Effect of Contact Ratio on Spur Gear Dynamic Load With No Tooth Profile Modifications

1996 ◽  
Vol 118 (3) ◽  
pp. 439-443 ◽  
Author(s):  
Chuen-Huei Liou ◽  
Hsiang Hsi Lin ◽  
F. B. Oswald ◽  
D. P. Townsend
Keyword(s):  
Dynamic Load ◽  
Spur Gear ◽  
Tooth Size ◽  
Contact Ratio ◽  
Gear Dynamics ◽  
Wide Range ◽  
Gear Contact ◽  
Center Distance ◽  
Selection Of ◽  
Better Than

This paper presents a computer simulation showing how the gear contact ratio affects the dynamic load on a spur gear transmission. The contact ratio can be affected by the tooth addendum, the pressure angle, the tooth size (diametral pitch), and the center distance. The analysis presented in this paper was performed by using the NASA gear dynamics code DANST. In the analysis, the contact ratio was varied over the range 1.20 to 2.40 by changing the length of the tooth addendum. In order to simplify the analysis, other parameters related to contact ratio were held constant. The contact ratio was found to have a significant influence on gear dynamics. Over a wide range of operating speeds, a contact ratio close to 2.0 minimized dynamic load. For low-contact-ratio gears (contact ratio less than two), increasing the contact ratio reduced gear dynamic load. For high-contact-ratio gears (contact ratio equal to or greater than 2.0), the selection of contact ratio should take into consideration the intended operating speeds. In general, high-contact-ratio gears minimized dynamic load better than low-contact-ratio gears.

scholarly journals Effect of Contact Ratio on Spur Gear Dynamic Load

1992 ◽  
Author(s):  
Chuen-Huei Liou ◽  
Hsiang Hsi Lin ◽  
Fred B. Oswald ◽  
Dennis P. Townsend
Keyword(s):  
Dynamic Load ◽  
Spur Gear ◽  
Tooth Size ◽  
Contact Ratio ◽  
Gear Dynamics ◽  
Wide Range ◽  
Gear Contact ◽  
Center Distance ◽  
Selection Of ◽  
Better Than

Abstract This paper presents a computer simulation showing how the gear contact ratio affects the dynamic load on a spur gear transmission. The contact ratio can be affected by the tooth addendum, the pressure angle, the tooth size (diametral pitch), and the center distance. The analysis presented in this paper was performed by using the NASA gear dynamics code DANST. In the analysis the contact ratio was varied over the range 1.20 to 2.40 by changing the length of the tooth addendum. In order to simplify the analysis, other parameters related to contact ratio were held constant. The contact ratio was found to have a significant influence on gear dynamics. Over a wide range of operating speeds a contact ratio close to 2.0 minimized dynamic load. For low-contact-ratio gears (contact ratio less than 2.0), increasing the contact ratio reduced the gear dynamic load. For high-contact-ratio gears (contact ratio equal to or greater than 2.0), the selection of contact ratio should take into consideration the intended operating speeds. In general, high-contact-ratio gears minimized dynamic load better than low-contact-ratio gears.

scholarly journals Optimal Tooth Numbers for Compact Standard Spur Gear Sets

1982 ◽  
Vol 104 (4) ◽  
pp. 749-757 ◽  
Author(s):  
M. Savage ◽  
J. J. Coy ◽  
D. P. Townsend
Keyword(s):  
Optimal Design ◽  
Objective Function ◽  
Design Space ◽  
Spur Gear ◽  
Gear Ratio ◽  
Contact Ratio ◽  
Bending Fatigue ◽  
Gear Mesh ◽  
Compact Design ◽  
Center Distance

The design of a standard gear mesh is treated with the objective of minimizing the gear size for a given ratio, pinion torque, and allowable tooth strength. Scoring, pitting fatigue, bending fatigue, and the kinematic limits of contact ratio and interference are considered. A design space is defined in terms of the number of teeth on the pinion and the diametral pitch. This space is then combined with the objective function of minimum center distance to obtain an optimal design region. This region defines the number of pinion teeth for the most compact design. The number is a function of the gear ratio only. A design example illustrating this procedure is also given.

Dynamic Load Capabilities of Active Electromagnetic Bearings

1991 ◽  
Vol 113 (3) ◽  
pp. 598-603 ◽  
Author(s):  
K. R. Bornstein
Keyword(s):  
Dynamic Load ◽  
Load Capacity ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Saturation Point ◽  
Dynamic Capacity ◽  
Static Capacity ◽  
Wide Range ◽  
Selection Of

Magnetic bearings are finding increasing use in a wide range of applications. It is well known that the static capacity of a bearing can be determined by its saturation point. The static capacity has often been the prime criterion for the selection of magnetic bearing size. The dynamic capacity of a bearing is a much more complicated function. This paper will develop equations to express the dynamic load capacity of a magnetic bearing in terms of its amplifier size, the frequency of excitation, the magnetic airgap, the method of force actuation, and certain nondimensional terms.

Effect of Involute Contact Ratio on Spur Gear Dynamics

1999 ◽  
Vol 121 (1) ◽  
pp. 112-118 ◽  
Author(s):  
A. Kahraman ◽  
G. W. Blankenship
Keyword(s):  
Transmission Error ◽  
Spur Gear ◽  
Design Guidelines ◽  
Forced Response ◽  
Contact Ratio ◽  
Test Rig ◽  
Response Curves ◽  
Gear Mesh ◽  
Dynamic Transmission Error ◽  
Selection Of

The influence of involute contact ratio on the torsional vibration behavior of a spur gear pair is investigated experimentally by measuring the dynamic transmission error of several gear pairs using a specially designed gear test rig. Measured forced response curves are presented, and harmonic amplitudes of dynamic transmission error are compared above and below gear mesh resonances for both unmodified and modified gears having various involute contact ratio values. The influence of involute contact ratio on dynamic transmission error is quantified and a set of generalized, experimentally validated design guidelines for the proper selection of involute contact ratio to achieve quite gear systems is presented. A simplified analytical model is also proposed which accurately describes the effects of involute contact ratio on dynamic transmission error.

Probabilistic Optimum Design of Compact Spur Gear Sets

1995 ◽  
Author(s):  
Chinyere Onwubiko ◽  
Landon Onyebueke ◽  
Feng C. Chen
Keyword(s):  
Optimum Design ◽  
Material Properties ◽  
Probabilistic Method ◽  
Spur Gear ◽  
Optimization Techniques ◽  
Design Parameters ◽  
Deterministic Method ◽  
Wide Range ◽  
Comparison Of The Results ◽  
Center Distance

Abstract Several methods have been proposed in the past for optimum design of spur gears. These methods have utilized deterministic design optimization techniques to obtain what could be considered satisfactory design parameters. At least two problems arise with the results of the deterministic approach; the inability to deal with uncertainties in material properties and over conservative design. On the other hand, probabilistic analysis methodology seeks to account for the uncertainties in material properties, loading conditions and disparate failure models. This paper discusses the application of probabilistic design methodology to the design of compact gear set. This is done by minimizing the gear center distance while constrained by the allowable surface pressure and bending stress. A comparison of the results of compact gear design using both deterministic and probabilistic methodologies is presented. The results indicate that deterministic method though satisfactory does not provide the designer enough information to make vast design decisions. The deterministic method provides only one value of the center distance while the probabilistic method provides the designer a range of choices. In fact, a designer is provided a wide range of design options depending on a desired level of reliability.

scholarly journals A New Analytical Method for Modeling the Effect of Assembly Errors on a Motor-Gearbox System

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4993
Author(s):  
Bilal El El Yousfi ◽  
Abdenour Soualhi ◽  
Kamal Medjaher ◽  
François Guillet
Keyword(s):  
Gear Tooth ◽  
Induction Machine ◽  
Spur Gear ◽  
Detection Algorithm ◽  
System Response ◽  
Contact Ratio ◽  
Contact Points ◽  
System Vibration ◽  
Potential Energy Method ◽  
Center Distance

The well-known gear tooth defects such as root cracks and flank spalls have been widely investigated in previous studies to model their effects on the time varying mesh stiffness (TVMS) and consequently the dynamic response of motor-gearbox systems. Nevertheless, the effect of assembly errors such as the center distance and the eccentricity has been less considered in past works. Determining the signature of these errors on the system response can help for their early detection and diagnostic to avoid overloading and failure of gears. An original geometric-based method combined with the potential energy method is proposed in this paper to accurately model the effect of these assembly errors on the TVMS of mating spur gear pairs. This is achieved by updating the line of action equation (LOA) at each meshing step using the actual coordinates of gear centers and employing a contact detection algorithm (CDA) to determine the actual contact points coordinates. An electrical model of a three-phase induction machine was then coupled with a dynamic model of a one-stage spur gear system to simulate the effect of assembly errors on the electromechanical response of the motor-gearbox system. The simulation results showed that the center distance error induces a reduction in the TVMS magnitude and the contact ratio, whereas the eccentricity error causes a double modulation of the TVMS magnitude and frequency. In addition, the results showed that assembly errors can be detected and diagnosed by analyzing the system vibration and the motor phase-current.

scholarly journals Comparison of Analysis and Experiment for Dynamics of Low-Contact-Ratio Spur Gears

1991 ◽  
Author(s):  
Fred B. Oswald ◽  
Brian Rebbechi ◽  
James J. Zakrajsek ◽  
Dennis P. Townsend ◽  
Hsiang Hsi Lin
Keyword(s):  
Dynamic Load ◽  
High Speed ◽  
Design Tool ◽  
Operating Conditions ◽  
Average Error ◽  
Spur Gears ◽  
Tooth Root ◽  
Bending Stress ◽  
Contact Ratio ◽  
Gear Dynamics

Abstract Low-contact-ratio spur gears were tested in the NASA gear-noise rig to study gear dynamics including dynamic load, tooth bending stress, vibration, and noise. The experimental results were compared with a NASA gear dynamics code to validate the code as a design tool for predicting transmission vibration and noise. Analytical predictions and experimental data for gear-tooth dynamic loads and tooth-root bending stress were compared at 28 operating conditions. Strain gage data were used to compute the normal load between meshing teeth and the bending stress at the tooth root for direct comparison with the analysis. The computed and measured waveforms for dynamic load and stress were compared for several test conditions. These are very similar in shape, which means the analysis successfully simulates the physical behavior of the test gears. The predicted peak value of the dynamic load agrees with the measurement results within an average error of 4.9 percent except at low-torque, high-speed conditions. Predictions of peak dynamic root stress are generally within 10 to 15 percent of the measured values.

Dynamic Analysis of High-Contact-Ratio Spur Gears With Asymmetric Teeth

2008 ◽  
Author(s):  
F. Karpat ◽  
S. Ekwaro-Osire
Keyword(s):  
Numerical Technique ◽  
Spur Gear ◽  
Dynamic Loads ◽  
Spur Gears ◽  
Load Carrying Capacity ◽  
Contact Ratio ◽  
Mesh Stiffness ◽  
Gear Teeth ◽  
Load Carrying ◽  
Gear Contact

In this research, a numerical technique is used to study the performance of high-contact-ratio (HCR) spur gears with asymmetric teeth. Asymmetric teeth have been shown to minimize dynamic loads and to increase the load carrying capacity. This is due to the fact that these teeth have a larger pressure angle on the drive side compared to the coast side. In literature, symmetric gear teeth with HCR have been shown to also yield low dynamic loads and high load capacities. HCR gears have these positive attributes because for gears in a mesh, the number of tooth pairs sharing the transmitted load alternates between two and three. In this study, the separate benefits of an HCR gear and asymmetric teeth are unified into a spur gear with asymmetric teeth. In this case, the effect of the gear contact ratio, addendum factor, mesh stiffness, pressure angles, and operation speeds on dynamic tooth loads are considered. The influences of these parameters on dynamic response are presented and discussed. A comparison between standard and non standard gear pairs in literature is also presented, with respect to dynamic tooth loads. Sample simulation results, which were obtained by using an in-house computer program, are discussed. The results obtained are shown to match well with some related analytical and experimental results in literature. It is further demonstrated that HCR spur gears with asymmetric teeth do provide a marked advantage compared to the conventional spur gears with symmetric teeth.

Dynamic Load Factors in Internal Spur Gear Drives

1985 ◽  
Vol 107 (3) ◽  
pp. 424-429 ◽  
Author(s):  
A. Pintz ◽  
R. Kasuba
Keyword(s):  
Dynamic Load ◽  
Dynamic Performance ◽  
Spur Gear ◽  
Contact Ratio ◽  
Gear Mesh ◽  
Load Factors ◽  
Parametric Studies ◽  
Computer Based ◽  
Gear Drives ◽  
Very High

A comprehensive computer-based methodology was developed exclusively for the static and dynamic load analysis of internal spur gear (ISG) drives. An iterative procedure was applied to solve the statically indeterminate problem of multitooth pair contacts, load sharing, and operational contact ratios as influenced by both the gear mesh and the radial deflections of components. This methodology can be applied to involute and noninvolute spur gearing as well as to the very high contact ratio gearing. The performd parametric studies indicate that internal spur gear drives have considerably better dynamic performance (lower dynamic load factors) over equivalent external spur gear drives. Much of this improvement is due to the inherently higher contact ratios in the ISG drives.

scholarly journals Efficiency of Nonstandard and High Contact Ratio Involute Spur Gears

1986 ◽  
Vol 108 (1) ◽  
pp. 119-126 ◽  
Author(s):  
N. E. Anderson ◽  
S. H. Loewenthal
Keyword(s):  
Prediction Method ◽  
Spur Gears ◽  
Contact Ratio ◽  
Oil Viscosity ◽  
Proper Selection ◽  
Face Width ◽  
Loss Prediction ◽  
Gear Geometry ◽  
Center Distance ◽  
Selection Of

A power loss prediction method previously developed by the authors was extended to include involute spur gears of nonstandard proportions. The method can now be used to analyze the effects of modified addendum, tooth thickness, and gear center distance in addition to the parameters previously considered which included gear diameter, pitch, pressure angle, face width, oil viscosity, speed, and torque. Particular emphasis is placed on high contact ratio gearing (contact ratios greater than two). Despite their higher sliding velocities, high contact ratio gears can be designed to levels of efficiency approaching those of conventional gears while retaining their advantages through proper selection of gear geometry.

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