Model Of Gearbox Research Articles

Vibration mechanism and improved phenomenological model of the planetary gearbox with broken ring gear fault

Accurate modeling of the vibration signal model of planetary gearboxes is essential for the subsequent fault diagnosis. According to the existing improved phenomenological model based on the meshing vibration, this paper conducts further investigations on the vibration mechanism of the gearbox. The time delay phenomenon of faulty ring gear tooth participating in meshing is theoretically analyzed, and the assisted phases for experimental verification are proposed and deduced. Based on the improved model, the vibration signal under the fault condition is simulated and compared with the results of traditional methods. Subsequently, the paper proposes to divide and reconstruct this signal and use the maximum correlation kurtosis deconvolution (MCKD) to enhance its impact characteristics. The results show that the phase between the fault impact and its adjacent meshing impact is consistent with the proposed assisted phase. Finally, the correctness of the vibration mechanism and the improved phenomenological model are verified experimentally.

Vibration mechanism and improved phenomenological model of planetary gearbox with broken sun gear fault

Multiple vibration signal models for planetary gearboxes have been built, but details in the signals are often ignored when verifying their correctness. The main reason is that the vibration mechanism of the gearbox is not well studied. To overcome this problem, the stiffness model of the faulty external gear pair is firstly developed and the end meshing time of the broken tooth under different fault sizes is explored. Based on this, an improved phenomenological model is established, and the assisted phases for verifying its correctness are proposed. Subsequently, the simulated signal is decomposed into two components, which mainly contain meshing impacts and fault impacts, respectively. Based on the time difference between these two types of impacts, the mapping relationship between the assisted phases and the fault size is verified. Finally, the correctness of the vibration mechanism of the gearbox and the improved phenomenological model are verified by simulation and experiments.

Numerical Simulation of a Certain Engineering Vehicle Gearbox under Low Temperature Conditions

The gearbox is an important part of the reducer. Its components must have high bearing capacity and reliability. Cracks often appear in the gearbox body in the actual work, so it is necessary to carry on the structure analysis to the gearbox body performance. In this paper, a 3-D model of an engineering vehicle gearbox is established by using Solidworks software. Based on the model, the stress State and maximum displacement of the gearbox under low temperature conditions are analyzed. According to the calculation, the structure of the gearbox meets the design requirements. The analysis results provide a theoretical basis for the structural optimization of the gearbox.

MODEL OF AN ADJUSTABLE ELECTROMAGNETIC GEARBOX WITH A THREE-PHASE STATOR WINDING IN THE STATE SPACE

A magnetic gearbox with a three-phase stator winding, powered by a static frequency converter with a sinusoidal current, which is in phase or in antiphase with the EMF of the idling winding, will have in this mode the maximum values ​​of the electromagnetic moments of the shafts proportional to the stator current. Such a gearbox will have no “overturning” of the rotors as long as the frequency converter is able to increase its current with increasing load.
 
 The electromagnetic moments of the rotors of the magnetic gear are a consequence of the presence of the electromagnetic moment of the stator. The electromagnetic moments of the rotors are rigidly related to the electromagnetic moment of the stator through constant coefficients.
 
 A mathematical model of an adjustable magnetic gearbox with a three-phase stator winding and the results of modeling a dynamic system are presented. Offers the structure of the output shaft speed stabilization system, such as a wind turbine. The introduction of the main research results is illustrated.

Preliminary Evaluation of the Influence of Surface and Tooth Root Damage on the Stress and Strain State of a Planetary Gearbox: An Innovative Hybrid Numerical–Analytical Approach for Further Development of Structural Health Monitoring Models

Wind turbine gearboxes are known to be among the weakest components in the system and the possibility to study and understand the behavior of geared transmissions when subject to several types of faults might be useful to plan maintenance and eventually reduce the costs by preventing further damage. The aim of this work is to develop a high-fidelity numerical model of a single-stage planetary gearbox selected as representative and to evaluate its behavior in the presence of surface fatigue and tooth-root bending damage, i.e., pits and cracks. The planetary gearbox is almost entirely modelled, including shafts, gears as well as bearings with all the rolling elements. Stresses and strains in the most critical areas are analyzed to better evaluate if the presence of such damage can be somehow detected using strain gauges and where to place them to maximize the sensitivity of the measures to the damage. Several simulations with different levels, types and positions of the damage were performed to better understand the mutual relations between the damaged and the stress state. The ability to introduce the effect of the damage in the model of a gearbox represents the first indispensable step of a Structural Health Monitoring (SHM) strategy. The numerical activity was performed taking advantage of an innovative hybrid numerical–analytical approach that ensures a significant reduction of the computational effort. The developed model shows good sensitivity to the presence, type and position of the defects. For the studied configuration, the numerical results show clearly show a relation between the averaged rim stress and the presence of root cracks. Moreover, the presence of surface defects seems to produce local stress peaks (when the defects pass through the contact) in the instantaneous rim stress.

Dynamic Characteristic Analysis and Clutch Engagement Test of HMCVT in the High-Power Tractor

Hydromechanical continuously variable transmission (HMCVT) is capable of bearing large torque and has wide transmission range, which is suitable for high-power tractors. Dynamic characteristics could influence the tractor life, especially in a high-power tractor. Wet clutch is the crucial component in the HMCVT, which could smooth and soft power transmission. Therefore, it is important to study the dynamic characteristics and implement the wet clutch test of HMCVT. In this paper, AMESim is used to establish virtual models of gearbox, pump-controlled hydraulic motor system, and shifting hydraulic system. Then, a simulation study of tractor operation under working condition is carried out. The internal and external meshing forces of the planetary row are analyzed. Finally, the wet clutch engagement process of HMCVT in the high-power tractor is tested to verify the oil pressure. The simulation results show that the values of internal and external meshing force become larger as the throttle opening increases. At the moment of shifting change, the meshing forces of the planetary gear have great impact. The clutch test shows that the trend of the oil filling curve obtained from the bench test is similar to that obtained from the theoretical curve, which verifies the simulation results.

Hybrid Gearbox Modeling Using Modelica4.0

Gearbox modeling with mixed continuous and discrete events has been studied for long time. The gearbox power loss depends on the angular velocity and load. In this report, the LossyGear model of the Modelica standard library was constructed with a new configuration from the viewpoint of system engineering utilizing the synchronous feature of Modelica Standard Library 4.0. The proposed method can also be regarded as a case study for general cyber-physical modeling approach.

Development and validation of a dynamic model for a two-stage speed-reducer

This paper presents the development and validation of a six degree of freedom (DOF) dynamic model of a two-stage parallel shaft gearbox, without flaws, which is able to determine the reaction of gearbox components to varying torque inputs and loads. The model utilises flexible shafts and gears rather than using a rigid assumption, to further understand the effect of varying mesh stiffness. The paper replicates the results presented by Diehl and Tang, and improves the number of frequencies that can be analysed. The gear meshing frequencies were expected to dominate the result, however due to the use of a sinusoidal approximation of the varying tooth mesh frequency, the presented model shows the additional gear generated frequencies are present and analysable in the data.

CFD-Based Investigation of Lubrication and Temperature Characteristics of an Intermediate Gearbox with Splash Lubrication

In this study, we propose a computational fluid dynamics (CFD)-based method to study the lubrication and temperature characteristics of an intermediate gearbox with splash lubrication. A volume of fluid (VOF) multiphase model was used to track the interface between oil and air. A multiple reference frame (MRF) model was adopted to accurately simulate the movement characteristics of the gears, bearings, and the surrounding flow field. The thermal-fluid coupling computational model of an intermediate gearbox with splash lubrication was then established. Combined with experimental results, we verified that the lubricating oil temperature was below the limit requirement (<110 °C). The numerical results revealed that large amounts of lubricating oil were splashed onto the tooth surfaces near the gear meshing area. A large convective heat transfer coefficient corresponds to a low gear tooth surface temperature. The tooth surface temperature of the driving gear is higher than that of the driven gear. The distribution law of oil volume fraction of the bearing roller was jointly affected by the roller rotation direction and gravity. The convective heat transfer coefficient of the roller wall was largely related to the lubrication environment of the roller, including the oil distribution inside the bearing cavity and the flow rate.

A comparative study on the dynamic behaviour of 10 MW conventional and compact gearboxes for offshore wind turbines

AbstractThis study compares the dynamic behaviour of a conventional and a compact gearbox for the DTU 10 MW wind turbine supported on a monopile offshore structure. The conventional gearbox configuration is composed of two planetary epicyclic stages and one parallel stage, while the compact gearbox configuration consists of a fixed planetary stage and a differential compound epicyclic stage. The design methodology for these two gearboxes is described, and the final gearbox specifications show a lighter weight and smaller volume for the compact gearbox design compared to the conventional one. Computational gearbox models are established using the multi‐body system dynamic analysis method. A decoupled approach is employed for the gearbox load effect analysis. Comparisons of the dynamic behaviour between these two gearboxes are conducted under pure torque load cases, tangential pin position error conditions and non‐torque load cases. The results demonstrate that the compact gearbox has better dynamic performance under different torque load cases and is more robust to withstand the effects of manufacturing errors and rotor non‐torque loads compared to the conventional gearbox. It is believed that the proposed compact gearbox concept is promising and would be a good alternative for multi‐megawatt floating wind turbines, although challenging with respect to the design and operation complexity.

Optimization of planetary gear of onboard gear-box using the method of differential evolution

Problem. Further modernization of combat vehicles, associated with the installation of additional equipment, requires the use of more powerful engines, which leads to increased loads on parts and components of the onboard gearbox. In modern conditions, the onboard gearbox of the T-64 tank works at the limit of its technical capabilities. To maintain the existing advantages and eliminate these short-comings, the design of the onboard planetary gear-box needs to be upgraded. Goal. The goal is to increase the load capacity and as a consequence to increase the service life of the elements of the onboard gearbox by carrying out optimization of the onboard planetary gearbox. Methodology. Methods for calculating planetary mechanisms and methods for analyzing the strength of gears were used to build a mathematical model. When constructing the optimal design algorithm, the method of differential evolution was used. Results. The literature review of the existing methods of multicriteria optimization of planetary gears has been made. According to the developed method of optimization of the onboard gearbox, a study of the parameters of planetary gear for optimality according to the criteria of maximum load capacity and minimum dimensions has been made. Originality. An algorithm for optimal design using the method of differential evolution for optimization of planetary gearboxes has been developed. Practical value. The use of the received design of a planetary gear reduce loading on elements of a transmission of the T-64 tank, thus the overall dimensions and design features of an onboard gearbox remain. The proposed approach to optimization of planetary gears can be used in the design of modern models of planetary gearboxes.

Numerical model of a single stage gearbox under variable regime

Condition monitoring of gearboxes running under nonstationary regimes continue to be an important source of interest for industrialists and researchers. Despite the diversity of models in the literature, none allows simulating all cases of machine operations and failures modes in nonstationary regimes. This paper will discuss through a modeling approach how speed and load variations will influence the dynamic response of a single-stage gearbox supported by four rolling-element bearings, in the healthy case and in the case of gear and/or bearing defects. Combining 72 degrees of freedom and taking into consideration meshing and bearing nonlinear excitations, the proposed model allowed to compute the dynamic behavior of the real system for the case of gear tooth crack defect, pinion eccentricity defect, and the three localized bearing defects (outer race, inner race, and ball defects). Fast Fourier transform, Squared envelope spectrum, Short-time Fourier transform, and Kurtogram was used to reveal the vibration signature of the introduced defects under the different operating modes. A special envelope spectrogram was also designed to reveal the bearing defect frequencies variations in the case of a variable-driven speed.

Design and Dynamic Analysis of a Compact 10 MW Medium Speed Gearbox for Offshore Wind Turbines

Abstract This paper deals with the design of a compact gearbox for the DTU 10 MW reference offshore wind turbine. An innovative gearbox concept consisting of a fixed planetary stage and a differential compound epicyclic stage is proposed. Power splitting and compound epicyclic transmission technologies are employed, which can effectively reduce the gearbox size. The power transmission principle of the gearbox is described and power distribution ratios in two transfer paths are calculated via the geometrical and mechanical relationships among the gearbox components. The gearbox is designed based on the design loads and fatigue criteria by referring to relevant international standards. A high-fidelity drivetrain numerical model is established by means of a multi-body system (MBS) approach. Then, the power distribution ratios in two transfer paths are compared between the simulation results and the design values with a good agreement. Resonance analysis of the drivetrain model is conducted by means of the Campbell diagram and energy distribution of components, and the results show that no severe resonance phenomena appear in this drivetrain model. Additionally, the load-sharing behavior of the gearbox model is assessed under different environmental conditions, and the results indicate that the compact gearbox has a good load-sharing performance. Such a compact gearbox design, which fulfills all the design requirements for offshore applications, could be a good alternative for offshore wind turbines.

Failure analysis and restructuring model of transfer feeder gear box in thermal powerplant

The main purpose of this paper is to focus on the various possibilities of failure and preventive methods in the transfer feeder gear boxes. It also proposed that the various components which are used to design the gear boxes. The major failures causes in transfer feeder gear box due to lubrication contamination, overload, teeth misalignment, improper railtrack and output shaft because of poor design. To avoid these failures, it is necessary to reconstruct the gear box design model. This restructuring model in gear box improves the performances and reduces the overall maintenance cost.

Theoretical investigation of the improved nonlinear dynamic model for star gearing system in GTF gearbox based on dynamic meshing parameters

In the previous study, the gear meshing parameters are usually treated as constants, however, the translational motion, caused by bearing deformation, will lead to the variation of these parameters. In order to investigate the dynamic response of the GTF (Geared Turbofan engine) gearbox that more close to the actual working condition, the improved nonlinear dynamic model of GTF gearbox is proposed in this paper, in which the structure-based time-varying gear meshing parameters and multiple nonlinear clearances are fully considered, including time-varying mesh stiffness, pressure angles, contact ratios, position angles, and dynamic gear backlashes. Afterwards, the improved model is compared with the previous model, and their dynamic characteristics are demonstrated in time, and frequency domain. The results indicate that the nonlinear dynamic behaviors could be altered along with tooth impact state due to the time-varying meshing parameters, which could provide better understanding of the structural design and vibration control of the system.

A novel wind turbine gearbox fault diagnosis method based on ASO-VMD and NRF

The combination of feature extraction and pattern recognition can make it possible to realize wind turbine gearboxes based on vibration signals. However, these methods need to be constantly adjusted parameters and spend time training when processing different vibration signals, which is time-consuming. Aiming at reducing the number of parameters that need to be adjusted and training time, this paper proposes a variational mode decomposition (VMD) based on atomic search optimization (ASO) and neural random forest (NRF) fault diagnosis model. The parameters of the VMD are adaptively adjusted by the ASO, which has the advantages of less adjustment parameters. After ASO-VMD decomposition, signals will be used as the input of NRF. We evaluate our method on simulation gearbox model which is established by Solidworks and Adams. Experimental results show that our method has faster training speed and higher recognition accuracy without set many parameters manually.

REDUCTION OF THE TENSION OF MODIFIED TEETH OF NOVIKOV GEARING IN THE THREE-STEP GEARBOX Ц3НШ-450-40 DRIVE OF OIL PUMPING UNIT

The article is devoted to the actual topic – reduce the tension of the modified teeth of Novikov gearing drive gearbox of widely used oil pumping unit for oil production in order to increase the resource of their work and load-bearing capacity. As the object is considered a typical three-stage gearbox model Ц3НШ-450-40, produced by the plant “Izhneftemash” (Izhevsk). Gearbox is equipped with Novikov gearing with the basic rack profile according to GOST 15023–76. It is shown that the use of the proposed longitudinal modification of the working surfaces of the teeth in combination with an increase in gear module provides a very significant effect on reducing effective contact and bending stresses, on increase the load-bearing capacity and service life of the gearbox in comparison with the serial version currently produced by the domestic industry. The research is based on the results of solving the spatial contact problem of the stress-strain state of a tooth, as well as modeling the real multipoint engagement of Novikov gearing taking into account the technological errors of manufacture and assembly of gears. Recommendations on the implementation of the longitudinal modification of the teeth are given and it is shown that there are no technological difficulties. The effect achieved at different stages of the gearbox is: to reduce tooth stresses from 1.75 to 2.54 times, to increase the load-bearing capacity of the gearbox from 2.81 to 4.1 times, to increase the service life of the gearbox by an order of magnitude. In the future, the research outlined is supposed to spread to other models of gearboxes produced oil pumping units.

Dynamic behavior of the nonlinear planetary gear model in nonstationary conditions

The nonlinear effects in gearboxes are a key concern to describe accurately their dynamic behavior. This task is difficult for complex gear systems such as planetary gearboxes. The main aim of this work is to provide responses to overcome this difficulty especially in nonstationary operating regimes by investigating a back-to-back planetary gearbox in steady conditions and in the run-up regime. The nonlinear Hertzian contact of teeth pair is modeled in stationary and nonstationary run-up regime. Then it is incorporated in to a torsional model of the planetary gearbox through different mesh stiffness functions. In addition, motor torque and external load variation are taken into account. The nonlinear equations of motion of the back-to-back planetary gearbox are computed through the Newmark- β algorithm combined with the method of Newton–Raphson. An experimental validation of the proposed numerical model is done through a test bench for both stationary and run-up regimes. The vibration characteristics are extracted and correlated to speed and torque. Time–frequency analysis is implemented to characterize the transient regime during the run-up.

Modal Analysis and Experimental Study of Marine Gear Box

In this paper, the finite element model of marine gearbox is established, using Lanczos method performed the modal analysis of the gearbox system mathematical, the modal frequencies and modal shapes of each order of the box were obtained, and the modal experiment of marine gearbox is carried out. The results show that by comparing the data obtained from the experimental modal analysis with the theoretical calculated values, it is verified that the theoretical analysis values and experimental test values are in better agreement, and the maximum frequency error is 4.04%, the fea model is reliable, thus theoretical model could better reflect the natural vibration characteristics of the box on the marine gear box.

Friction-Tracker-Embedded Discrete Finite-Time Sliding Mode Control Algorithm for Precise Motion Control of Worm-Gear Reducers Under Unknown Switched Assistive/Resistive Loading

This paper proposes a novel method for simultaneous estimation of unknown switched external disturbance and precise position control of dynamical systems which employ worm gear drive reducers. This algorithm is based on an improved discrete sliding mode control (DSMC) design which ensures convergence to the desired sliding set without introducing chattering effects to the dynamical system. In order to improve the performance of DSMC and to obtain an accurate estimation of gearbox model, a new method for incorporation of switched friction is proposed in the presence of external disturbance. To this end, the dynamical response of worm gear drive reducer is investigated in distinct switched disturbance modes of resistive disturbances, assistive disturbances and no disturbance to obtain approximate functions describing system dynamics in aforementioned configurations. In comparison with the feedback data, the obtained models permit appropriate incorporation of friction into the improved DSMC scheme. Based on multiple common Lyapunov functions and calculation of virtual reference signals for armature currents, the feasibility of control algorithm is ensured in all modes of switched dynamics. The effectiveness of the proposed estimation and control schemes has been verified using an experimental setup employing a worm gear drive reducer on which multiple permanent magnet DC motors are installed, and improvements resulted from incorporation of friction estimation algorithm are analyzed.