Efficient running-in of gears and improved prediction of the tooth flank load carrying capacity

2019 ◽  
Vol 71 (3) ◽  
pp. 366-373
Author(s):  
Martin Zimmer ◽  
Dirk Bartel
Keyword(s):  
Carrying Capacity ◽  
Plastic Material ◽  
Rough Surfaces ◽  
Elastohydrodynamic Lubrication ◽  
Load Carrying Capacity ◽  
Content Type ◽  
Load Carrying ◽  
Life Model ◽  
Extended Life ◽  
Tooth Flank

Purpose The purpose of this paper is to determine parameters for an efficient running-in of gears and an improved method for the prediction of the tooth flank load carrying capacity. Design/methodology/approach In this contribution, a model for the calculation of the pitting life of involute spur gears is introduced, which is based on an extension of the life model according to Ioannides and Harris for rough surfaces. To achieve the most realistic thermal elastohydrodynamic lubrication simulation and stress calculation possible, measured real surfaces and elastic-plastic material properties of the area close to the surface are used. Special attention is paid to the compatibility of the fatigue life calculation for heterogeneous rough surfaces and their consistent consideration in the lifespan calculation. Findings A non-destructive running-in for twin-disc pairings can be performed using suitable operating parameters, which subsequently can be transferred to tooth flank tests. Using the extended life model according to Ioannides and Harris, an enhanced prediction of the tooth flank load carrying capacity is possible. Originality/value The developed extended life model includes a new numerical approach for calculating the tooth flank load carrying capacity. It has the potential to reliably support and hence to accelerate the design process of gears.

scholarly journals Understanding the Mechanism of Load-Carrying Capacity between Parallel Rough Surfaces through a Deterministic Mixed Lubrication Model

Lubricants ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 12
Author(s):  
Yuechang Wang ◽  
Abdullah Azam ◽  
Gaolong Zhang ◽  
Abdel Dorgham ◽  
Ying Liu ◽  
...  
Keyword(s):  
Carrying Capacity ◽  
Rough Surfaces ◽  
Elastohydrodynamic Lubrication ◽  
Mixed Lubrication ◽  
Stribeck Curve ◽  
Future Research ◽  
Load Carrying Capacity ◽  
Proposed Model ◽  
Load Carrying ◽  
Lift Off

Experimental results have confirmed that parallel rough surfaces can be separated by a full fluid film. However, such a lift-off effect is not expected by the traditional Reynolds theory. This paper proposes a deterministic mixed lubrication model to understand the mechanism of the lift-off effect. The proposed model considered the interaction between asperities and the micro-elastohydrodynamic lubrication (micro-EHL) at asperities within parallel rough surfaces for the first time. The proposed model is verified by predicting the measured Stribeck curve taken from literature and experiments conducted in this work. The simulation results highlight that the micro-EHL effect at the asperity scale is critical in building load-carrying capacity between parallel rough surfaces. Finally, the drawbacks of the proposed model are addressed and the directions of future research are pointed out.

Numerical investigation of squeeze film lubrication on bioinspired hexagonal patterned surface

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Binbin Su ◽  
Xianghe Zou ◽  
Lirong Huang
Keyword(s):  
Flow Rate ◽  
Carrying Capacity ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Two Dimensional ◽  
Working Mechanism ◽  
Content Type ◽  
Patterned Surface ◽  
Load Carrying ◽  
Film Lubrication

Purpose This paper aims to investigate the squeeze film lubrication properties of hexagonal patterned surface inspired by the epidermis structure of tree frog’s toe pad and numerically explore the working mechanism of hexagonal micropillar during the acquisition process of high adhesive and friction for wet contacts. Design/methodology/approach A two-dimensional elastohydrodynamic numerical model is employed for the squeezing contacts. The pressure distribution, load carrying capacity and liquid flow rate of the squeeze film are obtained through a simultaneous solution of the two-dimensional Reynolds equation and elasticity deformation equations. Findings Higher pressure is found to be longitudinally distributed across individual hexagonal pillar, with pressure peak emerging at the center of hexagonal pillar. Expanding the area density and shrinking the channel depth or initial film thickness will improve the magnitude of squeezing pressure. Relatively lower pressure is generated inside interconnected channels, which reduces the load carrying capacity of the squeeze film. Meanwhile, the introduction of microchannel is revealed to downscale the total mass flow rate of squeezing contacts. Originality/value This paper provides a good proof for the working mechanism of surface microstructures during the acquisition process of high adhesive and friction for wet contacts.

Influence of water contamination in gear lubricants on wear and micro-pitting performance of case carburized gears

2017 ◽  
Vol 69 (4) ◽  
pp. 612-619 ◽  
Author(s):  
Christian Engelhardt ◽  
Jochen Witzig ◽  
Thomas Tobie ◽  
Karsten Stahl
Keyword(s):  
Carrying Capacity ◽  
Research Work ◽  
Load Carrying Capacity ◽  
Wear Performance ◽  
Content Type ◽  
Effect Of Water ◽  
Base Oils ◽  
Load Carrying ◽  
Different Types ◽  
Influence Of Water

Purpose Water can alter the performance of modern gear lubricants by influencing the flank load carrying capacity of gears significantly. The purpose of this paper is to investigate the influence of water contaminations in different kinds of base oils on the micro-pitting and wear performance of case carburized gears. Design/methodology/approach Concerning micro-pitting and wear, tests, based mostly on the following standardized tests, are performed on a Forschungsstelle fuer zahnraeder und getriebebau (FZG)-back-to-back gear test rig: micro-pitting short test Graufleckenkurztest (GFKT) according to DGMK 575 (screening test), micro-pitting test Graufleckentest (GT) according to FVA 54/7 (load stage test and endurance test) and Slow-speed wear test according to DGMK 377. To investigate the effect of water on the gear load carrying capacity dependent on different types of base oils, two polyglycol oils (PG1 and PG2), a polyalphaolefin oil, a mineral oil and an ester oil E are used. Each of these oils are common wind turbine gear oils with a viscosity ISO VG-220. Additionally, a manual transmission fluid with a viscosity of society of automotive engineers (SAE) 75W-85 is tested. Findings Considering the micro-pitting and wear performance, a significant decrease caused by water contaminations could not be detected. Regarding pitting damages, a generally negative influence was observed. This influence was differently distinctive for different base oil types. Especially non-polar lubricants seem to be affected negatively. The documented damages of the tooth flanks confirm this observation. While typical pitting damages appeared in test runs with polar lubricants, the disruption in test runs with non-polar lubricants was more extensive. Based on the experimental investigations, a general model of the damaging mechanisms of water contaminations in lubricants was derived. It is split into three partitions: interaction lubricant–water (effect of water on the molecular structure of base oils and additives), chemical-material-technological (especially corrosive reactions) and tribological influence (effect of water droplets in the contact zone). It has to be considered that the additive package of lubricants affects the influence of water contaminations on the flank load carrying capacity distinctively. An influence of water on the micro-pitting and wear performance in other than the given lubricants cannot be excluded. Originality/value While former research work was focused more on the effects of water in mineral oils, investigations concerning different types of base oils as well as different types of damages were carried out within this research project.

A study into the ability of SPD to restore the buckling strength and modes of rib stiffened panels with simulated stress corrosion cracks

2017 ◽  
Vol 8 (1) ◽  
pp. 63-78 ◽  
Author(s):  
Rhys Jones ◽  
Neil Matthews ◽  
Daren Peng ◽  
Nicholas Orchowski
Keyword(s):  
Experimental Study ◽  
Stress Corrosion ◽  
Carrying Capacity ◽  
Particle Deposition ◽  
Load Carrying Capacity ◽  
Load Path ◽  
Premature Failure ◽  
Content Type ◽  
Buckling Strength ◽  
Load Carrying

Purpose The purpose of this paper is to describe the results of a combined numerical and experimental study into the ability of supersonic particle deposition (SPD) to restore the load carrying capacity of rib stiffened wing planks with simulated stress corrosion cracking (SCC). Design/methodology/approach In this context the experimental results reveal that SCC can result in a dramatic reduction in the load carrying capacity of the structure and catastrophic failure via cracking that tears the length of the structure through buckling. A combined numerical and experimental study then reveals how this reduction, in the load carrying capacity can be overcome by using SPD. Findings This paper is the first to show that SPD can be used to restore the load carrying capacity of rib stiffened structures with SCC. It also shows that SPD repairs can be designed to have only a minimal effect on the local stiffness and hence on the load path. However, care should be taken to ensure that the design is such that premature failure of the SPD does not occur. Originality/value This is the first paper to show that a thin layer of SPD deposited 7,075 aluminium alloy powder on either side of the SCC-simulated stiffener has the potential to restore the load carrying capability of a rib stiffened structure. As such it represents an important first step into establishing the potential for SPD to restore the buckling strength of rib stiffened wing panels containing SCC.

Influence of hard rolling and the cooling lubricant on the material properties and the rolling strength of PM gears

2019 ◽  
Vol 71 (3) ◽  
pp. 406-410
Author(s):  
Fritz Klocke ◽  
Thomas Bergs ◽  
Christoph Löpenhaus ◽  
Philipp Scholzen ◽  
Tim Frech
Keyword(s):  
Boundary Layer ◽  
Carrying Capacity ◽  
Material Properties ◽  
Rolling Process ◽  
Surface Zone ◽  
Load Carrying Capacity ◽  
Content Type ◽  
Load Carrying ◽  
Phosphorous Content ◽  
Cooling Lubricant

Purpose The lower density of powder metallurgical (PM) gears compared to solid steel gears leads to not only a lower weight but also a lower load-carrying capacity. Therefore, PM gears are cold rolled before hardening to increase the density in the highly stressed surface zone and, thus, the flank load-carrying capacity. A further approach to increase the flank load-carrying capacity is the reduction of friction and wear in the tooth contact. The purpose of this paper is to analyze the hard rolling process as a new manufacturing step in the PM process chain to influence the boundary layer. Design/methodology/approach The investigation includes the new process of hard rolling, the variation of the cooling lubricant in the hard rolling process and the evaluation of its influence on the material properties and the flank load-carrying capacity. Therefore, the additives of the cooling lubricant are varied regarding the sulfur and phosphorous content. The load-carrying capacity is evaluated on disk-on-disk test rig and the material properties are evaluated by metallographic tests and boundary layer. Findings The results of the specimen characteristics in the micro and nano range show a significant influence of hard rolling on the residual stresses and the chemical surface composition. Because of hard rolling, residual compressive stresses as well as roughness are reduced and the flank load-carrying capacity is increased by high phosphorous content of the cooling lubricant. Originality/value This paper investigates a new manufacturing step to increase resource efficiency by increasing the flank load-carrying capacity of spur gears.

Analysis of misaligned water-lubricated polymer bearing with axial grooves

2019 ◽  
Vol 71 (3) ◽  
pp. 411-419 ◽  
Author(s):  
Fangrui Lv ◽  
Chunxiao Jiao ◽  
Donglin Zou ◽  
Na Ta ◽  
Zhu-shi Rao
Keyword(s):  
Carrying Capacity ◽  
Hydrodynamic Pressure ◽  
Maximum Pressure ◽  
Load Carrying Capacity ◽  
Misalignment Angle ◽  
Content Type ◽  
Load Carrying ◽  
Polymer Bearing ◽  
Journal Misalignment ◽  
Practical Implications

Purpose The purpose of this paper is to analyze the lubrication behavior of misaligned water-lubricated polymer bearings with axial grooves. Design/methodology/approach A lubrication model considering journal misalignment, bush deformation and grooves is established. In dynamic analyses of shaft systems, bearings are usually simplified as supporting points. Thus, an approach for solving the equivalent supporting point location is presented. The influence of misalignment angle and groove number on film thickness, hydrodynamic pressure distribution, load-carrying capacity and ESP location is investigated. Findings As the misalignment angle increases, the location of the maximum pressure and ESP are shifted toward the down-warping end, and the load-carrying capacity of the bearing decreases. In comparison to the nine-groove bearing, the six grooves bearing has a higher load-carrying capacity and the ESP is located closer to the down-warping end for an equivalent misalignment angle. Practical implications The results of this study can be applied to marine propeller shaft systems and other systems with misaligned bearings. Originality/value A study on the lubrication behavior of misaligned water-lubricated polymer bearings with axial grooves is of significant interest to the research community.

Influence of tribofilms on failures and friction of gears with particular focus on running-in

2019 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Andreas Ziegltrum ◽  
Stefan Emrich ◽  
Thomas Lohner ◽  
Klaus Michaelis ◽  
Alexander Brodyanski ◽  
...  
Keyword(s):  
Surface Analysis ◽  
Carrying Capacity ◽  
Experimental Investigations ◽  
Spur Gears ◽  
Load Carrying Capacity ◽  
Friction Behavior ◽  
Content Type ◽  
Load Carrying ◽  
Gear Contact ◽  
Local Pressures

Purpose This paper aims to address the influence of tribofilms and running-in on failures and friction of gears. The operation regime of gears is increasingly shifted to mixed and boundary lubrication, where high local pressures and temperatures occur at solid interactions in the gear contact. This results in strong tribofilm formation due to interactions of lubricant and its additives with the gear flanks and is related to changes of surface topography especially pronounced during running-in. Design/methodology/approach Experiments at a twin-disk and gear test rig were combined with chemical, structural and mechanical tribofilm characterization by surface analysis. Pitting lifetime, scuffing load carrying capacity and friction of ground spur gears were investigated for a mineral oil with different additives. Findings Experimental investigations showed a superordinate influence of tribofilms over surface roughness changes on damage and friction behavior of gears. Surface analysis of tribofilms provides explanatory approaches for friction behavior and load carrying capacity. A recommendation for the running-in of spur gears was derived. Originality/value Experimental methods and modern surface analysis were combined to study the influence of running-in and tribofilms on different failures and friction of spur gears.

Effect of surface roughness and elastic deformation on the performance of a magnetic fluid-based squeeze film in rotating porous annular plates

2014 ◽  
Vol 66 (3) ◽  
pp. 490-497
Author(s):  
Mukesh E. Shimpi ◽  
Gunamani Deheri
Keyword(s):  
Elastic Deformation ◽  
Magnetic Fluid ◽  
Carrying Capacity ◽  
Type Equation ◽  
Squeeze Film ◽  
Rotational Inertia ◽  
Load Carrying Capacity ◽  
Content Type ◽  
Annular Plates ◽  
Load Carrying

Purpose – The purpose of this paper is to study and analyse the behaviour of a magnetic fluid-based squeeze film between rotating transversely rough porous annular plates, taking the elastic deformation into consideration. Design/methodology/approach – The stochastic film thickness characterizing the roughness is considered to be asymmetric with non-zero mean and variance and skewness while a magnetic fluid is taken as the lubricant. The associated stochastically averaged Reynolds-type equation is solved with appropriate boundary conditions to obtain the pressure distribution, which in turn is used to derive the expression for the load-carrying capacity. Findings – It is observed that the roughness of the bearing surfaces affects the performance adversely, although the bearing registers an improved performance owing to the magnetic fluid lubricant. Also, it is seen that the deformation causes reduced load-carrying capacity. The bearing can support a load even in the absence of flow, unlike the case of conventional lubricants. Originality/value – The originality of the paper lies in the fact that the negative effect of porosity, deformation and standard deviation can be minimized to some extent by the positive effect of the magnetic fluid lubricant in the case of negatively skewed roughness by suitably choosing the rotational inertia and aspect ratio. This effect becomes sharper when negative variance occurs.

Extreme pressure properties of nanolubricants for metal-forming applications

2016 ◽  
Vol 68 (1) ◽  
pp. 30-34 ◽  
Author(s):  
Laura Peña-Parás ◽  
Demófilo Maldonado-Cortés ◽  
Jaime Taha-Tijerina ◽  
Patricio García-Pineda ◽  
Gerardo Tadeo Garza ◽  
...  
Keyword(s):  
Carrying Capacity ◽  
Metal Forming ◽  
Design Methodology ◽  
Load Carrying Capacity ◽  
Extreme Pressure ◽  
Synthetic Lubricant ◽  
Content Type ◽  
Load Carrying ◽  
Practical Implications ◽  
Nanoparticle Additives

Purpose – The purpose of this paper is to evaluate the extreme pressure properties of CuO and TiO2 nanoparticle additives with the incorporation of a surfactant within a synthetic fluid for metal-forming applications. Design/methodology/approach – The paper studies the effect of CuO and TiO2 nanoparticle additives at various concentrations (0.01, 0.05 and 0.10 wt. per cent) in a synthetic lubricant fluid under extreme pressure conditions. Oleic acid surfactant is added to the nanolubricant to improve dispersion and stability of nanoparticles. Extreme pressure tribological tests are performed on a four-ball T-02 tribotester according to the ITEePib Polish method for testing lubricants under conditions of scuffing. Findings – The results show that the addition CuO and TiO2 nanoparticles under the presence of OA resulted in an increase of the load-carrying capacity (poz) of the lubricant up to 137 and 60 per cent, respectively. The seizure load was also increased by 50 and 15 per cent, respectively. Practical implications – The results show that CuO and TiO2 nanoparticles can be successfully used as additives improving extreme pressure properties of lubricants. Originality/value – This demonstrates the potential of nanoparticle additives using surfactants for improving the extreme pressure properties of lubricants. These nanolubricants can be used for metal-forming applications like deep-drawing, achieving an increased tool life.

Performance characteristics of rectangular aerostatic thrust bearing by conformal mapping

2018 ◽  
Vol 70 (8) ◽  
pp. 1457-1475
Author(s):  
Shang-Han Gao ◽  
Sheng-Long Nong
Keyword(s):  
Conformal Mapping ◽  
Pressure Distribution ◽  
Carrying Capacity ◽  
Thrust Bearing ◽  
Performance Characteristics ◽  
Load Carrying Capacity ◽  
Möbius Transform ◽  
Content Type ◽  
Air Supply ◽  
Load Carrying

Purpose This paper aims to analyze the pressure distribution of rectangular aerostatic thrust bearing with a single air supply inlet using the complex potential theory and conformal mapping. Design/methodology/approach The Möbius transform is used to map the interior of a rectangle onto the interior of a unit circle, from which the pressure distribution and load carrying capacity are obtained. The calculation results are verified by finite difference method. Findings The constructed Möbius formula is very effective for the performance characteristics researches for the rectangular thrust bearing with a single air supply inlet. In addition, it is also noted that to obtain the optimized load carrying capacity, the square thrust bearing can be adopted. Originality/value The Möbius transform is found suitable to describe the pressure distribution of the rectangular thrust bearing with a single air supply inlet.

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