Vibration Accelerometer Research Articles

Vibration Characteristics and Mesoscopic State Evolution of Ballasted Track During Dynamic Stabilizing Operation

Dynamic stabilization of large machines is necessary procedures before the commencement of operations railway lines that are newly built. However, limited or no studies have been carried out to reveal the operational mechanism from the vibration transfer characteristics of ballasted track subjected to excitation by stabilizing machines. The focus of this study is to solve this shortcoming. First, a typical new railway line was selected to test the dynamic response of the ballasted track during stabilizing operation, and then a stabilizing machine-ballasted track model was established with the help of the DEM-MBD coupling method. And the biaxial vibration accelerometers were inserted at various locations in the ballast bed to monitor the evolution of the vibration level on real-time basis. The influence of the stabilizing operation process on the vibration transmission and attenuation characteristics of sleeper and ballast bed was explored using wavelet analysis and Fast Fourier Transform method. The vibration absorption capacity and energy dissipation characteristics of the ballasted track under various stabilizing frequencies were analyzed. At the same time, the contact state and movement posture of ballast particles during the stabilizing operation were explored. Results showed that the vertical vibration attenuation rate of the slope toe of the ballast bed after the first stabilizing machine pass is 92.32%, while the vertical vibration attenuation rate of the second stabilizing machine is reduced by 3.14%. The second stabilizing machine can cause a large lateral movement of the ballast at the bottom of the sleeper. Under the excitation of 25[Formula: see text]Hz stabilizing frequency, it was observed that, the vibration absorption capacity of the ballast bed at the bottom of the sleeper is high, the vibration level at the ballast bed slope is low, and the stability is better. This is the optimal frequency for the stable operation of the new railway. This study can provide theoretical support for the establishment of the internal correlation mechanism between the vibration characteristics of stabilizing machines and the mechanical state of the ballast bed.

Sensitivity enhanced vector accelerometer based on FBG-FP inscribed on multicore fiber.

We propose and fabricate a high-sensitivity vector vibration accelerometer with a multicore fiber Bragg grating Fabry-Perot (FBG-FP) structure. The acceleration sensitivities of the FBG and FBG-FP are 0.15 and 1.26V/g, respectively. After packaging, the acceleration sensitivity of the FBG-FP is further improved to 6.89V/g, which is 45.9 times higher than that of the FBG. The resonant frequency of the accelerometer increases from 30 to 86Hz. Both the sensitivity and resonant frequency of the accelerometer are improved. Owing to the asymmetry of the outer core of the multicore fiber, high-sensitivity two-dimensional vector acceleration sensing can be realized.

Enhancing the Performance of FBG Accelerometers by Using In-Fiber Fabry Perot Interferometers

An in-fiber Fabry–Perot interferometer (FPI) is proposed and designed for performance improvement of a fiber Bragg grating (FBG) accelerometer. It consists of two FBGs which are inscribed using the femtosecond laser point-by-point technology. The spectral characteristics of the FBG Fabry–Perot (FBG-FP) were studied. Edge filter interrogation configuration was employed in the vibration measurement system. In contrast to the conventional FBG accelerometer used in wavelength interrogation or edge filter interrogation configurations, the scheme has a higher sensitivity and lower detection threshold which are achieved improving the optical properties of the accelerometer. We fabricated a high-frequency accelerometer and experiments were carried out to verify its performance. The sensitivity and detection threshold were 27.3 mV/g and 1.5 mg, respectively. This study presents a feasibility analysis of the short cavity FBG-FP, as opposed to a single FBG, for the vibration accelerometer.

Improving shallow and deep seismic-while-drilling with a downhole pilot in a desert environment

Processing seismic data from drillbit-generated vibrations requires a reliable source signature for correlation and deconvolution purposes. Recently, a land field trial has been conducted in a desert environment. A memory-based downhole vibration accelerometer has been used together with a more conventional top-drive sensor to continuously record the pilot signal from 590 to 8600 ft (180–2621 m). Past results indicate that seismic-while-drilling (SWD) data processed using the top-drive accelerometer exhibit good quality in the middle sections of the well but a reduced signal-to-noise ratio for shallow and deep sections. One of the main challenges in using the downhole pilot is a substantial drift of the downhole clock time. To resolve it, a novel automated time-alignment procedure using the GPS-synchronized signal of the top-drive sensor as a reference is applied. The downhole recording provides a source signature of better quality. In shallow sections of the well, it helps to overcome the intense surface-related vibrational noise, whereas, in deeper sections, it provides a cleaner extraction of weaker signals from the polycrystalline diamond compact bits. Processing with the downhole pilot results in better surface seismic data quality than with a conventional top-drive sensor. Therefore, enabling the use of the synchronized downhole pilot signal is of crucial importance for SWD applications. Modern cost-effective near-bit vibrational sensors widely used for different nonseismic applications could be an effective acquisition solution, as shown in this study.

Применение параллельных вычислений для аннотирования сенсорных данных

Sensor data annotation involves automated marking of a time series of readings taken from the sensor, which highlights various activities specified by the specified series. Activity marking has a wide range of practical applications: predictive maintenance, intelligent management of life support systems, climate modeling, etc. Previously, we developed a parallel PSF algorithm for annotating sensor data using a GPU based on the concept of snippets. Snippet is a subsequence that many other subsequences of a given series resemble in the sense of a specialized similarity measure based on Euclidean distance. This article describes two case studies performed using the PSF algorithm: annotation of the readings of a wearable vibration accelerometer mounted on a person and a stationary vibration accelerometer mounted on a small crusher. As part of the research, computational experiments were conducted to evaluate the speed and accuracy of the developed algorithm. Also there was the research on the dependence of the efficiency of the algorithm on the values of the input parameters: the number of the desired snippets and the length of the subsequence.

The Empirical Assessment of Vibration in HVAC Systems

Background and purpose: Vibration caused by ventilation systems in buildings is one of the harmful physical factors that can cause harm to residents. Therefore, measuring and controlling vibration is important.
 Materials and Methods: In the first step of the study, the vibration accelerometer was placed on the base of a fan where the vibrations were sent toward the duct wall. A vibration assessment of the building was conducted in the other steps to compare with guidelines. In the next step, isolation method was used to control vibration. By placing the isolator on the duct wall, the accelerometer was located on the body of the duct wall and the value of vibration was measured in a millimeter per second. All stages of the experiment were performed in the Faculty of Health of Isfahan University of Medical Sciences in 2018.
 Results: The maximum vibration velocity reduction in the building was related to the frequency of 68 Hz, which reached 33 mm/s after isolation. In addition, the fan vibration at 485 Hz was equal to 2.1 m /s, which decreased to 2 mm /s after isolation.
 Conclusion: Comparison of vibration after fan isolation with standard showed that this method has been effective in reducing the fan vibration resulting in the vibration to reach below the standard.

Стендовая отработка алгоритмов диагностирования подшипников качения бортовой системы диагностики и прогноза остаточного ресурса основных и вспомогательных узлов МПВС

The experimental study of bearing vibration and use of the fast Fourier transformation (FFT) as an intelligent tool for diagnosing and identifying bearing defects of motor car rolling stock units (MCRSU) is presented. It is shown that the use of new means of technical diagnostics due to the detection of malfunctions at an early stage of their development reduces the cases of violations of the normal operation of cars and rolling stock. The article presents the results of vibration diagnostics of rolling bearings on the stand, spectral characteristics are obtained for bearings with rolling body defects, internal track and external track. During the bench tests, a specially developed intelligent vibration sensor was used as a vibration sensor, consisting of a sensitive element, a vibration accelerometer, the necessary interfaces and an analogdigital converter. The radial arrangement of sensors in diagnostic systems in repair depots and on-board systems makes it difficult to diagnose defects associated with the appearance of defects under the influence of axial loads, primarily separator defects. Bench tests using intelligent sensors and cloud services on the Internet showed the possibility of creating a mobile system for diagnosing the technical condition of bearing units of motor-car rolling stock and freight car units.

Performance Comparison of Cryogenic Treated Tool Vs Untreated Tool using an Accelerometer Sensor

In this paper, performance of the Cryogenic treated tool along with the untreated tool is investigated in turning of En8 Medium carbon steel. Results are got by comparing parameters of vibration in tool. For vibration Accelerometer sensor, it is used to find the Acceleration of tool in X, Y and Z axis for incremental depth of cut. The cryogenic tool has lesser machining time, increased tool life and surface finish due to the reduced vibration than the untreated tool.

Development of a Miniature Recorder for Drilling Motors

A recorder is designed to record the vibration data of the drilling motor for health assessment of the motor to improve the drilling efficiency. It is installed in the rotor catch of the drilling motor without increasing the length of the bottom hole assembly(BHA). The recorder is equipped with two triaxial vibration accelerometers with different ranges, a rate gyroscope, a temperature sensor, and an integrated circuit (IC) for timestamps. The recorder can measure and record the vibration data of the entire operation cycle of the ground transportation, rig-side handling and downhole operations of the motor. Vibration recorder does not require any configuration or intervention at rig sides so that it can be easily deployed to motor operations. The Python-based data analysis software was developed for the miniature vibration recorder. The analyzer can make statistics on the recorded data and display it with time plots and histogram. The vibration recorders provided adequate information of a drilling motor to maintenance shops and operator. These statistical data and charts can help users understand transportation, rig-side handling and downhole drilling.

Vibration of drilling motors in unconventional oil and gas exploration with a miniature recorder

A low-cost and miniature vibration recorder was developed to capture the vibration data of drilling motors for their health assessment. The recorder is installed in the rotor catch of a conventional drilling motor in such a way that no additional length is added to the bottom hole assembly. The recorder is fitted with two triaxial vibration accelerometers with different ranges, a rate gyroscope, a temperature sensor, and an integrated circuit (IC) for timestamps. The recorder can log data over the full operation cycle of a drilling motor, including vibration during surface activities and downhole operation. It allows the vibration recorders to be easily deployed to motor operations. The vibration recorder has been deployed to drilling motors in unconventional horizontal wells. The data analysis showed that the recorder captured vibration data from the installation of the recorder in maintenance bases until the return of the tools. Not only downhole drilling vibration data were successfully obtained, but also surface vibration data during shipment, and rig-side handling was recorded; the vibration recorders provided adequate information of a drilling motor to asset owners for maintenance and operation optimisation.

ИСПОЛЬЗОВАНИЕ УСКОРЕНИЯ СВОБОДНОГО ПАДЕНИЯ ПРИ КАЛИБРОВКЕ ВИБРОАКСЕЛЕРОМЕТРОВ ДЛЯ ДИАГНОСТИКИ УЗЛОВ МОТОРВАГОННОГО ПОДВИЖНОГО СОСТАВА

The paper presents the possibility of using gravitational acceleration methods for calibration of MEMS vibration accelerometers, vibration and vibration shock sensors. Such calibration is carried out without disassembling of sensors of on-board system for controlling the technical condition of motive-coach stock bearing assemblies.

A multi-sensor information fusion for fault diagnosis of a gearbox utilizing discrete wavelet features

A gear box is widely employed in automobiles and industrial machines for transmitting power and torque. It operates under various working conditions for prolonged hours increasing the chance of gearbox failure. Major faults in gear systems are caused due to wear, scoring, pitting, tooth fracture, etc. Gear box failure leads to increases in machine downtime and maintenance costs. The nature and location of such failures can be identified with precision using condition monitoring techniques. In this study, machine condition data are acquired from the gear box using a vibration accelerometer, microphone and acoustic emission sensors under different operating conditions, such as three loading conditions (0 N, 5 N, 10 N) and three rpm variations (500, 750, 1000). The wavelet features are extracted from the acquired vibration, sound and acoustic emission signal, and prominent features are identified. To automate the process of fault diagnosis, machine learning algorithms (artificial neural network, support vector machine, and proximal support vector machine) are utilized. Dual and multi-sensor fusion is implemented with the help of prominent features, to intensify the classification accuracy. The performance of the individual signals, and dual and multi-sensor fused models in gearbox fault diagnosis are compared and discussed in detail.

표준 측정 방법에 기반한 가속도 지진 센서 특성 평가

The current calibration process for seismometers is not in accordance with the international meteorological standard. The contemporary increase in seismic and volcanic activity around the Korean Peninsula has highlighted the necessity for and importance of compliance with the international meteorological system. This paper details the evaluation of a characteristic seismic accelerometer according to the international standard procedure. The dynamic and static sensitivities of the seismic accelerometer are calibrated, and the degree of uncertainty of the calibration process is also evaluated based on the standard procedure for vibration accelerometers. Results indicate that the seismic accelerometer is notably sensitive to changes to the excitation frequency and direction of vibration. Therefore, the results show that the conventional method widely used in the field of seismology, of merely noting a single nominal value when using a seismometer, is subject to clear limitations.

Experimental study on the effects of mechanical vibration on the heat transfer characteristics of tubular laminar flow

In this study, experiments were performed to investigate the effects of sinusoidal vibrations on the heat transfer characteristics of internal flow in a circular heated tube. Water was used as the working fluid with inlet Reynolds numbers varying between 512 and 2047. The frequencies of the mechanical vibration generator varied from 158 to 3000Hz, and the vibration accelerations were 1.0g, 3.0g, and 5.0g. The time domain acceleration signal was obtained using a vibration accelerometer and then transferred to the frequency domain using the fast Fourier transform method in the experiments. The results demonstrated that mechanical force vibration significantly influences the heat transfer in a heated pipe flow. The Nusselt number increases indistinctively with the vibration acceleration augmentation, while the enhancement in the Nusselt number is weakened as the inlet velocity increases. The Nusselt number increases rapidly when the vibration frequency increases to the resonance frequency value of 400Hz and then decreases sharply and levels off at the frequency of 1500Hz. Finally, a new correlation was derived using the key parameters of vibration frequency, vibration acceleration, and Reynolds number.

Self-powered triboelectric nano vibration accelerometer based wireless sensor system for railway state health monitoring

Vibration exists everywhere especially in the public railway operation system. The vibration acceleration is the key factor to monitor and evaluate the structure health of the railway equipment. In this paper, a kind of self-powered triboelectric nano vibration accelerometer (TEVA) is presented. A low frequency spring mass vibration model is built to calculate the vibration sensitive performance and the electric output of the TEVA. The prototype of the TEVA is demonstrated and characterized through the railway vibration simulation platform. It has been testified that TEVA can successfully harvest the low frequency vibration energy and convert it to electrical power to achieve the self-powered vibration acceleration monitoring system. The output current and voltage of TEVA are also sensitive to the vibration acceleration from 1.07m/s2 to 1.25m/s2 linearly. Hence it can be used as a self-powered nano vibration accelerator for the fault diagnosis. In addition, the generated electricity is used for charging the lithium battery (from 1.5V to 3.1V) which supplies power to the ZigBee module. The experiment shows that the charged battery through TEVA can support the wireless communication between ZigBee modules, with temperature and humidity sensors embedded on it. The temperature and humidity on the train are 22°C and 35%RH respectively. Therefore, the vibration energy can be harvested and stored for the power supply of wireless sensor network nodes in the near future.

Semi-analytical FEM Analysis and Experimental Measurement for Propagating Guided Waves Modes in Rail

Acoustical guided waves modal analysis in rail is the basis of long distance guided wave inspection and rail vibration and noises control. In particular the various propagating guided waves in the rail are identified in terms of their propagation wavenumber coefficients and their corresponding deformed shapes. The semi-analytical finite element method is used to formulate the governing equation for guided waves propagating in elastic waveguides of arbitrary cross-section on the basis of the virtual work principle, wavenumber dispersion curves and deformed shapes are extracted by solving governing equation, which provide the basis for selecting mode and frequency during application. The propagating guided waves wavenumber dispersion curves and deformed shaped under 0-8 k Hz frequency range for CHN60 type free rail are obtained using semi-analytical finite element method, and the characteristics of the eight based guided waves mode in rail are discussed. Instrumented hammer experimental study and modal analysis using sever vibration accelerometers mounted on rail are carried out to verify the vertically vibrating mode and horizontally vibrating mode guided waves wavenumber dispersion coefficient. Modeling and experimental investigations of lateral and vertical excitation in railhead shows that good agreement between numerical calculation and experiment.

Evaluation of Running Safety for Railway vehicles Based on Vibration Acceleration of Bogie

The lexical meaning of derailment shall be the wheels of trains going off the track and it is an important factor for the running safety of railway vehicles. For the measurement of interaction forces between the wheel and the rail, wheel set is used with normal method and the vibration accelerometer is used with simplified method to assess the safety of a railway vehicle in the derailment process. The result has been recorded by measuring vibration acceleration.

1-3 Piezocomposite for Vibration Accelerometer Applications

The new type of vibration accelerometer with 1-3 piezocomposite transducer was investigated. Piezoelectric ceramic PZT-5A was used as piezoelectric phase and epoxy resin as the polymer phase to fabricate the 1-3 piezocomposite transducer. The dynamic properties of this new vibration accelerometer were discussed. The results show that when the operating frequency is far less than the nature frequency of piezoelectric sensitive element, the voltage sensitivity of 1-3 piezocomposite vibration accelerometer is a function of piezoelectric phase and polymer phase, and a function of the volume fraction of 1-3 piezocomposite transducer. When the materials of piezoelectric phase and polymer phase were defined, the voltage sensitivity of 1-3 piezocomposite vibration accelerometer is only a function of the volume fraction of 1-3 piezocomposite. The theoretical and experimental values of voltage sensitivities of vibration accelerometer based on 1-3 piezocomposite transducer are 5.8 times and 4.2 times that of vibration accelerometer based on PZT-5A disk.

Fault Detection with Vibration Transducers

Abstract Mechanical faults, usages, slackness's, cause different noises and vibrations with different amplitude and frequency against the normal sound and movement of the equipment. The vibration transducers, accelerometers and microphone are used for noise and/or sound and vibration detection with fault detection purpose. Vibration transducers and accelerometers have three functioning domain, if the input frequency is les then the resonant frequency of the sensor it is working as an accelerometer, if the input frequency is higher then the resonant frequency of the sensor it is working as vibrometer. Detecting and analyzing the signal of the transducer, amplitude and spectral analyzing, we can detect usages, slackness and forces which act and produce the fault. Analyzing the output signal of the sensor and compare with a base signal or with nominal values mechanical faults can be detect in functioning time without stopping and to take to pieces the equipment. It is an undestroyed method to find out the functioning problems. In this paper are presented simple transfer functions for two cases, if the mechanical system is vibrating and if through the base is transmitted a vibration to the system. The system behavior is analyzed in Matlab surround the natural frequency of the system. The amplitude and phase modification can be used for signal analysis and fault detection.

Noise Analysis of a Range Hood

In order to find the vibration and noise sources of a certain type of range hood and analyze the aerodynamic noise's generating mechanism of it, vibration and radiated noise produced by a working range hood were measured with vibration accelerometers, microphones and other precision instruments under the condition of semi-free sound field, according to the national standards. Spectrum analysis methods were adopted to analyze the spectral characteristics of the noises, and the frequency distribution was obtained. A model of the range hood fan was built, and the inner flow field distribution of the fan was analyzed with numerical simulation method. The vibration and noise sources of the range hood were finally found and the presence of the aerodynamic noise was proved. Some suggestions on the improvement of the range hood fan were also given.