Simulation of Sliding Wear in Mixed Lubrication

2007 ◽  
Vol 129 (3) ◽  
pp. 544-552 ◽  
Author(s):  
Dong Zhu ◽  
Ashlie Martini ◽  
Wenzhong Wang ◽  
Yuanzhong Hu ◽  
Bohdan Lisowsky ◽  
...  
Keyword(s):  
Surface Topography ◽  
Contact Pressure ◽  
Sliding Wear ◽  
Numerical Models ◽  
Elastohydrodynamic Lubrication ◽  
Numerical Approach ◽  
Engineering Practice ◽  
Wear Process ◽  
Local Contact ◽  
Wear Law

Sliding wear is a significant surface failure mode in many mechanical components. The magnitude of changes in surface topography due to wear may be comparable to or larger than the original surface roughness and elastic deformation. However, wear has rarely been incorporated into the numerical models used as predictive tools in engineering practice. This paper presents a numerical approach to simulate the wear process based on the deterministic mixed elastohydrodynamic lubrication (EHL) model developed and modified by Zhu and Hu (2001, Tribol. Trans., 44, pp. 383–398). It is assumed that wear takes place at locations where the surfaces are in direct contact, and the wear rate at those local contact spots is proportional to the relative sliding speed, the local contact pressure, and inversely proportional to the hardness of the surface. At each simulation cycle, the distributions of lubricant film thickness and contact pressure are calculated by using the mixed EHL model. The material removal at each contact location is evaluated and the surface topography modified correspondingly. The renewed surface topography is then used for the next cycle. The model is formulated such that any mathematically expressed wear law can be implemented, and therefore, the simulation can be applied to a wide variety of engineering applications.

Surface Topography Evolution of Engineered Surfaces during Sliding Wear

2021 ◽  
Vol 901 ◽  
pp. 199-207
Author(s):  
Deepak K. Prajaapti
Keyword(s):  
Surface Topography ◽  
Contact Pressure ◽  
Sliding Wear ◽  
Wear Model ◽  
Maximum Increase ◽  
Real Area Of Contact ◽  
Engineered Surfaces ◽  
Milled Surface ◽  
Very High ◽  
Insight Into

Due to experimental limitations, sometimes it is challenging to tackle the thorough change in asperity characteristics (contact pressure, real area of contact, asperity radius), which demands a more suitable analytical model for prediction of such characteristics. This work demonstrates an approach for modeling sliding wear that provides an insight into the evolution of surface topography with operational cycles. The wear model is applied on various engineered surfaces to study the change in surface topography with wear cycles. It is concluded that different engineered surfaces nearly with same roughness demonstrate totally different behavior during sliding wear. It is observed that milled surface in comparison to turned, honed and grinding surfaces experiences minimum contact pressure due to very high correlation length. Within the range of wear cycles, maximum increase in the asperity radius is observed for milled surface.

scholarly journals A Micropitting Study Considering Rough Sliding and Mild Wear

Coatings ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 639 ◽  
Author(s):  
Zhou ◽  
Zhu ◽  
Liu
Keyword(s):  
Surface Topography ◽  
Contact Fatigue ◽  
Elastohydrodynamic Lubrication ◽  
Surface Damage ◽  
Sliding Contact ◽  
Maximum Pressure ◽  
Surface Evolution ◽  
Mild Wear ◽  
As Stress ◽  
Wear Law

Micropitting is a typical surface contact fatigue in rolling–sliding contact. The kinematic sliding is of great significance in the initiation and progression of micropitting. A numerical surface fatigue model considering rolling–sliding contact and surface evolution is developed based on mixed-EHL (elastohydrodynamic lubrication) theory, rainflow cycle counting method and Archard’s law. Surface evolution is evaluated using Archard’s wear law based on measured teeth surface topography. Surface damage is determined via the Palmgren–Miner line rule and Goodman diagrams. The effect of rolling speed and surface roughness are discussed in detail. Results show that stress micro-cycles are introduced by rough sliding in the rolling–sliding contact. The mild wear reduces the height of asperities, the maximum pressure and alleviates subsurface stress concentration. For rolling–sliding contact, the faster moving surface dominates the composite height of asperities, then decides the fluctuations of pressure, as well as stress ranges. The combination of surface topography should be considered in the surface design.

Analysis and Modeling of Defects in Unsupported Overhanging Features in Micro-Stereolithography

2016 ◽  
Author(s):  
Vito Basile ◽  
Francesco Modica ◽  
Irene Fassi
Keyword(s):  
Finite Element ◽  
Numerical Models ◽  
Numerical Approach ◽  
Fe Analysis ◽  
Test Cases ◽  
Layer By Layer ◽  
Failure Condition ◽  
Micro Scale ◽  
Part Geometry ◽  
Shape Component

In the present paper, a numerical approach to model the layer-by-layer construction of cured material during the Additive Manufacturing (AM) process is proposed. The method is developed by a recursive mechanical finite element (FE) analysis and takes into account forces and pressures acting on the cured material during the process, in order to simulate the behavior and investigate the failure condition sources, which lead to defects in the final part geometry. The study is focused on the evaluation of the process capability Stereolithography (SLA), to build parts with challenging features in meso-micro scale without supports. Two test cases, a cantilever part and a bridge shape component, have been considered in order to evaluate the potentiality of the approach. Numerical models have been tuned by experimental test. The simulations are validated considering two test cases and briefly compared to the printed samples. Results show the potential of the approach adopted but also the difficulties on simulation settings.

Study of the Size Effects and Friction Conditions in Microextrusion—Part II: Size Effect in Dynamic Friction for Brass-Steel Pairs

2007 ◽  
Vol 129 (4) ◽  
pp. 677-689 ◽  
Author(s):  
Lapo F. Mori ◽  
Neil Krishnan ◽  
Jian Cao ◽  
Horacio D. Espinosa
Keyword(s):  
Grain Size ◽  
Friction Coefficient ◽  
Size Effect ◽  
Contact Pressure ◽  
Size Effects ◽  
Numerical Models ◽  
Kolsky Bar ◽  
Experimental Results ◽  
Material Response ◽  
Dynamic Coefficients

In this paper, the results of experiments conducted to investigate the friction coefficient existing at a brass-steel interface are presented. The research discussed here is the second of a two-part study on the size effects in friction conditions that exist during microextrusion. In the regime of dimensions of the order of a few hundred microns, these size effects tend to play a significant role in affecting the characteristics of microforming processes. Experimental results presented in the previous companion paper have already shown that the friction conditions obtained from comparisons of experimental results and numerical models show a size effect related to the overall dimensions of the extruded part, assuming material response is homogeneous. Another interesting observation was made when extrusion experiments were performed to produce submillimeter sized pins. It was noted that pins fabricated from large grain-size material (211μm) showed a tendency to curve, whereas those fabricated from billets having a small grain size (32μm), did not show this tendency. In order to further investigate these phenomena, it was necessary to segregate the individual influences of material response and interfacial behavior on the microextrusion process, and therefore, a series of frictional experiments was conducted using a stored-energy Kolsky bar. The advantage of the Kolsky bar method is that it provides a direct measurement of the existing interfacial conditions and does not depend on material deformation behavior like other methods to measure friction. The method also provides both static and dynamic coefficients of friction, and these values could prove relevant for microextrusion tests performed at high strain rates. Tests were conducted using brass samples of a small grain size (32μm) and a large grain size (211μm) at low contact pressure (22MPa) and high contact pressure (250MPa) to see whether there was any change in the friction conditions due to these parameters. Another parameter that was varied was the area of contact. Static and dynamic coefficients of friction are reported for all the cases. The main conclusion of these experiments was that the friction coefficient did not show any significant dependence on the material grain size, interface pressure, or area of contact.

A Survey of the Present State of Friction Modelling in the Analytical and Numerical Investigation of Brake Noise Generation

1999 ◽  
Author(s):  
Jörg Wallaschek ◽  
Karl-Heinz Hach ◽  
Ulrich Stolz ◽  
Parimal Mody
Keyword(s):  
Friction And Wear ◽  
Numerical Models ◽  
Engineering Practice ◽  
Noise Generation ◽  
Noise And Vibration ◽  
Levels Of Detail ◽  
Key Issues ◽  
Brake Noise ◽  
Automotive Brake

Abstract Noise and vibration have become key issues in the design of automotive braking systems. Efforts to improve present day braking systems must take noise and vibration behaviour into account. Good knowledge of the mechanisms involved in the generation of brake noise has thus become an important competitive factor in the design of automotive brake systems. The present paper summarizes some facts and hypotheses concerning the generation of brake noise. First the different brake noise phenomena are classified. Then several approaches, including models of various levels of detail which have been suggested to explain the root causes of brake noise generation are discussed in detail. It will be pointed out that friction and wear processes at the interface of brake pad and rotor play an important role in the understanding of brake noise generation. Unfortunately, our present day knowledge on these processes is quite limited. Further research of basic processes is still needed to improve the quality of analytical and numerical models of friction and wear processes, before reliable predictions of brake noise generation become possible. Based on a discussion of simple models frequently used in engineering practice, guidelines for further research in tribological modelling of the interface processes in pad/rotor interaction will be formulated.

The role of surface topography and normal load in the initiation of ratchetting-peak friction, seizure, scuffing, and elastic shakedown

2021 ◽  
pp. 1-12
Author(s):  
Vimal Edachery ◽  
V. Swamybabu ◽  
Gurupatham Anand ◽  
Paramasamy Manikandan ◽  
Satish V. Kailas
Keyword(s):  
Steady State ◽  
Surface Topography ◽  
Sliding Wear ◽  
Friction And Wear ◽  
Critical Parameter ◽  
Normal Load ◽  
Sliding Direction ◽  
Elastic Shakedown ◽  
Lubrication Conditions

Abstract Surface topography is a critical parameter that can influence friction and wear in engineering applications. In this work, the influence of surface topography directionality on seizure and scuffing initiation during tribological interactions is explored. For this, unidirectional sliding wear experiments were carried out in immersed lubrication conditions for various normal loads. The tribological interactions were studied using EN31-60 HRC flats and SAE52100-60HRC pins in a sphere on flat configuration. The results show that, in some cases, the sliding interactions in the initial cycles lead to a high friction coefficient of up to ∼0.68 in lubricated conditions, which was termed as ‘peak friction’, and this was accompanied by scuffing. The existence of peak friction was found to be dependent on surface topography directionality, especially when the directionality in topography was parallel to the sliding direction. Continuous ratchetting was found to be the cause of peak friction which was accompanied by seizure and scuffing. When the topography directionality was perpendicular or independent of sliding direction, elastic shakedown occurred at earlier cycles and prevented peak friction initiation, scuffing and also facilitated for higher steady-state friction values.

scholarly journals On the Two-Scale Modelling of Elastohydrodynamic Lubrication in Tilted-Pad Bearings

Lubricants ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 78 ◽  
Author(s):  
Gregory de Boer ◽  
Andreas Almqvist
Keyword(s):  
Surface Topography ◽  
Load Capacity ◽  
Three Dimensional ◽  
Elastohydrodynamic Lubrication ◽  
Multiscale Methods ◽  
Operating Conditions ◽  
Real Surface ◽  
Micro Scale ◽  
Macro Scale ◽  
Heterogeneous Multiscale

A two-scale method for modelling the Elastohydrodynamic Lubrication (EHL) of tilted-pad bearings is derived and a range of solutions are presented. The method is developed from previous publications and is based on the Heterogeneous Multiscale Methods (HMM). It facilitates, by means of homogenization, incorporating the effects of surface topography in the analysis of tilted-pad bearings. New to this article is the investigation of three-dimensional bearings, including the effects of both ideal and real surface topographies, micro-cavitation, and the metamodeling procedure used in coupling the problem scales. Solutions for smooth bearing surfaces, and under pure hydrodynamic operating conditions, obtained with the present two-scale EHL model, demonstrate equivalence to those obtained from well-established homogenization methods. Solutions obtained for elastohydrodynamic operating conditions, show a dependency of the solution to the pad thickness and load capacity of the bearing. More precisely, the response for the real surface topography was found to be stiffer in comparison to the ideal. Micro-scale results demonstrate periodicity of the flow and surface topography and this is consistent with the requirements of the HMM. The means of selecting micro-scale simulations based on intermediate macro-scale solutions, in the metamodeling approach, was developed for larger dimensionality and subsequent calibration. An analysis of the present metamodeling approach indicates improved performance in comparison to previous studies.

scholarly journals Cavitation Erosion and Sliding Wear of MCrAlY and NiCrMo Coatings Deposited by HVOF Thermal Spraying

2020 ◽  
Vol 20 (2) ◽  
pp. 26-38 ◽  
Author(s):  
M. Szala ◽  
M. Walczak ◽  
L. Łatka ◽  
K. Gancarczyk ◽  
D. Özkan
Keyword(s):  
Wear Resistance ◽  
Sliding Wear ◽  
Cavitation Erosion ◽  
Erosion Resistance ◽  
Nickel Content ◽  
Thermal Spraying ◽  
Point Of View ◽  
Engineering Practice ◽  
Hvof Thermal Spraying ◽  
Cavitation Erosion Resistance

AbstractThe investigation into wear resistance is an up-to-date problem from the point of view of both scientific and engineering practice. In this study, HVOF coatings such as MCrAlY (CoNiCrAlY and NiCoCrAlY) and NiCrMo were deposited on AISI 310 (X15CrNi25-20) stainless steel substrates. The microstructural properties and surface morphology of the as-sprayed coatings were examined. Cavitation erosion tests were conducted using the vibratory method in accordance with the ASTM G32 standard. Sliding wear was examined with the use of a ball-on-disc tribometer, and friction coefficients were measured. The sliding and cavitation wear mechanisms were identified with the SEM-EDS method. In comparison to the NiCrMo coating, the MCrAlY coatings have lower wear resistance. The cavitation erosion resistance of the as-sprayed M(Co,Ni)CrAlY coatings is almost two times lower than that of the as-sprayed NiCrMoFeCo deposit. Moreover, the sliding wear resistance increases with increasing the nickel content as follows: CoNiCrAlY < NiCoCrAlY < NiCrMoFeCo. The mean friction coefficient of CoNiCrAlY coating equals of 0.873, which almost 50% exceed those reported for coating NiCrMoFeCo of 0.573. The as-sprayed NiCrMoFeCo coating presents superior sliding wear and cavitation erosion resistance to the as-sprayed MCrAlY (CoNiCrAlY and NiCoCrAlY) coatings.

The Effect of Tooth Wear on the Vibration Spectrum of a Spur Gear Pair

2001 ◽  
Vol 123 (3) ◽  
pp. 311-317 ◽  
Author(s):  
J. H. Kuang ◽  
A. D. Lin
Keyword(s):  
Dynamic Load ◽  
Sliding Wear ◽  
Vibration Spectrum ◽  
Tooth Wear ◽  
Spur Gear ◽  
Damping Factor ◽  
Gear Pair ◽  
Mesh Stiffness ◽  
Wear Process ◽  
The Mathematical Model

In this paper, the effect of tooth wear on the vibration spectrum variation of a rotating spur gear pair is studied. In order to approximate the dynamic characteristics of an engaging spur gear pair, the load sharing alternation, position dependent mesh stiffness, damping factor and friction coefficient are considered in the mathematical model. The wear prediction model proposed by Flodin et al. is used to simulate the tooth profile wear process. The variation of the vibration spectra introduced from the interaction between the sliding wear and the dynamic load is simulated and analyzed. Numerical results indicate that the dynamic load histogram of an engaging spur gear pair may change greatly with the tooth wear. This finding implies that the variation of the gear vibration spectrum might be used to monitor the tooth wear of an engaging spur gear pair.

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