Fatigue Analysis of Bearings in Planetary Gearboxes of Turbofan Engines Taking into Account Dynamic Loading

2020 ◽  
pp. 75-83
Author(s):  
D.V. Kalinin ◽  
N.I. Petrov ◽  
Y.L. Lavrentyev
Keyword(s):  
Dynamic Loading ◽  
Gear Tooth ◽  
Planetary Gear ◽  
Variable Stiffness ◽  
Dynamic Coefficient ◽  
Planetary Gearbox ◽  
Turbofan Engines ◽  
Bearing Life ◽  
Calculation Results ◽  
Tooth Modification

This paper presents a calculation method for assessing dynamic loading of bearings in satellites of planetary gearboxes of turbofan engines. The method is based on the analysis of a dynamic model of a planetary gearbox with lumped parameters for a planetary gear set with a fixed carrier. Simulation of the variable stiffness function of gear tooth meshing using the finite element method in a quasistatic formulation is employed for a more accurate assessment of the main source of excitation in the tooth meshing, that is the kinematic error, which includes both tooth deformations under load and technological deviations. Based on the comparison of the frequency response of the dynamic coefficient with and without tooth modification, it is established that the introduction of a modification reduces the dynamic coefficient in some modes by 2 times. The calculation results demonstrate that without taking into account the dynamic loading of the bearings, the bearing life is overestimated by about 11%. The design of a gearbox with satellite bearings on rolling bearings is considered.

Meshing Theory and Simulation of Noninvolute Beveloid Gears With Crossed Axes

2007 ◽  
Author(s):  
Guangbin Yu ◽  
Yuxiang Shi ◽  
Wei Wang ◽  
Guixian Li
Keyword(s):  
Gear Tooth ◽  
Three Dimensional ◽  
Tooth Profile ◽  
Line Contact ◽  
Cad System ◽  
Engagement Theory ◽  
Beveloid Gears ◽  
Calculation Results ◽  
Tooth Modification ◽  
Crossed Axes

Based on the space engagement theory, a special type of non-involute beveloid gears meshing with line contact between crossed axes has been studied in this paper. The engagement equation and tooth profile equation have been presented by applying the theory of gearing. Meanwhile the tooth profile errors and axial errors have been calculated by means of numerical analysis in this paper. The changes of these errors and the main factors have been studied. As a numerical example, the three-dimensional simulation of beveloid gears between crossed axes has been finished by means of the CAD system, Pro/Engineer. A new way of gear tooth modification is developed based on the space engagement theory for the first time in this paper. By improving the wheel gear grinder of large plane grinding, the paper has provided the tooth modification method of manufacturing noninvolute beveloid gears meshing with line contact between crossed axes. Finally, an example and its calculation results are presented.

Effects of the Gear Tooth Modification on the Nonlinear Dynamics of Gear Transmission System

2010 ◽  
Vol 97-101 ◽  
pp. 2764-2769
Author(s):  
Si Yu Chen ◽  
Jin Yuan Tang ◽  
C.W. Luo
Keyword(s):  
Nonlinear Dynamics ◽  
Gear Tooth ◽  
Simulation Method ◽  
Transmission Error ◽  
Dynamic Responses ◽  
Meshing Stiffness ◽  
Gear Transmission System ◽  
Tooth Modification ◽  
Static Transmission Error ◽  
Misalignment Error

The effects of tooth modification on the nonlinear dynamic behaviors are studied in this paper. Firstly, the static transmission error under load combined with misalignment error and modification are deduced. These effects can be introduced directly in the meshing stiffness and static transmission error models. Then the effect of two different type of tooth modification combined with misalignment error on the dynamic responses are investigated by using numerical simulation method. The numerical results show that the misalignment error has a significant effect on the static transmission error. The tooth crowning modification is generally preferred for absorbing the misalignment error by comparing with the tip and root relief. The tip and root relief can not resolve the vibration problem induced by misalignment error but the crowning modification can reduce the vibration significantly.

scholarly journals The Structure and Optimal Gear Tooth Profile Design of Two-Speed Transmission for Electric Vehicles

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3736
Author(s):  
Jae-Oh Han ◽  
Won-Hyeong Jeong ◽  
Jong-Seok Lee ◽  
Se-Hoon Oh
Keyword(s):  
Electric Vehicle ◽  
Electric Vehicles ◽  
Automobile Industry ◽  
Bending Strength ◽  
Gear Tooth ◽  
Planetary Gear ◽  
Maximum Speed ◽  
Compact Structure ◽  
Simple Method ◽  
Paris Climate Agreement

As environmental regulations have been strengthened worldwide since the Paris Climate Agreement, the automobile industry is shifting its production paradigm to focus on eco-friendly vehicles such as electric vehicles and hydrogen-battery vehicles. Governments are banning fossil fuel vehicles by law and expanding the introduction of green vehicles. The energy efficiency of electric vehicles that use a limited power source called batteries depends on the driving environment. Applying a two-speed transmission to an electric vehicle can optimize average speed and performance efficiency at low speeds, and achieve maximum speed with minimal torque at high speeds. In this study, a two-speed transmission for an electric vehicle has been developed, to be used in a compact electric vehicle. This utilizes a planetary gear of a total of three pairs, made of a single module which was intended to enable two-speed. The ring gear was removed, and the carrier was used in common. When shifting, the energy used for the speed change is small, due to the use of the simple method of fixing the sun gear of each stage. Each gear was designed by calculating bending strength and surface durability, using JGMA standards, to secure stability. The safety factor of the gears used in the transmission is as follows: all gears have been verified for safety with a bending strength of 1.2 or higher and a surface pressure strength of 1.1 or higher. The design validity of the transmission was verified by calculating the gear meshing ratio and the reference efficiency of the gear. The transmission to be developed through the research results of this paper has a simple and compact structure optimized for electric vehicles, and has reduced shift shock. In addition, energy can be used more efficiently, which will help improve fuel economy and increase drive range.

Investigation of Noise Features of Planetary Gear Trains Based on Human Aural Characteristic

2017 ◽  
Author(s):  
Masao Nakagawa ◽  
Dai Nishida ◽  
Deepak Sah ◽  
Toshiki Hirogaki ◽  
Eiichi Aoyama
Keyword(s):  
Gear Tooth ◽  
Structural Complexity ◽  
Planetary Gear ◽  
Transmission Error ◽  
Sound Level ◽  
Tooth Surface ◽  
Surface Error ◽  
Planetary Gear Trains ◽  
Tooth Stiffness ◽  
Gear Trains

Planetary gear trains (PGTs) are widely used in various machines owing to their many advantages. However, they suffer from problems of noise and vibration due to the structural complexity and giving rise to substantial noise, vibration, and harshness with respect to both structures and human users. In this report, the sound level from PGTs is measured in an anechoic chamber based on human aural characteristic, and basic features of sound are investigated. Gear noise is generated by the vibration force due to varying gear tooth stiffness and the vibration force due to tooth surface error, or transmission error (TE). Dynamic TE is considered to be increased because of internal and external meshing. The vibration force due to tooth surface error can be ignored owing to almost perfect tooth surface. A vibration force due to varying tooth stiffness could be a major factor.

scholarly journals Planetary Gearbox Dynamic Modeling Considering Bearing Clearance and Sun Gear Tooth Crack

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2638
Author(s):  
Xianhua Chen ◽  
Xingkai Yang ◽  
Ming J. Zuo ◽  
Zhigang Tian
Keyword(s):  
Dynamic Model ◽  
Dynamic Modeling ◽  
Failure Modes ◽  
Gear Tooth ◽  
Working Environment ◽  
The Sun ◽  
Planetary Gearbox ◽  
Bearing Clearance ◽  
Vibration Responses ◽  
Planet Gear

Planetary gearbox systems are critical mechanical components in heavy machinery such as wind turbines. They may suffer from various failure modes, due to the harsh working environment. Dynamic modeling is a useful method to support early fault detection for enhancing reliability and reducing maintenance costs. However, reported studies have not considered the sun gear tooth crack and bearing clearance simultaneously to analyze their combined effect on vibration characteristics of planetary gearboxes. In this paper, a dynamic model is developed for planetary gearboxes considering the clearance of planet gear, sun gear, and carrier bearings, as well as sun gear tooth crack levels. Bearing forces are calculated considering bearing clearance, and the dynamic model equations are updated accordingly. The results reveal that the combination of bearing clearances can affect the vibration response with sun gear tooth crack by increasing the kurtosis. It is found that the effect of planet gear bearing clearance is very small, while the sun gear and carrier bearing clearance has clear impact on the vibration responses. These findings suggest that the incorporation of bearing clearance is important for planetary gearbox dynamic modeling.

The Research of Calculation Method on Vertical Natural Frequency of the New Full-Prefabricated Floor

2016 ◽  
Vol 846 ◽  
pp. 506-511
Author(s):  
Chong Fang Sun ◽  
Shu Ting Liang ◽  
Xiao Jun Zhu
Keyword(s):  
Numerical Simulation ◽  
Natural Frequency ◽  
Calculation Method ◽  
Variable Stiffness ◽  
Series Method ◽  
Numerical Simulation Result ◽  
Stiffness Method ◽  
Calculation Results ◽  
New Type ◽  
Test Result

New-type floor is composed of three kinds of slabs joined together through fittings. It is a kind of anisotropic two-way slab. In order to study the calculation method of natural frequency, series method, variable thickness method and variable stiffness method are adopted to calculate the natural frequency. The calculation results of three methods are compared with test result and numerical simulation result. The conclusion is that the calculation result of the variable stiffness method is the closest to the real natural frequency of new-type floor.

scholarly journals Design of a Mechanical Power Circulation Test Rig for a Wind Turbine Gearbox

2020 ◽  
Vol 10 (9) ◽  
pp. 3240
Author(s):  
Geun-Ho Lee ◽  
Young-Jun Park ◽  
Ju-Seok Nam ◽  
Joo-Young Oh ◽  
Jeong-Gil Kim
Keyword(s):  
Control System ◽  
Wind Turbine ◽  
Mechanical Power ◽  
Hydraulic Control ◽  
Test Rig ◽  
Wind Turbine Gearbox ◽  
Planetary Gearbox ◽  
Bearing Life ◽  
And Control ◽  
Hydraulic Control System

We developed a mechanical power circulation test rig for a wind turbine gearbox with a power rating of 5.8 MW or less. The test rig consists of an electric motor, two auxiliary gearboxes, a torque-applying device, lubrication systems, cooling systems, and control systems. The torque generating device consists of a planetary gearbox and a hydraulic control system and is used to apply the desired torque to the test gearbox. The hydraulic control system applies the torque on the ring gear of the planetary gearbox. The gears and bearings of the two auxiliary gearboxes and planetary gearboxes met the design criteria for a safety factor of over 1.2 and a bearing life of 30,000 h. In addition, the master and slave gearboxes were connected to the test rig to verify whether the torque-applying device had applied variable torque in real-time during the test. The device was only able to induce a variable torque of up to 45.2 kN-m due to the limitation of the rated torque of the master and slave gearboxes. The test rig can test not only efficiency, vibration, and noise but also durability and overloading.

scholarly journals Examination of combined ferry on the dynamic work

2019 ◽  
Vol 265 ◽  
pp. 02008
Author(s):  
Dmitry Tryapkin ◽  
Yuriy Tryapitsin
Keyword(s):  
Dynamic Characteristics ◽  
Dynamic Coefficient ◽  
Test Results ◽  
Dynamic Work ◽  
Calculation Results

The results of the dynamic characteristics experiments and calculation of combined crossing dynamic coefficient are given. The experiments were carried out by temporal automobile load with using measuring rated complex. Agreement of calculation results and test results is obtained.

scholarly journals Analytical study of floating effects on load sharing characteristics of planetary gearbox for off-road vehicle

2020 ◽  
Vol 12 (7) ◽  
pp. 168781402094046
Author(s):  
Woo-Jin Chung ◽  
Joo-Seon Oh ◽  
Hyun-Woo Han ◽  
Ji-Tae Kim ◽  
Young-Jun Park
Keyword(s):  
Safety Factor ◽  
Planetary Gear ◽  
Load Sharing ◽  
Position Error ◽  
System Level ◽  
Load Factor ◽  
Road Vehicle ◽  
Design Modification ◽  
Planetary Gearbox ◽  
Position Errors

Uneven load sharing of a planetary gear set is the main cause of preventing the miniaturization and weight reduction of a planetary gearbox. Non-torque loads and carrier pinhole position errors are the main factors that worsen the load-sharing characteristics. However, their effects are seldom analyzed at a system level especially for an off-road vehicle. To make up this gap, some simulation models are proposed to investigate the effects of floating members on the load-sharing characteristics and the strength of a planetary gear set with non-torque load and carrier pinhole position error. When the error is not considered, the mesh load factor converges to unity irrespective of the type and number of floating members and the safety factors for pitting and bending are increased slightly. When the carrier pinhole position error is considered, the mesh load factor dramatically worsens. Although it is improved using the floating members, it does not converge to unity. However, the bending safety factor of the planet gear with the error is increased by 26%. This indicates that the design modification for the original planetary gearbox is needed to satisfy the safety factor requirement, but the problem is solved using only floating members.

Design and Test of Differential Planetary Gear System for Open Rotor Power Gearbox

2013 ◽  
Author(s):  
Hideyuki Imai ◽  
Tatsuhiko Goi ◽  
Kenichi Kijima ◽  
Tooru Nishida ◽  
Hidenori Arisawa ◽  
...  
Keyword(s):  
Performance Test ◽  
High Efficiency ◽  
High Reliability ◽  
Gear Tooth ◽  
Planetary Gear ◽  
Design Concept ◽  
Gear System ◽  
Open Rotor ◽  
Planetary Gear System ◽  
Validation Tests

The open rotor engine is a next generation aero-engine that satisfies the demand for high fuel efficiency and low CO2 emission. A differential planetary gear system is incorporated in the open rotor engine to connect the turbine output shaft and fan rotors in order to counter-rotate the fan rotors as well as allow the turbine and fan rotors to operate at more efficient speeds. The open rotor gear system is required to have not only 20,000 hp high power transmission, but also an increasingly high efficiency, high reliability and light weight. To achieve these requirements, the following design works were conducted; (1) a low misalignment and lightweight carrier, (2) a flexible structure to absorb the displacement caused by the flight load, (3) an optimum gear tooth modification and (4) reduction of oil churning and windage losses. Also, extensive analyses and simulations such as lube oil flow CFD, FEA and tooth contact analysis were conducted. A full scale prototype gear system was manufactured and validation tests were conducted using a newly constructed test rig to validate the design concept. A slow roll test, rated performance test and efficiency test were conducted. And the design concept was found to be valid. This paper describes details of the prototype design and the results of the validation tests.

Sign in / Sign up

Export Citation Format

Share Document