A Numerical Study on Thermal Elastohydrodynamic Lubrication of Coated Polymers

Ziegltrum, A.; Maier, Enzo; Lohner, Thomas; Stahl, Karsten

doi:10.1007/s11249-020-01309-6

Cited by 12 publications

(25 citation statements)

References 38 publications

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“…In polymer-polymer pairs, the deflection of the driver gear tooth advanced the contact of the adjacent teeth. A similar contact zone deformation pattern was observed by Ziegltrum et al 35 in a pair of cylindrical disks under rolling contact. The deformation and contact area of the polymer-polymer pair was higher than the steelpolymer pair.…”

Section: Lsr Leading Pair ¼supporting

confidence: 85%

Effect of metal and polymer mating gears on the bending fatigue performance of asymmetric polymer gears

Pandian

Gautam

Senthilvelan

2021

Proceedings of the Institution of Mechanical Engineers, Part L:

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The material of the mating gear influences the fatigue life of polymer gears. The bending fatigue characteristics of polyamide 66 asymmetric gears (34°/20° and 20°/34°) corresponding to steel–polymer and polymer–polymer material combinations were investigated. The performance of symmetric gear pairs (20°/20°) was determined to serve as a comparison. Quasi-static numerical simulations were performed in a finite element analysis tool to predict root bending stress, load sharing ratio, and tooth deflection. The bending fatigue strength of steel–polymer and polymer–polymer pairs of each test configuration was determined using bending fatigue tests. The load sharing ratio and root bending stress of polymer–polymer pairs decreased substantially compared to steel–polymer pairs. The extent of deflection-induced load sharing was greater in polymer–polymer pairs. The bending fatigue life of polymer–polymer pairs was lower than that of steel–polymer pairs owing to the higher operating temperature. In polymer–polymer pairs, polymer driving and driven gears increased the heat generated and diminished the heat dissipation to the environment. In steel–polymer and polymer–polymer pairs, the configuration with the highest bending fatigue strength was 34°/20° and 20°/34°, respectively. This divergence was caused by the increase in temperature difference between the two configurations for polymer–polymer pairs. Analysis of hysteresis loops indicated that the loop area was higher for polymer–polymer pairs, signifying the increased amount of dissipated energy. No noticeable variation was observed between the failure modes of steel–polymer and polymer–polymer pairs despite the significant difference in the operating temperatures. The bending stress and operating temperature were the dominant factors affecting the performance of steel–polymer and polymer–polymer gear pairs, respectively.

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Section: Lsr Leading Pair ¼supporting

confidence: 85%

Effect of metal and polymer mating gears on the bending fatigue performance of asymmetric polymer gears

Pandian

Gautam

Senthilvelan

2021

Proceedings of the Institution of Mechanical Engineers, Part L:

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“…A second pressure maximum such as that of hard EHL contacts [ 22 , 32 ] is not visible. The absence of a second pressure peak is typically for soft EHL contacts [ 2 ] and not caused by insufficient spatial resolution of the sensor. The width of the pressurized zone of around ≈ 2.2 mm refers to the large deformation of the PEEK surface.…”

Section: Resultsmentioning

confidence: 99%

“…As a result, the fluid viscosity increases enough to form a lubricating film between the contact surfaces and remains low enough to reach a very low fluid friction level. The heat generated due to shearing is thus also low and is shown to be in the range of the compression heating according to Vicente et al [ 1 ] as well as Ziegltrum et al [ 2 ]. EHL contacts with technical polymers operate in a transition region between the soft and hard EHL regime, e.g., [ 3 , 4 , 5 ], and they may reach fluid friction in the range of superlubricity (µ < 0.01) as shown by Reitschuster et al [ 6 ].…”

Section: Introductionmentioning

confidence: 96%

“…Since the surface coatings typically exhibit a lower thermal effusivity than steel, high damping of the measured temperature can occur. Numerical calculations of the temperature distribution in coated EHL contacts from, e.g., Ziegltrum et al [ 2 ] revealed strong temperature gradients within surface coatings. Hofmann et al [ 26 ] applied thin-film sensors to dry lubricated soft-coated rolling-sliding contacts.…”

Section: Introductionmentioning

confidence: 99%

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In Situ Contact Analysis of Polyetheretherketone under Elastohydrodynamic Lubrication

2022

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The influence of the complex material behavior of thermoplastic polymers in lubricated contacts is poorly understood. It affects the optimal design of power-transmitting thermoplastic machine elements and the exploitation of its potential, e.g., lightweight design, low-noise operation, and cost-effective manufacturing when injection-molded. This study applies the in situ thin-film sensor technology on a twin-disk tribometer in order to study the elastohydrodynamic lubrication of rolling–sliding contacts with the thermoplastic polymer polyetheretherketone. The results provide insights into the effects and relevance of its thermoplastic material properties. Pressure measurements reveal a typical hydrodynamic profile in combination with a large deformation of the contact zone. The influence of speed and slip ratio is thereby negligible. The temperature rise is low compared to elastohydrodynamically lubricated contacts with steel and is mainly influenced by the slip ratio as well as the load, whereas speed plays a subordinated role. In general, the heat generation is governed by shearing and backflow in the contact inlet zone at low slip ratios and shearing in the contact zone at high slip ratios. No effects attributed to viscoelasticity or loading frequency were observed at the operating conditions considered.

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“…Solid losses are minimized owing to the lower strain in the material. A decisively enhanced thermal effusivity, also known as thermal inertia [38], by the fiber reinforcement cannot be assumed, as it has little effect on the thermal conductivity of the whole composite (see Table 1).…”

Section: Influence Of the Matrix Materialsmentioning

confidence: 99%

Friction and Temperature Behavior of Lubricated Thermoplastic Polymer Contacts

et al. 2020

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This work focuses on the friction and temperature behavior of thermo-elastohydrodynamically lubricated (TEHL) contacts under rolling-sliding conditions. For this purpose, a twin-disk test rig is used with a hybrid setup of plain and fiber-reinforced polyamide (PA) 66 and polyetheretherketone (PEEK) disks paired with case-hardened steel disks and three different lubricants. Experimental investigations include various lubrication regimes by varying sum velocity and oil temperature as well as load and slip ratio. The measured friction in thermoplastic TEHL contacts is particularly very low in the area of high fluid load portion, which refers to the large deformation of the compliant polymer surface. Newtonian flow behavior mainly determines fluid friction. The low thermal effusivity of polymers insulates the contact and can further reduce the effective lubricant viscosity, and thus the fluid friction. For low sum velocities, solid friction influences the tribological behavior depending on the solid load portion. Although the interfacial contact friction is comparably small, material damping strongly contributes to power losses and increases bulk temperature, which in turn affects the TEHL contact. Thus, loading frequency and the resulting bulk temperature are identified as one of the main drivers of power losses and tribological behavior of lubricated thermoplastic polymer contacts.

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A Numerical Study on Thermal Elastohydrodynamic Lubrication of Coated Polymers

Cited by 12 publications

References 38 publications

Effect of metal and polymer mating gears on the bending fatigue performance of asymmetric polymer gears

Effect of metal and polymer mating gears on the bending fatigue performance of asymmetric polymer gears

In Situ Contact Analysis of Polyetheretherketone under Elastohydrodynamic Lubrication

Friction and Temperature Behavior of Lubricated Thermoplastic Polymer Contacts

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