Engineering › Mechanical Engineering

Gear and Bearing Dynamics Analysis

Works Count: 48607

Wikipedia

Description

This cluster of papers focuses on the dynamics, faults, and lubrication aspects of gear systems, including topics such as mesh stiffness, tooth crack propagation, vibration analysis, elastohydrodynamic lubrication, rolling contact fatigue, bearing faults, and nonlinear dynamics. The papers cover various types of gears including spur gears and planetary gears.

Keywords

Gear Dynamics; Mesh Stiffness; Tooth Crack; Vibration Analysis; Elastohydrodynamic Lubrication; Rolling Contact Fatigue; Bearing Faults; Nonlinear Dynamics; Spur Gear; Planetary Gear

Contribution of Gear Body to Tooth Deflections—A New Bidimensional Analytical Formula

2004-07-01

P. Sainsot and , Philippe Velex , Olivier Duverger

The magnitude and variation of tooth pair compliance affects tooth loading and gear dynamics significantly. This paper presents an improved fillet/foundation compliance analysis based on the theory of Muskhelishvili applied … The magnitude and variation of tooth pair compliance affects tooth loading and gear dynamics significantly. This paper presents an improved fillet/foundation compliance analysis based on the theory of Muskhelishvili applied to circular elastic rings. Assuming linear and constant stress variations at root circle, the above theory makes it possible to derive an analytical formula for gear body-induced tooth deflections which can be directly integrated into gear computer codes. The corresponding results are in very good agreement with those from finite element models and the formula is proved to be superior to Weber’s widely used equation, especially for large gears.

Vibration signal models for fault diagnosis of planetary gearboxes

2012-07-08

Zhipeng Feng , Ming J. Zuo

Dynamic simulation of spur gear with tooth root crack propagating along tooth width and crack depth

2011-07-25

Zaigang Chen , Yimin Shao

Model for the vibration produced by a single point defect in a rolling element bearing

1984-09-01

P.D. McFadden , J. D. Smith

Hertzian Damping, Tooth Friction and Bending Elasticity in Gear Impact Dynamics

1987-06-01

Daniel C. H. Yang , Jiafan Lin

This investigation presents an analytical and computer-aided study on the dynamics of meshing gears with backlash. Based on the rotary gear impact model of Yang and Sun, a modified model … This investigation presents an analytical and computer-aided study on the dynamics of meshing gears with backlash. Based on the rotary gear impact model of Yang and Sun, a modified model with additional considerations of bending deflection, axial compression, and Coulomb friction is developed. Despite the complexity in gear geometry, formulas for modeling these phenomena are all analytically derived. A computer simulation package is developed for this model. Consequently gear impact dynamics and the relative importance among the included considerations are studied. Results show that the energy loss due to the Hertzian damping is usually larger than that from the Coulomb friction, and the axial compressive energy is negligible in comparison to tooth bending energy. It is believed that the model and the finding in this study contribute toward understanding of impact behaviors of high-speed geared systems with frequent stop-and-start or intermittent motions.

Mathematical models used in gear dynamics—A review

1988-03-01

H. Nevzat Özgüven , Donald R. Houser

Nonlinear dynamics of planetary gears using analytical and finite element models

2007-02-03

Vijaya Kumar Ambarisha , Robert G. Parker

Shear behaviour of elastohydrodynamic oil films

1977-08-24

Kenneth L. Johnson , J. L. Tevaarwerk

A simple constitutive equation is proposed for the isothermal shear of lubricant films in rolling/sliding contacts. The model may be described as nonlinear Maxwell, since it comprises nonlinear viscous flow … A simple constitutive equation is proposed for the isothermal shear of lubricant films in rolling/sliding contacts. The model may be described as nonlinear Maxwell, since it comprises nonlinear viscous flow superimposed on linear elastic strain. The nonlinear viscous function can take any convenient form. It has been found that an Eyring ‘sinh law’ fits the measurements on five different fluids, although the higher viscosity fluids at high pressure are well described by the elastic/perfectly plastic equations of Prandtl-Reuss. The proposed equation covers the complete range of isothermal behaviour: linear and nonlinear viscous, linear viscoelastic, nonlinear viscoelastic and elastic/plastic under any strain history. Experiments in support of the equations are described. The nonlinear Maxwell constitutive equation is expressed in terms of three independent fluid parameters: the shear modulus G , the zero-rate viscosity η and a reference stress τ 0 . The variations of these parameters with pressure and temperature, deduced from the experiments, are found to be in broad agreement with the Eyring theory of fluid flow.

Mesh stiffness calculation of a spur gear pair with tooth profile modification and tooth root crack

2012-12-28

Zaigang Chen , Yimin Shao

Ball Bearing Lubrication (The Elastohydrodynamics of Elliptical Contacts)

1982-04-01

B. J. Hamrock , D. Dowson , T. E. Tallian

The history of ball bearings is examined, taking into account rollers and the wheel in the early civilizations, the development of early forms of rolling-element bearings in the classical civilizations, … The history of ball bearings is examined, taking into account rollers and the wheel in the early civilizations, the development of early forms of rolling-element bearings in the classical civilizations, the Middle Ages, the Industrial Revolution, the emergence of the precision ball bearing, scientific studies of contact mechanics and rolling friction, and the past fifty years. An introduction to ball bearings is presented, and aspects of ball bearing mechanics are explored. Basic characteristics of lubrication are considered along with lubrication equations, the lubrication of rigid ellipsoidal solids, and elastohydrodynamic lubrication theory. Attention is given to the theoretical results for fully flooded elliptical hydrodynamic contacts, the theoretical results for starved elliptical contacts, experimental investigations, the elastohydrodynamics of elliptical contacts for materials of low elastic modulus, the film thickness for different regimes of fluid-film lubrication, and applications.

View PDF Chat

NON-LINEAR DYNAMIC RESPONSE OF A SPUR GEAR PAIR: MODELLING AND EXPERIMENTAL COMPARISONS

2000-10-01

Robert G. Parker , Sandeep Vijayakar , Takahisa Imajo

Computer Simulation of Stick-Slip Friction in Mechanical Dynamic Systems

1985-03-01

Dean Karnopp

Stick-slip friction is present to some degree in almost all actuators and mechanisms and is often responsible for performance limitations. Simulation of stick-slip friction is difficult because of strongly nonlinear … Stick-slip friction is present to some degree in almost all actuators and mechanisms and is often responsible for performance limitations. Simulation of stick-slip friction is difficult because of strongly nonlinear behavior in the vicinity of zero velocity. A straightforward method for representing and simulating friction effects is presented. True zero velocity sticking is represented without equation reformulation or the introduction of numerical stiffness problems.

The Measurement and Study of Very Thin Lubricant Films in Concentrated Contacts

1991-01-01

G. J. Johnston , R. Wayte , H. A. Spikes

Optical interferometry is now a widely used technique for measuring the separating film thickness in model rolling and sliding elastohydrodynamic contacts. There are two limitations of the method as conventionally … Optical interferometry is now a widely used technique for measuring the separating film thickness in model rolling and sliding elastohydrodynamic contacts. There are two limitations of the method as conventionally employed: first, it cannot easily be used to accurately measure films less than one quarter the wavelength of visible light, i.e. less than about 100 nm. Secondly, only certain, discrete thicknesses, spaced at least 50 nm apart can be determined. This paper describes work aimed at overcoming these limitations so as to make optical interferometry applicable to the study of boundary or very thin film elastohydrodynamic lubrication in rolling contacts. A combination of a solid spacer layer with spectrometric analysis of reflected light from the contact enables very thin lubricant films to be accurately measured. The approach is applied to the study of thin films formed in rolling contacts by low viscosity lubricants. Some anomalies in the relationship between film thickness and speed are found with films of less than 15 nm thickness.

Analytical modelling of spur gear tooth crack and influence on gearmesh stiffness

2008-07-24

Fakher Chaari , Tahar Fakhfakh , Mohamed Haddar

A Fast Algorithm for the Simplified Theory of Rolling Contact

1982-02-01

J. J. Kalker

SUMMARY An algorithm "Fastsim" for the simplified theory of rolling contact is described which is 15-25 times as fast as the existing programs Simrol (Kalker), and 3 times as fast … SUMMARY An algorithm "Fastsim" for the simplified theory of rolling contact is described which is 15-25 times as fast as the existing programs Simrol (Kalker), and 3 times as fast as Rolcon (Knothe). The relative total force computed with Fastsim differs at most 0.2 from that calculated with Simrol, Simcona (Goree & Law), Rolcon, and the "exact" program Duvorol (Kalker). Descriptions and lists of an Algol 60, and HP 67 program version are available upon request: the Fortran IV version is given in the paper.

A General Theory for Elastically Constrained Ball and Radial Roller Bearings Under Arbitrary Load and Speed Conditions

1960-06-01

A Jones

A completely general solution is obtained whereby the elastic compliances of a system of any number of ball and radial roller bearings under any system of loads can be determined. … A completely general solution is obtained whereby the elastic compliances of a system of any number of ball and radial roller bearings under any system of loads can be determined. Elastic yielding of the shaft and supporting structure are considered as well as centrifugal and gyroscopic loading of the rolling elements under high-speed operation. The solution defines the loading and attitude of each rolling element in each bearing of the system as well as the displacement of each inner ring with respect to its outer ring. For ball bearings the precise location of the load paths in each raceway are found. Life estimates can be more accurately made since the fatigue effects can be evaluated over known paths in the raceways. The solution, which is accomplished numerically by iterative techniques, has been programmed for an IBM-704 digital computer.

Simulation of spur gear dynamics and estimation of fault growth

2008-05-10

Siyan Wu , Ming J. Zuo , Anand Parey

Cyclostationary modelling of rotating machine vibration signals

2003-10-16

Jérôme Antoni , Frédéric Bonnardot , Amani Raad +1 more

The Intrinsic Variables affecting the Stick-Slip Process

1958-04-01

E. Rabinowicz

Stick-slip oscillations are normally analysed in terms of the kinetic friction-velocity and the static friction-time of stick characteristics of the rubbing surfaces. It is shown that, in addition, a critical … Stick-slip oscillations are normally analysed in terms of the kinetic friction-velocity and the static friction-time of stick characteristics of the rubbing surfaces. It is shown that, in addition, a critical distance, of the order of 10-3 cm, enters into the calculations, being the minimum resolving power of the friction process. Stick-slip oscillations must normally have an amplitude greater than the critical distance, and thus increased spring stiffness is often effective in eliminating stick-slip. Using the critical distance concept, it is possible to deduce a simple relationship between the static and kinetic coefficients of friction, and this is confirmed by experimental data.

Bearing fault diagnosis based on wavelet transform and fuzzy inference

2003-09-03

Xinsheng Lou , Kenneth A. Loparo

Non-linear dynamics of a spur gear pair

1990-10-01

Ahmet Kahraman , R. Singh

The flash temperature concept

1963-11-01

H. Blok

Rolling Bearing Analysis

1967-10-01

T. A. Harris , W. J. Anderson

View PDF Chat

Condition monitoring and fault diagnosis of planetary gearboxes: A review

2013-11-21

Yaguo Lei , Jing Lin , Ming J. Zuo +1 more

Isothermal Elastohydrodynamic Lubrication of Point Contacts: Part 1—Theoretical Formulation

1976-04-01

B. J. Hamrock , D. Dowson

The analysis of an isothermal elastohydrodynamic lubrication (EHL) point contact was evaluated numerically. This required the simultaneous solution of the elasticity and Reynolds equations. In the elasticity analysis the contact … The analysis of an isothermal elastohydrodynamic lubrication (EHL) point contact was evaluated numerically. This required the simultaneous solution of the elasticity and Reynolds equations. In the elasticity analysis the contact zone is divided into equal rectangular areas and it is assumed that a uniform pressure is applied over each element. In the numerical analysis of the Reynolds’ equation a phi analysis where phi is equal to the pressure times the film thickness to the 3/2 power is used to help the relaxation process. The EHL point contact analysis is applicable for the entire range of elliptical parameters and is valid for any combination of rolling and sliding within the contact.

Artificial neural networks and support vector machines with genetic algorithm for bearing fault detection

2003-10-01

B. Samanta , K. R. Al-Balushi , S.A. Al-Araimi

Fault diagnosis of ball bearings using machine learning methods

2010-08-08

Pavan Kumar Kankar , Satish C. Sharma , S. P. Harsha

A New Fatigue Life Model for Rolling Bearings

1985-07-01

Ε. Ιωαννίδης , T. A. Harris

This paper describes a novel model for the prediction of fatigue life in rolling bearings. Central to this model is the postulation of a statistical relationship between the probability of … This paper describes a novel model for the prediction of fatigue life in rolling bearings. Central to this model is the postulation of a statistical relationship between the probability of survival, the fatigue life, and a stress-related fatigue criterion level above a fatigue limit for an elementary volume of material in the bearing. Using this concept, the stress volume to fatigue and the fatigue life of the bearing can be calculated for different loads, material and operating conditions. Comparisons between experimentally obtained rolling bearing fatigue lives and lives predicted using this theory indicate its ability to account for phenomena hitherto excluded from fatigue life predictions. Furthermore, comparisons between experimentally obtained fatigue lives for other specimens used in structural fatigue tests and fatigue lives predicted using the new model show good agreement.

Analytical Characterization of the Unique Properties of Planetary Gear Free Vibration

1999-07-01

Jian Lin , Robert G. Parker

This work develops an analytical model of planetary gears and uses it to investigate their natural frequencies and vibration modes. The model admits three planar degrees of freedom for each … This work develops an analytical model of planetary gears and uses it to investigate their natural frequencies and vibration modes. The model admits three planar degrees of freedom for each of the sun, ring, carrier and planets. It includes key factors affecting planetary gear vibration such as gyroscopic effects and time-varying stiffness. For the linear, time-invariant case, examination of the associated eigenvalue problem reveals the well-defined structure of the vibration modes, where the special structure results from the cyclic symmetry of planetary gears. Vibration modes are classified into rotational, translational and planet modes. The unique characteristics of each type of mode are analytically investigated in detail. For each class of mode, reduced-order eigenvalue problems are derived.

A survey of models, analysis tools and compensation methods for the control of machines with friction

1994-07-01

Brian Armstrong-Hélouvry , Pierre E. Dupont , Carlos Canudas de Wit

While considerable progress has been made in friction compensation, this is, apparently, the first survey on the topic. In particular, it is the first to bring to the attention of … While considerable progress has been made in friction compensation, this is, apparently, the first survey on the topic. In particular, it is the first to bring to the attention of the controls community the important contributions from the tribology, lubrication and physics literatures. By uniting these results with those of the controls community, a set of models and tools for friction compensation is provided which will be of value to both research and application engineers. The successful design and analysis of friction compensators depends heavily upon the quality of the friction model used, and the suitability of the analysis technique employed. Consequently, this survey first describes models of machine friction, followed by a discussion of relevant analysis techniques and concludes with a survey of friction compensation methods reported in the literature. An overview of techniques used by practising engineers and a bibliography of 280 papers is included.

A simple theory of asperity contact in elastohydro-dynamic lubrication

1972-01-01

Kenneth L. Johnson , J. A. Greenwood , Stephen Poon

Isothermal Elastohydrodynamic Lubrication of Point Contacts: Part III—Fully Flooded Results

1977-04-01

B. J. Hamrock , D. Dowson

Utilizing the theory developed by the authors in an earlier publication, the influence of the ellipticity parameter, the dimensionless speed, load, and material parameters on minimum film thickness was investigated. … Utilizing the theory developed by the authors in an earlier publication, the influence of the ellipticity parameter, the dimensionless speed, load, and material parameters on minimum film thickness was investigated. The ellipticity parameter was varied from one (a ball on a plate configuration) to eight (a configuration approaching a line contact). The dimensionless speed parameter was varied over a range of nearly two orders of magnitude. The dimensionless load parameter was varied over a range of one order of magnitude. Conditions corresponding to the use of solid materials of bronze, steel, and silicon nitride and lubricants of paraffinic and naphthenic mineral oils were considered in obtaining the exponent in the dimensionless material parameter. Thirty-four different cases were used in obtaining the minimum film thickness formula given below as H¯min=3.63U0.68G0.49W−0.073(1−e−0.68k) A simplified expression for the ellipticity parameter was found where k=1.03RyRx0.64 Contour plots were also shown which indicate in detail the pressure spike and two side lobes in which the minimum film thickness occurs. These theoretical solutions of film thickness have all the essential features of the previously reported experimental observations based upon optical interferometry.

A Generalized Reynolds Equation for Non-Newtonian Thermal Elastohydrodynamic Lubrication

1990-10-01

Peiran Yang , Shizhu Wen

A new generalized Reynolds equation, which can incorporate most of the rheological laws found in the literature, is derived in this paper. A number of numerical solutions of the line … A new generalized Reynolds equation, which can incorporate most of the rheological laws found in the literature, is derived in this paper. A number of numerical solutions of the line contact thermal elastohydrodynamic lubrication problem has been obtained by using five rheological laws. The results show that, the influence of the non-Newtonian behavior of lubricant is not as important as that of the thermal one, when Roelands’ viscosity is used in the study.

A Review of Rolling Contact Fatigue

2009-09-24

Farshid Sadeghi , Behrooz Jalalahmadi , Trevor S. Slack +2 more

Abstract Ball and rolling element bearings are perhaps the most widely used components in industrial machinery. They are used to support load and allow relative motion inherent in the mechanism … Abstract Ball and rolling element bearings are perhaps the most widely used components in industrial machinery. They are used to support load and allow relative motion inherent in the mechanism to take place. Subsurface originated spalling has been recognized as one of the main modes of failure for rolling contact fatigue (RCF) of bearings. In the past few decades a significant number of investigators have attempted to determine the physical mechanisms involved in rolling contact fatigue of bearings and proposed models to predict their fatigue lives. In this paper, some of the most widely used RCF models are reviewed and discussed, and their limitations are addressed. The paper also presents the modeling approaches recently proposed by the authors to develop life models and better understanding of the RCF.

Rolling bearing analysis

1985-01-01

Christopher M. Taylor

Rolling bearing analysis

1992-06-01

Christopher M. Taylor

Dynamic modeling of gearbox faults: A review

2017-06-03

Xihui Liang , Ming J. Zuo , Zhipeng Feng

Rolling bearing fault feature learning using improved convolutional deep belief network with compressed sensing

2017-08-10

Haidong Shao , Hongkai Jiang , Haizhou Zhang +3 more

Essential Concepts of Bearing Technology

2006-10-09

T. A. Harris , Michael N. Kotzalas

For the last four decades, Tedric Harris' Rolling Bearing Analysis has been the "bible" for engineers involved in rolling bearing technology. Why do so many students and practicing engineers rely … For the last four decades, Tedric Harris' Rolling Bearing Analysis has been the "bible" for engineers involved in rolling bearing technology. Why do so many students and practicing engineers rely on this book? The answer is simple: because of its complete coverage from low- to high-speed applications and full derivations of the underlying mathemati

Advanced Concepts of Bearing Technology

2006-10-09

T. A. Harris , Michael N. Kotzalas

Nichtlineare Mechanik

1958-01-01

Hans Kauderer

Three-Dimensional Elastic Bodies in Rolling Contact

1990-01-01

J. J. Kalker

Digital twin-driven intelligent assessment of gear surface degradation

2022-11-03

Ke Feng , Jinchen Ji , Yongchao Zhang +3 more

Grenzschichten in Fluessigkeiten mit kleiner Reibung.

1907-01-01

Heinrich Blasius

Omni: A low-backlash planetary Wolfrom gearbox with beveloid gears for robotic applications

2025-06-25

Giuseppe Sciarra , Giovanni Mottola , Gustavo Casamenti +1 more | Mechanism and Machine Theory

Influence of time-varying excitation on vibration characteristics of the spiral bevel gear transmission system with pitting faults

2025-06-24

Keyuan Li , Heng Fang , Baijie Qiao +1 more | Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science

Time-varying mesh stiffness (TVMS) may cause noise and vibration in spiral bevel gear (SBG) transmission systems due to its role as an internal excitation source. Pitting faults as a typical … Time-varying mesh stiffness (TVMS) may cause noise and vibration in spiral bevel gear (SBG) transmission systems due to its role as an internal excitation source. Pitting faults as a typical mechanical fault can make TVMS reduce and alter the vibration characteristic of the SBG system. This paper aims to address the issue of unclear vibration characteristics of SBG systems. Firstly, an eight degrees of freedom (DOFs) dynamic model for SBGs with pitting defects is developed. An analytical model utilizing the slice strategy is proposed to evaluate the TVMS of SBG with pitting faults. The pitting fault is accounted for the dynamic model by incorporating the pitting faults into the evaluated TVMS. Then, the vibration responses of SBGs with tooth pitting can be obtained and the responses in both the time and frequency domains are analyzed. The analysis shows that pitting faults can make periodic impact in the time domain and enhance the energy in low frequency region and its influence on the meshing frequency is not remarkable. Finally, the experiment results are analyzed to verify the proposed dynamic model.

Nonlinear vibration of cylindrical roller bearing considering the surface roughness: simulation and experiment

2025-06-24

Hui Ma , Hong Guan , Duo He +6 more | Nonlinear Dynamics

Dynamic modeling and analysis of planetary S-gear train system considering time-varying pressure angle

2025-06-24

Chao Jia , Ling Lü , Ligang Yao +1 more | Journal of Vibration and Control

In view of the time-varying pressure angle characteristics of S-gears, a dynamic model of planetary S-gear train which is closer to the actual working condition is established in this paper. … In view of the time-varying pressure angle characteristics of S-gears, a dynamic model of planetary S-gear train which is closer to the actual working condition is established in this paper. Firstly, the machining method of internal and external S-gears is introduced and the equation of tooth surface is calculated. Subsequently, the pressure angle variation law of S-gears is derived according to the line-of-action (LOA) equation, then introducing it into the planetary S-gear train to establish a dynamic model considering time-varying pressure angle. Finally, the dynamic response of the planetary S-gear train is obtained by using the Runge–Kutta method, and the influence of time-varying pressure angle excitation on the dynamic characteristics of the system is revealed by comparing the dynamic mesh force (DMF), gear mesh deformation, and vibration displacement of components. The results clearly indicate that the time-varying pressure angle has a significant impact on the dynamic response of the planetary gear train, which cannot be ignored. The research results provide a useful source of reference for the dynamic design and vibration control of non-involute planetary gear trains.

Meshing theory and comprehensive analysis of offset enveloping cylindrical worm drive under point contact

2025-06-24

Xinyue Zhu , Hongwei Liu , Li Liu +1 more | Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science

In this paper, the meshing theory and parameter selection strategy of mismatched scheme for the offset enveloping cylindrical worm drive under point contact are investigated to provide the parameter basis … In this paper, the meshing theory and parameter selection strategy of mismatched scheme for the offset enveloping cylindrical worm drive under point contact are investigated to provide the parameter basis for numerical studies on the contact characteristics. Based on the tooth surface contact conditions, the system of contact equations of the point-conjugate tooth surface couple is established and then eliminated. The calculation formulas for geometric parameters, kinematic parameters, and motion errors related to worm angle are derived. Through comprehensively analyzing the requirements of point-conjugate drive pair for mismatched schemes, the methods of grouping mismatch parameters, presetting datum point, and displacing unknowns are proposed. These methods are used to determine the datum point and the two endpoints of the contact path, allowing for the quick acquisition of a reasonable set of mismatched parameters. According to this, a numerical simulation analysis is conducted on the geometry and kinematics characteristics, and the outcomes indicate that the offset point-conjugate drive pair has strong tooth surface bearing capacity and high operational stability.

Influence of profile modifications on spur gear sliding power losses: An integrated approach with advanced mesh stiffness and partial EHL

2025-06-24

Matteo Autiero , Giovanni Paoli , Marco Cirelli +1 more | Mechanism and Machine Theory

Prediction of Gear Face Deviation and Bearing Misalignment from Gear Transmission Error using Artificial Intelligence Model

2025-06-24

Kyu‐Sung Jeong , Beom‐Soo Kim , Dong-Joo Moon +2 more | Journal of the Korean Society of Manufacturing Process Engineers

Modeling and analysis of an EV-specific Differential Gearbox and its Casing

2025-06-23

Digvijay Gabhane | INTERANTIONAL JOURNAL OF SCIENTIFIC RESEARCH IN ENGINEERING AND MANAGEMENT

The rapid advancement of electric vehicles (EVs) demands innovative transmission systems that prioritize performance, efficiency, and weight reduction. One critical component is the differential gearbox, which must transmit torque effectively … The rapid advancement of electric vehicles (EVs) demands innovative transmission systems that prioritize performance, efficiency, and weight reduction. One critical component is the differential gearbox, which must transmit torque effectively while adapting to speed variations during turning. Traditional cast iron or steel differential housings significantly increase vehicle weight, reducing energy efficiency and limiting range. This study focuses on the design, modeling, and finite element analysis (FEA) of a lightweight differential gearbox and its casing specifically tailored for EV applications. 3D modeling and ANSYS 14.5 for structural and modal analysis, the project investigates stress distribution, displacement, and natural frequencies under various torque conditions. Modal analysis identifies critical vibration modes to prevent resonance-induced failures. The primary goal is to ensure structural integrity, reduce gearbox weight, and maintain thermal and acoustic performance. Statistical and dynamic simulations help optimize the gearbox casing, ensuring it meets strength and vibration control standards. This research ultimately contributes to enhancing EV efficiency, safety, and reliability by introducing lightweight materials and a robust gearbox design. Keywords – Electric Vehicles (EVs), Differential Gearbox, Casing , Finite Element Analysis (FEA), Modal Analysis etc.

Research on multi-state meshing nonlinear dynamics of a herringbone gear system with time-varying pressure angle and backlash

2025-06-23

Zongxiang Yue , Yuyuan Wang , Zhaobo Chen +4 more | Nonlinear Dynamics

Influence of motor rotor bending on vibration characteristics of electric drive system

2025-06-20

Fengchao Huang , Changzheng Chen , Zhengqi Wang +2 more | Mechanical Systems and Signal Processing

Nonlinear Dynamics of a Coupled Electromechanical Transmission

2025-06-20

Antonio Zippo , Moslem Molaie , Francesco Pellicanò | Vibration

The mechanical connection between a transmission system and an electric motor gives rise to a strong interaction between their respective dynamics. In particular, the coupling between an electric motor and … The mechanical connection between a transmission system and an electric motor gives rise to a strong interaction between their respective dynamics. In particular, the coupling between an electric motor and a nonlinear spur gear transmission significantly influences the overall dynamic behavior of the integrated system. This study presents a detailed investigation into the electromechanical coupling effects between a permanent magnet synchronous machine (PMSM) and a nonlinear spur gear transmission. To focus on these effects, three configurations are analyzed: (i) a standalone gear pair model without motor interaction, (ii) a combined gear–motor system without dynamic coupling, and (iii) a fully coupled electromechanical system where the mechanical feedback influences motor control. The dynamic interaction between the motor’s torsional vibrations and the gear transmission is captured using the derivative of the transmission error as a feedback signal, enabling a closed-loop electromechanical model. Numerical simulations highlight the critical role of this coupling in shaping system dynamics, offering insights into the stability and performance of electric drive–gear transmission systems under different operating conditions. It also underscores the limitations of traditional modeling approaches that neglect feedback effects from the mechanical subsystem. The findings contribute to a more accurate and comprehensive understanding of coupled motor–gear dynamics, which is essential for the design and control of advanced electromechanical transmission systems in high-performance applications.

Research on the Equal Probability Grouping Method for Automatic Fitting of Deep Groove Ball Bearings

2025-06-20

Peiqi Yang , Haoyi Wang , Xuejun Li +1 more | Machines

At present, the fitting process of deep groove ball bearings has the problems of low manual production efficiency and poor performance of fitted bearings. For the automatic bearing fitting production … At present, the fitting process of deep groove ball bearings has the problems of low manual production efficiency and poor performance of fitted bearings. For the automatic bearing fitting production line, there are some problems, such as a low success rate of fitting and easy interruption of the production process. In this article, two grouping methods, the equidistant grouping method and the equal probability grouping method, are proposed. We establish a dimensional deviation distribution model by measuring the dimensional deviation of deep groove ball bearing components. Using the bearing component dimensional deviation distribution model, we carry out the equidistant grouping method and the equal probability grouping method to fit the bearing component. And the influence of the traditional bearing fitting method and the two grouping methods on the success rate of deep groove ball bearing fitting is compared and analyzed. This research found that the traditional bearing fitting method is easy to fall into local optimization, and too many unmatched components which have a larger dimensional deviation lead to the interruption of the fitting process. The success rate of the traditional fitting method is lower than grouping methods. For the two grouping methods, the equal probability grouping method can ensure that the probability of each group of components entering the automatic production line is the same. Compared with the equidistant grouping method, it is easier to make it possible to fit the bearing component. The equal probability grouping method is recommended.

A Novel Rapid Design Framework for Tooth Profile of Double-Circular-Arc Common-Tangent Flexspline in Harmonic Reducers

2025-06-20

Xueao Liu , Jian Zhang , Hui Wang +2 more | Machines

Due to its small size, high transmission ratio and precision, the harmonic reducer is widely used. The design of the flexspline tooth profile is crucial for the transmission accuracy and … Due to its small size, high transmission ratio and precision, the harmonic reducer is widely used. The design of the flexspline tooth profile is crucial for the transmission accuracy and service life of harmonic reducers. However, the numerous design parameters and the lack of a unified design standard for the flexspline tooth profile make it challenging to accurately determine these parameters. This can lead to issues such as tooth profile interference and excessive stress on the gear teeth during transmission. To address these issues, we propose a novel rapid design framework for the tooth profile of a double-circular-arc common-tangent flexspline in harmonic reducers. Firstly, the mathematical formula for the flexspline tooth profile with a double-circular-arc common-tangent and its conjugate circular spline tooth profile is derived. Then, two-dimensional and three-dimensional parametric finite element models of the harmonic reducer are established, and radial and axial profile modifications of the flexspline are carried out. Based on the parametric two-dimensional finite element model of the harmonic reducer, the optimized Latin hypercube experimental design method is employed to determine the flexspline tooth profile parameters. The method proposed can be implemented using Python language code and integrated into the Abaqus 2019 software, offering the advantage of meeting the requirements for rapid engineering development. Finally, a case study is presented to verify the effectiveness of the proposed design method.

Research on torsional vibration characteristics and resonance mechanism of industrial robot joint transmission system based on electromechanical coupling

2025-06-19

Xiaobo Yang , Zhihai Wang , Xiaoqin Liu +2 more | Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering

Torsional vibration in industrial robot joints inevitably causes electromechanical parameter coupling in the transmission system during routine operation. This coupling triggers complex vibrations within the system, affecting its dynamic properties … Torsional vibration in industrial robot joints inevitably causes electromechanical parameter coupling in the transmission system during routine operation. This coupling triggers complex vibrations within the system, affecting its dynamic properties and stability, making it more difficult to obtain accurate health information about the system. To address these challenges, this study explores the torsional vibration behaviors and resonance mechanisms in the joint transmission systems of industrial robots, with a focus on the electromechanical coupling effects. First, a dynamic model of the joint transmission system with electromechanical coupling and its vibration simulation model is established. The impact of crucial mechanical parameters of the joint structure on both system vibration and the characteristics of its output speed is examined. In addition, a “motor-load” dual-inertia equivalent model of industrial robot joint transmission system considering the reduction ratio is proposed. The resonance equations are constructed, and the resonance mechanism is analyzed. The effects of key mechanical parameters on the joint resonance are fully considered. Additionally, the Kalman filter method is applied to determine the steady-state condition of the joint. The validity of the proposed model is confirmed through experimental data obtained from an industrial robot. The research can provide an important basis for studying industrial robots‘ mechanical torsional vibration characteristics and resonance mechanisms.

A comprehensive instantaneous power losses calculation method of planetary gear system considering tooth surface microtopography

2025-06-19

Quanming Luo , Wennian Yu , Changyu Fan +3 more | Journal of Tribology

Abstract Accurately calculating the instantaneous power losses of planetary gear system provides theoretical guidance for optimizing the system's structure and enhancing its energy efficiency. Existing power loss calculation methods neglect … Abstract Accurately calculating the instantaneous power losses of planetary gear system provides theoretical guidance for optimizing the system's structure and enhancing its energy efficiency. Existing power loss calculation methods neglect the influence of tooth surface microtopography and lubrication conditions, and are unable to accurately capture the time-varying characteristics of power losses. Moreover, there is a lack of research specifically addressing the coupled dynamics of planetary gear&#x96;bearing systems. To address this issue, a time-varying mesh stiffness calculation model has been established using elastohydrodynamic lubrication theory and fractal theory. On this basis, a novel bending&#x96;torsional coupled dynamic model of a planetary gear&#x96;bearing system was established, which incorporates the effects of tooth surface microtopography and lubrication conditions. The dynamic responses are obtained by solving the dynamic model. Based on the dynamic responses, a new method was proposed to calculate multiple forms of instantaneous power losses, enabling the evaluation of their time-varying characteristics. Finally, the accuracy of the proposed method was validated through test bench experiments. The results show that the proposed approach can more accurately and physically represent power loss behavior. Furthermore, the influence of surface fractal dimension and initial dynamic viscosity on power losses was investigated.

Fault Evolution Characteristics Analysis of Spur Gear Based on Dimensional Technique and Support Vector Machine

2025-06-19

Vishal G. Salunkhe , Yash Salodkar , Abhishek P. Mohite +5 more | Journal of Nondestructive Evaluation Diagnostics and Prognostics of Engineering Systems

Abstract Spur gears are essential for industrial machinery, ensuring efficient mechanical power transmission. Faults in these gears can cause significant operational disruptions, leading to costly downtimes and reduced productivity. This … Abstract Spur gears are essential for industrial machinery, ensuring efficient mechanical power transmission. Faults in these gears can cause significant operational disruptions, leading to costly downtimes and reduced productivity. This study presents a robust method for fault detection in spur gears by integrating dimensional analysis (DA), and support vector machine (SVM) techniques. Vibration signals are captured with a experimental setup and processed using fast fourier transform FFT, converting the data to the frequency domain and identifying characteristic fault frequencies. A mathematical model is developed to simulate gear fault dynamics, with theoretical predictions validated against experimental measurements. The DA approach achieves fault detection with an average error of 3.15%. Subsequently, SVM is employed for classification and regression, yielding a fault classification accuracy of 97.84%. The results demonstrate a strong correlation between theoretical and experimental data and classification, confirming the reliability of the proposed method. The integrated approach showcases its potential for precise fault detection and quantification in industrial spur gear systems.

Experimental Investigation of CNC Wire-Cut EDM Machining Accuracy on Vibration Characteristics of Non-Circular Gear Pairs

2025-06-19

Hong-Phong Nguyen , Van-The Tran , Tien–Long Banh +1 more | Iranian Journal of Science and Technology Transactions of Mechanical Engineering

A Semi-supervised Fault Diagnosis Method for Rolling Bearing Using Time-Frequency Transform Enhanced Contrastive Learning

2025-06-19

Jicai Wang , Shahrum Abdullah , Azli Arifin +2 more | Eksploatacja i Niezawodnosc - Maintenance and Reliability

This paper proposes a novel semi-supervised framework, time-frequency Contrastive Learning (CL), to address the challenge of accurate rolling bearing fault diagnosis under industrial small-sample conditions. Raw vibration signals are transformed … This paper proposes a novel semi-supervised framework, time-frequency Contrastive Learning (CL), to address the challenge of accurate rolling bearing fault diagnosis under industrial small-sample conditions. Raw vibration signals are transformed into discriminative time-frequency images using short-time Fourier transform (STFT). A CL network with a ResNet18 model is pre-trained on a lot of unlabeled samples to learn generalized feature, and the ResNet18 model is fine-tuned using small labeled samples for fault classification. Experimental validation on bearing fault datasets demonstrates that the proposed STFT-CL method achieves above 99% diagnosis accuracy with only 50 labeled samples per fault type, outperforming conventional semi-supervised methods by 6-12%. The proposed method provides a potential solution to the "small sample dilemma" in industrial applications through the synergistic effect of physically driven signal processing and self supervised representation learning.

Methodology for Comprehensive Testing and Optimization of Gears for Torsional Strength

2025-06-17

Paweł Knast , Jana Petrů , Stanisław Legutko +3 more | MANUFACTURING TECHNOLOGY

Research on ball bearing stiffness considering the uncertain bearing-shaft interference fit

2025-06-16

Yongzhen Liu , C. J. Liu , Tao Li +3 more | Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science

Bearing-shaft interference fit is very sensitive to the service performance of ball bearings, in recent years, scholars have taken this factor into consideration during the modeling process of ball bearing. … Bearing-shaft interference fit is very sensitive to the service performance of ball bearings, in recent years, scholars have taken this factor into consideration during the modeling process of ball bearing. However, the uncertainty in bearing-shaft interference fit is inherent due to the tolerance in the manufacturing process and the effect on the service performance of ball bearings has not been paid much attention by scholars. Moreover, the interference fit amount could change due to the influence of centrifugal force, which could influence the bearing stiffness. Therefore, this paper presents a non-intrusive stiffness model of ball bearing based on quasi-static model combined with the Chebyshev interval analysis method, in which the bearing-shaft interference fit model with uncertain parameters is incorporated. The effect of the average value and deviation coefficient of the interference fit on the bearing stiffness versus time, preload and rotating speed under different preload mechanism are investigated. The experimental results from the published works are compared to the present results to verify the validity of the bearing stiffness model. Then the Monte Carlo simulation (MCS) is conducted to validate the accuracy of the proposed method. The model and method used in this paper can better elucidate the fluctuation of the stiffness induced by the uncertain bearing-shaft interference fit, and provide theoretical guidance for the design of the rotor-bearing system.

Tribological Evaluation and Model of Wear Behavior in the Boundary Lubrication of the Contact Surfaces of Cycloidal Reducers

2025-06-16

Juozas Padgurskas , Aleksandr Dykha , Raimundas Rukuiža +4 more | Lubricants

Cycloidal reducers are widely used in precision drive systems due to their reduced backlash in meshing and compact design. However, their operational durability is limited by surface wear and lubricant … Cycloidal reducers are widely used in precision drive systems due to their reduced backlash in meshing and compact design. However, their operational durability is limited by surface wear and lubricant degradation under elevated contact loads and boundary lubrication conditions. This study introduces a modified wear prediction model based on four-ball tribological testing, specifically adapted to simulate the complex tribological conditions in cycloidal gear contacts. The model incorporates the total acid number (TAN) and thermal conductivity coefficient of the lubricant as dimensionless factors, enabling a dynamic prediction of wear intensity as the lubrication degrades. This innovation allows an accurate estimation of service life and reliability in high-load, small-contact-area mechanical systems and offers a practical diagnostic tool for the predictive maintenance of gear transmissions.

Dynamic modeling of cylindrical roller bearings considering raceway crack defects

2025-06-16

Zhifeng Shi , Gang Zhang , Changfeng Yan +2 more | Mechanical Systems and Signal Processing

The influence of cumulative wear on the dynamic response and meshing state of gear system with mixed elastohydrodynamic lubrication

2025-06-16

Shuai Mo , Yingxin Zhang , Keren Chen +2 more | Nonlinear Dynamics

Experimental study of non-involute free-form gear dynamics under varying operating conditions

2025-06-16

Ahmed Waleed Hussein , Mohammad Qasim Abdullah , Mustafa M. Kadhim | Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science

The non-involute Free-Form-Gear (FFG) has been recently developed to mitigate the involute gear drawbacks. Previous studies have shown that sliding velocity, meshing efficiency, filet, and contact stresses are enhanced in … The non-involute Free-Form-Gear (FFG) has been recently developed to mitigate the involute gear drawbacks. Previous studies have shown that sliding velocity, meshing efficiency, filet, and contact stresses are enhanced in comparison to the standard involute gear pair. However, the dynamic behavior in terms of noise and vibration of the newly developed gear drive has not been evaluated yet. So in this paper, an assessment of the dynamic behavior of the proposed FFG is established. The assessment is conducted by directly measuring the gearbox’s vibration, noise, and oil temperature at various loads and speeds. The tests have been conducted on special case studies in which extreme meshing conditions are present. The behavior of the proposed FFG is then compared to that of standard involute gear under the same operating conditions. The results have shown that the FFG pair may produce higher vibration levels than the involute gear at no load condition by 34%, but the vibration levels can be improved by 6% under load. The modified addendum versions of the FFG drive, on the other hand, can operate with lower vibration levels by 28% and 23% for no load and loading conditions, respectively. In addition, the suggested FFG pair has reduced the gearbox’s oil temperature in comparison to the involute gear pair. It has been concluded that under specific conditions, the FFG can operate with lower vibration and noise levels than the involute gear under the same operating conditions.

Digital twin-driven few-shot fault data generation and intelligent diagnosis for rolling bearings

2025-06-16

Zhang We , Baokang Yan , Shuang Lu +2 more | Journal of Control and Decision

Wear prediction of internal combustion engine cylinder liners based on adaptive generative adversarial networks

2025-06-16

Jianxiong Kang , Chang Shu , Haoran Yang +3 more | Results in Engineering

Dynamic modeling and vibration characteristics analysis of planetary system with herringbone gears containing cracks in wind turbine gearboxes

2025-06-15

Yue Bi , Hao Dong , Sheng-Sheng Liu +5 more | Mechanics Based Design of Structures and Machines

Study on Comparative Analysis of Characteristics for Split-Inner-Ring/Split-Outer-Ring Three-Point Contact Ball Bearings

2025-06-15

Jin-Hyeok Sa , Gilbert Rivera , Seong-Wook Hong | Journal of The Korean Society of Manufacturing Technology Engineers

Scuffing Risk of External Pinwheel Gear Set Pinion

2025-06-15

Soon Man Kwon , Yong‐Ho Lee | Journal of The Korean Society of Manufacturing Technology Engineers

Dynamic Response Analysis of Tooth Root Crack Failure in Helical Idler Gear System Under Different Working Flank Conditions

2025-06-14

Hengzhe Shi , Wei Li , Wanlin Zhou | Actuators

Helical idler gear transmission systems can adapt to high-speed, heavy-load working environments and are thus widely used in aerospace, shipbuilding, and other heavy industry sectors. Root crack is one of … Helical idler gear transmission systems can adapt to high-speed, heavy-load working environments and are thus widely used in aerospace, shipbuilding, and other heavy industry sectors. Root crack is one of the common fault types. Prior studies generally only considered cracks at a single working flank, lacking comparative analysis between the crack at the working flank and the non-working flank. This paper examines the dynamic response of helical idler gears with root cracks at different working flanks, comparing dynamic response differences between working and non-working flank cracks. First, a comprehensive dynamics model of the helical idler gear system is established. Second, the influence of root crack location (the working flank or the non-working flank) on time-varying meshing stiffness is considered based on potential energy method, and a flexible model is established by finite element method for the faulty gear. Finally, solution results of the rigid-flexible coupling dynamics model are analyzed. The dynamic response signal characteristics of root cracks at the working flank and the non-working flank are analyzed in time domain, frequency domain and time frequency domain, respectively. Corresponding experiments are designed based on the FZG experimental platform, and the experimental results are in good agreement with the simulation results, which verified the accuracy of the model.

Vibration characteristic analysis and optimization for gear systems considering anisotropic surface micromorphology

2025-06-14

Xin Zhang , Heng Xia , Fanshan Meng +2 more | Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science

Tooth surface micromorphology greatly affects the vibration characteristics of gear systems. By strategically modifying the tooth micromorphology, it is possible to optimize vibration characteristics and enhance overall transmission efficiency. In … Tooth surface micromorphology greatly affects the vibration characteristics of gear systems. By strategically modifying the tooth micromorphology, it is possible to optimize vibration characteristics and enhance overall transmission efficiency. In this context, a new method dual-driven by dynamic model and machine learning is proposed for the analysis and optimization of vibration characteristics. Specifically, the nonlinear dynamic model of gear systems characterized by 3D anisotropic fractal tooth surfaces is constructed and the vibration characteristics yielded by the micromorphology parameters are analyzed. Two vibration response prediction models are then developed by training an eXtreme Gradient Boosting (XGBoost) with the dynamic responses. Based on the prediction models, an optimization problem for fractal tooth surface parameters is formulated by minimizing dynamic transmission error amplitude and maintaining periodic system motion, and the particle swarm optimizer is adopted to realize the optimization for vibration characteristics of gear systems. Under the representation of 3D anisotropic fractal methodology, the tooth surface can more comprehensively depict its microscopic characteristics. The XGBoost-based vibration response prediction models perform excellently in processing small samples, which ensures the precision, efficiency, and reliability of the method, making it well-suited for guiding the research on noise and vibration reduction of gear systems.

Effect of manufacturing tolerances and uncertainties on the NVH response of spur and helical gears: A review

2025-06-14

Ranim Najib , Jessica Neufond , Francesco Franco +2 more | Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science

Over the years, there has been an ongoing concern regarding Noise, Vibration, and Harshness (NVH) issues in gearbox design. However, significant progress has been made in addressing these problems. Optimizing … Over the years, there has been an ongoing concern regarding Noise, Vibration, and Harshness (NVH) issues in gearbox design. However, significant progress has been made in addressing these problems. Optimizing gear design reduces the magnitude of gear mesh excitation, and effective solutions must be robust, efficient, and cost-effective. This paper extensively reviews studies addressing NVH challenges in transmission systems, focusing on gear design modeling for cylindrical steel gears. It examines the primary methodologies used, their limitations, and key areas such as (i) the impact of manufacturing and mounting uncertainties on gear meshing, (ii) the effectiveness of different optimization approaches across a wide range of operating conditions, and (iii) advancements in robustness to guide future research. This review aims to provide a comprehensive orientation to recent advancements in the field and identifies gaps in the existing literature.

Theoretical analysis of profile shift effects and design parameter interactions on herringbone gear mesh stiffness

2025-06-14

Yuedong Wu , Jinhai Wang , Jianwei Yang +1 more | Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science

Precise profile shift design enables targeted optimization of herringbone gear pairs through load distribution control. Time-varying meshing stiffness (TVMS) emerges as a significant dynamic excitation that can affect the operational … Precise profile shift design enables targeted optimization of herringbone gear pairs through load distribution control. Time-varying meshing stiffness (TVMS) emerges as a significant dynamic excitation that can affect the operational performance of herringbone gear pairs. This study develops an analytical framework for stiffness simulation in profile-shifted herringbone gears and systematically quantifies mesh stiffness variability under individual shift and compound shift configurations. The research further elucidates the synergistic effects of profile shift coefficients and key design variables—tooth width, helix angle, and normal module—on mesh stiffness evolution through parametric coupling analysis. The research results show that the positive shift decreases the mesh stiffness of gear pairs, with a 0.1 increment in the profile shift coefficient reducing the mean mesh stiffness by approximately 2.0%, while the negative shift increases it by approximately 1.9% per 0.1 decrement. For compound equal shift, mean stiffness decreases 0.9%–1.0% per 0.1 increment in the absolute value of the profile shift coefficient. For gear design parameters, quantitative analysis reveals substantial sensitivity differences: Negative shift gears exhibit 5.5%, 13.6%, and 8.9% higher mean stiffness sensitivity to tooth width, helix angle, and normal module variations, respectively, compared to standard gears. Conversely, positive shift configurations demonstrate stabilized stiffness sensitivity with 6.2%, 15.1%, and 9.9% reductions in parametric sensitivity for these respective variables. Moreover, the variation in mesh stiffness variance of the profile-shifted and standard gears caused by modifying the tooth width demonstrates monotonic trends, whereas alterations in helix angle and normal module induce non-monotonic relationships. These findings enable the precision design of herringbone gears with tailored stiffness characteristics, which is particularly beneficial for high-speed, heavy-load transmission applications.

EFFECTS OF ATTACHMENT DESIGNS ON CLEAR ALIGNER TOOTH MOVEMENT: A FINITE ELEMENT ANALYSIS

2025-06-13

Egon Mamboleo , Abdelhak Ouldyerou , Khaled Alsharif +4 more | bioRxiv (Cold Spring Harbor Laboratory)

This study investigates the impact of different attachment shapes and configurations on the displacement, stress, and strain profiles of maxillary first molar during clear aligner-based orthodontic treatment. A subject-specific 3D … This study investigates the impact of different attachment shapes and configurations on the displacement, stress, and strain profiles of maxillary first molar during clear aligner-based orthodontic treatment. A subject-specific 3D maxillary model was developed from CBCT imaging, incorporating cortical and trabecular bone, periodontal ligament (PDL), teeth, attachments, and aligner geometry. Five attachment shapes square, rectangle, trapezoid, ellipse, and semicircle were analyzed in single and dual (buccal-lingual) configurations across four clinically relevant movements: mesialization, intrusion, extrusion, and rotation. Finite-element simulation results indicated that flat-shaped attachments (rectangular and trapezoidal) generated the greatest crown displacement but induced higher PDL strain (up to 0.390 mm/mm) and localized bone stress (7.11 MPa), particularly at the root apex and alveolar crest. Curved attachments provided more diffused load distribution but significantly reduced movement efficiency. Dual attachments improved root engagement and bodily displacement in all movement types, mitigating undesired tipping and enhancing force symmetry, albeit with elevated strain. Rotational control was most influenced by attachment geometry, with flat designs producing greater angular movement. Overall, attachment shape and placement exert a substantial influence on orthodontic biomechanics during aligner therapy. The findings underscore the need for evidence-based attachment protocols tailored to specific movement goals and patient risk profiles. These insights can guide clinicians toward optimizing clear aligner treatments for improved movement precision, minimized biological risk, and enhanced treatment outcomes in complex orthodontic cases.

Effect of a Notch on the Fatigue Strength of a Gear Shaft

2025-06-13

H. M. Asanjitha Jayasekara , S. D. Rasika Perera | Engineer Journal of the Institution of Engineers Sri Lanka

A failure of a gear shaft in an industrial application led to this investigation. The fractographic analysis revealed that the shaft was subjected to a high stress gradient at the … A failure of a gear shaft in an industrial application led to this investigation. The fractographic analysis revealed that the shaft was subjected to a high stress gradient at the failed location. Finite Element Analysis revealed that the nominal stress was way below the endurance limit of the material, however, due to the design of the shaft, a stress relief groove was used at a point where the shaft diameter had an abrupt change. The relief groove was necessary to properly fit the bearing on the shaft. The stress relief groove acted as a stress riser at the location. This was further verified by an experimental investigation of the stress gradient when in operation, optical imaging of the failed section and further a numerical analysis. A fracture mechanics analysis was used to assess the fatigue life of the notched component.

A novel method based on wavelet transform and prototypical network for gearbox detection in few-shot learning

2025-06-13

Xianhua Chen , Zhigang Tian , Yuejian Chen | Expert Systems with Applications

Digital Twin-Driven Virtual–Real Hybrid Framework Based on Parameter Identification for Bearing Thermal Prediction

2025-06-13

Yu Wang , Qingbin Tong , Liu Yang +2 more | Applied Sciences

Accurate temperature prediction is critical for ensuring mechanical stability and operational safety during complex operating conditions and long-term operation of rolling bearings. This study proposes a digital twin (DT) system … Accurate temperature prediction is critical for ensuring mechanical stability and operational safety during complex operating conditions and long-term operation of rolling bearings. This study proposes a digital twin (DT) system for bearing thermal analysis and a digital twin-driven virtual–real hybrid framework, achieving thermal prediction from low-risk behaviors (low-speed/light-load) to high-risk behaviors (high-speed/heavy-load). To address the time-varying and ambiguous parameters, an efficient Nutcracker Optimization Algorithm (NOA)-based identification mechanism is introduced to dynamically calibrate the virtual thermal model, overcoming the limitations of static modeling and data isolation inherent in conventional thermal analysis methods. The Euclidean distance and uncertainty analysis between real temperature and predicted temperature demonstrate the highly reliable predictive ability of the proposed framework in terms of bearing thermal, especially under variable speed conditions. The proposed framework has certain guiding significance for enhancing thermal safety and fault early-warning capabilities of bearings during long-term operation.

Effect of Bearing Support Parameters on the Radial and Angular Deformation of Rotor Shaft Gear Based on CRDRS Support Configuration with Intermediate Bearing Support

2025-06-12

Xiaojie Yuan , Xiaoyu Che , Weifang Chen | Machines

The rotor shaft is a critical component responsible for transmitting engine power to the helicopter’s rotor. Deformation of the rotor shaft can affect the meshing performance of the output stage … The rotor shaft is a critical component responsible for transmitting engine power to the helicopter’s rotor. Deformation of the rotor shaft can affect the meshing performance of the output stage gears in the main gearbox, thereby affecting load transfer efficiency. By adjusting the support parameters of the rotor shaft, deformation at critical positions can be minimized, and the meshing performance of the output stage gears can be improved. Therefore, it is imperative to investigate the influence of rotor shaft support parameters on the deformation of the rotor shaft. This paper takes coaxial reversing dual rotor shaft (CRDRS) support configuration with intermediate bearing support as object. Utilizing Timoshenko beam theory, a rotor shaft model is developed, and static equations are derived based on the Lagrange equations. The relaxation iteration method is employed for a two-level iterative solution, and the effects of bearing support positions and support stiffness on the radial and angular deformations of rotor shaft gears under two support configurations, simply supported outer rotor shaft–cantilever-supported inner rotor shaft, and simply supported outer rotor shaft–simply supported inner rotor shaft, are analyzed. The findings indicate that the radial and angular deformations of gear s1 are consistently smaller than those of gear s2 in the CRDRS system. This difference is particularly pronounced in the selection of support configuration. The bearing support position plays a dominant role in gear deformation, exhibiting a monotonic linear relationship. In contrast, although adjustments in bearing support stiffness also follow a linear pattern in influencing deformation, their impact is relatively limited. Overall, optimal design should prioritize the adjustment of bearing positions, particularly the layout of b3 relative to s2, while complementing it with coordinated modifications to the stiffness of bearings b2, b3, and b4 to effectively enhance the static characteristics of the dual-rotor shaft gears.

Modeling and Validation of Vibration Response of Planetary Gear Systems Considering Meshing Impact

2025-06-12

Haodong Wang , Chenglong Wang , Yiliang Huang +1 more | Journal of Vibration Engineering & Technologies