Dynamic Features of Gear System With Tooth Crack and Tooth Surface Sliding due to Speed Variation

2012 ◽  
Author(s):  
Liming Wang ◽  
Zaigang Chen ◽  
Yimin Shao ◽  
Xi Wang
Keyword(s):  
Degrees Of Freedom ◽  
Surface Friction ◽  
Element Model ◽  
Spur Gear ◽  
Gear System ◽  
Tooth Surface ◽  
Dynamic Features ◽  
Mesh Stiffness ◽  
Speed Variation ◽  
Gear Mesh

It was found that the vibration features resulted from tooth crack and sliding on the contact interfaces due to speed variation are very similar with each other, which is difficult to distinguish. So, it is meaningful to study whether they are the same or not. Firstly, a finite element model of a spur gear pair in mesh with tooth crack at pitch circle is established to calculate the effect of tooth crack on gear mesh stiffness. Then, combined with the tooth crack through mesh stiffness, a spur gear dynamic model with six degrees of freedom (dof) is developed to extract the dynamic features affected by the tooth crack. The tooth surface friction due to different relative velocity is also involved to study its effects on the dynamic characteristics of the gear system. Finally, comparisons are made between the dynamic features of the gear system with tooth crack and the tooth surface sliding to expose their effects to supply some theoretical guidance on fault detection.

scholarly journals The Influences of Gradual Wears and Bearing Clearance of Gear Transmission on Dynamic Responses

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4731
Author(s):  
Ruiliang Zhang ◽  
Kaida Wang ◽  
Yandong Shi ◽  
Xiuquan Sun ◽  
Fengshou Gu ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Coupled Model ◽  
Nonlinear Dynamic System ◽  
Gear System ◽  
Dynamic Responses ◽  
Tooth Surface ◽  
Wear Depth ◽  
Mesh Stiffness ◽  
Gear Mesh ◽  
Bearing Clearance

Gears are important components of the transmission system. Tooth wear and bearing clearance are significant factors affecting the dynamics of the gear system. In order to reveal the effects of gradual wears and bearing clearance on the gear system dynamics, a six-degrees-of-freedom bending-torsion coupled model of gear-rotor-bearing which considers surface wear, bearing clearance and backlash is established. The Rung-Kutta method is used to solve the nonlinear dynamic system, and the dynamic responses of the system are obtained. The results show that the time-varying mesh stiffness decreases with the tooth surface from the unworn phase to severe wear phase. At the same time, the change of the mesh stiffness in the double-tooth mesh area and single-tooth area are different. Moreover, the amplitude of the X-displacement, Y-displacement and relative gear mesh displacement will be enlarged slightly with the increase of wear depth or bearing clearance. By analyzing variation tendency in the frequency domain, the different order harmonics show the different change characteristic with the variation of the wear phases or bearing clearances. This study provides a theoretical basis for improving the transmission performance and the selection of the bearing clearances in the gear system.

An Estimate of Mesh Stiffness and Load Sharing Ratio of a Spur Gear Pair

1992 ◽  
Author(s):  
J. H. Kuang ◽  
Y. T. Yang
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Spur Gear ◽  
Mesh Stiffness ◽  
Gear Mesh ◽  
Stiffness Constant ◽  
Generating Method ◽  
Single Tooth ◽  
Tooth Stiffness ◽  
Involute Gears

Abstract A curve fitted tooth stiffness equation was developed to calculate directly the variable gear mesh stiffness. To improve the accuracy, a tooth profile generating method introduced by Litvin (1989) was employed for finite element idealization. A quadratic finite element model was employed in deriving the tooth stiffness constant at the successive positions of a single tooth as it passed through the zone of loading. The developed stiffness equation is applicable to both the standard full-depth or addendum modified involute gears. Variation of the shared loads introduced by the consideration of mesh stiffness was also investigated.

Mesh stiffness modeling considering actual tooth profile geometry for a spur gear pair

2018 ◽  
Vol 19 (3) ◽  
pp. 306 ◽  
Author(s):  
Yong Yang ◽  
Jiaxu Wang ◽  
Qinghua Zhou ◽  
Yanyan Huang ◽  
Jinxuan Zhu ◽  
...  
Keyword(s):  
Gear Tooth ◽  
Analytical Description ◽  
Element Model ◽  
Spur Gear ◽  
Tooth Profile ◽  
Mesh Stiffness ◽  
Gear Mesh ◽  
Proposed Model ◽  
Tooth Stiffness ◽  
Gear Mesh Stiffness

Some tooth profile geometric features, such as root fillet area, flank modification and wear are of nonnegligible importance for gear mesh stiffness. However, due to complexity of analytical description, their influence on mesh stiffness was always ignored by existing research works. The present work derives analytical formulations for time-varying gear mesh stiffness by using parametric equations of flank profile. Tooth geometry formulas based upon a rack-type tool are derived following Litvin's vector approach. The root fillet area and tooth profile deviations can therefore be fully considered for spur gear tooth stiffness evaluation. The influence of gear fillet determined by tip fillet radius of the rack-type tool is quantified parametrically. The proposed model is validated to be effective by comparing with a finite element model. Further, the model is applied to investigate the stiffness variations produced by tooth addendum modification, tooth profile nonuniform wear and modification.

Integrated Excitation Models of the Helical Gear System

2007 ◽  
Author(s):  
Takayuki Nishino
Keyword(s):  
Gear Tooth ◽  
Moving Load ◽  
Helical Gear ◽  
Gear System ◽  
Tooth Surface ◽  
Response Analysis ◽  
Mesh Stiffness ◽  
Gear Mesh ◽  
Face Width ◽  
Single Tooth

The vibration of the helical gear system is generated by three kinds of excitation. The first cause is a displacement excitation due to the tooth surface error. The second is a parametric excitation by the periodical change of the tooth mesh stiffness. The third is a moving load on the tooth surface during the progress of mesh of the teeth. In mesh of a pair of helical gears, the composite load of the distributed load along a contact line moves its operating location from one end of face width to the other end during the process of mesh progress. This moving load causes fluctuation of bearing load that excites the housing. Therefore, it is important to treat gear mesh excitation as a moving load problem. For this purpose, two kinds of mesh models, in which the three different types of excitations above are incorporated, are proposed. In the first model, a pair of gear tooth is represented by the multiple springs and the moving load can be taken into account by the multiple mesh excitation forces that have the phase differences from each other. The second one incorporates the excitation moment into the single tooth spring model. Then, response analysis is done for a simple gear-shaft model. As the result, the moving load causes vibration with non-coupled or independent modes between the drive and driven shaft. Thus, the effectiveness of the proposed method is established.

Quasi-static Study of Gear Mesh Stiffness of a Polymer-Metallic Spur Gear System

2021 ◽  
pp. 301-307
Author(s):  
Ala Eddin Chakroun ◽  
Chaima Hammami ◽  
Ahmed Hammami ◽  
Ana De-Juan ◽  
Fakher Chaari ◽  
...  
Keyword(s):  
Spur Gear ◽  
Gear System ◽  
Mesh Stiffness ◽  
Gear Mesh ◽  
Gear Mesh Stiffness

BIDIMENSIONAL FINITE ELEMENT ANALYSIS OF SPUR GEAR: STUDY OF THE MESH STIFFNESS AND STRESS AT THE LEVEL OF THE TOOTH FOOT

2009 ◽  
Vol 33 (2) ◽  
pp. 175-187 ◽  
Author(s):  
Mohamed Nizar Bettaieb ◽  
Mohamed Maatar ◽  
Chafik Karra
Keyword(s):  
Finite Element ◽  
Stress State ◽  
Spur Gear ◽  
Fortran Program ◽  
Mesh Stiffness ◽  
Element Analysis ◽  
Gear Mesh ◽  
Finite Element Software ◽  
Time Calculation ◽  
Finite Element Meshing

The purpose of this work is to determine the spur gear mesh stiffness and the stress state at the level of the tooth foot. This mesh stiffness is derived from the calculation of the normal tooth displacements: local displacement where the load is applied, tooth bending displacement and body displacement [15]. The contribution of this work consists in, basing on previous works, developing optimal finite elements model in time calculation and results precision. This model permits the calculation of time varying mesh stiffness and the evaluation of stress state at the tooth foot. For these reasons a specific Fortran program was developed. It permit firstly, to obtain the gear geometric parameters (base radii, outside diameter,…) and to generate the data base of the finite element meshing of a tooth or a gear. This program is interfaced with the COSMOS/M finite element software to predict the stress and strain state and calculate the mesh stiffness of a gear system. It is noted that the mesh stiffness is periodic and its period is equal to the mesh period.

Coupled Bending-Torsion Vibration of Geared Rotors

1995 ◽  
Author(s):  
J. S. Rao ◽  
J. R. Chang ◽  
T. N. Shiau
Keyword(s):  
Finite Element ◽  
Natural Frequencies ◽  
Element Model ◽  
Mode Shapes ◽  
Mesh Stiffness ◽  
Present Program ◽  
Gear Mesh ◽  
Pressure Angle ◽  
Torsion Vibration ◽  
Gear Mesh Stiffness

Abstract A general finite element model is presented for determining the coupled bending-torsion natural frequencies and mode shapes of geared rotors. Uncoupled bending and torsion frequencies are obtained for examples available in literature and the present program is verified against these. The effect of the gear box is considered to determine the coupled frequencies. Parameters studied include the pressure angle, gear mesh stiffness, and bearing properties. The gear pressure angle is shown to have no effect on the natural frequencies of rotors supported on isotropic bearing supports. Several case studies with bending-torsion coupling are considered and the results obtained are compared with those available in literature. The results of a general rotor system with 8lodes are also presented.

An Energy-Based Load Distribution Approach for the Application of Gear Mesh Stiffness on Elastic Bodies

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Faysal Andary ◽  
Joerg Berroth ◽  
Georg Jacobs
Keyword(s):  
Degrees Of Freedom ◽  
Design Method ◽  
Mesh Stiffness ◽  
Gear Teeth ◽  
Gear Mesh ◽  
Elastic Bodies ◽  
Single Tooth ◽  
Traditional Approaches ◽  
Energy Based Design ◽  
Gear Mesh Stiffness

This study introduces a new potential energy-based design method for simplifying elastic gear bodies in low- to mid-range frequency applications by bridging over the gear teeth with external stiffness elements. The advantage of the introduced method over more traditional approaches, which are either based on rigid gears or on replacing the teeth, is that the complex gear body and its dynamic behavior are preserved, albeit with fewer degrees of freedom. The method is demonstrated on a gear by replacing a single tooth under load and then validated numerically against a typical flexible gear model. The simulation results show good accuracy within the chosen frequency range and with a clear reduction in calculation time compared to the unreduced model. Furthermore, the extension and optimization potential of the results is discussed.

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