Vibration Protection Research Articles

Intelligent Over-vibration Protection Modeling & Simulation For Three Phase Induction Motor

This paper presents an intelligent over-vibration simulation and protection preference for three phase medium and high power induction motor. Three phase induction motor is widely used in industry because they are rugged, reliable and economical.Monitoring and over-vibration protection of machines can avoid consequential damage and avoid its consequences.The effect of three main different abnormal operating cases which are rotor unbalance,shaft coupling misalignment and torque pulsations on the rotor vibration are examined.The results are collected and evaluated for motor status. Rotor unbalance and shaft coupling misalignment will cause radial vibrations,while torque pulsations will cause torsional vibrations.The vibration analysis and simulation is calculated using matlab(m-file)to produce the different vibration waves.Fuzzy logic technique is utilized in determining machine vibration source ,and if vibration displacement (r.m.s) at bearing exceeds limits,then fuzzy will feed a relay to trip machine.The fuzzy is programmed by the output of the simulation(m-file). A case study of 5100 kW motor was used in rotor vibration modeling,rotor stiffness and damping values were calculated. Fuzzy logic as an artificial intelligence technique can be used as a vibration monitoring and protection tool.

Решение современных задач динамики гидромеханических и виброзащитных систем

Решение современных задач динамики гидромеханических и виброзащитных систем

Use of mechanical models for the analysis of antivibration mounting

The paper considers a two-stage vibration isolation of rotary machines including rotor-frame elastic linkage. It proposes internal elastically inertial vibration protection inbuilt between a rotor and a frame. The method of dynamic compliance is used to define forces influencing the frame. The proposed vibration motor can be used for rotary actuators of compact devices. The main objective of the study is to increase the motor torque and durability.

Mathematical Model of the Dynamics in a One Nonholonomic Vibration Protection System

Mathematical Model of the Dynamics in a One Nonholonomic Vibration Protection System

The application of dynamic reactions of ties in the connection of elements to estimate the capabilities of vibration protection system

The application of dynamic reactions of ties in the connection of elements to estimate the capabilities of vibration protection system

Vibration Protection of Mechanical Systems Consisting of Solid And Deformable Bodies

In this paper active vibration protection of mechanical systems consisting of solid and deformable bodies is considered. To actively control the oscillations of dissipative mechanical systems, a constructive method is used to determine the structure of the reaction forces of servo constraints. As an example, we consider the system with a finite number of degrees of freedom. Numerical results for various harmonic are also given.

Vibration Protection of Mechanical Systems Consisting of Solid And Deformable Bodies

In this paper active vibration protection of mechanical systems consisting of solid and deformable bodies is considered. To actively control the oscillations of dissipative mechanical systems, a constructive method is used to determine the structure of the reaction forces of servo constraints. As an example, we consider the system with a finite number of degrees of freedom. Numerical results for various harmonic are also given.

Controlling the vibration process of vibration protection systems with dynamic damping

The article deals with theoretical aspects of controlling the oscillation process in vibration protection systems with a dynamic damping based on the use of modern information technologies. The justification of the principle of minimum and minimax procedure for the formation of optimal control of oscillation processes is given. It is shown that a direct method of integrating the equations of state, when observing the minimax procedure, allows us to find the values of the components of the optimal control vector directly at each integration step. The minimax procedure algorithm of the minimum principle is used to solve the optimization problem of dynamic damping of oscillations. A synthesizing control function is found that allows eliminating resonant phenomena and providing attenuation of transient processes within a single period of kinematic action.

A novel bio-inspired anti-vibration structure for operating hand-held jackhammers

Abstract Long-term exposure to high level vibration can lead to considerable pain and time off work, and even result in permanent disability. Therefore, vibration protection to operator when operating vibrating tools is a very important issue in construction. Targeted at operating heavy-duty jackhammers or road breakers etc, an innovative anti-vibration exoskeleton technology is successfully developed in this study, which is passive, portable, cost-efficient and crucially helpful for a significant vibration suppression during the drilling and hitting process. To explore the benefits of nonlinear dynamics and passive structure design in vibration control, the innovative anti-vibration exoskeleton is designed for the first time to mimic the limb structure of animals and fully employs the beneficial nonlinear benefits in the bio-inspired anti-vibration structure which can consequently significantly reduce vibration transmission without sacrificing loading capacity, while the latter is very important to increase the demolition efficiency during a demolishing work. Theoretical modeling, simulation and experiment results demonstrate the effectiveness and efficiency of this innovative technology, consequently solving such a long-time existing engineering problem in the construction field.

Observer-based H2 controller design for a vibration isolation stage having hybrid electromagnets

Vibration isolation systems based on hybrid electromagnets, consisting of electromagnet and permanent magnet, have a potential usage in many industrial areas, such as clean room design, transportation, semiconductor manufacturing, suspension systems, and robotic surgery due to providing mechanical contact free vibration isolation. Using permanent magnets in the electromagnet structure has some crucial advantages, such as a minimized volume and a more compact structure. Furthermore, the essential force for levitation of vibration isolation stage can be generated by only the permanent magnet(s), which means, by using hybrid electromagnets, magnetic levitation can be achieved with considerably low energy consumption against possible vibrations. This property is called zero-power behavior. However, the main problems of magnetic levitation process are as follows: it has highly nonlinear nature even if it can be linearized; it has unstable pole(s), which makes the system vulnerable in terms of stability. In recent years, linear matrix inequality-based design of controllers has received considerable attention and become very popular due to their ability to satisfy multiobjective design requirements. However, an observer-based H2 controller design for a vibration isolation system having hybrid electromagnets has not been considered yet. Therefore, the linear matrix inequality-based controller is employed to minimize the effect of disturbances on the following objectives, such as vibration isolation, zero-power property, and protection of the levitation gap. The effectiveness of the proposed method is shown with the numerical simulation studies and compared with classical Linear Quadratic Regulator (LQR) approach.

Vibration protection of a human-operator based on the application of disturbance-stimulated control mechanism

The article presents a short design algorithm for an effective vibration protection system of the human-operator of a special-purpose vehicle based on the principle of external disturbances compensation. The authors regard the results of its tests with random, deterministic and impact actions, which show that in the low-frequency range the maximum efficiency is 26 dB in acceleration and up to 46,69 dB on impact. The data are obtained which will allow to make timely changes in the design of the seat suspension of a special-purpose vehicle at the stage of its design.

Increasing efficiency of vibration protection system by using pneumatic rubber cord devices

The article is devoted to investigation of the vibration protection system based on pneumatic rubber-cord devices. The device and principle of operation of the combined vibration protection system with the use of rubber-cord shells as power elements are presented. The analysis of the developed mathematical model is carried out. New methods of construction and algorithms for controlling the active vibration protection system are investigated on the created experimental complex. The results obtained at the experimental complex are presented and analyzed. The study of the developed mathematical model of combined vibration protection system with throttle control of gas pressure in power cells has shown its efficiency in the low-frequency range. The evaluation of the quality of the combined vibration protection system using integral criteria has shown its effectiveness up to 40% in comparison with the passive vibration protection system with harmonic excitation. The obtained test results have a discrepancy in the low-frequency region of the operating range with mathematical modeling data at the level of 10%.

The design of modern absolute gravimeters based on atomic interferometers with cold atoms and prospects of their development in Ukraine

Absolute gravimeters on the basis of atomic interferometer with freely falling cold atoms have already demonstrated top-level performance in terms of sensitivity, long-term stability and accuracy which are comparable with the best characteristics of classical ballistic gravimeters, as confirmed in international comparisons. The accuracy of 10 nm·s‑2 is demonstrated not only by stationary laboratory absolute atomic gravimeters, but also by devices intended for field measurements [1]. Atomic gravimeters have a number of potential advantages — the absence of moving parts, a higher sampling rate and they are considered today as a promising area of modern gravimetric technology. In this paper, an overview of publications describing the physi­cal schemes of modern atomic gravimeters is given, the main units of the atomic gravimeter, their purpose and principles of functioning are considered in details. The main attention is paid to laser systems in terms of determining the achievement of necessary conditions for cooling atoms, manipulation of their motion, preparation of quantum states, functioning of the atomic interferometer and detection of the signal. As can be seen from the overview, in modern atomic gravimeters, predominantly semiconductor lasers are used with high, and in some cases, unique technical parameters, which ensure simultaneous achievement of high values of output power, monochromaticity, stability of energy parameters and frequency of radiation, precision control of wavelengths at sufficiently wide range of their values. The creation of such laser systems requires the solution of a number of complex technical problems — the development and creation of effective laser amplification schemes, modulators for the formation of the necessary laser frequencies, and the schemes for locking laser frequencies along the absorption lines of alkaline atoms. The paper also examines the requirements for a highly vacuum system, magnetic shielding schemes, vibration and seismic protection, and discusses the prospects of development of such gravimeters in Ukraine.

Comparative evaluation of the effectiveness of the vibration protection of the active suspension system with PID control

The pneumatic suspension is used to absorb vibration and provide comfortable labor conditions for transportation vehicle drivers. The cause of increased vibration of the tractor, often, are incorrectly matched elastic-damping characteristics of the cushions of the active suspension system, which can not cope (or cope extremely ineffectively) with fluctuations coming from the external background. Since the realization of an experiment for the dynamic analysis of pneumatic suspension takes a long time, the mathematical models of the vehicle suspension system are used to obtain the response parameters of the pneumatic suspension. In the given article the comparative characteristic of spring’s systems with a cylindrical spring and a linear pneumatic spring as a suspension system is given. To carry out the simulation, the Matlab/Simulink software complex was used, in which, based on the previously obtained values of equivalent rigidity, a simulation of the tractor was built. Since the tractor in this model is considered as a linear system, its spectral function was calculated from the spectrum of the input parameters of the path unevenness and the frequency response of the tractor. These parameters were used to analyze the vibration response of the suspension system to assess the effectiveness of the system and, as a result, assessment of the operator comfort. The algorithm of the proportional integral differentiating (PID) regulation of the suspension system was implemented depending on their output parameters as well. The comparative study shows how the linear model of the pneumatic suspension system controlled by a PID-regulator is able to suppress fluctuations arising from road roughness and whether it is effective than a passive suspension system for a vehicle with a coil spring. The criterion of efficiency in this work was the indicator of the tractor's displacement height.

The study of the acoustic-vibrational effect on the hardware of computer systems

The article is devoted to problems of hardware hardware protection of computer systems of critical infrastructure. It is shown that hard drives are the most sensitive to acoustic-vibrational effects in the computer system. The consequences of this effect may be the disruption of the hard disk drive, the loss of information or the complete failure of operation that arose as a result of mechanical damage to the working surface of the drive unit or the slider of the read head. It is determined that technical specifications of hard disks lack tolerance levels of acoustic impact. A test stand was developed for research of acoustic-vibration influence on computer equipment. An acoustic system is implemented to generate acoustic vibrations of the infrasonic range. Test measurements of acoustic-vibrational influence with different values of frequency, waveform and sound pressure on hard disks have been carried out. The most dangerous frequency of influence and shape of the signal are determined. The high destructiveness of the acoustic-vibrational influence on the computer system has been proved. The consequences of acoustic-vibration influence are revealed. During the experiment, the most dangerous frequencies and waveforms were detected, an interpolation of the result was performed using the Akimi spline, the effects of acoustic-vibrational effects on the hard disk and the computer system as a whole were determined. Graphs of the dependence of the rate of recording of a homogeneous data array on the frequency of the effect and the sound pressure in the form of a signal of the type of the meander and the sinusoid are constructed. Defective computer system after acoustic-vibrational influence has been made, the damage received by the system due to such influence is described. The study found that: the basic vibration protection of A-hard drives cannot effectively counteract infrasound effects, the greatest threat is the sinusoidal waveform and a signal of the type of meander, the effect at frequencies of 27 ± 2 Hz most negatively affects the hard disk and the computer system as a whole.

The simultaneous action of external excitations – features of the dynamical damping of vibrations

The article considers new dynamic effects arising in problems of vibration protection of objects under external disturbances, on the side of support surfaces. A method for constructing mathematical models for a vibration protection system is developed, in which the protection object has two degrees of freedom. It is demonstrated that is possible to introduce additional constraints in the form of motion transformation devices. The article estimates the possibilities of using screw non-locking mechanisms with flywheel nuts, the given moment of inertia of which can be regulated.

Study of torsion oscillations of pumping unit shafts

The method of detuning from resonant frequencies is an effective method of reducing the vibration activity of the HA at the design stage, which allows selecting the necessary operating mode for the HA, which will provide the necessary reliability of operation. In this connection, works in the field of increasing the vibration protection of NA are relevant. All calculations are based on the dynamic model of free torsional vibrations of the pumping unit, for which the oscillation equation was derived on the basis of Lagrange equations of the second kind, where the angle of rotation of the rotor was taken as the generalized coordinate. Next, expressions were obtained for the determination of the potential and kinetic energies that take into account all the characteristics of the shaft and the disk of the rotor HA; in particular, for the first time the mass of the shaft is taken into account. Then an expression was obtained for determining the frequencies of free torsional oscillations and the equation of motion of the rotor HA. Knowing the parameters of the oscillatory motion makes it possible to estimate the stresses that arise when the shaft rotates. The following is a case of a sudden stop of the shaft, for example, when the support is destroyed, and a graph is obtained from which the main conclusions are drawn.

Application of polarization interferometry to plasma diagnostics

Polarization interferometer has some significant advantages over beam-splitting ones in a wide range of applications. Most of restrictions in interferometry regarding to optical elements quality and vibration protection can be neglected in Nomarski scheme, it is easy in alignment and allows studies in a broad spectral range without the replacement of mirrors. We present a description of two- and three-wavelength polarization interferometers and a technique for measurement of transparent media optical properties with high spatial (∼ 10 μm) and temporal resolution (∼ 10 ns) in UV-NIR (∼ 380-900 nm) spectral range. As a result, atom and electron number densities have been evaluated in the case of about equal input of each of these components in refraction index change. Application of the proposed scheme to birefringent objects can be limited, but it also provides abilities to visualize strong electric and magnetic fields due to electro- and magneto-optical effects.

Determination of the frequency characteristics of a magnetorheological elastomers vibration control platform

To reduce the effects of external vibration disturbances, various methods of vibration protection are used, including active, semi-active and passive vibration isolation systems. For vibration isolation of modern precision equipment, it is proposed to use a plate-like vibration isolation based on magnetorheological elastomers. Studies of the frequency characteristics of this platform and its management capabilities are necessary to determine the effective modes of operation of the platform. Thanks to the tests on the vibration electrodynamic installation, the dependence of the coefficient of transfer of the amplitude of vibration displacement on the oscillation frequency at different currents was obtained and showed that the effective range of vibration isolation is from 38 to 100 Hz.

Slotted shell resilient elements for drilling shock absorbers

The new design of a resilient element for application in drilling devices of vibration protection is presented. A cylindrical shell with a cut along its generatrix is the peculiarity of the proposed design. The presented resilient element has high loaded and damping properties upon cross dimension hard restriction condition. Besides, the design is simple, technological and low cost. The drilling shock absorber is tested, which is manufactured on the base of several slotted shell resilient elements, operating in parallel manner. A calculation method for slotted shell resilient elements for drilling devices vibration protection is given. This work presents results of slotted cylindrical shell study in conditions of contact interaction with a resilient filler. To provide the research, the authors have developed a verified numerical model of the shell resilient element with a slit and used iterative algorithms for contact problem solving, considering contact surface friction. The stress-strain state of the shell resilient element of the drilling shock absorber was analyzed. Strength of the structure is evaluated by the energy criterion. Hysteresis loops were developed and analyzed for some histories of resilient element cyclic loading. The obtained results make possible rather accurately to take into account effect of the shell and the filler material resilient characteristics, their geometrical parameters and tribological properties on operational characteristics of drilling devices for vibration protection. In its turn, this makes possible to use efficient drilling vibration protection devices, develop vibroinsulator shell designs by the criteria of maximum compliance and required damping level.