Friction Values Research Articles

Development of Innovative Plate Load Testing Equipment for In-Situ Saturated Clays Soils

This study proposes a method of gradually loading plate load on-site using lever arms to squeeze out pore water from clayey soils, allowing the soil to settle. Several types of tests were conducted, including a conventional field plate load test (CFPLT), a numerical field plate load test (NFPLT) and an innovative field plate load test (IFPLT) proposed in this study. Three trial pits with soils of varied engineering properties were studied using CFPLT, which employed the use of a heavy jack for load application, the NFPLT test using PLAXIS and an IFPLT, which employed a lever arm to magnify the applied static load. Disturbed soil samples collected from these trial pits were tested for index properties while the undisturbed soil samples were tested using the undrained triaxial compression test (UTCT) and laboratory consolidation tests. The results of the index properties classified these three clay soils as silt of low plasticity (ML) for clay from site 1, and clay of low plasticity (CL) for clay from site 2 and 3. The cohesion and angle of internal friction from the UTCT recorded cohesion values were 28, 29 and 37 kN/m2 for sites 1, 2 and 3, respectively, while the angle of internal friction values were 13, 8 and 6° for sites 1, 2 and 3, respectively. The plate load testing using the three methods showed similar graph pattern except that the allowable load occurred at approximately 350 kN/m2 for the CFPLT and 150 kN/m2 for the IFPLT. The high value of bearing capacity in CFPLT is due to the short period of time taken to load from a jack, which allowed the test to be completed within a short period of time. The ultimate bearing capacities computed from the laboratory test have values of 315.0, 231.0 and 270.0 kN/m2 for sites 1, 2 and 3, respectively. These values agree closely with the bearing capacities obtained for CFPLT but higher than the values recorded for the IFPLT. This is probably due to the long period of sustained loading during testing, which allowed for dissipation of pore water during each loading. Settlements obtained using the IFPLT were close to 25 mm, which is recommended as minimum settlements for building structures BS 8004, 1986.

Experimental identification of the fractional parameter of the fractional derivative standard linear solid model for fiber-reinforced rubber concrete

This paper studies the influence of different factors, such as polymer and fiber type and aging, on the internal friction and fractional parameter, which are determined for rubber concrete and fiber-reinforced rubber concrete by means of the Resonant Frequency and Damping Analyzer (RFDA Basic) implementing the Impulse Excitation Technique (IET). Both materials contained low molecular weight cis-polybutadiene rubber SKDN-N as the main binder. Another type of binding material has been used for further investigation of internal friction phenomena in polymer concrete. Namely, low molecular weight polybutadiene rubber (BR) of mixed microstructure was utilized to produce the samples for the experimental program. Two different types of fiber are used: metal and polymer fiber. It has been found that the addition of steel fiber reduces internal friction in the material, whereas propylene fiber acts as additional damping material and increases internal friction. BR-based concrete and fiber-reinforced concrete show rather high values of internal friction, i.e. behave more viscoelastically. BR-based concrete performs higher values of the fractional parameter, and, therefore, more obvious viscoelastic properties. Introduction of steel fiber in the mixture reduces the fractional parameter, since it plays the role of additional bonds in the material structure. However, addition of propylene fiber increases fractional parameter in both, SKDN-N and BR-based concretes. It can be explained by additional damping effect of the polymer fiber. The obtained results are compared with those for the reference specimens made of ordinary Portland cement concrete, and a certain influence of the selected parameters on the internal friction of the considered materials are established.

Tribological Behavior of TiO2 PEEK Composite and Stainless Steel for Pediatric Crowns

Dental decay still presents a major health problem among children. Its treatment usually requires the use of stainless steel crowns. This study compares the wear behavior of 316 L stainless steel and polyetheretherketone (PEEK) composite under identical test conditions. The wear tests were conducted in a reciprocating ball-on-plate tribometer (Plint TE67/R) using alumina balls as a counterface and artificial saliva as a lubricant at 37 °C to faithfully mimic oral conditions. The coefficient of friction (COF) and specific wear rate (k) values were determined and SEM/EDS examinations were performed to identify the predominant wear mechanisms. Results showed that PEEK exhibited a significantly lower coefficient of friction (COF = 0.094 ± 0.004) and thus lower wear volume (ΔV = 0.0078 ± 0.0125 mm3) and higher wear resistance, with an average value of specific wear rate of k = 9.07 × 10-6 mm3N-1m-1 when compared to stainless steel (COF = 0.32 ± 0.03, ΔV = 0.0125 ± 0.0029 mm3, k = 1.45 × 10-5 mm3N-1m-1). PEEK was revealed to be a potential material for use in pediatric crowns due to its high wear resistance while overcoming the disadvantages associated with steel at both an aesthetic and biological level.

Different Behaviors of Friction in Open and Closed Forging Test Utilizing Palm Oil-Based Lubricants

Increasing demand for manufactured goods in industries such as automobiles, electronics, construction, and aerospace has motivated researchers to develop sustainable manufacturing processes. Most metal-forming lubricants are not eco-friendly; they may cause substantial chemical emissions and constitute a community threat. Bio-oil lubricants are seen as possible replacements for mineral oil-based lubricants. Computational modelling of the forging process uses the finite element method to accelerate and improve design. This research intends to act as a case study and demonstrate how friction behaves differently in open-closed forging tests of different palm oil derivatives. The relationship between the different types of friction was studied using a cold forging test in conjunction with the development of a Coulomb–Tresca friction model. From the results, it can be shown that the friction behavior for the closed forging test (CFT) and the ring compression test (RCT) differs; the CFT exhibits a diversified friction adaptation, while the RCT exhibits a single friction adaptation. From both tests, palm stearin (PS) shows the lowest friction behavior where at RCT the friction is estimated at m = 0.10/μ = 0.05 and the CFT has a varied friction and the average friction is estimated at m = 0.352/μ = 0.1626. On the other hand, commercial metal-forming oil (CMFO) shows the highest lubrication sample in friction, where the value of friction is similar to the no lubricant sample (NA-O), which is (m = 0.45/μ = 0.1875) on the RCT test and (m = 0.424/μ = 0.1681) on the CFT test.

Mechanical and tribological characterisations of PEG-based hydrogel coatings on XLPE surfaces

Hydrophilic hydrogel coatings can impart enhanced tribological and antifouling properties to biomedical device surfaces. The influence of crosslinking on the elastic moduli of poly (ethylene glycol) (PEG) hydrogels is well established, however, the effect of crosslinking on the ability of the hydrogels to form coatings on crosslinked polyethylene (XLPE) substrates is not fully understood, nor are the mechanics and tribological performance of the resultant hydrogel coated substrates. PEG hydrogels of four different crosslinking levels (5, 7.5, 10 and 12.5% crosslinker concentrations) were deposited onto XLPE substrates. Crosslinked matched hydrogel plugs were also manufactured for mechanical analysis. The wear performance and friction evolution of coated pins were assessed against sterilised cobalt chromium discs at a contact pressure of 0.08 MPa under an elliptical orbital motion. The indentation results showed an increase in the elastic modulus with increasing crosslinker concentration, which was augmented further by gamma sterilisation treatment. Hydrogel coated pins exhibited reduced friction levels compared to uncoated pins, and confocal imaging in conjuction with the roughness monitoring indicated that the coatings protected the asperities from being removed. The friction values increased as the tests progressed, in line with the coverage of the hydrogel coating decreasing and forming a hybrid XLPE/gel vs CoCr contact. The 10% cross-linker hydrogel coating produced the lowest friction and wear of all the coatings tested.

Thickening Properties of Carboxymethyl Cellulose in Aqueous Lubrication

Increasingly restricted availability and environmental impact of mineral oils have boosted the interest in sustainable lubrication. In this study, the thickening properties of sodium carboxymethyl celluloses (CMCs) were investigated in order to assess their potential as viscosity modifiers in aqueous gear and bearing fluids. The pressure, temperature and shear dependence of viscosity was studied at different concentrations and molecular weights MW. The tribological properties were investigated at different viscosity grades in both sliding and rolling contact, and compared to rapeseed oil and polyethylene glycol 400. The viscosity of the CMC solutions was adjustable to all application-relevant viscosity grades. Viscosity indices were similar or higher compared to the reference fluids and mineral oil. Temporary and permanent viscosity losses increased with MW. Permanent viscosity loss was highest for high MW derivatives, up to 70%. The pressure-viscosity coefficients α were low and showed a high dependency on shear and concentration. In rolling contact, low MW CMC showed up to 35% lower friction values compared to high MW, whereas no improvement of lubricating properties was observed in sliding contact. The results suggest that low MW CMC has great potential as bio-based thickener in aqueous lubrication.

Theoretical study on bio-convection of micropolar fluid with an exploration of Cattaneo–Christov heat flux theory

This research explores the heat transfer rate for micropolar fluid in a channel flow. In spite of formal Fourier’s law, the Cattaneo–Christov heat flux design is implemented in energy system. Using appropriate dimensionless parameters, the guiding coupled partial differential equations that represent the fluid flow are modified into ordinary differential equations. By executing Runge–Kutta integration procedure and the shooting method, the numerical results are achieved. The impacts of thermal relaxation time and bio-convection flow of micropolar fluid are examined in this assessment. Graphical analyses are used to assess the effects of physical factors for the momentum, micro-rotation, concentration, density of micro-organisms and temperature gradient. The skin friction values, motile density number, heat and mass transfer rate are the fascinating physical quantities whose numerical data are computed and validated against different parametric values. The variational iteration method (VIM) and Adomian decomposition method are the analytical modules which have been incorporated here for solving the nonlinear systems for showing better approximity. It is found from the study that larger the thermal relaxation time values, the more likely they are to increase heat transfer, hence lowering the fluid temperature. Moreover, both Fourier and Cattaneo–Christov heat conduction module exhibit qualitatively similar influence on embedded parameters also the temperature profile diminishes for larger values of [Formula: see text]. The culminations evidently disclose that the bio-convection Peclet number and the motile microbes parameter enhance the density of motile micro-organisms. From a computational perspective, the VIM is more effective, practical and ease of use. The numerical and analytical results are compared well with the existing articles. The optimum parameter level for maximum heat transfer is considered to be [Formula: see text]. Taguchi approach was successfully used to determine the optimum design parameters for maximum heat transfer is 1.724012 for the parameters A-5:B-5:C-0.5:D-0.5:E-0.7.

Rheological behavior of magnetized ZnO – SAE50 nanolubricant over Riga plate: A theoretical study

[Formula: see text] nanolubricant is one of the most important nanolubricants having widespread uses in heat exchange systems and automobiles. It minimizes friction between moving parts and prevents them from corrosion and scrape, improves durability and performance of the system and also minimizes the consumption of fuel. This work investigates the rheological behavior of magnetized [Formula: see text] nanolubricant over moving/stationary Riga plate with viscous dissipation and nonlinear heat generation. The novel features of the current work are the use of [Formula: see text] nanolubricant as a flow fluid across a Riga plate and the application of the Patel model to boost the thermal conductivity of the nanolubricant. The governing system of equations is transformed to nonlinear ODEs and then treated analytically by using HAM. The augmentation in the velocity of nanolubricant [Formula: see text] is observed due to increasing values of Grashof number. The higher values of nonlinear thermal radiation and nonlinear heat generation parameters upsurge the temperature profile. The value of skin friction increases by increasing modified Hartman number and velocity slip parameter while reverse trend is observed by enhancing magnetic parameter. The radiation parameter, temperature dependent heat source parameter and solid volume fraction tend to augment Nusselt number at the Riga surface.

Effects of Automotive Test Parameters on Dry Friction Fiber-Reinforced Clutch Facing Surface Microgeometry and Wear-Part 3 Tribological Parameter Correlations and Simulation of Thermo-Mechanical Tribological Contact Behavior.

Correlations among previously determined tribological properties, such as the coefficient of friction values, wear and surface roughness differences of hybrid composite dry friction clutch facings are revealed after pin-on-disk test apparatus examinations under three pv loads, where samples are cut from a reference, unused, and several differently aged and dimensioned, used-according to two different trends: dry friction fiber-reinforced hybrid composite clutch facings. In 'normal use' facings, increasing specific wear trend is detected as a function of activation energy according to a second-degree function, while a logarithmic trend line can be fitted to the values of the clutch killer facings, showing that even at low activation energy levels, significant (~3%) wear occurs. The specific wear rate also varies as a function of the radius of the friction facing, with the relative wear values measured on the working friction diameter being higher regardless of the usage trend. In terms of surface roughness variation measured in the radial direction, normal use facings show a varying roughness difference according to a third-degree function, while clutch killer facings follow a second-degree or logarithmic trend depending on the diameter (di or dw). From the statistical analysis of the steady-state, we find three different clutch engagement phase characterizing pv level pin-on-disk tribological test results for the specific wear of the clutch killer and normal use facings, and significantly different trend curves with three different sets of functions were obtained, showing that the wear intensity can be described as a function of the pv value and the friction diameter. In terms of radial direction surface roughness difference, the values of clutch killer and normal use samples can be described by three different sets of function showing the effects of the friction radius and pv.

Long-Term Performance and Safety Implications of High-Friction Surfacing Treatments

Although high-friction surface treatments (HFSTs) are a proven efficient countermeasure for the reduction of roadway departure crashes, their long-term pavement performance has yet not been fully understood with large-scale field monitoring. This paper presented and analyzed 3 years of monitoring results on 36 HFST sites located in 12 states in the US ranging from 0 to 11 years in treatment age. Taking the traffic directions and number of lanes at each site into consideration, a total of 65 HFST segments were measured. Onsite data were collected by a Grip Tester for pavement friction, the PaveVision3D laser imaging system for condition evaluation and high-resolution pavement images, and the AMES high-speed profiler for surface texture and roughness. The evolutions of HFST surface characteristics and field performance were evaluated. It was found that most HFST sites continued providing superior friction values compared with the neighboring nontreated surfaces. Cracking and surface delamination were observed as the major failure types on a few sites. The delaminated area exhibited higher roughness values and lower friction numbers. Subsequently, a multivariant friction prediction model was developed to assist in understanding its influencing factors and deterioration trends. Furthermore, a safety performance function was built for crash frequency estimation on HFST sites, through which the benefit of HFST in reducing roadway departure crashes could be further quantified.

Effects of internal surface roughness and viscous friction on mass flow rate and conductive heat transfer across a pipe element: Simulink Approach

The study, effects of internal surface roughness and viscous friction on mass flow rate and conductive heat transfer across a pipe element using simulink approach was successfully achieved. Block models were used to represent all the elements of pipe flow model. Pipe element was modeled to retain hydraulic diameter of 0.4 m within a length of 100 m. The shape factor and internal surface roughness were chosen to be 80 and 3e+3m, respectively. Initial temperature and pressure were set to 300k or 27ºC and 1 atm. turbulent regime Nusselt number correlation coefficients were 0.023, 0.8, 0.33, 0, and 0. The mass flow rate from the reservoir had initial value of 0.6 kg/s and signal block was adjusted to 1, 6, 5 for slope, start and maximum respectively. With Ode15s solver, simulation was allowed to run for 15seconds. System model mass flow rate, conductive heat transfer and temperature difference were found to be 0.6kg/s (same with initial value), 5.0346J/s and -80K or 193ºC within 15seconds of simulation. Findings depicted the effects of internal surface roughness and viscous friction on mass flow rate and conductive heat transfer. Also, simulation was run with the shape factor and internal surface roughness chosen to be 64 and 1.5e-5m, respectively. Under viscous friction influence, initial temperature and pressure were set to 298k or 25ºC and 1 atm. turbulent regime Nusselt number correlation coefficients were 0.023, 0.8, 0.33, 0, and 0. The mass flow rate from the reservoir had initial value of 0.6 kg/s. Results also showed that the system model mass flow rate, conductive heat transfer and temperature difference were found to be 0.058kg/s, -275J/s and 100K or -173ºC within 15seconds of simulation. Hence, increasing value of internal surface roughness increases conductive heat transfer at a constant mass flow rate of fluid and increasing value of viscous friction, decreases mass flow rate of fluid as well as conductive heat transfer across the pipe wall.

Electronic contacts and lubricity characteristics between monolayer WSe2 and Zr2C, Zr2CY2 (Y = F or OH)

The research on the interface contact characteristics is one of the hot topics for the van der Waals (vdW) heterostructure. We studied the electronic and frictional characteristics for the WSe2/Zr2C and WSe2/Zr2CY2 (Y = F or OH) vdW heterostructure by using DFT simulations. n-type Ohmic contacts are found for all the vdW heterostructures. The friction force and shear strength of the WSe2/Zr2CY2 (Y = F or OH) vdW heterostructures are more than one order of magnitude lower than the WSe2/Zr2C vdW heterostructure. The extremely low friction value of the WSe2/Zr2C(OH)2 vdW heterostructure is only 0.00185–0.00975 nN/atom. The weak interaction and smooth condition between interfaces are responsible for the small potential energy fluctuations and thus the low friction force.

Thermal elaboration of ethylene glycol-based magnetized nanostructures via a convective permeable heated vertical surface employing modified Buongiorno model

The current goal of the research is to investigate a mathematical model for chemically reacting nanofluids with Brownian movement and diffusive thermophoretic. The present flow model is articulated with the employ of novel thermophoretic diffusion, Brownian motion considering Au, Ag and Cu nanoparticles with ethylene glycol as base fluid. The basic model equations are changed to a dimensionless non-linear coupled ordinary differential equation adopting the competent similarity variables and then solved implementing Runge-Kutta Fehlberg-45 order numerical quadrature (shooting technique) is utilized. The outcomes obtained for momentum, angular flow rate, energy, and concentration on numerous motion parameters are introduced pictorially. Computed values for the device surface friction, local thermal and mass gradients are tabulated. The outcomes reveal that thermophoresis parameter is favorable to improve the liquid temperature and concentration distribution. The impact of nanoliquid reacting species reduced the nanoparticle concentration entirely in the stretching plate. Furthermore, computed outcomes are proved for restraining cases by comparison with numerous surveys and found outstanding accuracy.

Heat transfer effects on the oscillatory MHD flow in a porous channel with two immiscible fluids

The MHD oscillatory flow of two immiscible, viscous liquids in a porous channel with heat transfer is the subject of this investigation. The two liquid layers with different viscosities flow in both regions. The analytical expressions for velocity and temperature distribution have been derived by solving the governing flow equations using the regular perturbation method. The effects of various parameters on the velocity, temperature, and Nusselt number have been shown graphically, and numerical values of skin friction and flow rate are presented in tabular form and discussed. According to our analysis, the mass flux reduces as the magnetic field strength rises. While the temperature of the liquid enhances with an increase in the Eckert number and the Prandtl number, the temperature distribution rises with a decrease in the thermal conductivity ratio. To validate the results, the analytical solutions are compared with the fourth-order numerical Runge–Kutta method coupled with the shooting approach, and the results are found to be in excellent agreement.

Diffusion in a two-dimensional energy landscape in the presence of dynamical correlations and validity of random walk model.

Diffusion in a multidimensional energy surface with minima and barriers is a problem of importance in statistical mechanics and it also has wide applications, such as protein folding. To understand it in such a system, we carry out theory and simulations of a tagged particle moving on a two-dimensional periodic potential energy surface, both in the presence and absence of noise. Langevin dynamics simulations at multiple temperatures are carried out to obtain the diffusion coefficient of a solute particle. Friction is varied from zero to large values. Diffusive motion emerges in the limit of a long time, even in the absence of noise. Noise destroys the correlations and increases diffusion at small friction. Diffusion thus exhibits a nonmonotonic friction dependence at the intermediate value of the damping, ultimately converging to our theoretically predicted value. The latter is obtained using the well-established relationship between diffusion and random walk. An excellent agreement is obtained between theory and simulations in the high-friction limit but not so in the intermediate regime. We explain the deviation in the low- to intermediate-friction regime using the modified random walk theory. The rate of escape from one cell to another is obtained from the multidimensional rate theory of Langer. We find that enhanced dimensionality plays an important role. To quantify the effects of noise on the potential-imposed coherence on the trajectories, we calculate the Lyapunov exponent. At small friction values, the Lyapunov exponent mimics the friction dependence of the rate.

Volatile Lubricants Injected Through Laser Drilled Micro Holes Enable Efficiently Hydrocarbon-Free Lubrication for Deep Drawing Processes

In order to reduce the use of classic lubricants such as synthetic or mineral oils, emulsions or waxes in the deep drawing process, a new tribological system based on volatile lubricants was investigated. In this system, a volatile medium is injected under high pressure through laser drilled micro holes directly into the contact zone between the tool and the sheet metal and serves as a temporary lubricant. In order to investigate this tribological system under realistic conditions, strip drawing experiments with different volatile lubricants (air, nitrogen, carbon dioxide and argon) were performed on galvanized sheets. Therefore, a new generation of strip drawing tools was designed and numerically calculated for low elastic deformations to ensure a uniform contact pressure distribution over the entire friction contact area. To obtain a homogeneous distribution of the volatile lubricants, a number of micro holes with a depth of several millimeters were drilled into the hardened strip drawing jaws using ultrashort pulsed laser radiation. Taking into account the capabilities of this laser drilling technique in terms of size and shape of the micro holes, computational fluid dynamics simulations were performed to predict the flow behavior of the lubricant within the micro hole as well as the contact zone and were compared with observable effects in outflow tests. The chemical composition of the acting tribological layers was characterized by means of X-ray photoelectron spectroscopy and their changes during the deep drawing process were correlated with the lubricants used as well as the measured wear and friction values.

Tribological characteristics of ABS structures with different infill densities tested by pin-on-disc

Acrylonitrile butadiene styrene (ABS), a petroleum-based thermoplastic, is widely used in various industry. It is important to make product costs without reducing the wear characteristics of products. For this reason, over the past 20 years, researchers have focused on improving product performance by reducing material weight. The literature has limited information about the tribological properties of the ABS polymer samples produced with fused deposition modelling. In this study, gyroid-patterned ABS samples with different infill densities (25%, 50%, and 75%) were produced and the effect on the wear properties of the samples was investigated. The main aim of the study is to show the infill density effect on wear and friction performance of the samples and find the coefficient of friction values. So, this study is one of the first studies which investigated wear and friction properties of ABS polymer produced as gyroid pattern with different infill densities. The study might also be used to have an initial information whether ABS polymer can be used in additive manufacturing systems for the joint components. As the performance indicator, diameter deviation, hardness, surface roughness, test temperature, friction coefficient, weight loss, and wearing surface results of the samples were evaluated. The results show that infill density is an important property that effect the tribological and heating characteristic of ABS samples. The friction and heat of the samples increase by increasing infill density. According to the tribological test results, the highest coefficient of friction and friction temperature were reached in the samples with 75% infill density.

Potential of palm oil with tert-Butylhydroquinone in place of mineral oil lubricant for reducing environmental degradation

Lubrication has remained an important aspect of machines maintenance and designs since time immemorial, yet the quest for improved lubricant for sustainable life of both equipment and environment continues to intensify. Many lubricants that is, research for a lubricant that is capable of providing maintenance of sustainable equipment without compromise to the environment is on the rise have been formulated and a lot of discoveries have been found in approaches toward enhanced and sustainable lubricants performance. Addition of foreign materials in nano quantity to fortify base oil properties for special purposes has also received greater attention in recent years. While this approach has yielded amazing results, concerns bordering on non-biodegradability of the mineral oils and safety of their additives to the environment equally continue to grow. This has escalated research interest in vegetable oils and their derivatives such as palm oil and other seed oils as a substitute toward limiting the consequences of improper disposal and eventual natural habitat degradation. A new approach to this quest is the adoption of palm oil (in Super Olein IV64 grade) with 150–450particles per million of tert-Butylhydroquinone for comparison with tribological behavior of mineral oil (Shell Helix SAE40W10) within the temperatures of 40°C to 100°C using linear reciprocating tribometer Winducom ASTM G133 test rig. The results showed tremendous similarity in coefficient of friction values between 0.1 and 0.12 of Super Olein with 150 particles per million and 300 particles per million of tert-Butylhydroquinone correlating closely with that of Shell Helix SAE40W10 at 80°C and 100°C, respectively. Wear track on the 20mm square plate was observed on the low-resolution microscope while wear scar diameter of the 6 mm SKD11 ball was observed on the high-resolution microscope. The results obtained at a temperature of 100°C in Super Olein IV64 + 150 particles per million tert-Butylhydroquinone and Super Olein IV64 + 300 particles per million tert-Butylhydroquinone is very similar to that of SAE40W10 except for Super Olein IV64 + 450 particles per million TBHQ whose coefficient of friction maintained a higher value of 0.3 at those temperatures.

Effect of welding process parameters on surface topography and mechanical properties of friction-stir-welded AA2024/AA2099 alloys

The joining of two materials with different chemical composition was a major setback for conventional methods of metal joining. The results of this welding were showing considerably great improvement in the aspects of quality of weld, amount of heat generated, uniform distribution of material, refined microstructure, enhanced tribology, materials flowing pattern, good strength with reduced internal stresses. Optimized parameters were estimated by using Desirabilty approach and Response surface methodology. Optimum parameter combination for dissimilar material welding was observed to be 913.74 rpm, 45 mm min−1 and 8kN. The desirability values for dissimilar welding process were 0.912 respectively. The grain enhancements were decreased in the range of WC > WT > HAZ > Parent material. The wear rate of dissimilar AA2024 and AA2099 were superior as the wear value increases from 0 to 50 μm in the nugget zone. The coefficient of friction value remains constant throughout the wear experiment ranges from 0.3 to 0.55. A steady state friction value of 3N to 5N is observed when sliding distance increases. The wear loss was measured by finding the difference between initial weight and final weight and found as in the range from 0.2283 g to 0.4866 g.

Frictional behavior of severe plastic deformed copper sample by using friction calibration curves

Equal Channel Angular Pressing (ECAP) known as one of the most significant methods involving in severe plastic deformation. There are not many investigations which focus on the design of dies and its analysis by FEM, considering friction coefficients as die geometry parameters; likewise, only few studies have been reported in which the effect of die shape has been analyzed, for example. One of the challenging problems in industrialization of ECAP is designing and manufacturing of die. To avoid trial and error in the next designs, the measurement of right friction coefficient plays a key role, which is used in finite element method to prevent doing experimental test. The main objective of this study was to investigate and find generalized friction calibration curves utilizing the ring compression test. To perform the ring compression test, which is oxygen-free copper with 99.7%, (BS EN 15079 standard) the standard ring specimen ratio of 6:3:2 was used. With use of different lubricants during the ring compression test the relations between friction coefficients and changes of inner and outer diameters was revealed. To solve complicated plasticity equations with complex geometries and boundary conditions with various friction coefficients, finite element method was used. To use more accurate frictional coefficient values with considering different ECAP passes, friction calibration curves were updated.