Engine Vibration Research Articles

Enhancing concrete strength through precision vibration engineering: Aggregate settlement and pore stats

Enhancing concrete strength through precision vibration engineering: Aggregate settlement and pore stats

Experimental and Simulation Study on Vibration Transmission Characteristics and Vibration Isolation Effect of a New Floating Raft Vibration Isolation System

To enhance the floating raft vibration isolation system’s effect, a new two-stiffness floating raft vibration isolation experimental was constructed. First, the system’s mathematical model was established. The vibration transfer function was deduced via substructure derivative synthesis and four-end parameter matrix methods, and the structural parameter impacts on it were analyzed. Then, a modal test was conducted, and a finite element model was built. Comparing finite element analysis with test results verified the model’s validity, followed by a study of the support structure’s vibration characteristics. Finally, by measuring acceleration responses at the isolator’s upper and lower ends and using the difference as an evaluation index, the isolator’s vibration isolation effect on land and underwater was investigated, along with its impact on the device’s underwater acoustic radiation. The results demonstrate that the two-stiffness vibration isolator can reduce vibration transmission within a specific frequency range both on land and underwater, guiding practical engineering vibration isolation research.

Kinematic and vibration analysis of a single-cylinder engine: Effects of connecting rod length, fuel type, and engine speed

AbstractThis paper emphasizes the role of fuel substitution in mitigating vibrations and enhancing the performance and reliability of internal combustion engines (ICEs). Using MATLAB for modal analysis, the study investigates natural frequencies and identifies potential resonance issues within critical engine components. The primary focus is on analyzing a four-stroke single-cylinder engine under various speeds and measuring the effects of fuel type on engine performance and efficiency. A comparative assessment evaluated vibration levels between natural gas and petrol by measuring engine vibrations across a range of speeds and analyzing the impact of varying dimensions of internal moving components on performance parameters. Results indicate minimal differences between the engines at lower speeds (1,500–2,000 rpm), while significant increases in vibrations were observed at higher speeds (2,500–3,000 rpm) for the gas engine, highlighting potential mechanical instability. At higher speeds, vibrations peak at the top of the engine, reaching 200 m s−2 with petrol and 240 m s−2 with natural gas. The experimental setup, including accelerometer modules and control systems, enabled real-time vibration monitoring. Numerical results showed that the longest connecting rod (197 mm) yielded the highest displacement, velocity, and acceleration metrics. These findings underscore the advantages of using natural gas as a fuel, including its availability, cost-effectiveness, and environmentally friendly nature, as it produces significantly lower harmful emissions compared to petrol. Additionally, the study offers insights into vibration-damping mechanisms and the influence of modifications to internal moving parts, such as crankshaft diameter and connecting rod length, on engine performance and stability.

Vibration characteristics of a compression ignition engine fuelled with different biodiesel-diesel blends

Biodiesel has wide application prospects due to its good power performance, fuel economy and emission reduction. Experimental studies have found that the measured engine vibration presents an N-shaped nonlinear trend with the increase of the biodiesel proportion in blends, which cannot be explained solely based on the combustion characteristics of blended fuels. To study the mechanisms for this nonlinear trend of engine vibration, a two-degree-of-freedom nonlinear model of piston–cylinder system was established and verified to analyse the correspondence between in-cylinder combustion behaviour and engine dynamic responses. By correlating simulation results with measured signals, it is found that the root cause of the nonlinear vibration trend is the coupling effect of in-cylinder pressure and piston inertial force. The time integral of piston lateral force in the interval from combustion top dead centre (TDC) to the subsequent piston slap ultimately determines the trend of liner vibrations. These key findings pave the fundamentals for the vibration analysis of engines fuelled with other alternative fuels, which is important for improve engine operation performances including reliability assessment and NVH control.

Fluid-induced vibration response characteristics of the oxygen pump volute

The oxygen pump constitutes a crucial and intricate component within liquid rocket engines, serving as a primary source of engine vibration. This study delves into the unsteady fluid-induced excitation loading, considering the interplay between gap flow and main flow. The findings are validated through testing on a liquid rocket engine. Modal characteristics of the oxygen pump under varying liquid mediums are examined. The Rayleigh damping parameter is determined, accounting for the frequency characteristics of fluid-induced excitation, thereby establishing a comprehensive transient dynamic model. Subsequently, the transient dynamic response of the volute in an oxygen pump to unsteady fluid-induced excitation is analyzed, unveiling both time-domain and frequency-domain vibration response characteristics. The analysis methodology is corroborated through comparison with the statistical distribution of test results. Notably, the vibration response of the oxygen pump volute predominantly exhibits frequency doubling of rotational speed, with prominent occurrences observed at the 12X and 18X frequencies.

Dynamic tuning of terahertz atomic lattice vibration via cross-scale mode coupling to nanomechanical resonance in WSe2 membranes

Nanoelectromechanical systems (NEMS) based on atomically-thin tungsten diselenide (WSe2), benefiting from the excellent material properties and the mechanical degree of freedom, offer an ideal platform for studying and exploiting dynamic strain engineering and cross-scale vibration coupling in two-dimensional (2D) crystals. However, such opportunity has remained largely unexplored for WSe2 NEMS, impeding exploration of exquisite physical processes and realization of novel device functions. Here, we demonstrate dynamic coupling between atomic lattice vibration and nanomechanical resonances in few-layer WSe2 NEMS. Using a custom-built setup capable of simultaneously detecting Raman and motional signals, we accomplish cross-scale mode coupling between the THz crystal phonon and MHz structural vibration, achieving GHz frequency tuning in the atomic lattice modes with a dynamic gauge factor of 61.9, the best among all 2D crystals reported to date. Our findings show that such 2D NEMS offer great promises for exploring cross-scale physics in atomically-thin semiconductors.

Experimental study of the effect of the properties of motor oils on the vibration and noise levels of internal combustion engines

The article discusses the results of an experimental study of the effect of the properties of domestic engine oils with copper-based additives produced by Kupper on the vibration and noise levels of marine propulsion systems using the example of a 3D6 diesel engine. 3D6 diesels are representatives that widely cover both the transport and marine sectors of power plants, which explains their choice as an object of research. Increased noise and vibration levels on ships negatively affect crew members and passengers and lead to fatigue and distraction of the watchmen. The engine oil used was standard MS20 oil, which is used for high-speed marine diesel engines and an innovative oil with copper-based additives. Comparative measurements of vibration and noise were carried out on a Yaroslavets-class vessel using an authorized vibration and noise meter of the first class Ecophysics110A. As a result of the study, it was found that vibrations in the most vibro-active modes of operation of the 3D6 diesel engine are reduced by 30–50 % when using oil with copper-based additives. The use of oil with copper-based additives also has an effect on reducing noise in the engine room, but in the high-frequency spectrum with a frequency of more than 1000 Hz. More effectively, engine oil with copper-based additives affects the reduction of the overall noise level in the wheelhouse of the vessel and as a result, an effect of about 3 dB was achieved, which reduces the effect of noise by 1.4 times in terms of physical perception for humans.

"Modernization of the power unit of tractors of traction class 1.4 by using a reversible electric machine"

The technical development of tractor designs is characterized by an increase in consumer power, the use of electric drive units. Therefore, the load on the electrical system of a modern tractor is constantly increasing and exposes existing systems to excessive load. Today, with the relatively low efficiency of traditional generators, it is impossible to meet the growing needs of tractors and their systems. An integrated starter generator can serve as a solution to the problem of increasing power simultaneously with increasing efficiency (up to 85...90%). With sufficient power in the engine mode (up to 8 kW), the starter generator allows you to improve the starting and energy characteristics of the tractor's internal combustion engines. The proposed design of electric machines is placed between the cylinder block of the internal combustion engine and the tractor clutch. The adopted layout allows you to transfer significant power in both directions, improves the starting qualities of tractor diesel engines, and also implements the functions of damping torsional vibrations of the crankshaft, which significantly reduces engine noise and vibration. Based on the results of the study, the choice of a starter-generator device (SGU) based on a reversible electric machine is justified in relation to diesel engines of tractors of traction class 1.4 and a scheme for its placement in the clutch crankcase without changing its basic design is developed. The advantage of the proposed design is the use of electric machines to start the engine, which in this case turns on the electric motor mode and switches to generator mode during operation, providing power to the on-board network with electric energy. In addition, combining the starter and generator in a single unit simplifies the design, reduces manufacturing and assembly costs, which is an advantage in terms of production costs, replacing the starter and generator and on some tractors the starting piston engine.

Experimental studies of the influence of a gyroscopic damping system on the aeroelastic characteristics of a large aircraft model with elastic pylon-mounted engines under the wing

During production of modern large transport aircraft, engine arrangement mounted on the elastic pylons under the wing is widely used. This arrangement of engines has certain advantages, however, there are also significant dynamic features due to the fact that the partial frequencies of vertical and horizontal (lateral) vibrations of elastic pylon-mounted engines are close to the wing bending and torsional natural frequencies of low modes. It is this frequency spectrum that determines the dynamic response of the aircraft as a whole to external disturbance input, and also significantly affects the dynamic stability of the aircraft. A number of technical solutions have been proposed to damp vibrations of the elastic pylon-mounted engines, including the implementation of the “freed engine” principle. To increase the dissipative parameters of the pylon-mounted engines vibrations, this paper proposes to use special devices – powered gyroscopes, which are the main part of the gyroscopic damping system. Numerous theoretical studies of the possibility of using powered gyroscopes have shown that the stability of a dynamic system can be increased by introducing additional gyroscopic, dissipative and potential forces into it. It is known that a method of direct gyroscopic stabilization is proposed to control aeroelastic oscillations of aircraft structural elements. The article proposes to use powered gyroscopes to damp lightly damped vibrations of pylon-mounted engines of a large aircraft. In order to assess the possibility of practical application of the gyroscopic damping system (GDS), experimental studies were conducted on a dynamically similar flutter model (DSFM) of a large aircraft type An-124 with four pylon-mounted engines under the wing. The studies included two stages: frequency and flutter tests. A gyroscopic device made according to the scheme of a rate gyroscope, which was installed inside the engine nacelle, was used as the GDS. The article presents the results of the experiments to assess the effect of the GDS on the dynamic characteristics of the DPFM. The analysis of the normalized amplitude-frequency characteristics of vertical and horizontal oscillations in the center of mass of the outboard engines shows a significant (by 1.5...5 times) decrease in the peak values of the oscillation amplitudes across the entire frequency range covered. The results of the experimental studies of the effect of the GDS on the flutter characteristics of the aircraft model showed a significant (7...15%) flutter speed enhancement at all levels of aircraft refueling. At the same time, with the gyroscopic damping system powered on, the self-oscillations are sluggish and incoherent, and the flutter modes change from one to another due to the gyroscopic coupling of the longitudinal and lateral motion.

Effect of Different Benzoylthiourea Additives to Gasoline on Engine Noise and Vibration in a Spark Ignition Engine

Effect of Different Benzoylthiourea Additives to Gasoline on Engine Noise and Vibration in a Spark Ignition Engine

Diesel engine vibration signal decomposition method based on successive multivariate variational mode decomposition

Diesel engine vibration signal decomposition method based on successive multivariate variational mode decomposition

A coupling study of scavenging effect on pollutant formation and unclean combustion of a linear vibration engine

A coupling study of scavenging effect on pollutant formation and unclean combustion of a linear vibration engine

A study on the structural vibration of the main engine of a fishing boat

A study on the structural vibration of the main engine of a fishing boat

Early warning of vibration faults of marine diesel engine based on improved VMD

ABSTRACT To improve the prediction accuracy of vibration signals from marine diesel engines, a novel method is proposed. This method utilises the rime optimisation algorithm (RIME) to select the variable modal decomposition (VMD) parameters for data reconstruction in order to optimise the bidirectional gated recirculation unit (BIGRU). The RIME-VMD-BIGRU model employs sample entropy as the fitness function. RIME determines the optimal k and α values for VMD, and the vibration signals are decomposed into subsequences. After noise reduction, these subsequences are reconstructed. A BIGRU prediction model is then built for the reconstructed components. The prediction results of these components are combined to provide vibration prediction. Case studies show that the proposed model achieves smaller prediction errors and higher accuracy compared to other models. It effectively provides early warnings for diesel engine vibration signals.

Novel metamaterial wave barrier structure with multiple frequency wide band gaps for rail transit vibration isolation

As a new kind of artificial composite material, locally resonant phononic crystal (LRPC) can attenuate and suppress the propagation of elastic waves in certain frequency range, which has a broad application prospect and value in the field of vibration and noise control. The traditional LRPC can only open one band gap (BG), but the vibration and noise in practical engineering are often multi-band, so the traditional LRPC cannot effectively cover the target frequency range, and the efficiency of vibration and noise reduction is greatly limited. In response to the shortcomings of traditional LRPC, this paper designs a novel locally resonant phononic crystal with multiple primitive cell combination structure (LRPCWMPCCS), which is a locally resonant supercell structure composed of five types of locally resonant single primitive cells. Firstly, the band structure of the LRPCWMPCCS is calculated using the finite element method, and compared with the band structure of traditional LRPC. Secondly, the frequency response function of the LRPCWMPCCS is calculated to evaluate its attenuation effect on elastic waves in the BG frequency range, and the generation mechanism of its locally resonant BG is explored by analyzing the displacement field and energy distribution characteristics at the BG edge. Then, the equivalent model of the LRPCWMPCCS is established for theoretical calculation of the BG range. Finally, the vibration isolation performance of LRPCWMPCCS wave barrier in practical engineering is analyzed, and the application prospects of the LRPCWMPCCS are discussed. The results show that the LRPCWMPCCS designed in this paper can open the multifrequency BGs, and the BGs width is wider. The number of BGs opened is positively correlated with the type of primitive cells inside the LRPCWMPCCS. Within the BG frequency range, the LRPCWMPCCS has a good attenuation effect on vibration waves, with attenuation values exceeding 20 dB. The spring-mass system equivalent model of the LRPCWMPCCS can accurately calculate its BG range and has good accuracy. The LRPCWMPCCS wave barrier has remarkable control and attenuation effect on vibration. Among them, the maximum vibration acceleration of traditional LRPC wave barrier and LRPCWMPCCS wave barrier is reduced by 18.51% and 39.50%, respectively. The relevant research results of this paper have great value and prospects in the design of LRPC with multifrequency and wide BGs, which can also provide a new method and idea for solving vibration and noise problems.

Contributions on the Use of Dynamic Absorbers in a Vehicle Engine

In the study presented in the paper, a theoretical calculation will be made regarding engine vibration dampers. These will be validated with the experimental model. These validations bring results in static and dynamic balance through the reduction of torsional vibrations in the engine. Torsional vibrations are caused by various factors as well as engine operating conditions. The paper focuses on the reduction of torsional vibrations from a theoretical and experimental point of view. Therefore, in this study, a dynamic absorber was considered which was integrated into the system considered by the paper and was analyzed both from the point of view of its static and dynamic behavior.

Multiple Causes and Indicators of vibration Engineering Entrepreneurship in Nearshoring

En torno a la crisis sanitaria, los perfiles de emprendimiento pueden ser anticipados desde variables sociodemográficas, socioeducativas y socioeconómicas. En este sentido, el propósito del presente trabajo fue establecer un modelo híbrido de causas e indicadores en torno al emprendimiento. Se realizó un estudio transversal, correlacional y estructural con una muestra de 100 estudiantes seleccionados por el compromiso de su institución frente al emprendimiento académico. Los resultados demuestran la predicción del constructo a partir del género y su reflejo en seis indicadores que explicaron el 98% de la varianza total. En relación con el estado del arte donde prevalece el emprendimiento como un proceso de aprendizaje, se recomienda extender el modelo hacia los determinantes del aprendizaje del emprendimiento a fin de anticipar escenarios de formación del capital intelectual e incubación de proyectos.

Preface

XIV International Conference on Recent Advances in Structural Dynamics (RASD) The RASD conference series was initiated by the late Professor Maurice Petyt of the Institute of Sound and Vibration Research (ISVR), Southampton, in 1980 “to review the advances which have been made in the theory and practice of structural dynamics … leading to a valuable exchange of ideas and form the basis for new developments”. Following a successful and hugely enjoyable sojourn in Lyon, 2019, and a delay due to the Covid 19 pandemic, the fourteenth conference returned in July 2024 to its inaugural venue, with the same aim. Just over 100 talks were presented during three days, including the following inspirational keynote addresses: Mahmoud Hussein Metadamping and metaharvesting: Vibration engineering at the intrinsic material level Guglielmo Aglietti Vibration testing of spacecraft structure - Virtual Testing & Multi DoF Shakers Jason Zheng Jiang Generative design for dynamic performance transformation The drinks and canape reception at Solent Sky aircraft museum was a highlight for attendees from all engineering backgrounds. List of Organising committee is available in this Pdf.

Full-field measurements of high-frequency micro-vibration under operational conditions using sub-Nyquist-rate 3D-DIC and compressed sensing with order analysis

High-speed imaging is essential for high-frequency vibration measurement techniques that utilize images, such as digital image correlation (DIC). However, it poses challenges, including reduced displacement resolution due to decreased image resolution, increased measurement and calculation costs, and greater data volume. A previous method used compressed sensing to reconstruct time information from images captured with a high-resolution, low-speed camera, allowing high-frequency vibration measurements. However, this method was limited to steady vibrations since waveforms were reconstructed using the Fourier basis. In this study, order analysis is introduced into compressed sensing to measure operational vibrations, including rotation speed fluctuations, such as those in automobile engines. An out-of-plane vibration experiment on an aluminum plate confirmed the method’s accuracy in identifying mode shapes and displacement spectra of operational vibrations. The proposed method reconstructed vibrations (amplitude: several μm to several hundred μm, frequency: 33.3–133.2 Hz) using images captured at 10 fps. The modal assurance criterion (MAC) indicated 0.98 accuracy compared with finite element analysis. The mean squared error below 1 % compared to the frequency spectrum obtained with a laser Doppler vibrometer. Applied to automobile engine vibrations (amplitudes of a few μm), the method achieved errors under 2 % over a 1225 mm × 960 mm field of view. However, error increased for vibrations below the DIC displacement resolution. This method shows promise for analyzing vibrations in rotational machinery, such as engines and motors, through the full-field measurement of high-speed operational vibrations. In addition, the developed compressed sensing with order basis is expected to contribute to the advancement of the recovering missing signals and data compression.

Система подачи рабочей жидкости в модельный пружинный демпфер крутильных колебаний

The development of a system for supplying working fluid (engine oil) to ensure the similarity of operating conditions of a model of a spring damper for torsional vibrations of a marine diesel engine during experiments at the laboratory stand of the Marine Technology Service testing center of the Astrakhan State Technical University is considered. Currently, spring (mechanical) torsional vibration dampers of marine diesel engines are produced only by foreign companies. A lot of scientific work is required for their design, manufacture and operation, including physical modeling of the design and operating conditions of laboratory versions of dampers. The application of the physical modeling method makes it possible to reduce the cost of testing real spring dampers of torsional vibrations of marine diesel engines, determine the main dependencies of damping parameters on various operating conditions, develop basic criteria for non-selective diagnostics to assess its technical condition and predict the development of emergency situations. The modernization of the laboratory stand is necessary for the operation of model spring dampers with a developed system for supplying working fluid. The spread of spring dampers is justified by the design features of such devices, which allows the use of both elastic and hydraulic damping. For the development of the working fluid supply system, calculations were made of the stiffness and thermal power of the model spring damper, taking into account the design of the laboratory stand.