Analytical/Computational Investigation of Planetary Gear Dynamics in Rotorcraft Transmissions

2008 ◽  
Author(s):  
Robert Parker
Keyword(s):  
Planetary Gear ◽  
Computational Investigation ◽  
Gear Dynamics

A Review of Planetary and Epicyclic Gear Dynamics and Vibrations Research

2014 ◽  
Vol 66 (4) ◽  
Author(s):  
Christopher G. Cooley ◽  
Robert G. Parker
Keyword(s):  
Planetary Gear ◽  
Tooth Surface ◽  
Journal Articles ◽  
Mesh Stiffness ◽  
Gear Dynamics ◽  
The Past ◽  
Epicyclic Gear ◽  
Wide Range ◽  
Gyroscopic Effects ◽  
Dynamics And Vibration

This article summarizes published journal articles on planetary and epicyclic gear dynamics and vibration. Research in this field has increased dramatically over the past two decades. The wide range of research topics demonstrates the technical challenges of understanding and predicting planetary gear dynamics and vibration. The research in this review includes mathematical models, vibration mode properties, dynamic response predictions including nonlinearities and time-varying mesh stiffness fluctuations, the effects of elastic compliance, and gyroscopic effects, among other topics. Practical aspects are also included, for example, planet load sharing, planet phasing, tooth surface modifications, and characteristics of measured vibration response.

Suppression of Planet Mode Response in Planetary Gear Dynamics Through Mesh Phasing

2005 ◽  
Vol 128 (2) ◽  
pp. 133-142 ◽  
Author(s):  
Vijaya Kumar Ambarisha ◽  
Robert G. Parker
Keyword(s):  
Gear Tooth ◽  
Planetary Gear ◽  
Rotational Degree ◽  
Dynamic Simulations ◽  
Gear Dynamics ◽  
Lumped Parameter ◽  
Bearing Stiffness ◽  
Gear Systems ◽  
Mesh Phasing ◽  
Mode Response

This work analytically derives design rules to suppress certain harmonics of planet mode response in planetary gear dynamics through mesh phasing. Planet modes are one of three categories of planetary gear vibration modes. In these modes, only the plantes deflect while the carrier, ring, and sun gears have no motion (Lin, J., and Parker, R. G., 1999, ASME J. Vib. Acoust., 121, pp. 316–321;J. Sound Vib, 233(5), pp. 921–928). The dynamic mesh forces are not explicitly modeled for this study; instead, the symmetry of planetary gear systems and gear tooth mesh periodicity are sufficient to establish rules to suppress planet modes. Thus, the conclusions are independent of the mesh modeling details. Planetary gear systems with equally spaced planets and with diametrically opposed planet pairs are examined. Suppression of degenerate mode response in purely rotational degree-of-freedom models achieved in the limit of infinite bearing stiffness is also investigated. The mesh phasing conclusions are verified by dynamic simulations of various planetary gears using a lumped-parameter analytical model and by comparisons to others’ research.

scholarly journals Mathematical Modeling and Dynamic Analysis of Planetary Gears System with Time-Varying Parameters

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Zhengming Xiao ◽  
Jinxin Cao ◽  
Yinxin Yu
Keyword(s):  
Gear Tooth ◽  
Planetary Gear ◽  
Time Varying ◽  
Tooth Root ◽  
Planetary Gears ◽  
Varying Parameters ◽  
Gear Dynamics ◽  
Gear Mesh ◽  
Time Varying Parameters ◽  
Root Crack

Planetary gears are widely used in automobiles, helicopters, heavy machinery, etc., due to the high speed reductions in compact spaces; however, the gear fault and early damage induced by the vibration of planetary gears remains a key concern. The time-varying parameters have a vital influence on dynamic performance and reliability of the gearbox. An analytical model is proposed to investigate the effect of gear tooth crack on the gear mesh stiffness, and then the dynamical model of the planetary gears with time-varying parameters is established. The natural characteristics of the transmission system are calculated, and the dynamic responses of transmission components, as well as dynamic meshing force of each pair of gear are investigated based on varying internal excitations induced by time-varying parameters and tooth root crack. The effects of gear tooth root crack size on the planetary gear dynamics are simulated, and the mapping rules between damage degree and gear dynamics are revealed. In order to verify the theoretical model and simulation results, the planetary gear test rig was built by assembling faulty and healthy gear separately. The failure mechanism and dynamic characteristics of the planetary gears with tooth root crack are clarified by comparing the analytical results and experimental data.

Helicopter main reduction planetary gear fault diagnosis method based on SVDD

2020 ◽  
Vol 64 (1-4) ◽  
pp. 137-145
Author(s):  
Yubin Xia ◽  
Dakai Liang ◽  
Guo Zheng ◽  
Jingling Wang ◽  
Jie Zeng
Keyword(s):  
Fault Diagnosis ◽  
Planetary Gear ◽  
Gaussian Kernel ◽  
Support Vector ◽  
Support Vector Data Description ◽  
Vector Data ◽  
Energy Characteristics ◽  
Gear Fault ◽  
Channel Information ◽  
Diagnosis Method

Aiming at the irregularity of the fault characteristics of the helicopter main reducer planetary gear, a fault diagnosis method based on support vector data description (SVDD) is proposed. The working condition of the helicopter is complex and changeable, and the fault characteristics of the planetary gear also show irregularity with the change of working conditions. It is impossible to diagnose the fault by the regularity of a single fault feature; so a method of SVDD based on Gaussian kernel function is used. By connecting the energy characteristics and fault characteristics of the helicopter main reducer running state signal and performing vector quantization, the planetary gear of the helicopter main reducer is characterized, and simultaneously couple the multi-channel information, which can accurately characterize the operational state of the planetary gear’s state.

COMPUTATIONAL INVESTIGATION OF DIMPLE EFFECTS ON HEAT TRANSFER AND FRICTION FACTOR IN A LAMILLOY COOLING STRUCTURE

2015 ◽  
Vol 22 (2) ◽  
pp. 147-175 ◽  
Author(s):  
Lei Luo ◽  
Chenglong Wang ◽  
Lei Wang ◽  
Bengt Sunden ◽  
Songtao Wang
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Computational Investigation

In silico ADME, Bioactivity and Toxicity Parameters Calculation of Some Selected Anti-Tubercular Drugs

2016 ◽  
Vol 6 (6) ◽  
pp. 77 ◽  
Author(s):  
Shashank Shekhar Mishra ◽  
Chandra Shekhar Sharma ◽  
Hemendra Pratap Singh ◽  
Harshda Pandiya ◽  
Neeraj Kumar
Keyword(s):  
Antibiotic Resistance ◽  
In Silico ◽  
Bacillus Calmette Guerin ◽  
Computational Investigation ◽  
Pharmacological Profile ◽  
In Silico Toxicity ◽  
Is Development ◽  
Potent Drug ◽  
Minimal Resistance ◽  
Parameters Calculation

Tuberculosis, one of the most frequent infectious diseases, is caused by a mycobacterium tuberculosis bacteria and it infects several hundred million people each year, results in several million deaths annually. Because there is development of antibiotic resistance, the disease becomes incurable. So, in the absence of effective and potent drug with minimal resistance problems, the mortality rate increases annually. In this computational investigation, we performed In-silico ADME, bioactivity and toxicity parameters calculation of some selected anti-tuberculosis agents. To design a new molecule having good pharmacological profile, this study will provide the lead information.Key Words: Tuberculosis (TB), Bacillus Calmette-Guerin vaccine, TPSA, In Silico toxicity

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