Harmonic Vibration Research Articles

APPLICATION OF VISCOELASTIC SYSTEMS IN OIL PRODUCTION INTENSIFICATION PROCESSES

This paper provides an overview of viscoelastic behavior and the use of viscoelastic fluids (VBLs) in various oil production intensification processes. The first part provides basic models describing viscoelastic behavior and corresponding equations of state. Describes the method of testing under the action of harmonic vibrations (method of dynamic tests), possible options for its implementation and the determined rheological properties of the viscoelastic sample. To interpret the results of dynamic tests, a complex module is most often introduced, which consists of two components — the elastic modulus (G’) and the loss modulus (G’’). These dynamic modules and their relationship describe the behavior of the viscoelastic sample. It is shown that with respect to modules, it is possible to conclude on the type of sample - viscoelastic liquid or viscoelastic body. It is also noted that dynamic tests should be carried out in the area of low amplitudes of oscillating loads, in which the rheological properties do not depend on the applied stress or strain. The second part provides examples of viscoelastic systems used in operations such as water flow isolation, hydraulic fracturing, and modified acid treatments. The most common viscoelastic systems used in various technologies are solutions of surfactants and polymers of different structures. It is noted that in order to obtain a viscoelastic gel, polymer solutions are used with a crosslinker, while the rheological properties of surfactant solutions are controlled by external factors — pH, temperature, water mineralization. Viscoelastic surfactant solutions have an advantage over polymer solutions ‑ they are able to recover their properties after mechanical or thermal exposure due to the formation of supramolecular structures as a result of selforganization of surfactant molecules. The surfactant-based HLT property of reversibly collapsing and recovering is used, in particular, to reduce pressure losses to overcome friction. In flow-deflecting acid compositions, viscoelastic surfactants are mainly used, the most common of which are given in the second part of the article.

Developing a Robust Process for Design Margin Calculation Through Modal Scaling and Harmonic Analysis of Engine Mounted After Treatment System

The last few years have seen an increase in the complexity of emission standards. This has caused OEMs to start using Exhaust Gas Processors (EGP) or Exhaust After Treatment Systems (EATS)in complex integration. These systems are usually mounted on vehicle chassis or engine body with the help of mounting straps or brackets. The arrangement of the system leads to road loads and/or engine vibrations being transferred and causing damage to its components. New BS VI engines need some AT (After treatment) components to be mounted directly on the engine and others to chassis. The components that are directly mounted on engine are called close couple AT system which are subjected to engine harmonic vibrations which falls under forced vibration criteria. Most of the AT system are subjected to random vibrations and industry has a well-defined procedure to address the problem, but for harmonic vibrations there is no specific approach. In order to optimize the structural durability of close couple AT system against HCF (high cycle fatigue) fatigue harmonic vibration, there is a need for well-defined test analysis correlation procedure. The objective of this work is defining and documenting a robust process for design margin through calculation modal scaling and harmonic analysis of close couple AT system through test analysis correlation activity. Analytical, numerical and testing data were compared and conclusions are drawn. More case studies can be added to this work in order to validate the test analysis correlation activity and boost the degree of confidence. Future study may include recording additional failure modes in addition to the harmonic HCF failure mode.

Dependence of the Values of Inter-Component Phase Relations of the Harmonic Components of Vibration on the Displacement of Misaligned Shafts

The analytical dependence of the phases and values of intercomponent phase relations of the harmonic components of vibration displacement of misaligned shafts on their displacement has been presented in the article. Harmonic vibrations of the shafts were modeled using a Lagrangian connecting vibration displacement and forces acting in the system. For ease of derivation, the Lagrangian is rewritten in complex form. The resulting algebraic equations connect the complex amplitudes of vibration components with the amplitudes of periodic forces at the same frequencies and the parameters of the mechanical system (stiffness, damping). The amplitudes of periodic forces are related to the magnitude of the shafts angular and parallel misalignment according to the accepted model. Calculation of intercomponent phase relations values is used to get rid of the random initial phase shift caused by the choice of the timing reference. The magnitude of the effect produced by the misalignment of the shafts on the amplitudes and values of the intercomponent phase relations of the signal components is estimated. The obtained resultcan be used to construct devices for estimation shaft displacements and devices for assessing the condition of equipment based on the analysis of vibration signals.ls.

Development of HOTS-Based Interactive E-Modules to Train High School Students' Critical Thinking Skills on Harmonic Vibration Material

The goal of this project is to create an interactive e-module using Hots to teach high school students how to think critically about content related to harmonic vibration that is both realistic and well-received by the students. Thirty-five pupils from class X SMAN 01 Bengkulu City provided the data for this study. The 4D model research method—which stands for Define, Design, Develop, and Disseminate—is used in this study. The study employed many instruments, including observation sheets, student impression sheets, instructor needs questionnaires, and expert team validation sheets. In order to aid students in understanding the teaching materials, the resulting e-module includes text, tables, graphics, formulas, and learning videos. Additionally, an interactive quiz within the e-module allows students to practice their skills. The results of this study indicate that the developed e-module is included in the very feasible category with a value of 87.2%. Students' perception of this e-module is included in the very good category with a value of 84.4%.

Ekstraksi Frekuensi dari Bunyi Alqurans dengan Metode Discrete Fourier Transform: Studi Kasus Bunyi QS. Al-Fatihah

The Quran is a miracle received by the Prophet Muhammad. Alquran can use to reduce anxiety in patients with acute coronary syndrome, hemodialysis, schizophrenia, etc., when the sound retardation of this Qur'an, especially QS. Al-Fatihah. The physical properties of waves can be analyzed using the discrete Fourier transform method for frequency extraction. This method is scripted using the Python programming language. The results show that frequency in Qs. Al-Fatihah/1:1-7 are random in range 150 Hz – 800 Hz.Thus, the frequencies of the Quran, especially QS Al-Fatihah, are uneven waves that can cause harmonic vibrations against brain waves.

Mixing mechanism of power-law non-Newtonian fluids in resonant acoustic mixing

Resonant acoustic mixing (RAM) is a widely applied technology that utilizes low-frequency vertical harmonic vibration for fluid transfer and mixing. However, the current research on the mixing mechanism of RAM technology primarily focuses on the initial mixing stages, neglecting the subsequent turbulent transition. This lack of understanding hinders the further improvement of RAM technology. This paper aims to investigate the mixing mechanism of power-law non-Newtonian fluids (NNF) in RAM using the phase field model and the spectral analysis. The study focuses on understanding the facilitating effect of turbulent transition in mixing and explores the influence of the power-law index and the excitation parameter on the mixing characteristics. The results indicate that the flow field experiences Faraday instability due to the intense perturbation during transient mixing. This leads to the fluid mixing through the development of large-scale vortex to small-scale vortex. During this process, the frequency components of the flow field are distributed around the working frequency, demonstrating transient and broad frequency characteristics. The steady state then dissipates energy through the viscous dissipation of small-scale vortices and ultimately relies on the single-frequency components such as submultiples and multiples excited by the nonlinear effect to complete the mixing. The mixing effects of NNF and Newtonian fluids (NF) are essentially the same, but they consume energy in different ways. The mixing uniformity and mixing efficiency of NNF increase with increasing vibration acceleration and decrease with increasing vibration frequency. These findings provide new insights into the RAM mechanism of power-law NNF.

A Two-Stage Mathematical Model for Evaluating the Modes of Forced Vibrations of an Aircraft Skin Element with the Use of Fiber-Optic Technologies

The purpose of research is development of a mathematical model of vibration vibrations of an aircraft skin element made in the form of a plate with a two-stage transformation "vibration load parameters – deformation of the plate - change in the wavelength of the optical signal" in order to take into account the number of loading cycles and their characteristics, accumulated fatigue deformation of the plate and its life before the critical state in order to optimize planned repairs and reducing the risks of unpredictable failures associated with fatigue phenomena in the skin material and supporting structures of the aircraft.Methods. The described mathematical model uses the parameters of a harmonic vibration signal as input data and includes a two-stage transformation, firstly, of the parameters of the vibration signal (frequency, amplitude) into the amplitude of the vibration vibrations of the aircraft skin element made in the form of a plate, secondly, the amplitude of the vibrations of the plate in question into a change in the wavelength of the optical signal, the presence of which is caused by the use of fiber-optic technologies that are promising for the construction of modern systems for monitoring and diagnostics of aircraft.Results. The proposed mathematical model allows calculating and analytical methods to estimate the amplitude of forced vibration vibrations of the aircraft skin element, which causes the absence of plate resource consumption due to the effects of loading cycles (there is only natural aging of the material), plate resource consumption in elastic deformation mode, accumulation of fatigue deformation of the sample. The method of evaluating the plate for the resonant effect is given, which indirectly affects the processes of designing the elements of the aircraft skin in terms of weight and size indicators, which largely determine the frequency of natural vibrations of the plate. The resulting deformation of the plate is expressed in a change in the wavelength of the light beam for detection and analysis by the control and diagnostic system of the aircraft, made on the basis of fiber-optic technologies.Conclusion. The proposed mathematical model is designed to assess the residual life of a specific element of the aircraft skin, involves subsequent software modeling to confirm the correctness or refinement of the resulting calculation algorithm.

Study on the Mechanism and Suppression of Harmonic Vibration of AMB-Rotor System

The AMB-rotor system is complex and has strong coupling characteristics, which allows multi-harmonic disturbances to enter the system through different ways to produce vibrations with rich spectrum components, which has a great influence on the improvement of micro-vibration accuracy of the rotor system. To further achieve active control of the micro-vibration in the AMB-rotor system, firstly, the mechanism of multi-source disturbance is analyzed according to the working principle of the AMB-rotor system, and the mathematical and physical relationship between the mechanism of disturbance generation and the inducement is deeply studied. Then, the structure of a novel adaptive notch filter, the method of adaptive frequency estimation and analysis of harmonic current suppression in the AMB system are presented. Finally, simulation and experimental research using an MSCMG system demonstrate the feasibility of the proposed method regarding the elimination of harmonic control current.

On magnetization deviations as the dominant cause for vibration harmonics in the spectrum of a PMSM drive

On magnetization deviations as the dominant cause for vibration harmonics in the spectrum of a PMSM drive

Influence of structural damping and fluid compressibility on harmonic vibrations in concrete gravity dam

Influence of structural damping and fluid compressibility on harmonic vibrations in concrete gravity dam

Harmonic vibration suppression of MSCSG Based on an Improved Multiple Resonant Controller

Harmonic vibration suppression of MSCSG Based on an Improved Multiple Resonant Controller

Harmonic vibration suppression in active magnetic bearing systems with adaptive notch filter and repetitive control

Harmonic vibration suppression in active magnetic bearing systems with adaptive notch filter and repetitive control

Synthesis, spectroscopic, crystal structure and Hirshfeld surface analysis and DFT calculations of (E)-N-(2,6-dichlorophenyl)-1-(5-nitro-2-(piperidin-1-yl)phenyl) methanamine

In this study, experimental methods X-ray single crystal analysis, UV-vis spectroscopy and FT-IR spectroscopy, and theoretical methods Density Functional Theory (DFT) were used to study the structure of the new Schiff base (E)-N-(2,6-dichlorophenyl)-1-(5-nitro-2-(piperidin-1-yl)phenyl) methanamine. Theoretical calculations of the title compound and FT-IR harmonic vibration frequencies were carried out using B3LYP methods with the 6-31G(d,p) basis set. The optical properties have been studied by DFT calculation and the experimental UV-Vis spectrum presents its contribution to the HOMO-LUMO boundary. The molecular electrostatic potential map (MEP-ESP), analysis of frontier molecular orbitals (FMO), and determination of thermodynamic properties for the title compound were conducted using identical levels of theory. Besides, the structural state and crystal packing of the title compound were analyzed using molecular structure, Hirshfeld surfaces, interactions energies, energy frameworks and electrophilicity-based charge transfer (ECT) with DNA bases.

Examination of Fractures in Excavator Full Guardrails Using Vibration Based Finite Elements Method

Abstract
 There are multiple standards and safety measures in excavator construction machines. In this way, the safety of operators, maintainers or individuals around the work machine is ensured. Guardrails on excavators are also included in these standards. These structures, which are constantly used by operators, maintainers and test workers, are exposed to high vibration. Due to high vibration, fractures or cracks may occur, especially in the railing welding areas. In this article, Modal, Harmonic and Random Vibration analyzes of the full guardrail on a HİDROMEK excavator work machine will be performed. The acceleration values ​​to which the guardrails were exposed during working conditions were measured and tested from different regions. In this study, the test data measured on the machine is analyzed using MSC Nastran-Patran.
 Keywords: Guardrails, vibration, excavator

ON SOME NONSTANDARD PROBLEMS ON HARMONIC MOTION

This article is devoted to approaches to solving one type of non-standard problems about harmonic motion and issues of their teaching. The motions observed in such tasks are not of an oscillatory nature, and at first glance it is difficult to notice their hidden connection with oscillatory motion. However, a correct and in-depth analysis of the physical situation can reveal this initially invisible connection. By understanding the relationship between the observed motion and the corresponding harmonic vibrations, the problem can be solved using the idea of similarity. After the introductory part, two non-standard problems are considered, the first of which is solved by the force method, and the second by the energy method. A comparative analysis of the strengths and weaknesses of the use of force and energy methods in solving such problems was carried out. The body of the article develops a standard physics problem and brings to the level of an Olympiad task (by adding an additional question). The final part of the paper reveals the possibility of generalizing the discussed approach by implementing the apparatus. The scientific and methodological novelty of this work lies in the revision, development and presentation of problems and their solutions related to the harmonious motions of bodies or those close to them.

Features of using the over-skiving method for multi-pass cutting of external gears

Problem. There is a problem of determining the working parameters, including axial feed and cutting speed, as well as the helix angle of the teeth of the disc cutter and the tool spindle, the geometry of the cutting part, and the cutting depth per pass in Power skiving technology.Objective. It is necessary to investigate the cutting process using the Power Skiving method for generating external gears over multiple passes and develop recommendations for selecting its optimal parameters.Implementation methodology. The cutting force and its tangential component acting on the cutter are presented based on the fundamental principles of cutting theory, using the function of the cross-sectional area of the cut, the material strength limits of the workpiece for shear, and the intensity of plastic deformation of the chip. Calculations of the cut area are based on a graphoanalytical 3D model of the undeformed chip. The coefficient of shear intensity is determined depending on the thickness of the cut layers using the Deform 2D system. The study of the force factors is conducted in the initial stage for single-tooth cutting, considering the operation of a single tooth of the tool, and for multi-tooth cutting conditions, corresponding to real cutting and forming conditions in this method.Results. Analysis of harmonic vibrations with different frequencies of the investigated forces indicates that, under average loading, the maximum principal component of the cutting force occurs on the third pass, and the tangential force on the tool axis occurs on the first pass. The variation in the frequency of these signals is explained by changes in the contact angle between the tool and the gear wheel in the machine engagement and the different number of teeth involved in cutting.Conclusions. The obtained data allowed the development of a methodology for selecting rational parameters - axial feed values, the number of passes with different cutting depths to minimize time consumption, and achieve the desired accuracy of gears. It has been demonstrated that to reduce processing errors, it is most rational to decrease cutting force by increasing the number of passes, rather than reducing the axial feed.

Calculating permissible deviations of vibration accelerations of printed circuit assemblies by simulation modeling

Objectives. A variety of technical condition control methods are used in the production and operation of printed circuit assemblies (PCA) for radio-electronic means (REM). The main methods are optical, electrical, and thermal. However, not all possible defects can be detected using these methods. For example, a weakened PCA fastener in a block or the incorrect installation of an electric radioelement (ERE) on a printed circuit board (PCB) can be detected only by analyzing the mechanical characteristics of the REM. These factors, in particular, are the values of the vibration acceleration amplitudes on ERE or at selected PCB control points (hereinafter referred to as the PCA vibration acceleration amplitude). In order to draw a conclusion about the presence of a defect, the measured values of the vibration acceleration amplitudes obtained as a result of testing PCA for the effects of harmonic vibration are compared with the permissible values calculated during the simulation of mechanical processes in PCA. This takes into account the variations in the physical and mechanical parameters of materials and geometric parameters of the PCA design. The aim of this paper is to determine the permissible values of PCA vibration acceleration amplitudes to be compared with the measured values.Methods. The Monte Carlo simulation method is used to calculate the permissible deviations of vibration accelerations. This consists in repeatedly calculating the values of the vibration acceleration amplitudes at random values of the physical and mechanical parameters of materials and geometric parameters of the PCA design within their tolerances.Results. Experimental verification of this method was carried out using the SolidWorks software for modeling mechanical processes. This enabled the tolerance values for PCA vibration acceleration at the control point at the first resonant frequency to be established and experimental data to be obtained when introducing various defects. The results of comparing the measured values with the calculated tolerance enabled conclusions to be made with regard to the possibility of detecting PCA defects.Conclusions. Using this method of calculating tolerances for the PCA vibration acceleration amplitude allows the presence of defects in REM that do not affect the electrical or thermal characteristics of REM to be determined, thus increasing the efficiency of technical condition control.

Passive damping of vibrations of plates and cylindrical shells interacting with a flowing fluid using piezoelectric elements

The paper presents a mathematical formulation of the problem of natural and forced harmonic vibrations of electro-elastic thin-walled structures interacting with a flowing fluid. The numerical algorithm based on the finite element method is used to choose optimal parameters of a shunt electric circuit for problems of passive vibration damping. The key idea behind the proposed approach is a solution of eigenvalue problem. It allows us to obtain higher damping rate of free vibrations compared to those evaluated by the commonly used analytical expressions and leads to the smallest difference in the natural frequencies of the structure and the electric circuit.

Highly adaptive and broadband triboelectric energy harvester with stretching silicone rubber strip for variable harmonic frequency vibration

Highly adaptive and broadband triboelectric energy harvester with stretching silicone rubber strip for variable harmonic frequency vibration

Acceleration mechanism of abrasive particle in ultrasonic polishing under synergistic physical vibration and cavitation: Numerical study

Ultrasonic technology is widely applied in the engineering ceramic polishing processes without the limitation of material properties and ideally integrated into computer numerical control system. Ultrasonic-induced cavitation and mechanical vibration effect could accelerate the motion of solid abrasives. The individual behaviors of microjet/shockwave of ultrasonic cavitation in gases and liquids, and micro-abrasives with simple harmonic vibrations in solids and liquids has been extensively studied. To conduct a systematic and integrated study of abrasives behavior in the polishing contact region involving abrasive, surround-workpiece wall, ultrasonic physical vibration, and ultrasonic cavitation impact, a novel model integrating the free abrasive motion velocity and fixed abrasive indentation depth under multi-scale contact was proposed according to Hertzian contact theory, Greenwood-Williamson model, indentation deformation theory, the basic equations of cavitation bubble dynamics, cavitation impact control equations, and Newton's law of motion equation. The effects of ultrasonic amplitude, ultrasonic frequency, preloading force and particle size on the proposed model were investigated by theoretical analysis and numerical simulations. Ultrasonic physical vibration mainly influences the dynamic gap and further influence the number of different abrasives. Furthermore, the indentation depth of fixed abrasive depends mainly on the abrasive geometry. As the contact gap and abrasive size decrease, the indentation depth gradually decreases. Under the synergistic effect of cavitation-induced shock wave and microjet, the velocity of free abrasive in this paper is generally 0–150 m/s, and the kinetic energy of free abrasive increases roughly linearly with increasing frequency and approximately as a quadratic function with increasing particle size. Increasing the preloading force leads to a reduction in the abrasive kinetic energy. Besides, the kinetic energy induced by the shock wave has a cliff-like increment at an amplitude of 0.7–0.8 μm. It is revealed that the abrasive kinetic energy is suppressed by the cavitation bubble expansion and collapse at smaller ultrasonic pressure amplitude and surround-wall distance. This research provides a theoretical reference for the modeling of potential defects and material removal on the workpiece surface caused by abrasive motion during polishing, and reduces the trial cost for parameter optimization in actual polishing processing.