scholarly journals Effect of Coating and Low Viscosity Oils on Piston Ring Friction under Mixed Regime of Lubrication through Analytical Modelling

Lubricants ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 124
Author(s):  
Anastasios Zavos
Keyword(s):  
Coefficient Of Friction ◽  
Piston Ring ◽  
Roughness Parameter ◽  
Contact Conditions ◽  
Low Viscosity ◽  
Mixed Regime ◽  
Uncoated Steel ◽  
Coating Morphology ◽  
Friction Prediction ◽  
The Impact

This paper presents the impact of coating topography in piston ring-liner conjunction under mixed regime of lubrication using low viscosity oils. The study provides a time efficient analytical model including mixed-hydrodynamics regime of lubrication under different contact conditions. The method modified the expressions of the contact load and area of Greenwood-Tripp model in order to capture the real asperities interaction into contact. The model represents the tribological behavior of a thin top ring at Top Dead Centre, where boundary and mixed conditions are predominant. Electroplated CrN and PVD TiN coated rings were studied to predict the ring friction. The results are compared with an uncoated steel ring. The CrN coating shows slighter coefficient of friction, due to the coating morphology and roughness parameters. The TiN coating presents thicker lubricant films and higher coefficient of friction because the surface topography is quite rough with high peaks. This can be explained because of the major contribution of the roughness parameter and asperity slope in the boundary friction prediction.

Advanced Tribological Assessment of Ring Coatings

2012 ◽  
Author(s):  
Max Maschewske ◽  
Kimm Karrip ◽  
Carol Lynn Deck
Keyword(s):  
Coefficient Of Friction ◽  
Surface Finish ◽  
Internal Combustion Engines ◽  
Gas Flow ◽  
Piston Ring ◽  
Friction Reduction ◽  
Bench Test ◽  
Test Rig ◽  
Frictional Characteristic ◽  
The Impact

Friction reduction within the power cylinder assembly of internal combustion engines continues to be a one of the foremost focuses of engine manufactures. In an effort to better address this topic previously developed bench test rigs, such as the Falex, Cameron-Plint, and EMA-LS9 [1,2], have been utilized. These devices were formerly focused solely on wear mechanisms and material compatibility. Current development of new piston ring coatings has demanded significant refinements to the previously mentioned EMA-LS9 test rig for specific frictional characteristic evaluations. These developments have allowed for coefficient of friction ranking between various piston ring materials in addition to the influence and surface finish on coefficient of friction. This paper examines how the test rig is utilized to characterize upper compression ring materials, surface treatments, and the impact of surface finish. The significance of these results will be examined as it applies to analytical evaluations. From these calculations a demonstration of the effect of surface finish on ring dynamics and gas flow, as well as future piston ring coating developments will be discussed.

scholarly journals Identifying Critical Binder Attributes to Facilitate Binder Selection for Efficient Formulation Development in a Continuous Twin Screw Wet Granulation Process

Pharmaceutics ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 210
Author(s):  
Lise Vandevivere ◽  
Maxine Vangampelaere ◽  
Christoph Portier ◽  
Cedrine de Backere ◽  
Olaf Häusler ◽  
...  
Keyword(s):  
Dissolution Kinetics ◽  
Wet Granulation ◽  
Continuous Manufacturing ◽  
Formulation Development ◽  
Granulation Process ◽  
Low Viscosity ◽  
Twin Screw ◽  
Poorly Soluble ◽  
Selection For ◽  
The Impact

The suitability of pharmaceutical binders for continuous twin-screw wet granulation was investigated as the pharmaceutical industry is undergoing a switch from batch to continuous manufacturing. Binder selection for twin-screw wet granulation should rely on a scientific approach to enable efficient formulation development. Therefore, the current study identified binder attributes affecting the binder effectiveness in a wet granulation process of a highly soluble model excipient (mannitol). For this formulation, higher binder effectiveness was linked to fast activation of the binder properties (i.e., fast binder dissolution kinetics combined with low viscosity attributes and good wetting properties by the binder). As the impact of binder attributes on the granulation process of a poorly soluble formulation (dicalcium phosphate) was previously investigated, this enabled a comprehensive comparison between both formulations in current research focusing on binder selection. This comparison revealed that binder attributes that are important to guide binder selection differ in function of the solubility of the formulation. The identification of critical binder attributes in the current study enables rational and efficient binder selection for twin-screw granulation of well soluble and poorly soluble formulations. Binder addition proved especially valuable for a poorly soluble formulation.

Investigating the influence of carbon nanotube on the performance of asphalt binder

2021 ◽  
pp. 147776062110194
Author(s):  
Peerzada Mosir Shah ◽  
Mohammad Shafi Mir
Keyword(s):  
High Temperature ◽  
Asphalt Binder ◽  
Storage Condition ◽  
Modified Bitumen ◽  
Creep And Recovery ◽  
Low Viscosity ◽  
Temperature Performance ◽  
Modified Asphalt Binder ◽  
Viscosity Grade ◽  
The Impact

The purpose of this study aims at investigating the impact of multi-walled carbon nanotubes (MWCNT’s) on the properties of low viscosity grade asphalt binder. Asphalt binder with viscosity grade-10 is selected as the control binder and later it is modified with different percentages of MWCNT’s (0.5–2.5%). Penetration, softening point, ductility and rotational viscosity test were employed for evaluating the effect of MWCNT’s on basic physical properties of modified asphalt binder. Dynamic Shear Rheometer (DSR) is used for evaluating the rheological properties of the base and modified bitumen, for both aged and unaged bitumen. Based on the conventional and basic rheological tests, it was seen that the addition of MWCNT’s improved the high-temperature performance of modified bitumen. Multiple Stress Creep and Recovery (MSCR) test results revealed that the addition of MWCNT’s improved the creep and recovery of modified binders for both stress intensities (0.1 kPa and 3.2 kPa) which confirms that the modified binder is more rut resistant. Moreover, it was observed that there was a significant improvement in the aging resistance of the asphalt binder due to addition of MWCNTs. However low temperature performance of MWCNTs was not encouraging. Also, MWCNTs addition to asphalt binder was found to be stable under high-temperature storage condition. Overall, there is a significant amount of improvement using MWCNTs in the base asphalt binder.

scholarly journals An Effective Method for Preparation of Liquid Phosphoric Anhydride and Its Application in Flame Retardant Epoxy Resin

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2205
Author(s):  
Qian Li ◽  
Yujie Li ◽  
Yifan Chen ◽  
Qiang Wu ◽  
Siqun Wang
Keyword(s):  
Flame Retardant ◽  
Epoxy Resin ◽  
Epoxy Resins ◽  
Oxygen Index ◽  
Decomposition Temperature ◽  
Ease Of Use ◽  
Limiting Oxygen Index ◽  
Good Thermal Stability ◽  
Low Viscosity ◽  
The Impact

A novel liquid phosphorous-containing flame retardant anhydride (LPFA) with low viscosity was synthesized from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and methyl tetrahydrophthalic anhydride (MeTHPA) and further cured with bisphenol-A epoxy resin E-51 for the preparation of the flame retardant epoxy resins. Both Fourier transform infrared spectroscopy (FT-IR), mass spectrometry (MS) and nuclear magnetic resonance (NMR) measurements revealed the successful incorporation of DOPO on the molecular chains of MeTHPA through chemical reaction. The oxygen index analysis showed that the LPFA-cured epoxy resin exhibited excellent flame retardant performance, and the corresponding limiting oxygen index (LOI) value could reach 31.2%. The UL-94V-0 rating was achieved for the flame retardant epoxy resin with the phosphorus content of 2.7%. With the addition of LPFA, the impact strength of the cured epoxy resins remained almost unchanged, but the flexural strength gradually increased. Meanwhile, all the epoxy resins showed good thermal stability. The glass transition temperature (Tg) and thermal decomposition temperature (Td) of epoxy resin cured by LPFA decreased slightly compared with that of MeTHPA-cured epoxy resin. Based on such excellent flame retardancy, low viscosity at room temperature and ease of use, LPFA showed potential as an appropriate curing agent in the field of electrical insulation materials.

On the Impact of Liquid Drops on Immiscible Liquids

2016 ◽  
Author(s):  
Eduardo Castillo-Orozco ◽  
Ashkan Davanlou ◽  
Pretam K. Choudhury ◽  
Ranganathan Kumar
Keyword(s):  
Oil Spills ◽  
Silicone Oil ◽  
Density Ratio ◽  
High Viscosity ◽  
Impact Behavior ◽  
Immiscible Fluid ◽  
Liquid Droplets ◽  
Liquid Drops ◽  
Low Viscosity ◽  
The Impact

The release of liquid hydrocarbons into the water is one of the environmental issues that have attracted more attention after deepwater horizon oil spill in Gulf of Mexico. The understanding of the interaction between liquid droplets impacting on an immiscible fluid is important for cleaning up oil spills as well as the demulsification process. Here we study the impact of low-viscosity liquid drops on high-viscosity liquid pools, e.g. water and ethanol droplets on a silicone oil 10cSt bath. We use an ultrafast camera and image processing to provide a detailed description of the impact phenomenon. Our observations suggest that viscosity and density ratio of the two media play a major role in the post-impact behavior. When the droplet density is larger than that of the pool, additional cavity is generated inside the pool. However, if the density of the droplet is lower than the pool, droplet momentary penetration may be facilitated by high impact velocities. In crown splash regime, the pool properties as well as drop properties play an important role. In addition, the appearance of the central jet is highly affected by the properties of the impacting droplet. In general, the size of generated daughter droplets as well as the thickness of the jet is reduced compared to the impact of droplets with the pool of an identical fluid.

scholarly journals The impact of rheological uncertainty on dynamic topography predictions

Solid Earth ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 2167-2178 ◽  
Author(s):  
Ömer F. Bodur ◽  
Patrice F. Rey
Keyword(s):  
Mantle Convection ◽  
Numerical Experiments ◽  
Mantle Flow ◽  
Dynamic Topography ◽  
Density Anomaly ◽  
Low Viscosity ◽  
Local Reduction ◽  
Dynamic Components ◽  
Mantle Rheology ◽  
The Impact

Abstract. Much effort is being made to extract the dynamic components of the Earth's topography driven by density heterogeneities in the mantle. Seismically mapped density anomalies have been used as an input into mantle convection models to predict the present-day mantle flow and stresses applied on the Earth's surface, resulting in dynamic topography. However, mantle convection models give dynamic topography amplitudes generally larger by a factor of ∼2, depending on the flow wavelength, compared to dynamic topography amplitudes obtained by removing the isostatically compensated topography from the Earth's topography. In this paper, we use 3-D numerical experiments to evaluate the extent to which the dynamic topography depends on mantle rheology. We calculate the amplitude of instantaneous dynamic topography induced by the motion of a small spherical density anomaly (∼100 km radius) embedded into the mantle. Our experiments show that, at relatively short wavelengths (<1000 km), the amplitude of dynamic topography, in the case of non-Newtonian mantle rheology, is reduced by a factor of ∼2 compared to isoviscous rheology. This is explained by the formation of a low-viscosity channel beneath the lithosphere and a decrease in thickness of the mechanical lithosphere due to induced local reduction in viscosity. The latter is often neglected in global mantle convection models. Although our results are strictly valid for flow wavelengths less than 1000 km, we note that in non-Newtonian rheology all wavelengths are coupled, and the dynamic topography at long wavelengths will be influenced.

scholarly journals INFLUENCE OF ROUGHNESS ON THE TRIBOLOGICAL BEHAVIOR OF A STEEL-STEEL COUPLE LUBRICATED WITH THREAD COMPOUND

2019 ◽  
Vol 49 (3) ◽  
pp. 193-200
Author(s):  
N. A. ZABALA ◽  
P. CASTRO ◽  
Walter TUCKART
Keyword(s):  
Surface Roughness ◽  
High Pressure ◽  
Tribological Behavior ◽  
Normal Load ◽  
Roughness Parameter ◽  
Small Scale ◽  
Contact Conditions ◽  
Threaded Joints ◽  
Copper Zinc ◽  
Wear Damage

The purpose of this study is to determinate the influence of surface roughness on the tribological behavior of a lubricated steel against steel tribosystem. Tests were carried out at high pressure and slow sliding speed, in order to simulate at small scale, the contact conditions found in the seal of the threaded joints used in oil & gas casing and tubing strings. Tests were carried out with a simplified block-onring test, varying the surface roughness of rings between 1.3 to 3 m Ra values. A thread compound lubricant containing lead, copper, zinc and graphite was used. During each cycle of test, the normal load was varied linearly between 250 N and 7000 N. An exponential correlation between Ra and Rt roughness values with the wear damage was found and the wear damage of the blocks decreases about 40 percent with the increasing of initial Ra roughness parameter in the movil surface.

scholarly journals A Multi-Scale Approach for Nonlinear Dynamic Response Predictions With Fretting Wear

2016 ◽  
Author(s):  
J. Armand ◽  
L. Pesaresi ◽  
L. Salles ◽  
C. W. Schwingshackl
Keyword(s):  
Dynamic Response ◽  
Nonlinear Dynamic ◽  
Accurate Prediction ◽  
Fretting Wear ◽  
Contact Interface ◽  
Contact Conditions ◽  
Nonlinear Dynamic Response ◽  
Multi Scale ◽  
Highly Nonlinear ◽  
The Impact

Accurate prediction of the vibration response of aircraft engine assemblies is of great importance when estimating both the performance and the lifetime of its individual components. In the case of underplatform dampers, for example, the motion at the frictional interfaces can lead to a highly nonlinear dynamic response and cause fretting wear at the contact. The latter will change the contact conditions of the interface and consequently impact the nonlinear dynamic response of the entire assembly. Accurate prediction of the nonlinear dynamic response over the lifetime of the assembly must include the impact of fretting wear. A multi-scale approach that incorporates wear into the nonlinear dynamic analysis is proposed, and its viability is demonstrated for an underplatform damper system. The nonlinear dynamic response is calculated with a multiharmonic balance approach, and a newly developed semi-analytical contact solver is used to obtain the contact conditions at the blade-damper interface with high accuracy and low computational cost. The calculated contact conditions are used in combination with the energy wear approach to compute the fretting wear at the contact interface. The nonlinear dynamic model of the blade-damper system is then updated with the worn profile and its dynamic response is recomputed. A significant impact of fretting wear on the nonlinear dynamic behaviour of the blade-damper system was observed, highlighting the sensitivity of the nonlinear dynamic response to changes at the contact interface. The computational speed and robustness of the adopted multi-scale approach are demonstrated.

Experiments on the breakup of drop-impact crowns by Marangoni holes

2018 ◽  
Vol 844 ◽  
pp. 162-186 ◽  
Author(s):  
Abdulrahman B. Aljedaani ◽  
Chunliang Wang ◽  
Aditya Jetly ◽  
S. T. Thoroddsen
Keyword(s):  
Surface Tension ◽  
Lower Surface ◽  
High Viscosity ◽  
Solid Substrate ◽  
Immiscible Liquid ◽  
Hole Formation ◽  
Low Viscosity ◽  
Stress Changes ◽  
Lower Surface Tension ◽  
The Impact

We investigate experimentally the breakup of the Edgerton crown due to Marangoni instability when a highly viscous drop impacts on a thin film of lower-viscosity liquid, which also has different surface tension than the drop liquid. The presence of this low-viscosity film modifies the boundary condition, giving effective slip to the drop along the solid substrate. This allows the high-viscosity drop to form a regular bowl-shaped crown, which rises vertically away from the solid and subsequently breaks up through the formation of a multitude of Marangoni holes. Previous experiments have proposed that the breakup of the crown results from a spray of fine droplets ejected from the thin low-viscosity film on the solid, e.g. Thoroddsen et al. (J. Fluid Mech., vol. 557, 2006, pp. 63–72). These droplets can hit the inner side of the crown forming spots with lower surface tension, which drives a thinning patch leading to the hole formation. We test the validity of this assumption with close-up imaging to identify individual spray droplets, to show how they hit the crown and their lower surface tension drive the hole formation. The experiments indicate that every Marangoni-driven patch/hole is promoted by the impact of such a microdroplet. Surprisingly, in experiments with pools of higher surface tension, we also see hole formation. Here the Marangoni stress changes direction and the hole formation looks qualitatively different, with holes and ruptures forming in a repeatable fashion at the centre of each spray droplet impact. Impacts onto films of the same liquid, or onto an immiscible liquid, do not in general form holes. We furthermore characterize the effects of drop viscosity and substrate-film thickness on the overall evolution of the crown. We also measure the three characteristic velocities associated with the hole formation: i.e. the Marangoni-driven growth of the thinning patches, the rupture speed of the resulting thin films inside these patches and finally the growth rate of the fully formed holes in the crown wall.

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