PSI - Issue 13

Seyit Mehmet Demet et al. / Procedia Structural Integrity 13 (2018) 2030–2035 Author name / Structural Integrity Procedia 00 (2018) 000–000

2035

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Damage on the tooth flank is not due to wear. Because there is no wear or friction in single-tooth fatigue test. Three type of damages were encountered on the tooth and these are explained as follows: 1. At high torques, gear tooth with both hardness values have been damaged in relatively low cycles. At high loads, gear tooth with both hardness values have been fractured from tooth root, it is known damage form. As the number of cycles increases at lower torques, the shape of the damage changes. 2. In the gear tooth with 48 HRC hardness, breaks occurred on the coast side flank surfaces which is in non contact at the high cycles. Due to high residual tensile stresses on the tooth flank surface, cracks and breakage due to fatigue on the coast side flank surface occurred under variable loading at high cycles. 3. In the tooth with 38 HRC hardness, the residual tensile stresses on the coast flank surface are somewhat lower, so no damage is observed on the non-contact surface. In these tooth, the strength at the loading point is weakened due to the chordal tooth thickness and surface hardness. As a result, crack forms somewhat inside from the surface and grow up in the tooth inner surface. So fracture damage occurs in tooth. These two types of damage are rarely encountered in single-tooth bending fatigue tests and appear to be types of damage that occur in high cycles. Stahl et al. (2013) and Boiadjiev et al. (2015) described this kind of damage on the tooth flanks in a similar way. Acknowledgements This study was supported by Selcuk University with project 2014-ÖYP-057. References Spitas, C. and V. Spitas, A FEM study of the bending strength of circular fillet gear teeth compared to trochoidal fillets produced with enlarged cutter tip radius. Mechanics Based Design of Structures and Machines, 2007. 35 (1): p. 59-73. Spitas, V., T. Costopoulos, and C. Spitas, Increasing the strength of standard involute gear teeth with novel circular root fillet design. American Journal of Applied Sciences, 2005. 2 (6): p. 1058-1064. Costopoulos, T. and V. Spitas, Reduction of gear fillet stresses by using one-sided involute asymmetric teeth. Mechanism and Machine Theory, 2009. 44 (8): p. 1524-1534. Kleiss, R., A. Kapelevich, and N. Kleiss Jr. New opportunities with molded gears . in AGMA Fall Technical Meeting, Detroit . 2001. Cavdar, K., F. Karpat, and F.C. Babalik, Computer Aided Analysis of Bending Strength of Involute Spur Gears with Asymmetric Profile. Journal of Mechanical Design, 2004. 127 (3): p. 477-484. Litvin, F.L., Q. Lian, and A.L. Kapelevich, Asymmetric modified spur gear drives: reduction of noise, localization of contact, simulation of meshing and stress analysis. Computer Methods in Applied Mechanics and Engineering, 2000. 188 (1): p. 363-390. Maršálek, P. and V. Moravec, A methodology for gear fatigue tests and their evaluation (part 2). Journal of Middle European Construction and Design of Cars, 2011. 9 (3): p. 18-22. Maršálek, P. and V. Moravec, A methodology for gear fatigue tests and their evaluation (part 1). Journal of Middle European Construction and Design of Cars, 2011. 9 (3): p. 13-17. Prabhu Sekar, R. and G. Muthuveerappan, Estimation of tooth form factor for normal contact ratio asymmetric spur gear tooth. Mechanism and Machine Theory, 2015. 90 (Supplement C): p. 187-218. Subaşı, M. and Ç. Karataş, AISI 4140 Çeli ğ inde Elde Edilen Farkl  Sertliklerin Kal  nt  Gerilmeler Üzerindeki Etkisinin Ara ş t  r  lmas  . Politeknik Dergisi, 2011. 14 (4). Boiadjiev, I., et al., Tooth Flank Fracture–Basic Principles and Calculation Model for a Sub-Surface-Initiated Fatigue Failure Mode of Case Hardened Gears. Gear Technology, 2015: p. 59-64. Stahl, K., B. Hohl, and T. Tobie. Tooth Flank Breakage: Influences on Subsurface Initiated Fatigue Failures of Case Hardened Gears . in 25th International Conference on Design Theory and Methodology . 2013. Demet, S.M., Imrek. H., Turkish patent and Trademark Office,2015/12969 , 2015.