Planetary Gear Fatigue Behavior in Automatic Transmission

Jao, Tze‐Chi; Henly, Timothy J.; Carlson, Gerald W.; Ved, Chintan; Carter, Roscoe O.; Hildebrand, D.; Ogorek, Wally

doi:10.4271/2006-01-3243

Cited by 6 publications

(5 citation statements)

References 8 publications

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“…Furthermore, the maximum amount of the equivalent stress in Sun-Planet contact is almost 50 MPa higher than that for the Planet-Ring contact, which indicates the fatigue failure is more likely to occur in the sun-planet contact which is in agreement with the findings in [10].…”

Section: 1-effects Of Tip Relief Amountsupporting

confidence: 87%

Effect of tooth profile modification on the durability of planetary hub gears

King¹,

Rahnejat²,

Trimmer³

et al. 2019

IJPT

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Planetary systems offer the advantage of desired speed-torque variation with a lighter, compact and coaxial construction than the traditional gear trains. Frictional losses and Noise, Vibration and Harshness (NVH) refinement are the main concerns. Modification of gear teeth geometry to reduce friction between the mating teeth flanks of vehicular planetary hubs, as well as refining NVH under varying load-speed conditions is one of the remedial actions. However, implementing modifications can result in reduced structural integrity and system durability. Therefore, a contradiction may arise between assuring a high degree of durability and achieving better transmission efficiency, which necessitates detailed system optimisation. An integrated multidisciplinary analytical approach, including tribology and sub-surface stress analysis is developed. As a preliminary step, Tooth Contact Analysis (TCA) is performed to obtain contact footprint shape of meshing gear teeth pairs, as well as contact kinematics and applied load distribution. Then, an analytical time-efficient Elastohydrodynamic Lubrication (EHL) analysis of elliptical point contact of crowned spur gear tooth is carried out to observe the effect of gear tip relief modification upon planetary hub sub-surface stresses.

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Section: 1-effects Of Tip Relief Amountsupporting

confidence: 87%

Effect of tooth profile modification on the durability of planetary hub gears

King¹,

Rahnejat²,

Trimmer³

et al. 2019

IJPT

View full text Add to dashboard Cite

show abstract

“…Therefore, other durability parameters such as scuffing and scratching as well as NVH refinement and efficiency should also be taken into account. 16 Furthermore, the maximum amount of the equivalent stress in Sun-Planet contact is almost 50 MPa higher than that for the Planet-Ring contact, which indicates the fatigue failure is more likely to occur in the sun-planet contact which is in agreement with the findings in [10].…”

Section: 1-effects Of Tip Relief Amountsupporting

confidence: 81%

“…Chittenden et al [22] equation is used to calculate the thin lubricant film thickness under the instantaneous operating conditions which is required for equation (10).…”

Section: -Viscous Frictionmentioning

confidence: 99%

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Effect of tooth profile modification on the durability of planetary hub gears

Fatourehchi

Mohammadpour

King

et al. 2019

IJPT

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Planetary systems offer the advantage of desired speed-torque variation with a lighter, compact and coaxial construction than the traditional gear trains. Frictional losses and Noise, Vibration and Harshness (NVH) refinement are the main concerns. Modification of gear teeth geometry to reduce friction between the mating teeth flanks of vehicular planetary hubs, as well as refining NVH under varying load-speed conditions is one of the remedial actions. However, implementing modifications can result in reduced structural integrity and system durability. Therefore, a contradiction may arise between assuring a high degree of durability and achieving better transmission efficiency, which necessitates detailed system optimisation.An integrated multi-disciplinary analytical approach, including tribology and sub-surface stress analysis is developed. As a preliminary step, Tooth Contact Analysis (TCA) is performed to obtain contact footprint shape of meshing gear teeth pairs, as well as contact kinematics and applied load distribution.Then, an analytical time-efficient Elastohydrodynamic Lubrication (EHL) analysis of elliptical point contact of crowned spur gear tooth is carried out to observe the effect of gear tip relief modification upon planetary hub sub-surface stresses.

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“…Since different machine element types are subjected to very different operating conditions and lubricating oils, the mechanisms of pit formation will vary among them. For example, the work of Jao et al . showed that although the basic mechanisms of gear and bearing fatigue failure modes are similar, they did not have the same root causes even in the same planetary gear set.…”

Section: Introductionmentioning

confidence: 99%

Investigations into the occurrence of pitting in lubricated rolling four-ball tests

2013

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Pitting, a form of rolling contact fatigue, is a complex phenomenon and several factors influence its occurrence, particularly under lubricated conditions. In this work, studies have been conducted to observe the events that occur during lubricated rolling four-ball tests that may affect or eventually lead to the formation of pits. This is performed to form an understanding of the pit formation process. Included is tribofilm formation, surface degradation, wear mode, material changes and crack initiation sites. These investigations have been performed on the ball samples from rolling four-ball tests, conducted using two API GL-5 gear oils. The analyses revealed the formation of a low hardness region beneath the surface of the running track due to martensite decay. The formation rate and expansion of this region was found to differ for the two lubricating oils. The pitted balls also indicated that the initial fatigue cracks were initiated at or close to the surface.

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Planetary Gear Fatigue Behavior in Automatic Transmission

Cited by 6 publications

References 8 publications

Effect of tooth profile modification on the durability of planetary hub gears

Effect of tooth profile modification on the durability of planetary hub gears

Effect of tooth profile modification on the durability of planetary hub gears

Investigations into the occurrence of pitting in lubricated rolling four-ball tests

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