Stress Concentration factor Analysis of Helical Gear Drives with Asymmetric Teeth Profiles

2018 ◽  
Vol 24 (5) ◽  
pp. 14
Author(s):  
Mohammad Qasim Abdullah ◽  
Mohammed Abdulaal Kadum
Keyword(s):  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Bending Strength ◽  
Spur Gear ◽  
Helical Gear ◽  
Tooth Profile ◽  
Bending Stress ◽  
Pressure Angle ◽  
Side Pressure

This study investigates the influence of asymmetric involute teeth profiles for helical gears on the bending stress. Theoretically, bending stress has been estimated in spur involute gears which have symmetric teeth profile by based on the Lewis, 1892 equation. Later, this equation is developed by, Abdullah, 2012. to determine the effect of an asymmetric tooth profile for the spur gear on the bending stress. And then these equations are applied with stress concentration factor once for symmetric and once other for asymmetric teeth profile. In this paper, the bending stresses for various types of helical gear with various types of asymmetric teeth profile are calculated numerically for defined the stress concentration factor. The numerical solution based on the finite element method technique which that done by using the software simulation SolidWorks 2016. The results of this study indicate that the helical gear drive with asymmetric teeth profile having 'loaded side pressure angle' of ( ) and 'unloaded side pressure angle' of ( ) is better than a helical gear with standard teeth profile having pressure angle of ( ) from the regarding of tooth bending strength. Also, notes that the great enhancement in the results of maximum tooth bending stress for modified involute of tooth profile compared with the standard teeth profile. In addition to, predict the equation of stress concentration factor which is a function of both unloaded side pressure angle and helix angle and then it used with Abdullah equation for to determine the nominal stresses in the root fillet.  

scholarly journals An Analytical Solution for the Maximum Tensile Stress and Stress Concentration Factor Investigations for Standard, Asymmetric fillets, Asymmetric Pressure Angle and Profile Shifted Helical and Spur Gears

2020 ◽  
Vol 26 (7) ◽  
pp. 217-237
Author(s):  
Ahmed Ali Toman ◽  
Mohammad Qasim Abdullah
Keyword(s):  
Stress Concentration ◽  
Tensile Stress ◽  
Stress Concentration Factor ◽  
Analytical Method ◽  
Concentration Factor ◽  
Radial Distance ◽  
Maximum Tensile Stress ◽  
Shift Factor ◽  
Spur Gears ◽  
Pressure Angle

This research introduces a developed analytical method to determine the nominal and maximum tensile stress and investigate the stress concentration factor. The required tooth fillets parametric equations and gears dimensions have been reformulated to take into account the asymmetric fillets radiuses, asymmetric pressure angle, and profile shifting non-standard modifications. An analytical technique has been developed for the determination of tooth weakest section location for standard, asymmetric fillet radiuses, asymmetric pressure angle and profile shifted involute helical and spur gears. Moreover, an analytical equation to evaluate gear tooth-loading angle at any radial distance on the involute profile of spur and helical gears, (taking into account the effect of profile shift factor) has been derived. In addition, numerical solution for the evaluation of the maximum fillet tensile stress and the combined tensile stress concentration factor for the verification of the analytical method using computer-aided engineering software (ANSYS Version 18.1). The analytical and FE result have been compared and found to be very close. The most effective method for reducing the stress concentration factor have been found by applying negative profile shifting on asymmetric tooth with lower unloaded pressure angle and high loaded pressure angle and fillet radius, which can lead to an enhancement percentage of (20%) when using a (35o/20o) asymmetric spur gear of a (24) teeth number with a shift factor of (-0.3mo) compared with standard (20o) one.

Research on the Maximum Bending Stress on Driving Tine of SCMW

2012 ◽  
Vol 184-185 ◽  
pp. 445-449 ◽  
Author(s):  
Yang Zhi Chen ◽  
Shun Ke Liang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Concentration ◽  
Theoretical Result ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Helix Angle ◽  
Bending Stress ◽  
Actual Result ◽  
Two Factors

In this study, equations of the maximum bending stress (MBS) on the root of driving tine of the space-curve meshing-wheel (SCMW) are deduced. Four factors have an impact on stress concentration of the driving tines, the helix angle, the fillet, the diameter of driving tines and the radius of the spiral curve for driving tine. They have been studied by Finite Element Method (FEM). Results show the former two factors have great impact on stress concentration while the last two could be ignored. Then the method to gain the stress concentration factor is proposed. It makes the theoretical result of the MBS on the root of driving tine match the actual result.

Effect of Adjacent Teeth Load on Bending Strength of High Contact Ratio Asymmetrical Spur Gear Drive

2017 ◽  
Vol 9 (1) ◽  
Author(s):  
R. Thirumurugan ◽  
C.C.C. Deepak ◽  
K. Karthieeban
Keyword(s):  
Computer Aided Design ◽  
Bending Strength ◽  
Gear Tooth ◽  
Spur Gear ◽  
Design Tool ◽  
Bending Stress ◽  
Contact Ratio ◽  
Element Analysis ◽  
Gear Drive ◽  
Pressure Angle

This paper describes methodology for predicting the bending stress of the spur gear accurately by including the load on the adjacent teeth for high contact ratio asymmetric spur gear drive. Higher contact ratio is obtained by enlarging the addendum from the standard addendum value where as the asymmetric is achieved by keeping various pressure angles (170, 200 and 220) at non drive side while the drive side pressure angle was kept as 200. The bending stress developed for the given load according to the load sharing calculated by using stiffness based method along with the effect of adjacent teeth loads are explored in this work. Computer aided design tool is used for generating the gear tooth profile and ANSYS is used to carry out the finite element analysis. The result shows that the maximum bending stress level in a mesh cycle is increased when the load on adjacent teeth are taken into account. The higher pressure angle at the non-drive side yields lesser stress at the fillet region when compared to the lower pressure angle.

scholarly journals Revised Lewis Bending Stress Capacity Model

2020 ◽  
Vol 14 (1) ◽  
pp. 1-14
Author(s):  
Edward. E. Osakue ◽  
Lucky Anetor
Keyword(s):  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Gear Tooth ◽  
Shear Stresses ◽  
Bending Stress ◽  
Moment Arm ◽  
Contact Ratio ◽  
Helical Gears ◽  
Cylindrical Gears

Background: During operation, cylindrical gearset experiences tangential, radial, and axial (helical gears only) force components that induce bending, compressive, and shear stresses at the root area of the gear tooth. Accurate estimation of the effective bending stress at the gear root is a challenge. Lewis was the first person who attempted estimating the root bending stress of spur gears with some reasonable accuracy. Various gear standards and codes in use today are modifications and improvements of the Lewis model. Objective: This research aims at revising the Lewis model by making adjustments for dynamic loads, shear stresses, axial bending stress for helical gears, and stress concentration factor that is independent on the moment arm of tangential or axial force component. Methods: An analytical approach is used in formulating a modified formula for the root bending stress in cylindrical gears starting with the original Lewis model. Intermediate expressions are developed in the process and works from many previous authors are reviewed and summarized. The new model developed is used to estimate the root bending stress in four example gearsets of 0o to 41.41o helix angle and the results are compared with those of AGMA (American Gear Manufacturers Association) formula. Results: Analysis from the examples shows that neglecting the radial compressive stress over-estimated the root bending stress by 5.27% on average. When shear stresses are ignored, the root bending stress is under-estimated by 7.49% on average. It is important, therefore, to account for both compressive and shear stresses in cylindrical gear root bending stress. When the root bending stress estimates from the revised Lewis model were compared with AGMA results, deviations in the range of -4.86% to 26.61% were observed. The stress estimates from the revised Lewis formulae were mostly higher than those of AGMA. Conclusion: The new root bending stress model uses stress concentration factors (normal and shear) that are independent of the point of load application on the gear tooth. This decoupling of stress concentration factor from the load moment arm distinguishes the new model from AGMA formula and brings bending stress analysis in gear design in line with classical bending stress analysis of straight and curved beams. The model can be used for both normal contact ratio and high contact ratio cylindrical gears.

Effect of Transition Curve on Gear Bending Strength

2010 ◽  
Vol 34-35 ◽  
pp. 1640-1644
Author(s):  
Li Ping Wang ◽  
Ying Qiang Xu ◽  
Lei Lei Wang ◽  
Qiong Wei Zhang
Keyword(s):  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Bending Strength ◽  
Transition Curve ◽  
Relation Model ◽  
Relationship Of ◽  
The Relationship ◽  
Transition Curves

Transition curve is very important to bending strength and life of gear. In order to improve the bending strength of gear, the shape of three kinds of transition curve (ordinary fillet cutter tip, single circle arc cutter tip and double circle arc cutter tip) was analyzed respectively, the relationship of double circle arc cutter tip parameters was established, the relation model of sensitive part of gear and stress concentration factor ( J and γ) was determined, the effect of different transition curves of gear on bending strength ( ) was explored. The results of analysis show that the bending strength of gear cut by double circle arc cutter tip increases by 10% comparing with that of gear cut by ordinary fillet cutter tip. It provides theories foundation for the design of high bending strength gear.

Sign in / Sign up

Export Citation Format

Share Document