Measurement Of Vibration Acceleration Research Articles

Tribological Behavior Characterization and Fault Detection of Mechanical Seals Based on Face Vibration Acceleration Measurements

A mechanical seal is a common type of rotating shaft seal in rotating machinery and plays a key role in the fluid seal of rotating machinery, such as centrifugal pumps and compressors. Given the performance degradation caused by the wear to the face of the contact mechanical seal during operation and the lack of effective predictive maintenance monitoring methods and evaluation indexes, a method for measuring the acceleration of the mechanical seal face’s vibration was pro-posed. The influence of face performance degradation and rotational speed change on the tribo-logical regime of the mechanical seal was investigated. The proposed fault detection model based on support vector data description (SVDD) was constructed. A mechanical seal face degradation test rig verifies the usability of the proposed method. The results show that in the mixed lubrication (ML) regime, the vibration sensitivity of the face increases with the increase in rotational speed. With the decrease in the face performance, the vibration-sensitive characteristic parameters of the face in-crease and change from the ML regime to the boundary lubrication (BL) regime. The incipient fault detection model can warn about incipient faults of mechanical seals. Here, the axial detection result predicted that maintenance would be required 10.5 months earlier than the actual failure time, and the radial and axial detection results predicted required maintenance 12 months earlier than the actual failure.

Optimization and Validation of Piezoelectric Cantilever Designs for Energy Harvesting from Bridge Vibrations

This study proposes an optimization strategy for bridge applications with a vibration-based energy harvester design. Piezoelectric cantilevers with multiple degrees of freedom (DOF) are designed and optimized to match resonant frequencies with the vibration frequencies of a full-scale bridge structure under different loading conditions and measurement locations. The specific optimization procedures include bridge vibration acceleration measurement, simulation model development for estimating the resonant frequencies, a regression model for optimization of mass combinations, and final installation on the full-scale bridge for validation. The results show that the simulation model predicted the resonant frequencies of cantilevers with less than 1 Hz difference compared with laboratory measurements. Following the entire optimization procedures proposed in this study, the optimized 2-DOF and 3-DOF cantilevers were capable of generating 18.9 [Formula: see text] J and 23.4 [Formula: see text] J energy under one loading pass, respectively, which were significantly higher than those from the baseline designs. The feasibility of the proposed optimization strategy was demonstrated and validated for vibration-based energy harvesting from bridge structures.

Monitoring and forecasting of tool wear based on measurements of vibration accelerations during cast iron milling

The research focused on the possibility of predicting the wear of cutting tools during milling of EN-GJL-250 cast iron by using machine learning in the form of two different classification trees. The measurement of vibration acceleration as one of the physical quantities tested during the cutting process can be measured in an accessible way (measurement on the workpiece or through the tool). Implementation of the measurement method presented in the research is possible in every field of industry with various methods of cutting. As input data for the models, measures based on vibration acceleration signals were selected. From the conducted experimental tests, the values of wear on the end mill flank VBc at the corner of the tool and vibration acceleration during machining at variable cutting speeds (vc = 150–500 m/min) of cast iron castings were obtained, these values were correlated with each other. The machining was performed with the use of monolithic end mills made of cemented carbide. The test results show the possibility of predicting cutting edge wear using machine learning, obtaining an error of around 1 % compared to the regression models, which in the best variant reached an error of as much as 25 %.

Экспериментальные исследования колебаний трамвая «Витязь-М»

Objective: Based on experimental studies of vibrations of Vityaz-M tram car occurring at speeds of 50 km/h or more on track straight sections with P65 rails on reinforced-concrete sleepers, to evaluate the effect of transversal vibrations on traffic safety and passenger comfort. To show the inconsistency of existing regulatory documentation on the structure and maintenance of tram tracks and tram chassis with the development prospects. Methods: Experimental measurements of vibration accelerations of tram body and tram chassis, having different mileage, when moving along track experimental section. Measurement and analysis of geometric parameters of rail track experimental section and of trams. Results: Measurements of vibration accelerations occurring during tram motion with 20 to 50 km/h speeds were performed as well as geometric parameter analysis for rail track experimental section and rolling stock wheels’ profiles, participated in the tests, was pursued. During the races, vibration accelerations that occur during movement were measured in three directions — longitudinal, transversal and vertical. The appearance of transversal vibrations of tram body affecting passenger discomfort and traffic safety has been confirmed. The root mean-square values of the amplitudes of vibration accelerations towards three directions in acceleration gravity (g) fractions have been obtained in two variants — at trolley motion between joints and at joints. Vibration acceleration frequency analysis has confirmed a sharp increase in the amplitude of transversal vibrations at frequencies in the region of 1–2 Hz at a speed of 50 km/h for a tram with worn wheels. The compliance of rail track experimental section geometry with the accepted standards as well as the compliance of rolling stock wheels dimensions with constructive documentation are noted. Practical significance: The need for further comprehensive study of the interaction of track and rolling stock while high-speed tram introduction with the purpose to improve existing standards on the structure and maintenance of tram tracks and tram chassis.

A low-frequency vibration acceleration sensor based on a long-period fiber grating and a double-clamped beam

We have designed, fabricated and characterized a low-frequency vibration acceleration sensor. The sensor consists of a double-clamped beam and a long-period fiber grating (LPFG) that inscribed in a single mode fiber (SMF) by femtosecond laser. The LPFG was glued tightly to the beam top surface. Its transmission spectrum changes with beam bending, enabling vibration acceleration measurements. The experimental results display that the sensor has an accurate and steady frequency response over the frequency range of 1.5 ∼ 10 Hz with a maximum frequency response error of 4.4 %. The maximum measurable acceleration is 0.3 g, and the maximum acceleration sensitivity is 2.8 mW/g with a linearity greater than 99.6 %. The temperature drift of the sensor is less than 0.001 g/℃. The sensor has good immunity to electromagnetic interference and reliability.

Application of vibration diagnostics methods in the creating of elements of personal electric transport

The study of vibration loading of the main elements of personal electric vehicles and the search for ways to reduce vibration characteristics was conducted. The issues of measuring vibration arising on a bicycle, which is driven by human muscle power and an electric drive, are considered. Measurements of vibration acceleration and frequency spectra in a certain area of motion were carried out using the “Octave-101VM” spectrum analyzer in three stages. At the first stage, the electric bike was driven by a pedal drive, at the second – by an electric drive, at the third – the pedals and the electric drive worked in parallel. As a result of the tests carried out, it was found that the greatest vibration occurred in the “Motor” mode during the use of an electric bicycle, the least vibration occurred when driving with the electric motor turned off. It was found that the electric drive increases the vibration level (at the same time, the electric bike does not exceed the maximum permissible values of vibration levels on all axes). In order to reduce the vibration arising from the electric motor on a personal electric vehicle, a 3D computer model has been developed and an airless wheel mover has been manufactured using this model on a 3D printer (a wheel for an electric scooter with internal damping has been manufactured). Bench tests have shown that the developed wheel, in comparison with a pneumatic tire, has a smaller (up to 45 %) contact spot. The results obtained can be used in the development of competitive products, in particular personal electric vehicles.

Analysis of the Possibility of Using Vibration Parameters for Diagnostics of Selected Defects in Welded Joints of the Hull Plating Elements

Abstract The article presents results of vibration tests of thin-walled plates used in shipbuilding for plating hulls of vessels. The conducted tests were aimed at determining the possibility of using measurements of vibration acceleration recorded on the tested objects as parameters enabling the detection of damages in the performed welded joints. Seven plates were compared, six of which had joints in different technical conditions, and one was a board without a weld. The quality of the welds was verified using X-ray methods. The adopted research methodology and the obtained results were presented.

A PROPOSAL FOR A MOBILE SYSTEM OF VEHICLE AND RAIL TRACK DIAGNOSTICS

The proper technical condition of a vehicle and rail track in operation is a key aspect in terms of safety and travel comfort. This issue is of particular importance for operators and managers of rolling stock and rail infrastructure. Currently, many diagnostic systems have been developed to monitor the technical condition of selected vehicle systems or rail track from the viewpoints of both the vehicle and track. This article proposes the use of vibration signals in selected quantitative and qualitative analyses as the main diagnostic parameter. For this purpose, over a dozen vibration measurements were carried out during the normal operation of a freight wagon as part of a so-called passive experiment. Measurement points were located on the axle boxes of the wheelsets. The proposed research methodology served as a basis for comparative analyses of the selected operational cases that were investigated. The most important conclusion from the study is that it is possible to monitor the technical condition of vehicles and tracks in real time on the basis of measurements of vibration accelerations at the vehicle level. This directly increases the service life of rolling stock and optimises operating costs by changing the maintenance strategy to one that takes into account the idea of modern on-board technical diagnostics. Another important aspect is the possibility of the varied use of the proposed measurement system, depending on the purpose of the research, which is also associated with the diagnostician’s experience in processing vibroacoustic signals and the utilisation of simple or complex quantitative and qualitative analyses.

Results of evaluating the smoothness of automatic transmission gear shifting during car operation

Various malfunctions may occur during the car operation. These include automatic gearbox malfunctions which reveal themselves during operation in the form of a rigid (jerky, bumpy) untimely engaging the up or down gear in an automatic gearbox. The quality criteria for automatic gearbox shifting which currently exist do not allow to give a reliable assessment of the required gear selection. In such cases, people operating the car often ask questions about the technical condition of the automatic gearbox and the quality of gear shift. The authors have studied the process of gear shifting, smoothness of it and peculiarities of automatic gearbox functioning of during car operation. The article describes the urgency of the problem of jerks and vibrations when changing gears. When assessing the smoothness of gear shifting, the method of technical state vibroacoustic diagnostics is applied. The method is based on the recorded parameters of vibration velocity, vibration acceleration, vibration movement with their further conversion (fast Fourier transform) into a spectral signal. The procedure of longitudinal vibration acceleration measurements on cars in operation is described. Comparative analysis of automatic gear change smoothness. As a result of the analysis the quantitative characteristics of different smoothness gear changes are obtained and its comparison with the permissible level is given. According to the results of the parameters registration and their comparative analysis, it was suggested that it is possible to assess the quality of the gear shift and determine the quantitative indicators of smoothness. Keywords: iron ore raw materials, quarry transport, process

Analysis of Ride Comfort in Selected Types of Rail Vehicles

Abstract The subject of the article is the analysis of ride comfort for a passenger of selected types of rail vehicles on the basis of the main factor determining its level - mechanical vibrations. The research was based on measurements of vibration accelerations and the RMS values in one-third octave bands which were calculated from the measured accelerations. The tested objects were four types of rail vehicles. This article presents the results of the analysis carried out for each vehicle, using two methods of assessing the impact of vibrations on the human body.

Re-Design of Machine Tool Joint Components Based on Polymer Fillings for High-Speed Performance.

In this paper, we report the results of an experimental study of a re-design approach using filling polymers and particulate composites with a polymer matrix, thus creating a macroscopic hybrid structure. The re-design is focused on the joint of a textile machine. It is a re-design of already existing machine parts of a joint in order to increase the damping of components, reduce the amplitudes of high-frequency vibrations and acoustic emission for high-speed operation of textile rotors, and to compare individual structural modifications of the rotor housing body and absorber of high-speed textile rotor in a spinning unit with respect to dynamic properties of that measured mechanical system. The experiments included a bump test, determination of logarithmic decrement, measurement of vibration acceleration, a wavelet analysis, and measurement of acoustic emission. When excited by high frequency signal amplitudes up to 5 g, the benefits of polymer filling were manifested by an approximately 50% reduction in amplitude vibrations, a 66% reduction in acoustic emission amplitude, and an 85% reduction of the maximum peak in the acoustic emission FFT spectrum. In the area above 10 g, the stiffness of the component dominated to reduce the magnitude of vibrations.

MEASURING SYSTEM BASED ON THE SBRIO-9636 CONTROLLER AND THE MEMS ADXL1005 BROADBAND ACCELEROMETER

This article describes a measurement system based on a programmable single-Board controller sbRIO-9636, which is designed to control vibration acceleration measurements. A low-noise broadband accelerometer MEMS ADXL1005 is used as a measuring sensor. This paper provides information about the limitations of the considered measuring system related to the technical characteristics of the controller and sensor. A listing of the programme developed in the LabVIEW environment is also provided. The frequency and amplitude ranges that the system can measure are indicated. The given values are justified. The measurement system was validated, and the results are summarised in a table. Based on the results of the work, conclusions are made, which state that the considered measuring system should be used in research works related to experimental modal analysis.

Analysis of Dynamic Parameters of the System of Raster Formation and Control

The presented research work analyzes the sensing system, the main aim of which is a raster formation and controlling this process using the optical measuring equipment and high precision angle encoders. Optical measuring equipment are used for the raster position detection, meanwhile angle encoders for controlling the tape speed. The main parameter of raster formation process is fixed transportation speed, but there are difficulties to realize it, because there is imperfection of the device elements. The article analyzes the dispersion of vibration accelerations of the raster formation device and tape in the two directions (transverse and longitudinal) and presents an analysis of their parameters in application of the theory of covariance functions. The results of the measurements of vibration accelerations at the fixed points of the device constructions and the tape were recorded on a time scale in the form of digital arrays (matrices). Values of auto-covariance and inter-covariance functions of digital arrays of the vibration accelerations measurement data were calculated by changing the quantum interval in a time scale. The developed software Matlab 7 in operator package environment was used in the calculations.

Inverse algorithm for real-time road roughness estimation for autonomous vehicles

Human drivers take instant decisions about their speed, acceleration and distance from other vehicles based on different factors including their estimate of the road roughness. Having an accurate algorithm for real-time evaluation of road roughness can be critical for autonomous vehicles in order to achieve safe driving and passengers comfort. In this paper, we investigate the problem of interactive road roughness identification. We propose a novel inverse algorithm based on the knowledge of a vehicle dynamic characteristics and dynamic responses. The algorithm construct the road profile in time using one-iteration to update the wheels forces which are then used to identify the road roughness. The relation between the forces and the road profile is defined by a system of ordinary differential equations that are solved using the composite Gaussian quadrature. To reduce the error accumulation in time when noisy data is used for the vehicle response, a bidirectional filter is also implemented. We assume a simple model that is based on four degrees-of-freedom system and vibration acceleration measurements to evaluate the road roughness in real time. Although we present the results for this specific model, the algorithm can also be utilised with models of any number of degrees of freedom and can deal with models where the dynamic response is only available at some of the degrees of freedom. This is achieved by introducing a matrix reduction technique that is discussed in details. Furthermore, we evaluate the impact of uncertainty in the vehicle parameters on the algorithm estimation accuracy. The proposed algorithm is evaluated for different types of road roughness. The simulation results show that the proposed method is robust and can achieve high accuracy. The algorithm offers excellent potential for road roughness estimation not only for autonomous vehicle but also for vehicles and roads designing purposes.

Comparative results of evaluating the smoothness of automatic transmission gear shifting during car operation

The authors have studied the process of gear shifting, smoothness of it and peculiarities of automatic gearbox functioning of during car operation. The article describes the urgency of the problem of jerks and vibrations when changing gears. When assessing the smoothness of gear shifting, the method of technical state vibroacoustic diagnostics is applied. The method is based on the recorded parameters of vibration velocity, vibration acceleration, vibration movement with their further conversion (fast Fourier transform) into a spectralsignal. The procedure of longitudinal vibration acceleration measurements on cars in operation is described. A comparative analysis of the smoothness of gear shifting in an automatic transmission was carried out using the example of modern passenger cars. Keywords car; car operation; automatic gearbox; technical condition; gearbox malfunction; smoothness; jerks; jolts; gear shift quality criteria; vibration acceleration

Reduced Vibrations and Noise During Grinding

Abstract It is the duty of every employer to provide its employees with safe, hygienic and ergonomic working conditions. Available information suggests that working conditions in Poland improve each year, thanks to the ever-growing security culture prevailing in Polish enterprises. In spite of everything, there is still a problem of hazards in the workplace, and special attention should be paid to acoustic threats - vibrations and audible noise. Although entities operating on the market offering comprehensive services to reduce the exposure of employees to vibroacoustic hazards, there is still a need to develop new methods to protect the health of employees. Excessive exposure to vibrations and noise is associated with negative health effects that are exposed to, among others, employees involved in the mechanical processing of steel structures. Employees also experience the impact of local and general vibrations. Local vibrations can be relatively easily eliminated using anti-vibration gloves, while the reduction of general vibrations is often an unresolved problem for employees and employers. The publication presents the results of research on the development of the method of damping mechanical vibrations generated during grinding steel constructions. The research included several stages, among others: selection and preparation of the research material, design and construction of the test stand, measurements of vibration acceleration and industrial verification of the obtained results.

Analysis of Dynamic Parameters of a Railway Bridge

This article analyses the dispersion of vibration accelerations of a railway bridge during the passage of a train, and presents an analysis of their parameters after the application of the theory of covariance functions. The measurements of vibration accelerations at the fixed points of the beams of the overlay of the bridge were recorded in the time scale as digital arrays (matrices). The values of inter-covariance functions of the arrays of data of measurements of digital vibration accelerations and the values of auto-covariance functions of the individual arrays, changing the quantization interval in the time scale, were calculated. The compiled software Matlab 7 in the operator package environment was used in calculations. This article aims at determining the interdependencies of results of vibrations of bridge points rather than at the impact which a train makes on a bridge without emphasizing the modal parameters of the bridge. The aforementioned interdependencies make it possible to predict the results of hard-to-reach points.

КОРЕКЦІЯ ТЕМПЕРАТУРНОГО ВПЛИВУ НА П'ЄЗОЕЛЕКТРИЧНИЙ АКСЕЛЕРОМЕТР

In the article the possibility of compensation of non-informative component in measured signal obtained with the help of a piezoelectric accelerometer in the measurement of vibration acceleration is considered. This non-informative component in measured signal represents a constant level, which is caused by the generation of additional charge by piezoelectric element of the accelerometer in the absence of action on it from the side of the measurement object. The indicated additional charge is generated under the influence of environment temperature fluctuations. These temperature fluctuations add their negative component to the precision of the accelerometer, increasing the error of the measurement result. The greater their range of fluctuations in temperature and the rate of change in temperature over time are, the greater impact on the measurement results is obtained. Since the changes in temperature over time, in comparison with the frequency of measured vibrations, are much slower processes and their impact on the measurement results is constant throughout the dynamic range of the accelerometer, they represent an additive component of the error of the measurements. To reduce the influence of environment temperature, a solution for the improvement of piezoelectric accelerometer by introducing an element of compensation into its construction is proposed. In order to reduce the influence of environment temperature fluctuations on the measurement results, a controlled piezoelectric element which operates on reverse piezoeffect along the polarization axis is used as a compensation element. The control by the compensation element is carried

Effect of damping groove on flow dynamics and vibration characteristics of axial piston pump

This paper presents pressure, flow and vibration characteristics of an axial piston pump valve plate with damping grooves. For flow ripple and vibration of the pump reduction, an improved compressible fluid model of axial-piston pump with damping groove is developed to analyze flow dynamics and vibration characteristics. A parametric analysis is performed to analyze the effects of damping groove on the discharge pressure and flow ripples of axial piston pump. The sensitivity of discharge pressure and flow ripple are analyzed to different pressure levels, speeds, and damping groove parameters. The results of pressure ripple and vibration characteristics are validated by experimental test. The experimental and simulation results differ by only approximately 0.75 MPa in the pressure ripple amplitude. The results of the vibration acceleration measurements show that the valve plate with damping groove reduces the vibration level by 0.4 mm/s2 at the rated working condition. It is the effective method that the valve plate parameters are improved to reduce vibration characteristics of axial piston pump.

Operational Modal Analysis of Frame Building Module during Road Transport

A real structure performance does not necessarily match the way the structure’s numerical model reacts to a load applied – even though it was constructed by specialists in the field and with the use of a state-of-the-art generation of software based on the finite element method (FEM). Inconsistencies are even greater, when the construction material is not as uniform and isotropic as steel, but wood, whose mechanical properties depend on a greater number of variables, like whether the loads apply longitudinally or across the grain. In such cases, it is necessary to customise a previously developed numerical model (model calibration) to fit real conditions of the performance. More and more frequently, to carry out experimental modal analyses (EMA), some measuring equipment and software is used to this end, which allows for estimation of credible structure modal parameters, i.e. particular normal mode shapes and their equivalents of natural frequency and modal damping values, which are necessary for credible calibration of a numerical model developed in FEM. It is not in every case, however, that one can excite vibration in a structure by means of classical modal exciters or modal hammers. Being a relatively new approach in the structure modal analysis, vibrations present in immediate surroundings of a tested object are used for this purpose. An analysis of such type is called the operational modal analysis (OMA). This study seeks to estimate credible modal parameters for one of the wooden modules of a multi-storey, multi-unit residential building, constructed by UNIHOUSE in Bielsk Podlaski in Poland, during its test road transport to its project site. The operational modal analysis of the frame building module was conducted with the use of a dedicated software LMS Test.Lab Spectral Testing. Measurements of vibration accelerations were carried out in 12 measurement points of the tested frame building module using a 32-channel and 24-bit data acquisition hardware type SCADAS Recorder from SIEMENS with 130 dB dynamic range and signal to noise ratio – minimum 106 dB, as well as a set of 10 high sensitivity triaxial piezoelectric accelerometers type TLD356B18, manufactured by PCB Piezotronics and two uniaxial, high sensitivity accelerometers type 333B50 – also manufactured by PCB Piezotronics. As a result of the tests and analyses executed on the proposed structure modal model, it was possible to estimate modal parameters of a single module of a frame multistorey building, which may be used for calibration of the structure numerical calibration in the FEM software.