Equipment Vibration Research Articles

Vibration and acoustic waves of multilayered cylindrical shells carrying internal components attached by nonlinear compliant mounts

The structural-acoustic interactions of a coupled multilayered composite cylindrical shell and internal equipment system immersed in an infinite fluid medium are analyzed. The internal equipment is installed on the cylindrical shell by a series of nonlinear compliant mounts, which are represented by nonlinear springs and linear viscous dampers. Both the translational and rotational vibrations of the internal equipment are considered, and they are strongly coupled together due to the nonlinear elastic mounts. The nonlinear dynamics model of the coupled cylindrical shell and internal equipment system is established using a modified variational method, and the fluid exterior to the shell is modeled by a time-domain boundary element method. A strongly coupled serially staggered procedure is adopted to solve the governing equations of the structural system and the acoustic fluid as a coupled system. The results of the present analysis are validated by comparing with those obtained from the finite element method. The nonlinear structural vibration and acoustic wave behaviors of the coupled system containing compliant mounts with linear or nonlinear stiffnesses (including quadratic, cubic, quartic, quadratic-quartic types of stiffness) are analyzed. The effects of the translational and rotational motions of the internal equipment as well as their coupling on the nonlinear vibration and acoustic wave responses of the coupled system are examined. Physical insights into the super-harmonics in the vibration and sound pressure responses of the coupled system are provided.

Dynamic optimization design of the suspension parameters of car body-mounted equipment via analytical target cascading

Under dynamic conditions, the dynamic force between the suspended equipment and the car body is substantially increased. This increase not only affects the ride comfort but also substantially raises the likelihood of fatigue damage to the suspended equipment. A multiobjective analytical target cascading (ATC) optimization is proposed to improve the ride comfort of high-speed trains and reduce the vibration of the suspended equipment. A mathematical simulation model of the vehicle equipment system is established, and the acceleration frequency-response function expression of the car body and the suspension system is obtained. The comfort index of the car body and the acceleration root mean square (RMS) of the suspended equipment are calculated by combining the German vertical irregular track spectrum and the comfort filter function. Meanwhile, the ATC method is used to optimize the car body comfort index and the acceleration RMS of the underframe suspended equipment. Then, the availability of the optimization method is evaluated via numerical simulation. Compared with the original suspension scheme of the underframe equipment, when the running speed of the vehicle is 300 km/h, the RMS value of the vibrational acceleration of the underframe equipment after optimization decreases by 19.9 %, and the ride comfort indexes at the car body center and above the front and rear bogies are improved by 6.4 %, 0.1 %, and 1.1 %, respectively. Simulation results demonstrate that ATC optimization can improve the railway vehicle ride comfort and reduce the vibration of the suspended equipment. This paper provides a new approach to the suspension parameter design of equipment.

A bi-objective model to include workers’ vibration exposure in assembly line design

In several occupational sectors, workers are daily exposed to vibrations induced by automatic, pneumatic, or electric tools, with a consequent increase of musculoskeletal disorders. In this paper, a bi-objective manual assembly line design model is proposed, aiming to avoid excessive daily vibration exposures. The developed model allows to minimise both total equipment costs and vibration levels by respecting the threshold values defined in the ISO 5349-1. The ϵ-constraint approach is used to address both objectives and to find the Pareto frontier. The model is applied to several instances to evaluate the computational limit of the solving method, as well as to an industrial case to provide managerial guidelines. The results show that the method can solve small and medium size instances. Moreover, the case study points out that safe vibration exposure levels can be achieved also with a low additional investment and that solutions equal from an economic point of view can be different from a vibrations exposure one.

Adaptive Visual Servoing Control for Hoisting Positioning Under Disturbance Condition

This paper proposes a visual servo scheme for hoisting positioning under disturbance conditions. In actual hoisting work, disturbances such as equipment and load vibration are inevitable, which brings challenges to the development of a visual servo for hoisting positioning. The main problems are as follows: (1) the correlation between visual error and disturbance is not considered or well resolved; (2) the disturbance has a great influence on the control stability, but it is difficult to model. At present, there is no detailed research on the above problems. In this paper, the visual error is defined by the image error of the feedback signal based on dynamic equations containing disturbances. An adaptive sliding mode control algorithm is employed to decrease the influence of external disturbance, and the coefficient of the slide surface is established based on the adaptive gain. In view of the belief that it is difficult to model disturbance terms, a nonlinear disturbance observer is introduced to obtain equivalent disturbance. On this basis, an adaptive control algorithm with disturbance compensation is proposed to improve the robustness of the visual servo system. We use Lyapunov’s method to analyze the stability conditions of the system. Compared with the other state-of-the-art methods, the simulation results show that our method has superior performance in convergence, accuracy, and restraining disturbance. Finally, the proposed algorithm is applied to the hoisting platform for experimental research, which proves the effectiveness of the controller.

Metrological support of diagnostic complexes for assessment of technical conditions

This article is dedicated to main aspects of implementation of monitoring of vibration in power equipment. An example of planning of current repairs for the analysis based on diagnostic signs is illustrated. The probable frequency ranges and magnitude of the increase in vibration levels of mechanisms for various operational defects are demonstrated. The requirements for the system of metrological support of diagnostic complexes are noted. The normalized metrological characteristics of measuring channels for diagnostic complexes are listed. The interface of a promising diagnostic complex for assessing the technical condition of rotary equipment is presented. The conclusion about the economic efficiency of the use of diagnostic systems with standardized metrological characteristics of measuring channels for monitoring of technical condition of rotor equipment is made.

Properties of Fine-Grained Concrete Mixtures during the Construction of Monolithic Structures

The article presents the results and methods of studying the rheological properties of fine-grained concrete mixtures with various additives, as well as the regression equation obtained by calculations using the apparatus of mathematical analysis, which shows the significance of the parameters included in the process of compaction of the ICZB. These data are necessary for the correct design and selection of sealing mechanisms in order to obtain the design physical and mechanical properties of ICZB. In many regions of the world there is an acute shortage of high-quality raw materials for large aggregate in conventional concrete, which necessitates its transportation over distances from 400 to 1000 km. In this regard, the cost of one cubic meter of coarse aggregate in many regions is 2-3 or more times higher than the cost of sand, the deposits of which are more common. In addition, obtaining the desired fractions of quality aggregates requires artificial addition and fractionation of the resulting granules. The experience of using ICZB for the manufacture of parts and structures at the plants of ZHBK gave positive results, but in mass construction (hydraulic), he did not get spread due to insufficient study of physical and mechanical properties, weak efficiency of existing vibration equipment, insufficient development of new technological equipment for laying and sealing. In this regard, we believe that the research aimed at studying the physical and mechanical properties of ICZB and the further development of technological equipment, methods of laying and sealing for their widespread implementation, determine the relevance of this problem.

Study on two-stage mounting systems having distributed intermediate mass

Nowadays, two-stage mounting system having integral intermediate mass is widely applied and researched to attenuate vibration of marine machinery equipment, while two stage mounting system having distributed intermediate mass which has the feature of lightweight and installation dimension is rarely used and studied. The theoretical models of two types of mounting systems are set up and force transmissibility rate of the two mounting systems are deduced through four-pole parameters method. A scale experimental prototype is established to test the isolation efficiency of the two-stage mounting system having distributed intermediate mass. FEMs of the two systems are established to make a comparison ascertaining the difference between the two about vibration isolation efficiency at the different frequency. The result shows that two stage mounting system having distributed intermediate mass achieve better vibration isolation efficiency and take less space than two-stage mounting system having integral intermediate mass if with equivalent intermediate mass. Two-stage mounting system having distributed intermediate mass can meet the requirements of practical projects and provides a new way for engineer to refer to when meet with machinery equipment vibration problems.

Design and Implementation of Portable Petrochemical Equipment Vibration Monitor Based on Multi-Layer Architecture

Current vibration monitors for petrochemical equipment show several problems, such as high cost, inconvenient for use, and so on. To solve these problems, this paper designed a vibration data collector and a data processing App system based on multi-layer architecture. The data communication is realized by Bluetooth. The collector collects the acceleration, the speed and displacement data of the equipment, and the data processing functions such as data storage, analysis, viewing, and uploading are realized by the mobile phone App system. This method not only can simplify the design of the collector but also can enrich the functions of the vibration monitor. Practices show that this vibration monitor has short response time for vibration measurement, works stably which can meet the actual demand for vibration measurement of petrochemical equipment.

Water Hummer Technology for Soil Destruction on Dredgers

The present investigation aims to propose a solution of the problem which is connected with slurry processing during the dredger’s operation under difficult conditions. On dredgers, depending on the degree of air dryness or low ambient temperatures very often arises technical problem that creates difficulties for the crew. It is connected with the fact that soil surface layer is very dense. It is very difficult to dredge the soil during extraction under water surface or unloading from the hold of a vessel at low ambient temperatures. The top layer of the very soil is characterized by a high degree of compaction and can be destroyed in two ways only. The first way is to use very powerful mechanical equipment (percussion mechanisms, vibration equipment, etc.). This method is associated with high energy spending and its use on a vessel is technically difficult. The second way is to use the soil cutting process with the use of mechanical cutters. Dredger’s operation with the use of milling equipment is always characterized by the fact that during soil mechanical treatment there is always occurs breakage of the cutter teeth or rapid wear of the cutting surfaces. A similar problem occurs when sandy or clay soil is extracted under water, which is compacted by its properties. In investigation a non-trivial solution was used to solve the problem of destruction of the compacted soil layer during the operation of the dredger. It was proposed to use the hydrodynamic method based on water hammer as the main mechanism for the destruction of compacted soil. As a result of the interaction of the compacted soil layer and high pressurized directed water jets, good performance of the dredger can be achieved. The two-dimensional mechanism of destruction of the compacted soil layer can be described by the condition of dynamic equilibrium of the three main flows - the jet, which flows from the conical nozzle and two flows along the soil surface. For these streams, a reactive force evaluation has been performed. Destructive jets can be generated by standard marine pumps in combination with the use of water hammer. Based on the results of the experiments, it was found that the qualitative destruction of the surface layer of compacted soil occurs using two or three phases of hydraulic water hummer.

An Overview of Methods of Reduction of Vibration for Diesel Generators

Mechanoelectrical devices will always vibrate because of several moving parts incorporated within them. When they are in operation, these machines usually have oscillatory motions around an equilibrium point. For generating sets, vibration is from the engines to the metal frame because vibration travels through mediums. Accelerometers are used to measure vibration when mounted on the generator frame where the vibratory motion is been converted into electrical signal with the use of piezoelectric accelerometer. The versatile uses of electronics make it easy to measure and analyse electrical signal. The accelerometers usually mounted perpendicular and concentric to the shaft of the rotating engine in the vertical and horizontal position. Mechanical vibrations are present in different degrees. Some vibrations are desirable, they perform useful work. Vibration is generated intentionally in component feeder, concrete compactor, eccentric grinders, ultrasonic clearing baths, rock drills and pile drivers. Excessive vibration in equipment can not only damage the equipment itself but also decrease functionality and they can cause destruction of power delivery. Minimizing vibration of generating set can both reduce the transfer of energy to building surrounding, generator equipment/component and human. This leads to longer life for generator. The rate of vibration and cost are the most important consideration before a designer can decide the methods that can effectively minimize the transmission of vibratory motion. Vibration can become a noise source. The paper discusses isolation as a means of preventing vibration from the system and damping as a means of absorbing of vibration energy from the system. Methods of reducing vibration such as elastomeric isolations, spring isolators and accelerometers are discussed.

Identification of Physical and Excitation Parameters of Under-Chassis Equipment for Railway Vehicles

Abstract The accuracy of the physical parameters and excitation parameters of the under-chassis equipment has a significant impact on investigations of the coupled vibration of the vehicle body and the under-chassis equipment. In this study, an equipment vibration isolator test bench is used to develop a physical parameter identification method based on the free vibration acceleration response of the equipment and an excitation parameter identification method based on the forced vibration acceleration response. The equipment mass parameter and the center of the gravity position parameter can be obtained first through a static load test, and then, the inertia parameters can be obtained through a dynamic test. Identification of the excitation parameters of the equipment is based on the physical parameters and the acceleration response. The accuracy of the physical parameters directly affects the excitation parameter identification results. The larger the frequency ratio, the smaller the identification error will be, and the larger the damping ratio, the larger the identification error will be. The identification test results of single-frequency excitation and multifrequency excitation show that the proposed excitation parameter identification method has high accuracy.

Active Control of Vibration and Noise of Energy Equipment

Vibration and noise control is an important topic in the field of energy equipment research. The traditional passive control has better control effect in dealing with high frequency vibration noise, but it is not satisfactory in low frequency noise control. The active control solves this problem better. This article gives a reference for subsequent research in this field through a review method, which has certain reference value.

Automated Activity Identification for Construction Equipment Using Motion Data From Articulated Members

Real-time monitoring and assessment of construction resources have always been a challenge due to the unique, dynamic, and complex nature of each construction site and operation. The ability to automatically classify activities performed by various equipment in real time can aid in making timely tactical operational decisions that can lead to increased fleet productivity, reduced time and cost of operations, and minimized idle times. Such endeavors have traditionally been performed manually through human observation, making it extremely labor and time-intensive. Meanwhile, the development of low-cost micro-electro-mechanical systems (MEMS) with rapidly evolving computing, networking, and storage capabilities, along with the advances in computational techniques such as machine learning present new opportunities in the real-time activity identification domain. Even though previous studies have shown promising results for equipment activity identification at limited levels of detail, they have a fundamental limitation in their reliance on the equipment vibration. Equipment vibration is highly dependent on factors that are extrinsic to the performance of an activity itself such as ground conditions, age and condition of equipment, and operator skill. This aspect of current methods necessitates the collection of training data from the specific equipment of interest and requires manual labeling of training data, thereby limiting its application across different types of equipment and operating conditions. This paper investigates the use of activity-specific equipment motions instead of vibration for activity identification. This approach is the first step towards the larger goal of generating training data automatically from virtual kinematic models of equipment in the future. This paper also provides an array of sensitivity analyses in order to determine the most appropriate parameters for implementing machine learning algorithms for equipment activity identification. A case study was performed using an excavator working on an earthmoving site that demonstrated a significant improvement in equipment activity identification results by utilizing IMU data of different articulated elements over previous efforts. The results of this paper indicate that more accurate results for activity identification can be obtained by using articulated equipment motion over vibration, which paves the way for the automatic generation of labeled training data in the future.

Experimental study of the aircraft air cycle machine rotor dynamics on gas foil bearings

In this paper the results of the experimental research of the dynamics of the rotor of a four-wheeled aircraft air cycle machine on gas foil supports under conditions of vibration. The description of the experimental unit, measuring system, and methods of results processing is given. The rotor of the turbomachine is mounted on compliant gas foil journal bearings of the second generation. The rotor speed varied from 20000 to 32000 rpm. The cooling turbine was exposed to broadband random vibration with a mean square value of Vibro-acceleration up to 5 g. The influence of vibration load level, air supply temperature, amplitude-frequency characteristics of the turbine cooler case, and vibration equipment on the rotor dynamics was assessed.

High Performance Hybrid Piezoelectric-Electromagnetic Energy Harvester for Scavenging Energy From Low-Frequency Vibration Excitation

There are many difficulties in the power supply of the wireless monitoring system for coal mine mechanical equipment. Vibration energy scavenging is a green and effective way to solve this problem considering the intense and continuous vibration of coal mechanical equipment. In this paper, a novel hybrid vibration energy harvester was designed and manufactured, which combined electromagnetic and piezoelectric transduction units. Vibration drives the two units to move in the vertical and horizontal directions to realize the energy conversion. The mathematic model was built to calculate and predict the performance while the simulation on the distribution of magnetic field and piezoelectricity potential provided the details in the design. Besides, the output signal generated by the vibration excitation of the electromagnetic unit, piezoelectric unit and the whole energy harvester were studied simultaneously. Moreover, the resonance frequency was tested to be 14Hz, and the optimum matching impedance was measured to be 1kΩ and 10kΩ with the parallel and series connection of PH and EH, respectively. The maximum output power of the HPEH with the parallel connection pattern can reach 80.10mW at the acceleration of 2g. In the application experiment, the HPEH can facilely light up 120 LEDs and supply stable power for the electronics and sensors.

A New Denoising Method for Underwater Acoustic Signal

In recent years, the rapid development of marine science has put forward higher and higher requirements for the processing of ship-radiated noise signal. Ship-radiated noise is the noise signal generated by the vibration of various mechanical equipment or the movement of the hull and radiated into the sea when the ship is traveling. Ship-radiated noise signal contains a large number of time-varying, nonlinear and non-stationary components. The denoising processing of ship-radiated noise is the most critical part of underwater acoustic signal processing. In order to more effective reduce the noise of the ship-radiated noise signal, a new denoising method for underwater acoustic signal based on mutual information variational mode decomposition (MIVMD), multivariate multiscale dispersion entropy (mvMDE), and lift wavelet threshold (LWTD) and Savitzky Golay filter (S-G filter), named MIVMD-mvMDE-LWTD-SG, is proposed. Firstly, MIVMD is used to decompose the original signal into $n$ sub-signals. Secondly, the mvMDE value of each sub-signal is calculated, and the $n$ sub-signals are divided into high-frequency components and low-frequency components according to the threshold. Then, S-G filter and LWTD method are used to reduce the noise of low-frequency components and high-frequency components respectively. Finally, the low-frequency components and high-frequency components after the denoising processing are reconstructed to obtain the denoising signal. In order to verify the effectiveness of the proposed method, the proposed method is used to reduce the noise of chaotic signal under different signal-to-noise ratios (SNR), and compared with the EMD-mvMDE-LWTD and MIVMD-mvMDE-LWTD method. The results show that the proposed method can effective remove the noise in the chaotic signal, better distinguish the adjacent trajectories in the phase space, approximate the real chaotic attractor trajectory, and better retain the useful information in the chaotic signal. The proposed method is further applied to the actual ship-radiated noise signal, and the experimental analysis shows its effectiveness, which lays a solid foundation for further prediction and detection.

Об уровнях вибрационных воздействий при испытаниях бортовой радиоэлектронной аппаратуры космических аппаратов

The tightening of avionics lifetime and reliability requirements necessitates a profound and efficient experimental method. At the same time, the not infrequent absence of even two equipment samples for conducting tests (considering the variation of properties of materials and technological processes) makes the problem of confirming hardware strength characteristics difficult to solve. The present paper describes a methodology for vibration tests of spacecraft onboard electronics that allows us to reliably confirm the strength of a random sample of the given equipment based on the testing of a single test specimen. Safety margins for different stages of equipment vibration testing are determined. These margins are necessary to ensure the given probability of design defect detection. The proposed methodology is compared with current foreign regulatory documents dedicated to testing spacecraft onboard electronics. The proposed method allows a flexible approach to the selection of vibration test levels since it takes into account the design features of the equipment affecting strength spread from sample to sample during the determination of the scope of required tests.

An alternate arrangement of geofoam blocks and air pocket to mitigate confined blast induced vibration

ABSTRACT The present study focuses on the performance of intermittent geofoam in-filled (IF) trench as a passive vibration screening when a reinforced concrete (RC) lining tunnel is subjected to internal blast load. The blast analysis of lined tunnel is performed using a three dimensional non-linear finite element (FE) method. The coupled Eulerian-Lagrangian (CEL) analysis tool has been employed in the FE software ABAQUS/Explicit for the purpose of this study. The explosive trinitrotoluene (TNT) has been modelled using Eulerian elements as the blast source in the tunnel. The IF has been installed at the far field from the source to protect the vibration sensitive buildings and equipment in that region. The parameter, which controls the design of intermittent geofoam trench, is its geometric parameters (width, depth, location). EPS geofoam density and soil Poisson’s ratio have been considered to investigate the performance. In addition to IF, another newly proposed technique named staggered intermittent geofoam (SIF) has also been investigated in the present study. The results of simulation show that both IF and SIF can be a very good passive vibration screening technique subjected to blast sources.

Working-Stand Equipment Vibrations of Continuous Cold Rolling Mills during the Production of Thin Strip Products

The article considers the nature, occurrence mechanism and development of resonant vibrations found in the working stand equipment of cold rolling mills during the production of strips with a thickness of 0.4–0.6 mm at speeds of more than 12 m/s. Vibration causes are possibly based on changes in the metal properties during rolling due to acquired hardening and forming of internal friction peaks.

TECHNOLOGICAL PARAMETERS EFFECT ON THE EFFICIENCY OF A DEPTH OPERATING METHOD

The oil production effectiveness depends on many parameters. The liquid flow rate of a well depends on the operating mode of the reservoir, the reservoir energy supply and the pressure distribution over the developed facility area. Geological parameters also have a great influence on the producing wells operational characteristics: the reservoir type, permeability and productivity coefficients, the degree of reservoirs heterogeneity by filtration and reservoir properties, and contamination of the well bottomhole zone largely determine the wells production capabilities. The next determining factor is the choice of the operating method, the pump type and its operating mode. Pump performance also depends on a number of factors. The oil physical properties, such as viscosity and density, determine the pump unit efficiency. Moreover, the larger these parameters, the lower the plants efficiency, the greater the load on the working elements of the pumps and the power consumption. The free gas content in the fluid produced from the well when it enters the pump also negatively affects the operation of most pumps types. In the pumps working cavities, a dead space is formed, filled with free gas, because of this, the pump productivity in the liquid decreases and additional loads on the installation arise due to vibration of the downhole equipment. At high values of the free gas content, a supply interruption can occur, which will entail a loss in the pump unit operability. When selecting pumping equipment for well operation, it is necessary to take into account all geological, hydrodynamic and oil production technical features from the considered development object. Only in this case is it possible to implement the process of efficient and cost-effective oil production from the reservoir when pumping units operate in optimal mode.