Questions related to Tribology
Hello fellow researchers
i am working on cermets tribology and using pin on disk methods with disk made of cermet sliding against a diamond pin.the tribometer data gives wear volume(mm3),wear rate(mm3/m) and cof with an interval of 0.328 seconds.the sliding istance is approximately 200m.thus we have a lage amount of plotted data.i have a few confusions which i want to clarify
1)total Wear volume is the total sum of all all data points?( i assume it is) or an average of all data points should be considered
2)Total wear rate?average or sum?( i assume sum is the right option)
3) cof?( i assume an average of all datapoints should be taken)
another question regarding wear coefficient k=wearvol(mm3)*hardness vickers(in mpa)/load(N)*total sliding distance(mm)
wear vol=i took sum of all data plots
hardness=avg hardness of test samples
distance=Distance in mm
one measurement gave a wear cof of 1.5e-06 which is good for cemented carbides(i assume)
am i following the correct methodology here?
please find enclosed image of some readings for guidance.
During dry sliding wear tests, the worn surfaces of magnesium alloys are oxidized at a specific load and sliding velocity. I want to know that in magnesium matrix composites, adding reinforcing particles (such as B4C) can prevent or postpone this oxide formation or not
I am doing some tribological tests with a reciprocal sliding tribological test.
To calculate the wear rate, the wear volume is needed with high accuracy. Do you have any accurate and easy method(s) to evaluate that wear volume? I have already tried some imaging with 3D digital microscopy but the initial roughness of the substrate makes the measurement difficult.
Thank you in advance,
Dear fellow contact mechanicians,
I just stumbled over a problem in analytic mechanics of plane Cattaneo problems in the presence of bulk stress.
It is said that the Ciavarella-Jäger principle for "small enough bulk stress" applies to this problem in the following form:
q(x) = \mu*(p(x; P, beta = 0) - p(x; P - Q/mu, beta)),
where q(x) is the tangential contact traction distribution, p(x) the pressure distribution, P the normal line load, Q the tangential line load, mu the friction coefficient and beta a "rotation angle" proportional to the bulk stress, which I will discuss in a minute.
The second term on the right side in above equation corresponds to a "fictious" normal contact problem of the same contacting bodies under the load (P - Q/mu) and with a relative rotation by beta.
The condition of "small enough bulk stress" is basically that the contact area for this "fictious" problem (which corresponds to the stick region in the actual Cattaneo problem), completely lies within the actual contact area. Moreover, a non-zero value of beta will increase the contact length on one side and decrease it on the other side. So, e.g., for Q = 0 the condition of "moderate bulk stress" is actually that beta = 0, i.e., there is no bulk stress.
Now, we know that tangential contact problems have a loading history. Even the Cattaneo problem has a history: first the normal load is applied, and then an increasing tangential load. However, when beginning to apply the tangential load, Q equals zero, so any (constant) bulk stress will violate the "moderate bulk stress condition".
Or to put it more generally: For any non-zero constant bulk stress, the "moderate bulk stress condition" is violated at the beginning of tangential loading.
Does that change anything about the final contact configuration at the end of the Cattaneo loading?
Or am I missing something?
Thank you very much for your help!
I found the following statement in a book on page 581:
"If, in a particular timestep a converged result is obtained with a negative calculated film thickness, then the most negative film thickness is set to zero."
Dowson, D., Priest, M., Dalmaz, G., & Lubrecht, A. A. (Eds.). (2003). Tribological Research and Design for Engineering Systems: Proceedings of the 29th Leeds-Lyon Symposium. Elsevier.
What exactly happens when the film thickness is zero? Can anyone explain this to me? I will greatly appreciate it.
I'm currently working on ball-on-disk tribological test using different oils.
Is there a direct relation between the coefficient of friction and the lubrication regime of the coupled surfaces?
Is the resulting coefficint of friction related to the materials properties or the lubricant properties? Or both of them?
Thank you to all that would help me.
I have a device with confriguration Au/PVDF/Au. The connections are taken from the gold electrode using copper tape and over that I have soldered copper wire and finally they are connected to DSO. When I am tapping the device (on gold electrode), then gold electrode is behaving as one tribo layer and my hand is behaving like a ground. So, now the device is behaving like a single-electrode TENG. How can I separate out piezosignal out of this tribo signal? If anybody have any idea then please share.
I am working on Mg composites fabricated by powder metallurgy. I have investigated the wear behavior of Mg-based composites with variation in temperature. I observed that wear rate increased with an increase in the wear temperature. Can anyone explain me in detail, why is it happening? What is the mechanism? I am looking for your responses.
Thank you so much.
To achieve superlubricity in two-dimensional heterostructures, do we need to stack it at a certain angle? or directly through mechanical exfoliation, we can achieve superlubricity in 2D heterostructures. Please provide some useful suggestions.
I am aware of the concept of commensurate and incommensurate, but in the heterostructure, do we need to follow that?
in my research group we would like to evaluate how the asperities of two rough planes deform when we press them together. We would like to use Abaqus, due to its advanced contact mechanics algorithms. It is not clear to us, though, how to model rough surfaces with certain statistics in Abaqus. Anyone knows any CAD software/code that could generate these models and be easily integrated with Abaqus?
Is there a relation between thermophysical properties (density, specific heat, viscosity, thermal conductivity) of fluids on tribological properties (friction coefficient, friction force)?
Please recommend some useful books or literature? need feed back
Is it possible to change or form new chemical bonding using frictional heating during high sliding operations?
A few years ago I and my colleague Peter Wall wrote a short summary for Switch Function and and Complementarity Problem based formulations in a chapter which is available Open Access:
Andreas Almqvist and Peter Wall (October 26th 2016). Modelling Cavitation in (Elasto)Hydrodynamic Lubrication, Advances in Tribology, Pranav H. Darji, IntechOpen, DOI: 10.5772/63533. Available from: https://www.intechopen.com/books/advances-in-tribology/modelling-cavitation-in-elasto-hydrodynamic-lubrication
Since there are many more models for cavitation in lubrication flows it would be interested to hear from the community which ones you think are the most suitable ones and in which situations they should/could be applied.
Chicken eggshell (Es) waste is an industrial byproduct, and its disposal constitutes a severe environmental risk. Eggshell is a new engineering reinforcement retaining excellent properties such as low density, renewable, eco-friendly, and high thermal stability. The researcher aims to study the effects of eggshell particle addition on microstructures, mechanical and tribological properties of aluminum/eggshell green metal matrix composites (MMCs) but how?
what are the drawbacks of the addition of waste eggshells with (MMCs) composite?
Good Afternoon to all ..
I hope you are all safe and healthy.......
I have one doubt please let me know what are the tribological properties we should take for while making of composite gear.....
I hope for your immediate response....
Hello Every one,
I have the velocity of two particles before and after impact and all the forces components during the impact. I need a formula that gives the surface penetration speed during tribological surface finishing. For forces and velocity, they are obtained after a DEM simulation but I need the surface penetration speed to calculate the amount of material removal.
Dear all I need to do errosion simulationfor tribology application in ansys fluent, as I am not familiar very well, I have some question.
We have a surface which being hited by water and sand, I defined K-epsilon modeling, disceret phase modeling,
Now my question is how can I get angel to the particles? I want to define for example, liquid and particle hit to the surface with the angel of 30 degree, and go out from outlet with this angel but I could not find any thing related.
Any body can help?
And there is any important point that I should consider?
I am a third year Biomedical Student at the University of Wollongong and I am currently completing an assignment on manufacturing processes involved in biomedical technology. I have selected the Total Hip Arthroplasty (THA) and recently read a journal 'Tribological assessment of a flexible carbon-fibre-reinforced poly(ether—ether—ketone) acetabular cup articulating against an alumina femoral head.' (Scholes, Inman, Unsworth and Jones, 2008) and am very intrigued by the CFR-PEEK design of the acetabular cup. I would like to understand the steps involved in developing such a piece.
Have there been any developments in using this material?
Thanks for your time!
I have data from an experiment conducted to measure kinematic co-efficient of friction. But to know how much slipping force is required to slip the interfaces (steel plates) , I need static co-efficient of friction (the threshold value). Is there any relation available to calculate this?
I wanna get ultrasonic vibrations using a screen generator of 300 watts and 33kHz frequency.
Is it possible to use that generator to study ultrasonic vibrations effect on tribological behavior of materials?
Or I need other materials for this purpose? like piezo actuators, amplifiers, ultrasonic generators?
Hi! I´m having problems trying to identify any compounds in this Raman spectrum. I´ve used a 532 nm laser.
This is a spectrum obtained from a steel ball, rubbed against a Bi2S3 coating. I´ve checked in other papers for the characteristic bands of Bi2S3, Bi2O3, magnetite, hematite, etc but I´m a little bit thrown off, specially for the bands at 1465 and 1520 cm-1.
XT-CF20 is a composite material composed of temperature-resistant co-polyester reinforced with 20% carbon fibers. This material is non-conductive with low tribology property. Could you propose a strategy to coat that material with Ni metal?
We had performed tribological experiments of magnetic fluids under the influnce of magnetic field. I want to perform the simulations of those experiments. Which is the best software for the simulation of effect of magnetic field on magnetic fluids? Suggestions are needed in this regard.
We have created a TENG, using PTFE ball and Aluminum electrode in vertical Contact separation mode. The output measured using a high precision Multimeter was 0.3 V. But when we tried to measure current by connecting a resistor in series, and by short circuiting, the output was zero. Can someone point out the problem behind this ?
I would like to conduct scratch and linear reciprocating tribo-test on my magensium alloy, which has a plasma electrolytic oxide (PEO) layer of about 20 um and 10 - 20 um of Parylene coating on top of it. So it is a double layer system.
I made a research on ASTM standard tests for scratch and linear reciprocating tribo-test and I found ASTM C1624 - 05 for the first and ASTM G133 - 05 for the second. However, I am not sure if these standards are applicable to a double layer coatings as in my system.
Are there some specific standard tribological tests for multilayer coatings?
Tribology test conditions: Substrate thermoplastic, Counterpart steel ball. Using 1N normal force and 0.5N normal force, Speed 100 mm/s
The empirical equation that i'm looking for, is required to be able to calculate the amounts of cohesion and internal friction angle by using Uniaxial compressive strength and elastic modulus.
What according to you should be researched/accessed with respect to WC based solid lubricant tools? What is your view with respect to future research in this area? (For e.g. Tribological study etc..)
Thanks in advance..
What are the main tribological parameters for sliding and impact abrasion mechanisms, other than initial material hardness controlling the wear behavior ?
Suppose i am performing ball on disc tribological tests under lubricated conditions containing nanoparticles. After the test i wash the sample with Acetone or Benzene, will the EDS analysis show the trace of nanoparticles???
Can steel pin of the pin on disk tribometer setup be used in doing wear rate testing of sintered Alumina??
Basically there are three parameters like speed, sliding distance and load in pin on disk apparatus . I want to know how can we select these parameters for testing hybrid fiber composited reinforced with polymers . With use of the Taguchi technique and Annova or any other methods for optimization.
If no what could be the reason for obtaining two different tribolayer of different colors viz. light grey and light grey shiny during on the wear track?
Archard's law does not consider the hardness of both the material.
No Sliding velocity term present
No Temperature term
Non-linear behavior of Wear coefficient not considered.
Are there better laws that can predict wear better.
some metal surfaces, rubbed against each other squeaks in a shrilling high frequency. Why? What is the role of surface roughness, friction factor, geometric shape, stress distribution,solid and medium sound velocity, strength, resilience and microstructure to frequency spectrum of the sound? Are there any set of differential equations that describe this phenomena? How to construct a model concerning the phenomena?
As there are a lot of works that are published over the years that compare the mechanical properties to abrasive wear behaviour. According to Lancaster model, the UTS, elongation (total) and hardness considered alone are can be sometimes related to abrasive wear behaviour. However, the combination of afore-mentioned mechanical properties can be related. similar study was conducted by Ratner et al. where they relate the stress and strain at rupture to abrasive wear that is in good agreement. On what basis we relate the mechanical properties with tribological properties.
The misconception of Cloud-cloud collision is unable to show continuous triboelectric effect and charge differentiation of clouds. Rather, now charge exchange. Rather, wikipedia mentioned charge exchange between uprising supercooled water and ice droplets and Graupel (soft haill).
But both are nearly same material (water and ice)- why and do they exchange charge? even if they dow, how only state and crystallinity change of a material can change its triboelectric properties? Is there any structure-property justification of triboelectric series, anyway?
The coating will be base on Siloxane or PTFE or any other inorganic material. The coating will cure at room temp. or ypto 250 degree centigrade temperature. The continues temperature will be 450 degree centigrade.
As they both follow Reynolds euqation and the same elastic deformation law, is there difference between the numerical model of them?
Researchers have explored relations between mechanical and tribological properties and still this process is on. I just wanted to ascertain if there is any possible relation ship between compressive strength and wear rate of metal matrix composites.
I have begun studying Contact Mechanics very recently, and I am having trouble in understanding the Reduced Young's Modulus (E*).
I have looked at several different books, and I haven't been able to understand why they define E* differently.
When two bodies of Young's Moduli E1 and E2, and Poisson's ratios of v1 and v2 are in contact, I have seen the following definitions:
1) as seen in the attachment 1.PNG:
1/E* = (1-v1²)/E1 + (1-v2²)/E2
2) as seen in the attachment 12.PNG:
1/E* = (1/2)*((1-v1²)/E1 + (1-v2²)/E2)
The first approach would result in a value of E* that is lower than both E1 and E2, while the second approach yields a value of E* that is between E1 and E2.
Another thing that makes me curious is that the first approach is more frequent in books, while I have only seen the second one in a couple of books and papers. But, for some reason, most of the online calculators for contact mechanics agree with the second approach.
Certainly, I am failing to understand this matter properly and, if possible, I would like to know the difference between both approaches with your assistance.
Thank you very much.
The knowledge of tribology is useful in reducing the unnecessary friction and wear between two rubbings surfaces or tribopair. Using tribology appropriate lubricant and lubrication mechanism can be adopted to minimize the friction and eliminate wear which would reduce the wastage of energy and enhance working life of tribopair.
Please add some more answers
I am doing nano scratch experiments on metallic glasses (thin films). In particular I did a series of constant load scratches. Generally if one does scratch testing at different loads, the COF can be divided into several regimes. 1st, adhsion dominated elastic only (COF decreases with increasing load), 2nd elastic plastic transition zone (COF inceases with increasing load) and 3rd plastic zone (COF stabalizes). Now when doing several constant scratches in the range of 10-10.000uN, it can be seen that the COF first decreases from around 0.3 (10uN) to 0.007 at 1000uN and then increases again to about 0.12, where it stabalizes at around 4000-6000uN. Does anyone know how it is possible to gain such a low COF at 1000uN? Im using a Hysitron Ti980 triboindenter and a conical indenter with a hemispherical tip with a radius of about 5um (dimond tip). A similar behavior can be seen in DLC coatings, however with a higher COF.
1-hardness of hard material is not considered
2-not discuss multipass
3-not addressed the role of wear debris size and shape
4-hardness after experiment not considered.
I wish to know more points, apart from the above plz suggest.
I want to find data about oil viscosity, water in oil, metallic wear debris particles for condition monitoring for electromechanical systems. The data should be monitored by online sensors because the sampling period of offline analysis is large. Let me know if you have any suggestion.
In my wear results, the effect of parameter will give different results for wear volume loss and wear rate. For instance, the wear volume loss is increase with the increase of applied load, However, if I use wear rate, the wear volume loss will divided with load and sliding distance which will make the wear rate decrease with increasing applied load. So which one I should use i.e. wear volume loss or wear rate to report my wear data?
For our final year project we thought of doing viscosity,wear and friction in nano Lubricant but our professor says there will be no change in viscosity. So what are the other options we have?
I want to coat over a small area with the diameter of the circular area being just 3 mm. The coating material is epoxy nanocomposite with a inorganic filler and the material has to be coated over the Pin of pin on disc tribometer.
Suppose I test sliding wear resistance of a nanocomposite material using a pin on disc tribometer. Now once I get the specific wear rate can I use it to predict the wear rate of the same material when it is used as a coating over a substrate. Is there any standard to do the same ?
I am enrolled in 1st year PhD, in November 2018 at the Faculty of Science and Technology, Department of Science of the material,, chemistry specialty of the University of khenchela- Algiers.
The subject that I intend to develop in my thesis is Synthesis and structural, electrochemical and tribological characterization of a nanostructured titanium-based compound (Ti-Ni) for biomedical applications .
i'm searching for co superviseur to make an international convention to start my research in TiNi
I want to improve the wear resistance of a clinical implant that its tribologic properties are significant. but I don't know precisely which implant has poor wear resistance
Two experiments were carried out: one with mineral oil and other with vegetable oil. In case of mineral oil the trend of Stribeck curve is followed but in vegetable oil it is opposite. Each test was done five times hence no experimental error is possible.
In tribology of polymer cases we know that:
In contrast to other materials, the tribological properties of polymers depend on the tensile strength and the toughness rather than on the hardness. Due to their thermal properties, polymers are very sensitive to frictional heating. Please suggests in case of friction stir welding of polymer, property mainly depend on tensile strength or toughness or hardness?
Your opinion is highly appreciated
In normal tribological condition when silding speed increase wear volum loss increase but at certain increasing speed wear volum loss deacrease, why?
A fish in river forming tribo couple where 2nd and 3rd system is water.
Can you tell me some more example where 2nd and 3rd system is same.
On conducting ball on disc test, i found friction and wear rate of pure copper sample increases initially with load then it starts decreasing with load. On analyzing the SEM micrographs ( cannot share due to plagiarism issues), i found initially with increase in load abrasive wear occurs then on further increasing the load adhesion becomes the major wear event. Is there any other study, which supports my result? If it is there, Plz give me the reference.
gravel road is three body abrasive wear,
smooth road is two body abrasive wear.
I had a mineral oil of 460cSt (containing sulphur and phosphorus), after addition of nanparticles (carbon nano tubes and graphene) the viscosity decreased significantly. literatures says that the presence of asphaltenes and nanoparticles may lead to a decrease in viscosity.
We found that sliding of cartilage against an artificial meniscus could increase friction during the swing phase and long term elevated friction could cause cartilage wear.
I have deposited pure Cr and W films by unbalanced magnetron sputtering method and then prepared films by doping them with Ag. The hardness and modulus of these coatings are lower than that of the pure films. What can be the main reason behind this ? Usually addition of another element increases hardness and modulus.I would really appreciate any research article or help from experts.
Thank you !!
Hello, just a quick question, why do we use tests in the tribological laboratories of bovine serum, diiodomethane ... to check the wettability of dlc ?
I am following “Hydrodynamic Lubrication by Yokio Hori’’.
Stability of a Rotating Shaft—Oil Whip
Femoral head and acetabular cup generally has ball-socket joint with conformal contact. Many research papers have taken either line contact or point contact (in reciprocating tribometer) and a few have taken surface contact to demonstrate tribological performance of Hip Implant materials.
Can anybody explain this?
During XRD i found the peaks of CuAl2O4, CuMo2S3, AlB12 compounds and i want to know the effect of these compounds on tribological properties of Copper matrix composite during dry sliding. Plz tell If there is some literature available regarding this.
I am designing experiments to study the tribological behaviour of coated Ti6Al4V in synovial fluid. Any help would be highly appreciated.