Multi-physics analysis of valve train systems: From system level to microscale interactions

Teodorescu, Mircea; Kushwaha, Manvir S.; Rahnejat, Homer; Rothberg, Steve

doi:10.1243/14644193jmbd77

Cited by 29 publications

(40 citation statements)

References 19 publications

(30 reference statements)

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“…Additionally, boundary shear strength of surfaces contributes to friction, given by ς . For surfaces with a layer of ferrous oxide: (27) where ζκσ is the roughness parameter (Bowden and Tabor (28)), ' E is the equivalent plane strain elastic modulus of the counterfaces and the statistical functions are of the form:…”

Section: Frictionmentioning

confidence: 99%

The influence of piston ring geometry and topography on friction

Morris

Rahmani

Rahnejat

et al. 2012

Proceedings of the Institution of Mechanical Engineers, Part J:

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This article provides solution for isothermal mixed hydrodynamic conjunction of the compression ring to cylinder liner. This is obtained using the average flow model representation of Reynolds equation based on pressure- and shear-induced flow factors. In particular, the effects of compression ring axial profile along its face-width and surface topography of contiguous solids are investigated. It is shown that ring geometry may be optimized to improve lubrication, whilst care should be taken in order to avoid oil loss or degradation resulting from any loss of sealing. In predicting friction, it is shown that appropriate surface parameters should be used in-line with the state of wear of the ring. For a new ring against a plateau honed liner, boundary friction contribution during the initial running-in wear phase should be predicted according to the average asperity peak heights protruding above the plateau, whilst the plateau height also takes into account the valleys within the surface roughness or grooves created by any cross-hatch honing would be the appropriate measure of topography for worn rings. The main contributions of the article are in providing an analytic solution as well investigation of ring face-width geometry and effect of wear upon friction. However, it is acknowledged that generated heat, inlet boundary starvation and circumferential non-conformity of ring to the bore surface would affect the film thickness and exacerbate generated friction accordingly. These further considerations would require a numerical solution, rather than an analytical one presented here.

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Section: Frictionmentioning

confidence: 99%

The influence of piston ring geometry and topography on friction

Morris

Rahmani

Rahnejat

et al. 2012

Proceedings of the Institution of Mechanical Engineers, Part J:

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“…Generally, if the average film thickness is less than three times the composite surface roughness, the surface asperities will force direct solid-solid contact [15,17]. In this study, we measure the surface roughness of the crank pin journal and bearing.…”

Section: Resultsmentioning

confidence: 99%

Evaluation of lubrication performance of crank pin bearing in a marine diesel engine

2018

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Abstract:In this study, the lubrication performance of the crank pin bearing in a marine two-stroke diesel engine is evaluated to investigate the adhesional failure on the crank pin bearing. A numerical algorithm for the lubrication analysis considering motion analysis of the crank pin system is developed. The film pressure and thickness for three clearances and three lubricant temperatures are calculated. The results show that the lubricant temperature has a higher effect on film thickness than clearance. In terms of the film parameter, the operating condition that can result in solid-solid contact is investigated. We also suggest the desirable operating conditions of clearance and lubricant temperature to prevent the solid-solid contact.

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“…Boundary friction is due to the interaction of counterface asperities, as well as any pockets of lubricant entrapped between them, which are assumed to be subject to the limiting Eyring [25] shear stress as [9]:…”

Section: The Numerical Modelmentioning

confidence: 99%

“…As the result, many contacts suffer from a lack of a coherent lubricant film where a proportion of applied load is carried by the ubiquitous asperities on the counterface surfaces. These interactions increase the generated friction, for example in the cases of piston-cylinder system at dead centre reversals [5][6][7][8] and cam-follower contact in the inlet reversal positions [9]. Various palliative actions are undertaken in order to mitigate these adverse effects within the mixed regime of lubrication, including the use of hard wear-resistant coatings.…”

Section: Introductionmentioning

confidence: 99%

Surface specific asperity model for prediction of friction in boundary and mixed regimes of lubrication

et al. 2016

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Machine downsizing, increased loading and better sealing performance have progressively led to thinner lubricant films and an increased chance of direct surface interaction. Consequently, mixed and boundary regimes of lubrication are prevalent with ubiquitous asperity interactions, leading to increased parasitic losses and poor energy inefficiency. Surface topography has become an important consideration as it influences the prevailing regime of lubrication. As a result a plethora of machining processes and surface finishing techniques have emerged. The stochastic nature of the resulting topography determines the separation at which asperity interactions are initiated and ultimately affect the conjunctional load carrying capacity and operational efficiency. The paper presents a procedure for modelling of asperity interactions of real rough surfaces, from measured data, which do not conform to the usually assumed Gaussian distributions. The model is validated experimentally using a bench top reciprocating sliding test rig. The method demonstrates accurate determination of the onset of mixed regime of lubrication. In this manner, realistic predictions are made for load carrying and frictional performance in real applications where commonly used Gaussian distributions can lead to anomalous predictions.

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Multi-physics analysis of valve train systems: From system level to microscale interactions

Cited by 29 publications

References 19 publications

The influence of piston ring geometry and topography on friction

The influence of piston ring geometry and topography on friction

Evaluation of lubrication performance of crank pin bearing in a marine diesel engine

Surface specific asperity model for prediction of friction in boundary and mixed regimes of lubrication

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