies. The use of mechanical vibration at 4 Hz prior to matrix gelation was found to facilitate clay dispersion and to reduce the area fraction of I.30E clay agglomerates in addition to increasing flexural strength by over 40%.

Pollination of habanero pepper (Capsicum chinense) and production in enclosures using the stingless bee Nannotrigona perilampoides

SummaryA flower isolation experiment was conducted to determine the effect of self and cross pollination in habanero pepper (Capsicum chinense) in Yucatán, Mexico. The number of fruits increased, differing significantly (p<0.01) between bagged flowers (BF=25%), flowers that received one visit (V= 79%) and those with unrestricted visits (UV=86%). Likewise the numbers of seeds and the fertilization index differed significantly between treatments (p<0.01). In a second experiment, the efficiency of the stingless bee Nannotrigona perilampoides (SB) for pollinating this crop was evaluated. The quality of the fruit and the production in kg/m2 were not different between SB and mechanical vibration (MV) but the latter showed significantly lower values in the polar diameter, weight and number of seed per fruit (p<0.01). Both SB and MV showed significantly higher values compared with a test treatment where no pollinator was used in all the evaluated variables (p<0.01). We conclude that C. chinense can be self pollinated but cross pollination is needed to increase the number and quality of fruits and especially for high seed production probably due to the increased transference of pollen grains. The use of N. perilampoides seems a good alternative to the use of mechanical vibration and non native bees for pollination of peppers in enclosures under tropical conditions.

Continuous wavelet transform technique for fault signal diagnosis of internal combustion engines

A fault signal diagnosis technique for internal combustion engines that uses a continuous wavelet transform algorithm is presented in this paper. The use of mechanical vibration and acoustic emission signals for fault diagnosis in rotating machinery has grown significantly due to advances in the progress of digital signal processing algorithms and implementation techniques. The conventional diagnosis technology using acoustic and vibration signals already exists in the form of techniques applying the time and frequency domain of signals, and analyzing the difference of signals in the spectrum. Unfortunately, in some applications the performance is limited, such as when a smearing problem arises at various rates of engine revolution, or when the signals caused by a damaged element are buried in broadband background noise. In the present study, a continuous wavelet transform technique for the fault signal diagnosis is proposed. In the experimental work, the proposed continuous wavelet algorithm was used for fault signal diagnosis in an internal combustion engine and its cooling system. The experimental results indicated that the proposed continuous wavelet transform technique is effective in fault signal diagnosis for both experimental cases. Furthermore, a characteristic analysis and experimental comparison of the vibration signal and acoustic emission signal analysis with the proposed algorithm are also presented in this report.

Analysis of Excavation Processes for the Purpose of Realizing Intelligent Excavation Machinery. 3rd Report. Physical Parameters Measured in Three-dimensional Excavation Using a Real-sized Bucket.

In order to investigate problems related to soil and construction machinery, such as a hydraulic excavator, an understanding of the physical interactions between the soil and the machine is essential. The purpose of this study is to empirically examine actual excavation processes by measuring various physical parameters. In this article we present results from the outdoor excavation experiments in which two different soil types, sand and loam, were excavated by using a real-sized bucket equipped with many sensors. Several physical parameters were measured such as excavation load, lateral and longitudinal distributions of pressure and friction exerted on the bucket surface and fracture of soils. Also effects of artificially reduced friction of the bucket surface were tested in two different ways; use of a low friction polymer and use of mechanical vibration.