Wide Range Measurement of Lubricant Film Thickness Based on Ultrasonic Reflection Coefficient Phase Spectrum

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Pan Dou ◽  
Tonghai Wu ◽  
Zhaopeng Luo
Keyword(s):  
Reflection Coefficient ◽  
Film Thickness ◽  
Phase Spectrum ◽  
Lubricant Film ◽  
Slight Variation ◽  
Lubricant Film Thickness ◽  
Blind Zone ◽  
Wide Range ◽  
Ultrasonic Reflection Coefficient ◽  
Highly Correlated

The ultrasonic technique is very effective in measuring lubricant film thickness in a noninvasive manner. To estimate the film thickness with reflection signals, two main ultrasonic models are often applied in cases of different film thicknesses; they are the spring model for thin films and the resonant model for thick films. However, when measuring oil film thicknesses distributed in a wide range, there is an inherent blind zone between these two models. This problem is especially prominent in online monitoring because the abrupt variation of film thickness is highly correlated with the occurrence of abnormal conditions. To address this issue, we further proposed a method using the phase spectrum of reflection coefficient which can cover a wide range of film thicknesses. The slight variation of reflection signal in the blind zone can then be identified and bridged the measurement gap between those two traditional models. A calibration rig was used to verify the theoretical analysis and the results indicated that the developed model is capable of providing reliable ultrasonic measurement of lubricant film thicknesses in a wide range.

Film Thickness Study of Lubricated, Compliant Contacts

2009 ◽  
Author(s):  
C. Myant ◽  
H. A. Spikes
Keyword(s):  
Film Thickness ◽  
Contact Area ◽  
Lubricant Film ◽  
Challenging Problem ◽  
Lubricant Film Thickness ◽  
Measuring Range ◽  
Metallic Contacts ◽  
Wide Range ◽  
High Roughness ◽  
Range Of Values

Obtaining lubricant film thickness values within a compliant contact is a challenging problem for several reasons [1]: • Lubricant film thickness covers a wide range of values. • The required measuring range is from fractions to hundreds of microns. • Contact area is considerably large when compared to “hard”, metallic contacts. • Many soft components have a high roughness compared to surfaces usually investigated with established techniques.

Elastohydrodynamic Film Thickness in Concentrated Contacts: Part 1: Experimental Investigation for Lubricant Entrainment Aligned with the Major Axis of the Contact Ellipse

1986 ◽  
Vol 200 (3) ◽  
pp. 207-217 ◽  
Author(s):  
R J Chittenden ◽  
D Dowson ◽  
C M Taylor
Keyword(s):  
Experimental Investigation ◽  
Film Thickness ◽  
Major Axis ◽  
Lubricant Film ◽  
Capacitance Measurement ◽  
Experimental Investigations ◽  
Lubricant Film Thickness ◽  
Wide Range ◽  
Experimental Apparatus ◽  
Contact Ellipse

Experimental investigations of the lubricant film thickness generated in elastohydrodynamic elliptical contacts have been undertaken since the early 1960s. The majority of these studies has been concerned with circular or near circular contact situations, although a wide range of geometries in which lubricant entrainment was directed along the minor axis of the contact ellipse has also been considered. The information available on lubricant film thickness in geometrical conditions where lubricant entrainment was aligned with the major axis of the contact ellipse has, however, been severely limited. The experimental investigation described in this paper is therefore concerned with the measurement of lubricant film thickness in the unusual geometrical conditions recently analysed theoretically by the authors (1, 2). The measurements were made with the aid of a twin disc machine for geometries ranging from a radius ratio of unity down to a value of 0.112. The experimental apparatus is described and details are given of the special test discs which were manufactured to produce such geometries. The capacitance measurement technique adopted is detailed along with the numerical model developed to allow the measured values of inter-disc capacitance to be interpreted in terms of the lubricant film thickness. The lubricant film thickness developed in four geometrical situations was investigated at four rotational speeds and five loads. This allowed a comparison to be made with the film thickness values predicted by recent elastohydrodynamic theory for changes in both speed and load. The film thickness deduced from the capacitance measurements was considered to be representative of that found at the centre of contact, and good agreement was found between experiment and all aspects of the theoretical predictions.

Study of Direct Measuring of Lubricant Condition in Rolling Element Bearings With Microcomputer Technique

1990 ◽  
Vol 112 (1) ◽  
pp. 92-97 ◽  
Author(s):  
Dongchu Zhao
Keyword(s):  
Film Thickness ◽  
Strain Gage ◽  
Lubricant Film ◽  
Rolling Element Bearings ◽  
Main Program ◽  
Test Apparatus ◽  
Lubricant Film Thickness ◽  
Rolling Element ◽  
Lubricant Films ◽  
Flow Charts

A method for measuring the lubricant condition with strain gage in rolling element bearings and the instrument used are introduced. In order to illustrate the method and the instrument, the theory of measuring lubricant films in rolling element bearings using strain technique, test apparatus, microcomputer hardware as well as software, flow charts for the main program and subprograms, are first described in detail. In addition, the lubricant film thickness is measured for several different lubricants and results are compared with theoretical ones. It is demonstrated that using the method and the instrument introduced in this paper, one can measure the lubricant condition inside bearings very accurately.

scholarly journals An investigation into the oil transport and starvation of piston ring pack

2018 ◽  
Vol 233 (1) ◽  
pp. 112-124 ◽  
Author(s):  
SR Bewsher ◽  
M Mohammadpour ◽  
H Rahnejat ◽  
G Offner ◽  
O Knaus
Keyword(s):  
Film Thickness ◽  
Boundary Conditions ◽  
Piston Ring ◽  
Gasoline Engine ◽  
Reverse Flow ◽  
Lubricant Film ◽  
Total Power ◽  
Lubricant Film Thickness ◽  
Piston Ring Pack ◽  
Ring Pack

In order to accurately predict the lubricant film thickness and generated friction in any tribological contact, it is important to determine appropriate boundary conditions, taking into account the oil availability and extent of starvation. This paper presents a two-dimensional hydrodynamic model of a piston ring pack for prediction of lubricant film thickness, friction and total power loss. The model takes into account starvation caused by reverse flow at the conjunctional inlet wedge, and applied to a ring pack, comprising a compression and scraper ring. Inlet boundaries are calculated for an engine cycle of a four-cylinder, four-stroke gasoline engine operating at 1500 r/min with conditions pertaining to the New European Drive Cycle. The analysis shows the two main sources of starvation: first, due to a physical lack of inlet meniscus and second, due to reverse flow at the inlet wedge significantly affecting the prevailing conditions from the generally assumed idealised boundary conditions. Such an approach has not hitherto been reported in literature.

Instrumented Engine Bearings for Lubricant Film Thickness Measurement

MTZ worldwide ◽  
2021 ◽  
Vol 83 (1) ◽  
pp. 28-37
Author(s):  
Henry Brunskill ◽  
Andrew Hunter ◽  
Hosung Nam ◽  
Junsik Park
Keyword(s):  
Film Thickness ◽  
Thickness Measurement ◽  
Lubricant Film ◽  
Lubricant Film Thickness ◽  
Film Thickness Measurement

Gear Tribology and Lubrication

2005 ◽  
pp. 19-38
Keyword(s):  
Film Thickness ◽  
Case History ◽  
Failure Modes ◽  
Gear Tooth ◽  
Lubricant Film ◽  
Flash Temperature ◽  
Lubricant Film Thickness ◽  
Film Lubrication

Abstract This chapter reviews the knowledge of the field of gear tribology and is intended for both gear designers and gear operators. Gear tooth failure modes are discussed with emphasis on lubrication-related failures. The chapter is concerned with gear tooth failures that are influenced by friction, lubrication, and wear. Equations for calculating lubricant film thickness, which determines whether the gears operate in the boundary, elastohydrodynamic, or full-film lubrication range, are given. Also, given is an equation for Blok's flash temperature, which is used for predicting the risk of scuffing. In addition, recommendations for lubricant selection, viscosity, and method of application are discussed. The chapter discusses in greater detail the applications of oil lubricant. Finally, a case history demonstrates how the tribological principles discussed in the chapter can be applied practically to avoid gear failure.

scholarly journals The Impact of Lubricant Film Thickness and Ball Bearings Failures

Lubricants ◽  
2019 ◽  
Vol 7 (6) ◽  
pp. 48 ◽  
Author(s):  
Matthew David Marko
Keyword(s):  
Film Thickness ◽  
Fatigue Failure ◽  
Failure Mechanisms ◽  
Roller Bearing ◽  
Lubricant Film ◽  
Theoretical Formula ◽  
Empirical Equations ◽  
Ball Bearings ◽  
Lubricant Film Thickness ◽  
The Impact

An effort was made to find a relationship between the lubricant thickness at the point of contact of rolling element ball bearings, and empirical equations to predict the life for bearings under constant motion. Two independent failure mechanisms were considered, fatigue failure and lubricant failure resulting in seizing of the roller bearing. A theoretical formula for both methods was established for the combined probability of failure using both failure mechanisms. Fatigue failure was modeled with the empirical equations of Lundberg and Palmgren and standardized in DIN/ISO281. The seizure failure, which this effort sought to investigate, was predicted using Greenwood and Williamson’s theories on surface roughness and asperities during lubricated contact. These two mechanisms were combined, and compared to predicted cycle lives of commercial roller bearing, and a clear correlation was demonstrated. This effort demonstrated that the Greenwood–Williams theories on the relative height of asperities versus lubricant film thickness can be used to predict the probability of a lubricant failure resulting in a roller bearing seizing during use.

Sign in / Sign up

Export Citation Format

Share Document