Vibration Research Articles

Robust Approach Estimates Effective Length for Lateral Vibrations

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 217755, “To What Extent Can the Notion of an Effective Length Be Reliable To Assess the BHA Lateral Behavior?” by Mohamed Mahjoub, SPE, Ngoc-Ha Dao, SPE, and Khac-Long Nguyen, Helmerich & Payne, et al. The paper has not been peer reviewed. _ Many models in the industry use the notion of an effective length to make predictions about the bottomhole assembly (BHA). A criterion is chosen to cut the drillstring at a certain distance from the bit and use only that part for the computations. Though this method is computationally efficient, no consensus exists regarding what criteria should be chosen or a perfect method regarding the computation of that length. This study aims to compensate for the lack of in-depth analysis on this important subject. It shows the importance of understanding the strengths and limits of frequency-based models compared with more-complex time-domain modeling. Introduction The notion of effective length is widely used in the industry for various types of drillstring mechanical models, whether for directional purposes, survey corrections, or assessment of vibration behavior of the BHA. The drillstring is cut at a given distance from the bit, known as the effective length (see example in Fig. 1, where an approximately 45-m effective length is used for a computation to predict the BHA build and turn rates). Ideally, the choice of this length should reflect the independence of what is happening close to the bit from the rest of the drillstring. This approach has the obvious advantage of reducing computation time significantly but has the shortcoming of being insufficiently well defined. The study of BHA lateral dynamics is more challenging because of the transient nature of the external forces that act on the drillstring. In the complete paper, different computations are conducted on several types of BHAs in order to examine when the notion of an effective length is valid and reliable and to determine the primary factors that make it challenging to isolate BHA behavior from the rest of the drillstring. Models and Data The BHA model used in this paper was used in the literature to study the microtortuosity of well trajectories. The model combines bit directional characteristics with the BHA design, namely stabilizer placement, in order to predict BHA preferential or equilibrium 3D curvature. The effective length can affect the results of this type of computation by changing the distribution and intensity of contact forces, thereby changing the overall preferential curvature. For BHA dynamics, the simplest type of modeling is frequency-based and consists of predicting the natural frequencies of the system, which can be translated into critical or forbidden rotation speeds that should be avoided to prevent resonance. An intermediary approach, also based on frequency domain, is the use of forced vibration computations. Both frequency-based models are considered linear models and, thus, cannot account for the nonlinearities related to the contact and friction forces. The most complex type of dynamics study is carried out in time domain. In this case, the nonlinearities related to the contact and friction forces are taken into consideration in addition to other transient external excitations.

Detaching cells in culture medium using forced vibration for removing a centrifugation from culture process

Detaching cells in culture medium using forced vibration for removing a centrifugation from culture process

What are the effects of adjunctive light vibrational forces for accelerating tooth movement in people undergoing orthodontic treatment?

What are the effects of adjunctive light vibrational forces for accelerating tooth movement in people undergoing orthodontic treatment?

"Torsional vibration control in diesel engine-driven centrifugal pump: Validation through experimental results"

This study addresses the critical issue of torsional vibration in turbomachinery, which can lead to significant damage if not properly managed. The primary objective is to develop a practical design approach to enhance system resilience against torsional vibration problems. The research focuses on post-natural frequency analysis steps, including methods like Holzer's method for natural frequency determination and mode shape analysis. The study suggests that while identifying natural frequencies is manageable, accurately predicting torsional vibration problems remains challenging. The analysis recommends analyzing all interference points before considering design modifications, advocating for techniques like examining mode shapes or torque vs. speed curves to eliminate non-critical interference points. For remaining points, a damped forced vibration analysis is recommended, with guidelines provided for different machinery classes. Overall, this study provides a comprehensive, step-by-step analysis procedure applicable to most turbomachinery systems. By addressing the complexities of torsional vibration, this research aims to contribute to the development of safer and more reliable turbomachinery systems Specifically, conducting a torsional analysis on a pump package driven by a diesel engine to achieve similar behavior when it is driven by an electric motor. Replacing the electric motor with a diesel engine as a driver for the pump could cause a maximum to increase the vibration with 25 % while using the optimal damping for the diesel engine could lead to vibration deduction with 70 % when operate the pump without diesel engine damping.

Modeling of cutting force and tool vibration in helical milling using mechanistic models and artificial neural network

Modeling of cutting force and tool vibration in helical milling using mechanistic models and artificial neural network

Axisymmetric forced vibration of the hydro-elastic system consisting of a pre-strained highly elastic plate and compressible viscous fluid

The paper studies the axisymmetric harmonic forced vibration of the hydro-elastic system composed of an initially strained plate made of highly elastic material, a compressible viscous fluid layer, and a rigid wall restricting the fluid flow. It is assumed that the plate is in contact with the fluid layer after the appearance of the finite axisymmetric homogeneous initial strains within which are caused by the stretching of the plate by uniformly distributed radial forces acting at infinity. Also, it is assumed that after this contact, the point located time-harmonic force begins to act on the free-face plane of the plate. Within this framework, the steady-state forced vibration of the hydro-elastic system under consideration is studied by employing the eq. and relations of the so-called three-dimensional linearized theory of elastic waves in bodies with finite initial strains to describe the motion of the plate and by employing the linearized Navier-Stokes eq. to describe the flow of the fluid. The corresponding mathematical problem is solved by employing the Hankel integral transform method, and the originals of the sought values are found numerically by employing the algorithms and PC programs composed by the authors. Numerical results are presented and discussed on the frequency response of the normal stress acting on the interface plane between the plate and fluid layer. According to these discussions, corresponding conclusions on the influence of the problem parameters on the frequency response of the interface stress are made. In particular, it is established that in the axisymmetric forced vibration case, the resonance-type phenomenon appears due to the fluid viscosity.

Computer Vision-Based Research on the Mechanism of Stick–Slip Vibration Suppression and Wear Reduction in Water-Lubricated Rubber Bearing by Surface Texture

Water-lubricated rubber bearings are a critical component of the propulsion systems in underwater vehicles. Particularly under conditions of low speed and high load, friction-induced vibration and wear often occur. Surface texturing technology has been proven to improve lubrication performance and reduce friction and wear; however, research on how different texture parameters affect friction-induced vibration and wear mechanisms remains insufficient. In this study, various texture patterns with different area ratios and aspect ratios were designed on the surface of water-lubricated rubber bearings. By combining these designs with an in situ observation system based on computer vision technology, the effects of texture parameters on bearing friction, vibration, and wear were thoroughly investigated. The experimental results show that surface textures play a critical role in improving hydrodynamic effects and stabilizing the lubrication film at the friction interface. Specifically, textures with a high area ratio (15%) and aspect ratio (3:1) exhibited the best vibration suppression effect, primarily due to the reduction in actual contact area. However, excessively high area ratios may lead to increased surface wear. This study concludes that a reasonable selection of texture area and aspect ratios can significantly reduce frictional force fluctuations and vibration amplitude, minimize surface wear, and extend bearing life.

Experimental study on the aerodynamic force and vibration of a scratched stay cable perpendicular to the wind

The wind load and wind-induced vibration of stay cables, as the primary load-bearing component in cable-stayed bridges, are highly important. Inevitably, cables experience scratches during production, transportation, and installation. Scratches may have an important effect on a cable's aerodynamic force and wind-induced vibration. Consequently, three sectional cable models with varying scratches were prepared for wind tunnel tests. The incoming wind was perpendicular to the cable model. The aerodynamic and vibration responses in precritical, critical Reynolds number regions were investigated. The results showed that scratched cables exhibit Reynolds number effects similar to those of smooth cables. Within attack angles ranging from 50° to 85°, scratching significantly reduced the corresponding Reynolds numbers of the TrBL0-1 and TrBL1-2 transitions. This caused the scratched cable to vibrate substantially at a lower Reynolds number (wind speed) than the smooth cable. There is a smaller attack angle range between 50° and 90° in which scratches cause the average lift coefficient to climb slowly with the Reynolds number, without a bistable phenomenon. This implies that there is no significant vibration. The critical Reynolds number effect effectively predicts the vibration of the scratched cable, and the complex flow in the critical Reynolds number region limits the accuracy of the Den Hartog criterion.

On the contact and vibration characteristics of TBM cutter with abnormal damage under hard rock conditions

Tunnel Boring Machines (TBM) play a pivotal role in the construction of modern tunnels, with their performance directly determining the progress, economic benefits, and safety levels of the construction. As the core component interfacing with the rock, the condition of the TBM cutter significantly impacts the machine's boring performance. Faced with increasingly complex geological conditions, the cutters frequently suffer from abnormal damage, including partial wear, polygon wear, and chipping. Such damages are typically accompanied by reduced rock-breaking ability and increased vibration intensity, leading to severe performance degradation. To propose effective monitoring and maintenance strategies to prevent serious consequences of abnormal damage, such as cutterhead damage or personnel injuries, it is necessary to understand the changes in the operational characteristics of the cutter in such conditions and to accurately assess the specific impacts of abnormal damage on cutter performance. This study uses bench tests and discrete element-dynamics coupled simulations to explore the differences in load-bearing, cutter-rock contact, vibration, and noise characteristics between the normal wear cutter and those with abnormal damages. The results show that abnormal damages affect the cutter's load-bearing and cutter-rock contact properties, thereby increasing the proportion of cutting resistance and reducing energy utilization and rock-breaking efficiency. Additionally, partial wear and polygon wear not only significantly increase the noise/vibration levels of the cutter but also cause the mode of noise and vibration to shift from random to periodic, thus increasing the likelihood of forced vibrations in the system. By combining simulation and experimental results, this study elucidates the mechanisms by which different types of abnormal damage affect cutter performance by altering the motion form and cutter-rock contact mode. The operational characteristics of cutters with abnormal damages, as revealed in this study, in terms of load, vibration, and noise, provide theoretical support for the state monitoring and maintenance strategies of TBM cutters.

H$_{3}$Se in the $Im\overline{3}m$ Phase: A High-Pressure Superconductor with $T_{\text{c}}$ Reaching 200 K at 64 GPa Mediated by Anharmonic Phonons

Abstract Hydrogen-based compounds have attracted significant attention in recent years due to the discovery of conventional superconductivity with high critical temperature under high pressure, rekindling hopes for searching room temperature superconductor. In this work, we investigated systematically the vibrational and superconducting properties of H$_{3}$Se in $Im\overline{3}m$ phase under pressures ranging from 50 to 200 GPa. Our approach combines the stochastic self-consistent harmonic approximation with first-principles calculations to address effects from the quantum and anharmonic vibrations of ions. It turns out that these effects significantly modify the crystal structure, increasing the inner pressure by about 8 GPa compared to situations where they are ignored. The phonon spectra suggest that with these effects included, the crystal can be stabilized at pressures as low as about 61 GPa, much lower than the previously predicted value of over 100 GPa. Our calculations also highlight the critical role of quantum and anharmonic effects on the electron-phonon coupling properties. Neglecting these factors could result in a substantial overestimation of the superconducting critical temperature $T_{\text{c}}$, by approximately 25 K at 125 GPa, for example. With anharmonic phonons, the $T_{\text{c}}$ derived from the Migdal-Eliashberg equations, reaches 200 K ($\mu^\star=0.1, \lambda$=4.1) as the pressure decreases to 64 GPa, making the crystal a rare high-$T_{\text{c}}$ superconductor at moderate pressures.

On the Thermal Conductivity and Local Lattice Dynamical Properties of NASICON Solid Electrolytes.

The recent development of solid-state batteries brings them closer to commercialization and raises the need for heat management. The NASICON material class (Na1+xZr2PxSi3-xO12 with 0 ≤ x ≤ 3) is one of the most promising families of solid electrolytes for sodium solid-state batteries. While extensive research has been conducted to improve the ionic conductivity of this material class, knowledge of thermal conductivity is scarce. At the same time, the material's ability to dissipate heat is expected to play a pivotal role in determining efficiency and safety, both on a battery pack and local component level. Dissipation of heat, which was, for instance, generated during battery operation, is important to keep the battery at its optimal operating temperature and avoid accelerated degradation of battery materials at interfaces. In this study, the thermal conductivity of NaZr2P3O12 and Na4Zr2Si3O12 is investigated in a wide temperature range from 2 to 773 K accompanied by in-depth lattice dynamical characterizations to understand underlying mechanisms and the striking difference in their low-temperature thermal conductivity. Consistently low thermal conductivities are observed, which can be explained by the strong suppression of propagating phonon transport through the structural complexity and the intrinsic anharmonicity of NASICONs. The associated low-frequency sodium ion vibrations lead to the emergence of local random-walk heat transport contributions via so-called diffusons. In addition, the importance of lattice dynamics in the discussion of ionic transport as well as the relevance of bonding characteristics typical for mobile ions on thermal transport, is highlighted.

A SGM-IHB approach for nonlinear free and forced vibration analysis of FG-GPLRC beams rested on viscoelastic foundation

A SGM-IHB approach for nonlinear free and forced vibration analysis of FG-GPLRC beams rested on viscoelastic foundation

Fan Non-Synchronous Forced Vibration Under Crosswind

Abstract In this paper, a new aeroelastic phenomena for fans, referred to as non-synchronous forced vibration (NSFV), is presented. This type of aeroelastic instability can occur at high crosswind conditions when the flow at the intake lip separates and the disturbances caused by flow separation become unsteady. The results show that in the presence of unsteady separation in the intake, the fan can experience non-synchronous frequency excitations, which can result in resonant response in modes that are not identified by the Campbell diagram. The findings are corroborated by aeroacoustic theories. To the best of authors knowledge, this is the first time that fan forced response due to unsteady distortion is studied and the findings can unlock some of unexplained and unexpected vibrations experienced by engines.

Quantifying uncertainty in neural network predictions of forced vibrations

AbstractThe prediction of forced vibrations in nonlinear systems is a common task in science and engineering, which can be tackled using various methodologies. A classical approach is based on solving differential (algebraic) equations derived from physical laws ('first principles'). Alternatively, Artificial Neural Networks (ANNs) may be applied, which rely on learning the dynamics of a system from given data. However, a fundamental limitation of ANNs is their lack of transparency, making it difficult to understand and trust the model's predictions. In this contribution, we follow a hybrid modelling approach combining a data‐based prediction using a stabilised Autoregressive Neural Network (s‐ARNN) with a priori knowledge from first principles. Moreover, aleatoric and epistemic uncertainty is quantified by a combination of mean‐variance estimation (MVE) and deep ensembles. Validating this approach for a classical Duffing oscillator suggests that the MVE ensemble is the most accurate and reliable method for prediction accuracy and uncertainty quantification. These findings underscore the significance of understanding uncertainties in deep ANNs and the potential of our method in improving the reliability of predictive nonlinear system modelling. We also demonstrate that including partially known dynamics can further increase accuracy, highlighting the importance of combining ANNs and physical laws.

A theoretical study on muoniated N-heterocyclic carbenes using path integral molecular dynamics.

Several N-heterocyclic carbenes (NHCs) are experimentally observed upon the addition of muonium (Mu), and the hyperfine coupling constants (HFCCs) of muon are measured. Theoretical investigation of Mu has been challenging due to significant quantum effects. Herein, we performed an abinitio path integral molecular dynamics (PIMD) simulation, which accurately considers multi-dimensional quantum effects, to theoretically investigate muoniated 1,3-dihydro-2H-imidazole-2-ylidene (Mu-IY). Our findings indicate that quantum effects have two contradictory contributions: the quantum effect of bond vibrations increases the HFCC values, whereas that of out-of-plane angular vibrations decreases the HFCC values. Moreover, we show that the HFCC values of other NHCs can be predicted without the PIMD simulations by applying the structural changes caused by the quantum effect derived from the PIMD simulations of Mu-IY.

Research on Radial Vibration Model and Low-Frequency Vibration Suppression Method in PMSM by Injecting Multiple Symmetric Harmonic Currents

Driven by frequency conversion, the windings of a three-phase permanent magnet synchronous motor (PMSM) contain both odd and even harmonic currents. Due to the motor’s pole–slot conductance modulation, the interaction between the magnetic fields generated by these harmonic currents and the permanent magnet field results in harmonic radial vibrations of the motor. This paper analyzes the three-phase currents of the prototype and derives the radial magnetomotive force (MMF) spatiotemporal models for symmetric harmonic currents. By integrating Maxwell’s magnetic force formula and vibration response formula, the radial vibration models for symmetric harmonic currents are developed. The characteristics of vibrations caused by odd and even harmonic currents, as well as positive sequence and negative sequence harmonic currents, are analyzed separately. A cyclic sequence, low-frequency vibration suppression control method incorporating multiple harmonic current injections was designed. Experimental results of this method are compared with those obtained using an ideal sinusoidal current. Except for the second harmonic vibration, all other vibrations are significantly suppressed, with a maximum suppression rate of 92.28%. The total vibration level is reduced by 12.7619 dB, and the average torque is reduced by 0.67% with the total harmonic distortion of the current at 2.89%. The experimental results show that the vibration method in this paper has little influence on the average torque of the motor, the current distortion rate is small, and the vibration suppression effect is good.

Transient analysis of functionally graded axisymmetric plates via finite element method in the Laplace domain

The principal goal of this research article is to examine the forced vibration of Functionally Graded Material (FGM) axisymmetric plates with the aid of the finite element method in the Laplace space. The material properties are assumed to be isotropic, linear viscoelastic, or elastic and vary continuously in the direction of the thickness of the plate. The governing equations of motion are transferred to the Laplace domain and solved for a set of Laplace parameters. Then, a modified Durbin’s inverse Laplace method is employed to retransfer the obtained results back to the time domain. A convergence analysis is conducted to optimize the number of Laplace parameters and time steps. An 8-node quadratic quadrilateral element featuring two degrees of freedom per node is employed to generate the model of the axisymmetric plates. Different loads such as step load, square wave, and sawtooth wave loads are used to observe the impact of load type on the transient response of FGM plates. In viscoelastic analysis, the Kelvin damping model is preferred, and the effect of the damping ratio is investigated. The obtained results are validated with the aid of the available literature and the accuracy of the suggested model is confirmed. It is carried out that the material variation significantly affects the dynamic behavior of the plates, for instance as the material coefficient increases, displacement amplitudes decrease, and periods increase. The novelty of this paper is the employment of the finite element method together with Laplace transformation for addressing the present class of problems for the first time.

Torsional damper design for diesel engine: theory and application

Abstract Torsional vibration is the primary cause of engine crankshaft failure. Consequently, the reduction of engine vibration is of paramount importance for the enhancement of automotive safety and comfort. However, the lack of comprehensive insight into the damping mechanism of the torsional damper has impeded the effective control of engine torsional vibration. In order to gain insight into the vibration characteristics of the shaft system in an inline six-cylinder diesel engine, an analysis of the system’s behaviour during both free and forced vibration was conducted. A mathematical relationship was deduced between the dimensions, material, operational temperature and damping properties of the silicone oil damper. The objective was to determine the optimal damping and moment of inertia of the damper, with the aim of minimizing the torsional amplitude of the sixth harmonic. The results demonstrate a reduction in the six-harmonic torsional amplitude from 0.32° to 0.14° following the installation of the damper. The mean and relative deviations between the calculated and experimental results are 0.0018° and 0.83%, respectively. To facilitate the design of the silicone oil damper, a software program, Vibsim, was developed based on Visual Studio for the design and torsional vibration analysis of the silicone oil damper. This software is reliable in calculating results and is user-friendly.

Computational and experimental studies of vibration-protective properties of a pneumatic wheel of the MTZ-82 BELARUS tractor with external spring-hydraulic mini-suspension

BACKGROUND: Currently used in various sectors of the national economy, numerous wheeled suspensionless vehicles on pneumatic tires have a low level of vibration protection of the frame and limited cross-country ability. Therefore, the development and study of the design characteristics of a pneumatic wheel with increased elastic-damping properties and cross-country ability is a relevant technical problem. AIM: Development of the design and study the vibration-protective properties of a pneumatic wheel with an external spring-hydraulic mini-suspension to improve the ride smoothness and cross-country ability of large-sized suspensionless vehicles. METHODS: A description of the design of a wheel with mini-suspension and a support roller is presented. The wheel modeling was carried out in the PascalABC software, which takes into account the nonlinearity of the total force of the pneumatic tire and the spring-hydraulic mini-suspension, which is installed parallel to the tire at an angle to the vertical axis of the wheel. The test method consisted of comparison of free and forced vibrations of the rear pneumatic wheel of the MTZ-82 BELARUS tractor with a 400-965/15.5-38 tire, which operated without and with mini-suspension at a vertical load of 0.6 tons and various excessive pressure in the tire. RESULTS: The results of computational and experimental studies show that if the tire is radially compressed by 75 mm, the excess pressure inside the pneumatic wheel almost does not change, and if the pressure in the tire decreases from 1.6 to 0.4 bar, the resonant vibration frequency of the standard wheel axle decreases by 25%, while the dynamic coefficient remains unacceptably high (more than 5), leading to the tire breakaway from the supporting surface. Installing a mini-suspension parallel to the wheel in the form of a spring-hydraulic shock-absorbing strut leads to an increase in the resonant frequency by 1 Hz, however, the resonant peaks are reduced by almost 3 times to a dynamic coefficient of 2.5...2, which significantly increases the ride smoothness of suspensionless vehicles and reduces the likelihood of wheel breakaway from the supporting surface. CONCLUSION: It was found with the studies that the proposed wheel with a mini-suspension as a spring-hydraulic strut and a support roller has a relatively simple design, ensures high vibration-protective properties with small amplitudes of kinematic disturbance and can be used to improve the ride smoothness and cross-country ability of wheeled suspensionless vehicles.

Dynamic analysis of a pedestrian bridge using monitoring and computational techniques

Soil-structure interaction (SSI) represents an important parameter when analyzing the dynamic behavior of bridges, considering the combined effects of soil, foundation, and structure to ensure an adequate structural representation. This paper applied a computational modeling strategy associated with soil-structure interaction methodology to represent the dynamic behavior of a timber-concrete pedestrian bridge of the Polytechnic School of the University of São Paulo. The computational models were validated and calibrated using monitoring results from an extensive structural health monitoring campaign. The bridge monitoring program was characterized using embedded sensors and remote monitoring technology: ground-based radar interferometry and video motion amplification. The instrumentation results were compared to establish the capabilities and advantages of this novel remote monitoring technique. The experimental results obtained from free and forced vibrations in the asset served as a basis for validating the developed computational model and allowed the evaluation of the asset behavior in service for different loading conditions. This paper emphasizes the importance of considering an SSI approach to represent the bridge dynamic behavior more accurately, enabling the use of more reliable numerical models to assess the bridge structural responses throughout its life-cycle.