Experimental and numerical investigation of the bending fatigue performance of symmetric and asymmetric polymer gears

Abstract

In this work, the bending fatigue strengths of injection-molded symmetric and asymmetric nylon 66 gears were evaluated experimentally, and the results were substantiated using numerical studies. The symmetric (20°/20°) and asymmetric (34°/20° and 20°/34°) configurations were subjected to bending fatigue tests under a load controlled mode. The bending stresses of the symmetric and asymmetric gears were predicted by quasi-static simulations using a commercial finite element analysis software. The form factor ( $Y_{F}$ ) and the stress correction factor ( $Y_{S}$ ) were computed using an adapted ISO method. The 34°/20° configuration exhibited the lowest bending stress and highest bending fatigue life among the tested configurations. The form factor exerted a decisive influence on the magnitude of the bending stress compared to the stress correction factor. For the considered loading conditions, deflection-induced load sharing occurred in the 20°/20° and 20°/34° configurations but was absent in the 34°/20° configuration. Failure analysis indicated that a high stress concentration caused multiple cracks in the fillets of asymmetric gears.

Keywords

Asymmetric tooth polymer gear bending fatigue finite element analysis form factor stress correction factor

Get full access to this article

View all access options for this article.

References

Kapelevich

. Plastic gear design specifics. In: Asymmetric gearing, Boca Raton, FL: CRC Press, 2019. pp. 157–178.

Costopoulos

Spitas

. Reduction of gear fillet stresses by using one-sided involute asymmetric teeth. Mech Mach Theory 2009; 44: 1524–1534.

Kapelevich

Shekhtman

. Tooth fillet profile optimization for gears with symmetric and asymmetric teeth. Gear technology 2009, pp. 73–79.

Pedersen

. Improving bending stress in spur gears using asymmetric gears and shape optimization. Mech Mach Theory 2010; 45: 1707–1720.

Prabhu Sekar

. Performance enhancement of spur gear formed through asymmetric tooth. Proc IMechE, Part J: J Engineering Tribology 2019; 233: 1361–1378.

ISO 6336-3:2006. Calculation of load capacity of spur and helical gears, Geneva: ISO, 2008.

Lisle

Shaw

Frazer

. External spur gear root bending stress: a comparison of ISO 6336:2006, AGMA 2101-D04, ANSYS finite element analysis and strain gauge techniques. Mech Mach Theory 2017; 111: 1–9.

Mao

. Frictional effects on gear tooth contact analysis. Adv Tribol. https://doi.org/10.1155/2013/181048 (2013).

Karimpour

Dearn

Walton

. A kinematic analysis of meshing polymer gear teeth. Proc IMechE, Part L: J Materials: Design and Applications 2010; 224: 101–115.

10.

Hasl

Liu

Oster

, et al. Method for calculating the tooth root stress of plastic spur gears meshing with steel gears under consideration of deflection-induced load sharing. Mech Mach Theory 2017; 111: 152–163.

11.

Kapelevich AL and Shekhtman Y V. Rating of asymmetric tooth gears. AGMA Technical Paper, October 2015.

12.

Cavdar

Karpat

Babalik

. Computer aided analysis of bending strength of involute spur gears with asymmetric profile. J Mech Des 2005; 127: 477–484.

13.

Pedrero

Rueda

Fuentes

. Determination of the ISO tooth form factor for involute spur and helical gears. Mech Mach Theory 1999; 34: 89–103.

14.

Prabhu Sekar

Muthuveerappan

. Estimation of tooth form factor for normal contact ratio asymmetric spur gear tooth. Mech Mach Theory 2015; 90: 187–218.

15.

Thomas

Sankaranarayanasamy

Ramachandra

, et al. Search method applied for gear tooth bending stress prediction in normal contact ratio asymmetric spur gears. Proc IMechE, Part C: J Mechanical Engineering Science 2018; 232: 4647–4663.

16.

Jin

. Research on composite bending stress of asymmetric gear in consideration of friction. Proc IMechE, Part C: J Mechanical Engineering Science 2019; 233: 2939–2955.

17.

Prabhu Sekar

. Determination of load dependent gear loss factor on asymmetric spur gear. Mech Mach Theory 2019; 135: 322–335.

18.

SAE J1619. Single tooth gear bending fatigue test, Warrendale, PA: SAE, 1997.

19.

Brown FW, Davidson SR, Hanes DB, et al. Analysis and testing of gears with asymmetric involute tooth form and optimized fillet form for potential application in helicopter main drives. AGMA Technical Paper, October 2010.

20.

Sanders A, Houser DR, Kahraman A, et al. An experimental investigation of the effect of tooth asymmetry and tooth root shape on root stresses and single tooth bending fatigue life of gear teeth. In: Proceedings of the ASME 2011 international design engineering technical conferences & computers and information in engineering conference, Washington, USA, 2011.

21.

Anand Mohan

Senthilvelan

. Preliminary bending fatigue performance evaluation of asymmetric composite gears. Mech Mach Theory 2014; 78: 92–104.

22.

Tavcar

Grkman

Duhovnik

. Accelerated lifetime testing of reinforced polymer gears. J Adv Mech Des Syst Manuf 2018; 12: 1–13.

23.

Zorko

Kulovec

Duhovnik

, et al. Durability and design parameters of a Steel/PEEK gear pair. Mech Mach Theory 2019; 140: 825–846.

24.

Mao

Greenwood

Ramakrishnan

, et al. The wear resistance improvement of fibre reinforced polymer composite gears. Wear 2019; 426–427: 1033–1039.

25.

Kumar

Kommogi

Senthilvelan

. Injection molded asymmetric spur gear — development and preliminary performance evaluation. Int J Plast Technol 2009; 13: 186–192.

26.

Johnney Mertens

Senthilvelan

. Durability of injection moulded asymmetric involute polymer spur gears. Int J Powertrains 2016; 5: 264–280.

27.

Walton

Tessema

Hooke

, et al. Load sharing in metallic and non-metallic gears. Proc IMechE, Part C: J Mechanical Engineering Science 1994; 208: 81–87.

28.

Kodeeswaran

Verma

Suresh

, et al. Effects of frequency on hysteretic heating and fatigue life of unreinforced injection molded polyamide 66 spur gears. Proc IMechE, Part L: J Materials: Design and Applications 2019; 233: 781–789.

29.

Kalin

Kupec

. The dominant effect of temperature on the fatigue behaviour of polymer gears. Wear 2017; 376–377: 1339–1346.

30.

Mao

Hooke

, et al. Friction and wear behaviour of acetal and nylon gears. Wear 2009; 267: 639–645.

31.

Düzcükoğlu

. Study on development of polyamide gears for improvement of load-carrying capacity. Tribol Int 2009; 42: 1146–1153.

32.

Van Melick

HGH

. Tooth bending effects in plastic spur gears. Gear technology 2007, pp. 58–66.

33.

Fuentes A, Gonzalez-perez I, Sanchez-marin FT, et al. On the behavior of asymmetric cylindrical gears in gear transmissions. In: Proceedings of the FISITA 2010 world automotive congress. Berlin, Heidelberg: Springer, 2010, pp.143–149.

34.

Andrews

. A finite element analysis of bending stresses induced in external and internal involute spur gears. J Strain Anal Eng Des 1991; 26: 153–163.

35.

Walton

Tessema

Hooke

, et al. A note on tip relief and backlash allowances in non-metallic gears. Proc IMechE, Part C: J Mechanical Engineering Science 1995; 209: 383–388.