Influence of Linear Profile Modification and Loading Conditions on The Dynamic Tooth Load and Stress of High-Contact-Ratio Spur Gears

1991 ◽  
Vol 113 (4) ◽  
pp. 473-480 ◽  
Author(s):  
Chinwai Lee ◽  
Hsiang Hsi Lin ◽  
Fred B. Oswald ◽  
Dennis P. Townsend
Keyword(s):  
Computer Simulation ◽  
Contact Stress ◽  
Dynamic Load ◽  
Applied Load ◽  
Gear Tooth ◽  
Load Force ◽  
Loading Conditions ◽  
Contact Ratio ◽  
Profile Modification ◽  
Root Stress

This paper presents a computer simulation for the dynamic response of high-contact-ratio spur gear transmissions. High contact ratio gears have the potential to produce lower dynamic tooth loads and minimum root stress but they can be sensitive to tooth profile errors. The analysis presented in this paper examines various profile modifications under realistic loading conditions. The effect of these modifications on the dynamic load (force) between mating gear teeth and the dynamic root stress is presented. Since the contact stress is dependent on the dynamic load, minimizing dynamic loads will also minimize contact stresses. This paper shows that the combination of profile modification and the applied load (torque) carried by a gear system has a significant influence on gear dynamics. The ideal modification at one value of applied load will not be the best solution for a different load. High-contact-ratio gears were found to require less modification than standard low-contact-ratio gears. High-contact-ratio gears are more adversely affected by excess modification than by under modification. In addition, the optimal profile modification required to minimize the dynamic load (hence the contact stress) on a gear tooth differs from the optimal modification required to minimize the dynamic root (bending) stress. Computer simulation can help find the design tradeoffs to determine the best profile modification to satisfy the conflicting constraints of minimizing both the load and root stress in gears which must operate over a range of applied loads.

Tooth Load Sharing in High-Contact Ratio Spur Gears

1985 ◽  
Vol 107 (1) ◽  
pp. 11-16 ◽  
Author(s):  
A. H. Elkholy
Keyword(s):  
Contact Stress ◽  
Applied Load ◽  
Normal Load ◽  
Closed Form Solution ◽  
Load Sharing ◽  
Form Solution ◽  
Spur Gears ◽  
Contact Ratio ◽  
Profile Modification ◽  
The Individual

A closed-form solution is presented for calculating the load sharing among meshing teeth in high contact ratio gearing (HCRG). The procedure is based upon the assumption that the sum of the tooth deflection, profile modification and spacing error at each of two or three pairs of contacts are all equal. It is also assumed that the sum of the normal loads contributed by each of two or three pairs of contacts is equal to the maximum normal load. Once the individual loads are determined, the tooth fillet stress, contact stress may be determined from the applied load and tooth geometry. An experimental example appears to verify the method.

scholarly journals Computer-Aided Design of High-Contact-Ratio Gears for Minimum Dynamic Load and Stress

1993 ◽  
Vol 115 (1) ◽  
pp. 171-178 ◽  
Author(s):  
Hsiang Hsi Lin ◽  
Chinwai Lee ◽  
F. B. Oswald ◽  
D. P. Townsend
Keyword(s):  
Dynamic Load ◽  
Computer Aided Design ◽  
Numerical Procedure ◽  
Tooth Profile ◽  
Lower Sensitivity ◽  
Contact Ratio ◽  
Profile Modification ◽  
Parabolic Profile ◽  
Profile Design ◽  
Optimum Profile

This paper presents a numerical procedure for minimizing dynamic effects on high-contact-ratio gears by modification of the tooth profile. The paper examines and compares both linear and parabolic tooth profile modifications of high-contact-ratio gears under various loading conditions. The effects of the total amount of modification and the length of the modification zone were systematically studied at various loads and speeds to find the optimum profile design for minimizing the dynamic load and the tooth bending stress. Parabolic profile modification is preferred over linear profile modification for high-contact-ratio gears because of its lower sensitivity to manufacturing errors. For parabolic modification a greater amount of modification at the tooth tip and a longer modification zone are required. Design charts are presented for high-contact-ratio gears with various profile modifications operating under a range of loads. A procedure is illustrated for using the charts to find the optimum profile design.

The Combined Influence of Helix Angle and Total Contact Ratio on the p-FEM Calculated Tooth Root Stress in Cylindrical Gears

2000 ◽  
Author(s):  
Andrea Piazza ◽  
Maurizio Uberti
Keyword(s):  
Transverse Section ◽  
Helix Angle ◽  
Tooth Root ◽  
Finite Element Method Analysis ◽  
Contact Ratio ◽  
Profile Modification ◽  
Cylindrical Gears ◽  
Angle Correction ◽  
Method Analysis ◽  
Root Stress

Abstract Many parametrical studies about the effect of the helix angle on the maximum tooth root stress on cylindrical gears were conducted by means of a p-FEM (polynomial Finite Element Method) analysis, using models that comprehend all the contacting teeth and the adjacent ones. The studies were conducted in a way that the helix angle was varied from 0 to 35 degrees, keeping the transverse section constant (i.e. twisting the gears). Many non-HCR existing spur and helical gearsets, with different transverse contact ratio εα, transmission ratio, pressure angle, correction factor, and facewidth to module ratio were examined. Neither profile modification, nor crowning were considered. For each gearset the maximum p-FEM-calculated tooth root stress in both pinion and gear drops considerably when the total contact ratio εγ reaches the value of 2, with a minimum noticed around εγ = 2.1 ÷ 2.4; then the stress rises monotonically except for a non-remarkable drop when εγ reaches the value of 3. The p-FEM results were also compared with those based on ISO 6336-3 method B and AGMA 2001, showing noticeable differences.

Effect of Tooth Profile Modifications on the Dynamics of High-Contact-Ratio Gears With Different Tooth Spacing Errors

2006 ◽  
Author(s):  
Hsiang H. Lin ◽  
Jing Liu
Keyword(s):  
Computer Simulation ◽  
Dynamic Analysis ◽  
Dynamic Performance ◽  
Tooth Profile ◽  
Dynamic Loads ◽  
Contact Ratio ◽  
Gear Dynamics ◽  
Profile Modification ◽  
Tooth Profile Modification

A computer simulation was conducted to investigate the effectiveness of profile modification for reducing dynamic loads in high-contact-ratio gears with different tooth spacing errors. The simulation examined varying amplitudes of spacing error and differences in the span of teeth over which the error occurs. The modification considered included both linear and parabolic tip relief. The dynamic analysis was performed using a revised version of a NASA gear dynamics code, modified to take into consideration the tooth spacing errors in the dynamic analysis. The findings of this study can be used to design robust tooth profile modification for improving dynamic performance of high-contact-ratio gear sets with different tooth spacing errors.

Analysis of Spur Gear with Tooth Circular Discontinuity for Weight Reduction

2018 ◽  
Vol 17 (02) ◽  
pp. 249-265 ◽  
Author(s):  
R. Ravichandran ◽  
S. Neelakrishnan
Keyword(s):  
Internal Stress ◽  
Weight Reduction ◽  
Gear Tooth ◽  
Stress Relief ◽  
Spur Gear ◽  
Contact Ratio ◽  
Tangential Load ◽  
Single Tooth ◽  
Gear Drives ◽  
Root Stress

The design of gears and gear drives are becoming challenging in automobile applications in which low contact ratio gears are required to transmit higher loads and be lighter in weight. There are various methods available for optimizing the design. Some researches have been taken place in the areas of gear tooth profile modifications for providing internal stress relief and weight reduction. In most cases, the maximum loads are assumed to be acting on the tip of the tooth. In this study, investigations are carried out on the effect of circular discontinuity on the weight reduction without affecting the root stress. The maximum tangential load is applied on the highest point of single tooth contact. The results show that with the modified gear tooth having a combination of two circular discontinuities of size 0.4 times the module not only provides weight reduction but also gives stress relief at the root.

scholarly journals Contact Stresses and Bending stresses for Worm & Helical Gear

2019 ◽  
Vol 8 (4) ◽  
pp. 11326-11328
Keyword(s):  
Contact Stress ◽  
Applied Load ◽  
Gear Tooth ◽  
Helical Gear ◽  
Contact Stresses ◽  
Bending Stress ◽  
Surface Strength ◽  
Face Width ◽  
The Face ◽  
Bending Stresses

Surface Strength of the gear tooth depends on the contact stress and the bending stress caused due to the applied load on the tip of its gear tooth. Analysis has become popular in decreasing the failures. Fatigue causes in the root bending stress and Surface indentation causes in the contact stress. Then modified Lewis beam strength is used for bending stress and the AGMA method is used for contact stresses by varying the face width. Analytical results are based on Lewis formula and the theoretical values were calculated by AGMA standard so the results were validated.

Probabilistic Analysis of MEMS Asymmetric Gear Tooth

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Fatih Karpat ◽  
Stephen Ekwaro-Osire ◽  
Morshed P. H. Khandaker
Keyword(s):  
Gear Tooth ◽  
Load Capacity ◽  
Probability Of Failure ◽  
Mems Devices ◽  
Contact Ratio ◽  
Microelectromechanical System ◽  
Gear Teeth ◽  
Failure Theory ◽  
Gear Drives ◽  
Root Stress

Currently, there is an increased interest in the application of microelectromechanical system (MEMS) gear drives. Additionally, requirements for transmitted power and related reliability issues have increased. Reliability issues often occur due to uncertainties of material, geometry, and loading conditions of the MEMS gears. Asymmetric gear teeth are used to improve the performance of gears by increasing the load capacity or by reducing vibrations. In this paper, asymmetric gear teeth are proposed for MEMS applications. The objective of this research is to investigate the feasibility of applying asymmetric gears for MEMS devices while accounting for uncertainty. The Weibull failure theory was applied to four different MEMS gear configurations. The following analyses were carried out in this research: (i) for the calculation of root stress, four different asymmetric gears were used; (ii) for the calculation of the probability of failure, the Weibull failure theory formulization was used, and (iii) the efficacy of the various asymmetric tooth configurations was discussed. Specifically, the probability of failure of the asymmetric gear was extracted for various parameters. The parameters considered included pressure angle, tooth height, and contact ratio. The efficacy of using asymmetric gear teeth was shown in this study.

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.

Comparative study of stress analysis of gears with different helix angle using the ISO 6336 standard and tooth contact analysis methods

2016 ◽  
Vol 230 (7-8) ◽  
pp. 1350-1358 ◽  
Author(s):  
Layue Zhao ◽  
Robert C Frazer ◽  
Brian Shaw
Keyword(s):  
Stress Analysis ◽  
Contact Stress ◽  
Helix Angle ◽  
Contact Analysis ◽  
Bending Stress ◽  
Contact Ratio ◽  
Tooth Contact Analysis ◽  
Tooth Contact ◽  
Iso Standard ◽  
Analysis Methods

With increasing demand for high speed and high power density gear applications, the need to optimise gears for minimum stress, noise and vibration becomes increasingly important. ISO 6336 contact and bending stress analysis are used to determine the surface load capacity and tooth bending strength but dates back to 1956 and although it is constantly being updated, a review of its performance is sensible. Methods to optimise gear performance include the selection of helix angle and tooth depth to optimise overlap ratio and transverse contact ratio and thus the performance of ISO 6336 and tooth contact analysis methods requires confirmation. This paper reviews the contact and bending stress predicted with four involute gear geometries and proposes recommendations for stress calculations, including a modification to contact ratio factor Zɛ which is used to predict contact stress and revisions to form factor YF and helix angle factor Yβ which are cited to evaluate bending stress. The results suggest that there are some significant deviations in predicted bending and contact stress values between proposal methods and original ISO standard. However, before the ISO standard is changed, the paper recommends that allowable stress numbers published in ISO 6336-5 are reviewed because the mechanisms that initiate bending and contact fatigue have also changed and these require updating.

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