Materials and Surface Engineering in Tribology

Takadoum, J.

doi:10.1002/9780470611524

Cited by 59 publications

(77 citation statements)

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“…The proposed micro-nozzle part to reduce wear in the gears modifies the system tribology which Takadoum [11] defined as critical. Takadoum defined four parameters important to minimize the wear: surface state, stress in the system, mechanical contact and tribology of the system respectively.…”

Section: Discussionmentioning

confidence: 99%

“…The proposed solutions essentially tune and modify the system parameters such as surface state [5], [6], stress, mechanical contact [7] and tribology [8]- [10] parameters that Takadoum [11] defined as critical to minimize the effects of wear. There are methods to measure the excessive tooth wear to predict when the failure will occur were presented by Mashue et al [12] and Nordex Energy [13].…”

Section: Introductionmentioning

confidence: 99%

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New method for lubricating wind turbine pitch gears using embedded micro-nozzles

2017

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Aquesta és una còpia de la versió author's final draft d'un article publicat a la revista Journal of mechanical science and technology.La publicació final està disponible a Springer a través de http://dx.doi.org/10.1007/s12206-017-0131-3 This is a copy of the author 's final draft version of an article published in the journal Journal of mechanical science and technology. --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- AbstractThe increase of power generated by wind turbines has increased the stresses applied in all of its parts, which causes the appearance of premature failures. In particular, pitch and yaw gears suffer of excessive wear, mainly due to inappropriate lubrication. This paper presents a novel method to automatically lubricate the wind turbine pitch gear during operation. A micro-nozzle to continuously inject fresh grease between the teeth in contact was designed, manufactured and installed in a test bench of a 2 MW wind turbine pitch system. The test bench was used to characterize the fatigue behavior of the gear surface using conventional wind turbine greases under real cyclic loads. The measurements of wear evolution in a pitch gear with and without micro-nozzle show a decrease of 70% of the wear coefficient after 2x10 4 cycles.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

New method for lubricating wind turbine pitch gears using embedded micro-nozzles

2017

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“…The mass and thermal properties of these components were obtained by correspondent manufacturers [3] . Using L E  and n E  , the friction material energetic factor, L P , could finally be determined, according to Equation (14). Table A …”

Section: Braking Energy Calculationmentioning

confidence: 99%

“…Neglecting optical, noise, particles pulverization and other forms of energy [14] [15], the braking energy, q , can be expressed by: …”

Section: Braking Energy Generation and Heat Absorption 1) Mechanical mentioning

confidence: 99%

Friction Material Temperature Distribution and Thermal and Mechanical Contact Stress Analysis

Travaglia¹,

Lopes²

2014

ENG

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In brake systems, where the components are exposed to mechanical and thermal loads, the numerical analysis is very helpful. The main function of the brake system is to control or reduce vehicle's speed by transformation of kinetic and potential energy in thermal energy. Using finite element method and Abaqus application, the present work proposed a model to study the impact of these loads on the performance of a pneumatic S cam drum brake's friction material. The model included the effects of the rivet process; brake torque and warming in one of the 17 t bus front brake lining. Areas where the stresses vary with considerable amplitudes during temperature increase and brake application were identified. Also, it was possible to compare results of the numerical model to vehicle's experimental measurements and understand its proximity to real braking events. By the application of the methodology and using the numerical model, proposed in this work, it will be possible to contribute considerably for a more accurate design of the friction material, besides undertake a better selection of the sub-compounds which it is made of.

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“…Thus, he has developed the hydrodynamic lubrication theory, which found many useful applications. [7][8][9][10][11] With the advancement of technology, the friction is studied nowadays on micro-and nano-levels 12,13 indicating elastic and plastic deformations of the surface asperities during the sliding process. The seminal work of Hertz 5 on the friction between sliding elastic surfaces has been further developed in the middle of the previous century, 14,15 while the contribution of adhesion between the elastic bodies in contact has been accounted for in the Johnson-Kendall-Roberts 16 (JKR) and the Derjaguin-Muller-Toporov 17 (DMP) theories.…”

mentioning

confidence: 99%

Tribology of thin wetting films between bubble and moving solid surface

Karakashev

Stöckelhuber

Tsekov

et al. 2014

Advances in Colloid and Interface Science

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The tribology of a bubble rubbing on a solid surface is studied via interferometry. A unique experimental setup is designed for monitoring the thickness profiles of a wetting film, intercalated between the bubble and hydrophilic glass moving with speed up to 412 m/s. The determination of the 3D film thickness profiles allows us to calculate 3D maps over the wetted surface of the local capillary, disjoining and lift pressures, viscous stress and friction force. In this way the average friction force and the corresponding friction coefficient are obtained. A theoretical model for the dependence of the friction coefficient on the film thickness is developed. The relevant slip coefficient, being a measure for the slip between liquid and solid, is determined as a function of the speed of the solid surface. It is found out that below 170 m/s a friction regime exists which formally resembles dry friction, while at larger speed the friction force between the bubble and solid passes through a maximum. Furthermore, the friction coefficient has a large value at low speed of the solid and reduces substantially with the speed increase.The science of friction traces its roots five centuries back to the pioneering works of da Vinci 1 . Amontons 2 , Euler 3 and Coulomb 4 had later established the fundamental laws of dry friction between sliding solid bodies. Further on the dry contact between elastic bodies has been investigated by Hertz 5 , who laid out the foundations of contact mechanics. Reynolds 6 found out that a liquid layer, intercalated between two solid surfaces in relative motion towards each other, becomes a lubricant. Thus, he has developed the hydrodynamic lubrication theory, which found many useful applications. [7][8][9][10][11] With the advancement of technology, the friction is studied nowadays on micro-and nano-levels 12,13 indicating elastic and plastic deformations of the surface asperities during the sliding process. The seminal work of Hertz 5 on the friction between sliding elastic surfaces has been further developed in the middle of the previous century, 14,15 while the contribution of adhesion between the elastic bodies in contact has been accounted for in the Johnson-Kendall-Roberts 16 (JKR) and the Derjaguin-Muller-Toporov 17 (DMP) theories. The term tribology is suggested by Jost 18 as "the science and technology of interacting surfaces in relative motion and practices related to". The term nano-tribology appeared upon bringing the scale of the investigations of sliding surfaces to nano and atomic dimensions. 8,19,20 At present knowledge about nano-tribology is exploited for designing micro-and nano-electromechanical systems (MEMS/NEMS), self-lubricating and biologically inspired surfaces. 21

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Materials and Surface Engineering in Tribology

Cited by 59 publications

References 0 publications

New method for lubricating wind turbine pitch gears using embedded micro-nozzles

New method for lubricating wind turbine pitch gears using embedded micro-nozzles

Friction Material Temperature Distribution and Thermal and Mechanical Contact Stress Analysis

Tribology of thin wetting films between bubble and moving solid surface

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