Vibration Measurements Research Articles

In-situ measurement of subway train-induced vibration and noise of steel spring floating slab with MEMS-based sensing units

The concrete floating slab, as a widely-used measure to reduce the subway-induced vibration and noise, can deteriorate with the accumulation of trainload. To monitor the dynamic performance of the floating slab during operation, this study develops a lightweight sensing unit based on microelectromechanical systems (MEMS). This sensing unit, which can be easily mounted on the concrete slab, enables synchronous monitoring of vibration and noise at different sampling frequencies with a very low power consumption. With the advantage of easy installation, the sensing units are mounted on various concrete slabs and tunnel walls to collect massive vibration and noise data. With the monitoring data, the dynamic performance and vibration reduction capability of the floating slab can be assessed. A case study is conducted on two floating slab sections: one section has a floating slab with a potential defect on its shear hinge and the other has a normal floating slab. The monitoring results show that: (1) the train condition has a significant effect on the amplitude of the track-side vibration; (2) the train-induced noise data last longer than vibration data during the passage of trains; (3) for the floating slab with shear hinge defect, the vibration levels at edge points are much higher than that in the middle. Through the monitoring test, the performance of the MEMS-based sensing unit and its adaptability in subway circumstances are verified.

High-Pressure Polymorphism in Silver Ferrite Delafossite, AgFeO2.

The delafossites are a class of layered metal oxides that are notable for being able to exhibit optical transparency alongside an in-plane electrical conductivity, making them promising platforms for the development of transparent conductive oxides. Pressure-induced polymorphism offers a direct method for altering the electrical and optical properties in this class, and although the copper delafossites have been studied extensively under pressure, the silver delafossites remain only partially studied. We report two new high-pressure polymorphs of silver ferrite delafossite, AgFeO2, that are stabilized above ∼6 and ∼14 GPa. In situ X-ray diffraction and vibrational spectroscopy measurements are used to examine the structural changes across the two phase transitions. The high-pressure structure between 6 and 14 GPa is assigned as a monoclinic C2/c structure that is analogous to the high-pressure phase reported for AgGaO2. Nuclear resonant forward scattering reveals no change in the spin state or valence state at the Fe3+ site up to 15.3(5) GPa.

Determination of Optimal Machining Parameters Based on Roughness and Vibration Measurements of Pieces Produced by Whirling on a Lathe Machine

Worms can be produced using special machines or standard lathes equipped with a whirling thread-cutting device. A blank is placed on the mandrel and tightened using the three-jawed chuck of the standard lathe. If the workpiece diameter is excessively large, passage through the driven pulley is not possible, and the workpiece cannot be supported. Therefore, a new tool holder for whirling devices is needed. During the whirling process, vibrations in the form of machine velocity amplitudes were measured. After whirling was complete, roughness values were calculated. Using numerical procedures of Wolfram Mathematica 10, vibration peaks were extracted, from which frequencies and maximum amplitudes were determined. The data were then inputted into Design Expert, and the rotational speed and amount of separated material were optimized. The results of the study showed that the quality of the processed surface did not improve with processing in two passes of the tool. The measured vibration amplitudes on the lathe carrier and thread whirling attachment increased with cutting speed at the same cutting depth, whereas the quality of the machined surface was best at the smallest and largest cutting depths.

Sound pressure level determination around the transformer using coherent and incoherent analytical summation methods

In this paper, coherent and incoherent analytical summation methods from elementary sound sources on the transformer’s tank are presented. They aim to determine a one-third-octave spectrum of sound pressure levels (SPL) in points around the transformer. Each part of the transformer’s surface is treated as a separate plane source so the analytical calculation can be applied to find SPL in the surroundings. Reflections from the ground are also considered by putting an image of the plane sources on the other side of the reflecting plane and adding its contributions to the total pressure in the desired points. Grid-like vibration measurements of vibration velocity on the tank surfaces are used as input parameters. Vibrations and sound pressure levels are measured to validate the method on the 5 MVA transformer experimental object. The SPL around the transformer in short-circuit (SC) and open-circuit (OC) tests is measured in the semi-anechoic chamber to compare it with theoretical results. By analyzing the results, the coherent calculation with reflection provided the most accurate results. In the SC operating condition, the normalized root mean square error (NRMSE) is 17.2%, and in the OC operating condition, it is 10.9%. The novelty of the presented method is that it considers complicated transformer geometry where each surface is calculated as a separate noise source. It calculates noise at a distance from the elementary vibration sources, considering phase and reflection from the hard ground, and provides detailed noise maps that can be used for noise modeling around the substations.

Interferometric-scale full-field vibration measurement by a combination of digital image correlation and laser vibrometer

Interferometric-scale full-field vibration measurement by a combination of digital image correlation and laser vibrometer

Analysis of hot spots and trends in rolling bearing fault diagnosis research based on scientific knowledge mapping

Abstract As a key component of mechanical equipment, real-time monitoring and diagnosis of rolling bearings play a critical role in ensuring the stable operation of equipment and the safety of operators. In order to present the current status and trends of fault diagnosis research on rolling bearings more intuitively, the scientific knowledge mapping was used to visualize and analyze the relevant literature in the article. The results show that the number of publications in this area of research has grown significantly in recent years, with China, India, the United States, and England having contributed significantly. The journals such as MECHANICAL SYSTEMS AND SIGNAL PROCESSING, MEASUREMENT, and JOURNAL OF SOUND AND VIBRATION have played an important role in disseminating cutting-edge technologies in this field. In addition, the exploration of modern methods based on data-driven and artificial intelligence, as well as their application to real-world problems, are gradually becoming the focus of research. Through summarising and analysing, the application of modern data processing techniques, the development of more efficient and practical intelligent fault diagnosis techniques, and the close integration of laboratory research and practical applications will become future research trends.

Field measurement of track vibration induced by full-load and empty-load condition in curve section of underground metro line

In order to compare the differences in vibration before and after wheel re-profiling and assess the vibration impact of train under full-load and empty-load condition, the field vibration measurement was conducted on an underground metro track components (including rail, sleeper, and track-bed) by using a specific testing car. The results indicate that wheel re-profiling is effective in reducing track vibration, within the frequency range of 31.5–1250 Hz, the vibration acceleration levels of the track after wheel re-profiling were notably lower than those prior to re-profiling and the vibration acceleration levels of the rail, sleeper, and track-bed decrease by 4.7 dB, 6.6 dB, and 6.7 dB, respectively. In the frequency domain, the characteristic peak frequencies of the three track components, whether under full load or empty load, align closely with the frequencies associated with track irregularities. Full-load condition primarily affects the vibration acceleration at lower frequencies, with minor influence on higher frequencies. The vibration acceleration levels of all three track components are higher under full load than empty load. Additionally, under full-load condition, the transmission loss from the rail to the sleeper increases, while the transmission loss from the sleeper to the ballast remains nearly constant. The results of vibration acceleration levels obtained from routine vehicle operations validate the limited impact of axle load on track components vibration.

Hand-Arm-Vibrationsdosis und arbeitstechnische Voraussetzungen für die Berufskrankheit Nr. 2103 – Eine epidemiologische Fall-Kontroll-Studie

Hand-arm vibration dose and work-related requirements for occupational disease no. 2103 – An epidemiological case-control study Background: An epidemiological case-control study of dose-effect relationships between hand-arm vibration exposure and musculoskeletal disorders of occupational disease no. 2103 (BK 2103) was carried out in order to provide evidence-based recommendations for the recognition of BK 2103. Methods: Male cases and controls were recruited and standardised personal interviews were conducted between 1 January 2010 and 30 November 2021. In addition to leisure activities and comorbidities, work histories regarding the use of hand-operated and hand-held technical tools that can induce hand-arm vibrations were recorded in detail. To quantify the individual vibration exposure, a database of industrial hygiene measurements of vibration values of over 700 technical power tools was established (vibration register). The vibration measurements recorded in the database allows quantification of the daily dose and lifetime dose of the vibration exposure. The dose-effect relationships between hand-arm vibration exposure and musculoskeletal disorders as defined by BK 2103 were quantified for the various dose models using conditional logistic regression analyses. Results: In total, 209 cases and 614 controls were recruited. Compared to controls, cases suffered more frequently from gout, arm fractures, hip osteoarthritis, knee osteoarthritis, spinal osteoarthritis and trauma injuries or inflammatory conditions of the finger, elbow and shoulder joints. After adjusting for relevant confounders, the study analyses demonstrate consistent and statistically significant dose-effect relationships between hand-arm vibration exposure and musculoskeletal disorders as defined by BK 2103. A vibration dose of Dhv = 142.331 m2/s4 x day or Dhw = 38.724 m2/s4 x day is associated with a doubling of the risk of musculoskeletal disorders of the upper extremities as defined by BK 2103. Conclusions: These dose values serve as a guide and could also be applied in an assessment of the work-related requirements for the recognition of BK 2103. Sensitivity analyses indicate that an exposure duration with a defined threshold daily dose is not suitable for guiding the recognition of BK 2103. Keywords: hand-arm vibration – musculoskeletal disorders – dose-effect relationship – epidemiology – risk-doubling dose

Characterizing the Unsteady Flow Field in Low-Flow Turbine Operation

Abstract Current operational considerations require steam turbines to operate in a more flexible way, with more frequent and faster start-up and an increasing part-load operation. For very low mass flowrates, the interaction of highly separated flow with the high-speed rotor blades causes windage flow. This type of flow is characterized by increased temperature and highly unsteady flow, which forms vortex structures that rotate at a fraction of the rotor speed. If their magnitude is sufficiently high and the frequency is close to the blade eigenfrequency, non-synchronous vibration (NSV) can be induced. In this paper, low-flow turbine operation is investigated using a three-stage turbine rig that features an instrumentation concept focused on capturing aerodynamic and aeroelastic phenomena. Extensive steady probe, unsteady pressure, and tip-timing measurements are utilized. The experimental scope covers a wide range of operating points in terms of rotational speed and mass flowrates. Low-flow regimes are detected by a reversal in torque and increase in temperature. Unsteady measurements during transient operation identified large-scale vortical flow structures rotating along the circumference, so-called rotating instabilities (RIs). The onset, growth, and breakdown regimes of RI are characterized for different low-flow conditions. The quantitative characteristics of RI with regard to nodal diameter and rotational speed are derived by a cross-correlation of multiple unsteady sensors. The blade vibration measurements show a moderate structural response from unsteady aerodynamic excitation, indicating no significant NSV occurring in the present experimental setup. Later in the study, an acoustic excitation system has been applied to trigger a locked-in NSV without interrupting the coherent flow structures. From that, significant blade response has been observed, revealing a high degree of mistuning and damping of the rotor blading.

Research on Vibration Accumulation Self-Powered Downhole Sensor Based on Triboelectric Nanogenerators.

In drilling operations, measuring vibration parameters is crucial for enhancing drilling efficiency and ensuring safety. Nevertheless, the conventional vibration measurement sensor significantly extends the drilling cycle due to its dependence on an external power source. Therefore, we propose a vibration-accumulation-type self-powered sensor in this research, aiming to address these needs. By leveraging vibration accumulation and electromagnetic power generation to accelerate charging, the sensor's output performance is enhanced through a complementary charging mode. The experimental results regarding sensing performance demonstrate that the sensor possesses a measurement range spanning from 0 to 11 Hz, with a linearity of 3.2% and a sensitivity of 1.032. Additionally, it exhibits a maximum average measurement error of less than 4%. The experimental results of output performance measurement indicate that the sensor unit and generator set exhibit a maximum output power of 0.258 μW and 25.5 mW, respectively, and eight LED lights can be lit at the same time. When the sensor unit and power generation unit output together, the maximum output power of the sensor is also 25.5 mW. Furthermore, we conducted tests on the sensor's output signal in conditions of high temperature and humidity, confirming its continued functionality in such environments. This sensor not only achieves self-powered sensing capabilities, addressing the power supply challenges faced by traditional downhole sensors, but also integrates energy accumulation with electromagnetic power generation to enhance its output performance. This innovation enables the sensor to harness downhole vibration energy for powering other micro-power devices, showcasing promising application prospects.

Dual straight-wing FBG accelerometer for low-frequency vibration measurement

Fiber optic accelerometers have a wide range of applications in low-frequency vibration measurement, such as in earthquake monitoring, disaster early warning, underground resource exploration, and anti-seismic monitoring projects for critical structures like dams and bridges. In response to the current issues of Fiber Bragg Gratings (FBG) accelerometers being insensitive to low-frequency vibration signals and challenging to apply in engineering, a dual straight-wing FBG accelerometer for low-frequency vibration measurement is proposed. Firstly, a sensor model is established and theoretically analyzed. Secondly, the impact of the sensor's main structural parameters on sensitivity and natural frequency is analyzed, and the sensor is simulated using ANSYS. Finally, a prototype of the sensor is developed, and a low-frequency vibration testing system is set up to test the sensor's performance. Experimental results show that the accelerometer has a natural frequency of 39.1 Hz, operates in the 5–22 Hz frequency band, and has a sensitivity of 171.7 p.m./g, a dynamic range of 69.82 dB, and a transverse interference resistance of less than 9.5%. This research provides a new reference for the development of similar sensors.

On Site Measurement and Evaluation of Environmental Vibration Caused by Ordinary Speed Train Operation

On Site Measurement and Evaluation of Environmental Vibration Caused by Ordinary Speed Train Operation

Differential Slope-Assisted BOCDA Based on Multicore Fiber for High Sensitivity Radial Vibration Measurement

Differential Slope-Assisted BOCDA Based on Multicore Fiber for High Sensitivity Radial Vibration Measurement

Design and Analysis Method of Piezoelectric Liquid Driving Device with Elastic External Displacement.

In piezoelectric drive, resonant drive is an important driving mode in which the external elastic force and electric drive signal are the key factors. In this paper, the effects of the coupling of external elastic force and liquid parameters with the structure on the vibrator resonance frequency and liquid drive are analyzed by numerical simulation. The fluid-structure coupling model for numerical analysis of the elastic force was established, the principle of microdroplet generation and the coupling method of the elastic force were studied, and the changes in the resonant frequency and mode induced by the changes in the liquid parameters in different cavities were analyzed. Through the coupled simulation and calculation of the pressure and deformation of the cavity, the laser vibration measurement test was carried out to test the effect of the vibration mode analysis. The driving model of the fluid jet driven by the elastic force on the piezoelectric drive was further established. The changing shape of the fluid jet under different elastic forces was analyzed, and the influence law of the external elastic force on the change in the droplet separation was determined. It provides reference support for further external microcontrol of droplet motion.

Enhancing Vibration Analysis in Hydraulic Presses: A Case Study Evaluation

Vibration monitoring is essential for maintaining the optimal performance and reliability of industrial machinery, which experiences dynamic forces and vibrations during operation. This study delved into a comprehensive analysis of vibration monitoring in hydraulic presses, utilizing advanced measurement systems equipped with accelerometers. The proposed system included a three-axis accelerometer, data acquisition unit, and dedicated measurement software, facilitating the precise monitoring and analysis of vibrations. The influence of the sensor placement and sampling frequency on the measurement results was examined. A time and frequency analysis of the recorded measurements was performed. The results demonstrated the correlation between vibration levels and various production parameters, such as the number of parts simultaneously produced and press pressure. These findings underscore the potential for vibration measurement as a pivotal component in controlling production parameter settings.

Measurement of Vibrations on Installation of Internally Driven Pile

Measurement of Vibrations on Installation of Internally Driven Pile

Analysis of Ground Vibration Levels Due to the Blasting Process at PT. Bumi Suksesindo

Ground vibration is one of the effects of the blasting process; when the ground vibration reaches the highest level, it will disturb comfort and even cause damage to the surrounding building structure. This research aims to determine the magnitude of ground vibrations in Pit A and Pit C, as well as determine the relationship between Peak Particle Velocity (PPV) and scaled Distance, and determine the maximum explosive charge weight per delay based on the SNI 7571: 2010 reference. Actual ground vibration measurement data during research based on PPV theory and the actual PPV power regression relationship with scaled distance was used to obtain a ground vibration prediction formula to be a reference for determining the amount of explosive filling per delay. The ground vibration produced in the blasting process is hoped not to exceed the safe threshold. Prediction of the ground vibration formula at 100 m to 1500 m according to the US Bureau of Mines where the Mean Squared Error (MSE) value is 0.54, the MSE value from the Langefors-Kihlstrom equation is 1.85 while the MSE value from the Ambersays-Hendorn equation is 0.31 with the slightest deviation is very good to use as a reference for predicting ground vibrations with the predicted PPV formula. Hence, the maximum explosive charge with a PPV limit of 2 mm/s is 2.452 kg, a PPV limit of 3 mm/s is 11.332 kg, and a PPV limit of 5 mm/s is 23.040 kg. The factors that influence ground vibration are the Distance from the blasting location to the measurement location and the maximum number of explosives per delay, so the results taken from this research are that blasting in Pit A and Pit C is still categorized as safe for infrastructure and community housing.

A novel rotary ultrasonic motor based on multiple Langevin transducers: design, simulation, and experimental investigation

Traveling wave rotary ultrasonic motors (TRUSMs) have been applied in optical systems, robotics, biomedical and other fields. However, the disadvantages such as short working life, driving performance degradation, and low energy utilization significantly limit the long-term and stable operation of TRUSMs in advanced fields like aerospace mechanisms. To address the above issues, a novel rotary ultrasonic motor based on multiple Langevin transducers is proposed in this paper. First, the structural design, driving principle and general design criteria are described in detail. Then, the structural parameters are optimized by finite element simulation analysis. Second, a prototype is assembled controllably. Subsequently, the impedance test and vibration measurement are carried out. The results show that the traveling wave is successfully generated on the tooth-ring, and all the Langevin transducers are excited to the first-order longitudinal vibration modes, which strongly verify the correctness of design principle. Finally, the driving performance experiment is carried out. The experimental results show that the no-load speed is 62 r min−1 under the pre-pressure of 10 N. The stalling torque is 0.94 N m at the driving voltage of 500 Vp-p. The response characteristics show that the start/stop time are 4.6/5.5 ms, and the angular displacement resolution of clockwise/counterclockwise driving are 6.7/10.2 μrad. The motor proposed in this paper not only exhibits relatively high output performance with excellent vibration characteristics, but also maintains compactness of the structure. The sandwiched structure design effectively avoids the problem that the bonded-type piezoceramic rings in conventional TRUSMs are prone to damage or fall-off when vibrating for a long time. Furthermore, the general design criteria provide a new approach to develop high performance rotary ultrasonic motors. The proposed novel ultrasonic motor is expected to meet the demand for long-term and stable operation in aerospace mechanisms.

Проблемы диагностики современных тепловозных двигателей

Objective: to consider the issue of diagnostics of modern diesel engines, in particular vibration diagnostics. Consider modern strategies and methods based on vibroacoustic signals that allow you to track and diagnose diesel engine malfunctions, as well as an assessment of the working process in the engine. To determine which means of measuring vibration parameters and methods of processing vibration signals can be considered the most reliable and informative. Propose to make adjustments to the currently used methods of processing vibration signals. Methods: comparison of the effectiveness of vibration measurement tools and mathematical methods of vibration signal processing. Results: the necessity of choosing mathematical methods of vibration signal processing is indicated, both for individual components of a diesel locomotive engine and for evaluating the workflow. Modern mathematical methods, applied to vibration diagnostics, require updating, due to an increase in computing power, as well as due to the development of powerful signal processing methods. To increase the reliability of the comparison results, it is necessary to take into account the large variability of the components and processes of the diesel engine. The need for additional study of modern mathematical methods of vibration signal processing is revealed. Practical importance: the necessity of introducing more modern methods of vibration signal processing is shown, which will optimize the durability of the components’ design using long operating cycles, reduce maintenance costs, track the service life of the internal combustion engine during the operation of the locomotive, improve the monitoring and diagnostics systems of the locomotive engine. The presented methods of assessing the use of certain methods of vibration diagnostics for diesel locomotives can be recommended for practical use.

Direct detection Φ-OTDR based on UWFBG array using linear-phase-modulated double-pulse

We propose what we believe to be a novel direct detection phase-sensitive optical time-domain reflectometry (Φ-OTDR) based on ultra-weak fiber Bragg grating (UWFBG) array to achieve distributed vibration measurements with exceptional sensitivity and remarkable stability. Our system employs a pulse modulator to generate a double pulse and achieves linear phase modulation of one pulse by one cycle through a phase modulator. The phase change can be quantitatively demodulated using our proposed N-step phase-shifted demodulation algorithm. This method effectively mitigates the influence of phase noise of the laser and the pulse modulator, while also eliminating fluctuations in the half-voltage of the phase modulator. Compared with the existing phase modulation methods, our method avoids stringent requirements for the stability and precision of phase modulation. Moreover, we propose a phase-shifted approximation method, breaking the limitation of sensing length on the traditional differential approximation method and improving the accuracy significantly. The technique's effectiveness is experimentally demonstrated on a 1 km UWFBG array with a reflectivity of −40 dB to −45 dB and a spatial resolution of 10 m. Vibrations with different amplitudes are measured quantitatively with good linearity. The low-frequency self-noise is greatly suppressed and the overall self-noise is −54.3 dB rad2/Hz.