Effect Of Frictional Heating Research Articles

Investigating the microstructure and high-temperature wear resistance of TiAl/WC coating modified via scanning electron beam

In this study, TiAl/WC cladding coatings were modified to improve high-temperature wear resistance by scanning electron beam treatment. Results of the microstructure reveal that the modified coatings are composed of an α2-Ti3Al matrix, with a high density of TiC reinforced phase and Ti3AlC2 MAX phase. At a scanning speed of 6 mm/s, TiAl/WC coating exhibits superior microhardness and high-temperature wear resistance. After the wear test at 800 °C, the minimum wear volume of modified TiAl/WC coating is 0.084 mm3, which is 4.47 times smaller than that of the TC21 substrate. It is mainly attributed to the dense and uniform distribution of hard TiC with a rigid supporting role and Ti3AlC2 MAX phases with a self-lubricating effect. Furthermore, due to the effect of frictional heat, the decomposition of Ti3AlC2 promoted the formation of a dense Al2O3 protective film. The wear mechanism of modified TiAl/WC coatings exhibits a synergistic occurrence of slight adhesive wear, abrasive wear, and oxidative wear. Scanning electron beam technology shows significant potential for extending the service life of the coatings in high-temperature environments.

Electroosmotic effect on the flow of hybrid nanofluid containing para and ferri-magnetic nanoparticles through the micro-channel implementing Darcy law

This study investigates the flow of an incompressible electroosmotic hybrid nanofluid through a micro-channel. The hybrid nanofluid consists of paramagnetic (Ta) and ferrimagnetic (Fe3O4) nanoparticles suspended in ethylene glycol. The Darcy model is applied to the porous media in the momentum equation, and its effects are also considered in the temperature equation, accounting for frictional and Joule heating effects. The micro-channel is influenced by both pressure and magnetic flux. The study derives an exact solution for the proposed model and evaluates key engineering parameters, such as the heat transfer rate. The findings show that a higher particle volume fraction reduces the velocity distribution, while an increased Darcy parameter decreases the rate of heat transfer. Additionally, the heat transfer rate diminishes with increasing Darcy parameter and electric flux. Notably, the ferrimagnetic nanofluid exhibits better thermal conductivity than the paramagnetic nanofluid.

Numerical simulation of Darcy–Brinkman oscillatory flow of dissipative fluid: Utilization of finite difference method

This study investigates viscous flow behavior in a Darcy–Brinkman porous medium, considering the effects of porous dissipation and frictional heating. The fluid is flowing over a flat plate, oscillating in its plane. The velocity and temperature profiles are simulated using a mathematical model that includes linear convection and considers the effects of porous and viscous dissipation. After performing mathematical transformations, the governing equations are modified into coupled and nonlinear dimensionless PDEs. The forward time centered space method numerically solves the modeled dimensionless equations. The acquired results are explicitly validated against the findings of the literature in a situation where limits are considered. The numerical results are presented graphically, providing a comprehensive analysis of the variables impacting fluid characteristics, including temperature and velocity. Interestingly, this work shows that a rise in the porosity parameter causes temperature profiles to rise and velocity to decrease. Moreover, a drop in velocity is linked to a rise in the Prandtl number. Furthermore, the influence of surface friction is diminished by including the porosity parameter. Moreover, a rise in the heat transmission rate at the surface can be observed.

Exploring slip flow of viscoelastic fluid with frictional heating effects: Uncertainty analysis using response surface methodology (RSM)

Viscoelastic fluid flow along a slippery plate finds applications in different fields such as examining friction and wear characteristics of bearing surfaces using viscoelastic lubricants, extrusion, coating and moulding processes, thin film deposition among others. The present article explores boundary layer flow generated by a slippery stretching plate in a viscoelastic fluid and conducts uncertainty analysis of the governing model via response surface methodology. In addition, the analysis includes viscous dissipation mechanism that represents the conversion of mechanical energy into heat induced by viscosity. The inclusion of the wall slip condition results in a non-linear Robin-type condition for the velocity field. A dependable and user-friendly built-in package “bvp4c” of MATLAB is used to provide the computational results. The solution is used to illustrate the implication wall slip phenomenon on the resisting wall shear. One noteworthy finding is that the inclusion of either the frictional heating effect or the elasticity results in a significant decrease in the surface cooling rate. As the contribution of the heat source term grows, the rate of surface cooling decreases. Strengthening the heat sink effect reverses this result. Contour plots for stream function and isotherms are generated and compared in Newtonian and second grade fluid cases.

Synergistic enhancement of strength and ductility in novel solid-stir continuous extrusion: Influence of heterogeneous microstructure and alloy chemistry

Friction stir-derived solid-state processes leverage the synergistic effect of frictional heating and intense shear deformation to achieve localized microstructural modification for the improvement of mechanical properties. In the present work, a novel processing route called solid-stir extrusion (SSE) has been explored for continuous, high-rate extrusion of a high strength non-age-hardenable-AlMgSc alloy. In the current study, loss of strength associated with frictional heating during the process is mitigated as elevated strength is observed in as-extruded condition, thereby eliminating the need for post process heat treatment. The effect of process attributes on mechanical property and microstructure evolution was investigated. The SSE process caused extensive grain refinement and fragmentation of thermally stable Al3Sc intermetallic periodically at shear bands, which contributes to the elevated mechanical strength. The spatial variation in mechanical properties and microstructural heterogeneity was characterized using nanoindentation and microstructural correlation. The current findings indicate the significance of the process-specific alloy design approach to increase performance of material in as-processed condition.

Frictional heating effects on entropy generation with nonlinear Rosseland radiation: Implementation of generalized differential quadrature method

This article examines heat transfer and entropy generation analysis for boundary layer flow, considering the impacts of frictional heating and nonlinear Rosseland thermal radiation. The equations governing momentum and energy in a two-dimensional boundary layer are transformed into self-similar equations via similarity operations. The generalized differential quadrature method (GDQM) is then used to numerically solve the no-dimensional governing equations. Entropy generation and Bejan numbers are computed using the acquired solutions and are then plotted against the emerging flow parameters. An in-depth analysis of temperature distribution, entropy generation, velocity profile, and Bejan number. A high level of agreement was seen when the results from the literature were replicated using GDQM to verify the accuracy of the numerical code. It is found that a self-similar solution exists in the presence of viscous dissipation. The primary contributor to entropy generation at the interface is fluid friction, in contrast to heat transfer. Further, the findings indicate that entropy generation positively correlates with the Prandtl number, heating parameter, radiation parameter, and Eckert number. Notably, the results show that a decrease in operational temperature causes a decrease in entropy production.

Frictional heating effect of ball screw pairs for machine tools: A new calculation method

Frictional heat of the ball screw pairs is an important heat source for machine tools. Aiming at the shortcomings in current research, the frictional heating effect was studied in depth. The sliding and rolling frictional mechanisms were analyzed with the thermo-force coupling effect. The calculation method of sliding strokes based on relative motion principle of planetary transmission were proposed. A new frictional heating effect model was established and the nut temperature was calculated. The calculation value of the nut temperature was compared with its measurement value. The calculated residual was only − 0.64 ℃ ∼ 0.53 ℃. The traditional empirical model and the new model was compared in the same test, and the new model accuracy has been improved by 91.35%.

Study on the prediction of high-speed rotary lip seal wear in aero-engine based on heat-fluid-solid coupling

PurposeThis paper aims to investigate the effect of frictional heat on the wear of high-speed rotary lip seals in engines.Design/methodology/approachIn this research paper, the authors focus on the high-speed rotating lip seal of aircraft engines. Using the hybrid lubrication theory, a thermal-fluid-solid coupled numerical simulation model is established to investigate the influence of parameters such as contact pressure distribution, temperature rise and leakage rate on the sealing performance under different operating conditions. By incorporating the Rhee wear theory and combining simulation results with experimental data, a method for predicting the wear of the rotating seal lip profile is proposed. Experimental validation is conducted using a high-speed rotating test rig.FindingsThe results indicate that as the speed increases, the rise in frictional heat leads to a decrease in the sealing performance of the lip seal contact region. The experimental results show a similar trend to the numerical simulation results, and considering the effect of frictional heat, the predicted wear of the lip seal profile aligns more closely with the actual wear curve. This highlights the importance of considering the influence of frictional heat in the analysis of rotating seal mechanisms.Originality/valueThis study provides a reference for the prediction of wear profiles of engine high-speed rotary lip seals.

Analytical solution for unsteady Walters-B fluid flow by a deforming surface with acceleration using OHAM based package BVPh2.0

Current study aims at simulating fluid flow due to a deformable heated surface in an otherwise static viscoelastic fluid obeying Walters-B model. Velocity of the surface is supposed to grow as time from its initiation of motion progress. Simulations in this work are based on the assumption of quadratic surface temperature distribution. Temperature rise attributed to the frictional heating effect is accounted for in the analysis. By choosing appropriate base functions, homotopy solutions are developed for reasonably large values of material fluid parameter. Reliability of the analytical results is established by computing averaged squared residual of the system. The contributions of the surface acceleration and elasticity on the boundary layer formation are enlightened through the plots of velocity components and temperature. Skin friction measuring the stress experienced by the surface is evaluated and examined under different controlling parameters. The paper also presents a numerical solution using NDSolve of MATHEMATICA in a special case of steady flow, and such solution agrees very well with the corresponding homotopy solution.

Heat transfer and flow analysis over a linearly stretching sheet with constant wall temperature: Novel local non‐similar solutions in the presence of viscous heating

AbstractFlow over a linearly stretching sheet having constant temperature is examined in this article. The effects of frictional heating (viscous dissipation) and Ohmic heating (Joule dissipation) are also studied. As evidenced by the literature, energy equations are not always self‐similar when viscous dissipation is considered. It strongly depends on the form of stretching velocity and the surface temperature of the sheet. To facilitate the similarity transformations in these cases, one must find a constraint between the sheet velocity and the surface temperature. It is also observed that for the linearly stretching sheet with constant wall temperature, it is not possible to achieve self‐similar equations because in this case, a local variable appears in the viscous dissipation parameter. Hence, this problem corresponds to the non‐similar flow. In this analysis, pseudo‐similarity transformation is employed, and the viscous dissipation parameter is selected as a non‐similarity variable. Governing equations are transferred into non‐similar forms then a method known as Sparrow‐Quack‐Boerner (SQB) local non‐similarity (LNS) is used to derive the equations up to the second level of truncations which are then solved numerically. The slope linear regression (SLR) technique is used to compare the solutions obtained from the equations of the first and second levels of truncation.

Thermoelastic instability on a frictional surface and its implication for size effect in friction experiments

Recent laboratory friction experiments on large rock samples revealed that dynamic weakening, a remarkable reduction in the friction coefficient at elevated slip rates, occurs at lower slip rates in larger samples. There is a large difference between the sizes of natural faults and those in laboratory experiments. Therefore, it is crucial to understand the effect of size on rock friction. In the field of tribology, the interaction between frictional heating and thermoelastic effect has long been investigated. It was shown that higher slip rates than the critical value {V}_{mathrm{cr}} causes growth of temperature and normal stress heterogeneity (thermoelastic instability), and {V}_{mathrm{cr}} is proportional to the wavenumber of the heterogeneity. Severely heterogeneous normal stress may cause concentration of frictional power, thus locally activating dynamic weakening and leading to macroscopic weakening. Because a larger sample hosts a perturbation of a smaller wavenumber, it is expected to weaken at a lower slip rate than a smaller sample. In this study, a new numerical method was developed for analysis of thermoelastic instability based on the definition of memory variables and numerical approximation to the integration kernel, for the 2-dimensional problem of a planar fault embedded in an infinite medium. This method was advantageous over the standard integral equation method in terms of numerical costs. Numerical solutions with the new method on sinusoidal perturbations in the normal stress were compared with previously derived steady-state solution and its stability for validation. The typical thermoelastic properties of gabbro yield {V}_{mathrm{cr}} in a range of experimentally adopted slip rates, indicating that the thermoelastic effect may play an important role in high-velocity friction experiments. Because the temperature rise and the resulting normal stress change smear out after the friction experiments, measurement of the temperature distribution in a sample during a friction experiment is important for further understanding the dynamic weakening and scale effect of rock friction.Graphical

Finite Element Study of Electrical MHD Williamson Nanofluid Flow under the Effects of Frictional Heating in the View of Viscous Dissipation

This study addresses heat and mass transfer of electrical magnetohydrodynamics (MHD) Williamson fluid flow over the moving sheet. The mathematical model for the considered flow phenomenon is expressed in a set of partial differential equations. Later, linear and nonlinear ordinary differential equations (ODEs) are obtained. The finite element method tackles a reduced system of ODEs with boundary conditions. Galerkin weighted residuals and constructs of weak formulations constitute the basis of this method. An iterative procedure is considered for handling nonlinear terms in a given system of ODEs. Some results acquired using the finite element method are compared with those reported in previous research via the Matlab solver bvp4c in order to validate the obtained solutions of ODEs. It is seen that the velocity profile is decayed by enhancing the Wiesenberg number. The finite element method also converges to an accurate solution by increasing the number of elements, whereas Matlab solver bvp4c produces accurate results on small grid points. Our intention is for this paper to serve as a guide for academics in the future who will be tasked with addressing pressing issues in the field of industrial and engineering enclosures.

Effect of synovial fluid temperature on wear resistance of different polymer acetabular materials.

In order to investigate the effect of frictional heat on the wear resistance characteristics of polymeric acetabular materials, the tribological tests and wear numerical analysis of three common polymer acetabular materials were carried out under different synovial fluid temperatures. The study results show that XLPE and VE-XLPE exhibit superior wear resistance compared to UHMWPE in high-temperature, heavy load environments. The coefficient of friction of three materials gradually decreases as the temperature of the synovial fluid increases. The wear depth and wear volume of the three materials increased with the increase of the temperature of the synovial fluid, and the forms of wear at 46°C and 55°C were mainly adhesive wear and plastic deformation. The higher temperature of the synovial fluid accelerates the oxidative degradation of the material surface and generates oxidation functional groups, which leads to the breakage of C-C bonds in the surface molecular chains under the sliding shear effect, thus reducing the mechanical properties of the material. Specifically, the surface of the polymer material will soften at a higher ambient temperature, mainly due to the decrease of hardness, and then deteriorate in the friction property, and finally increase the wear rate. Ansys results showed that the volume wear of the three materials increased with the increase of synovial fluid temperature, and the trend could be approximately linear. Numerical calculations predict that VE-XLPE has the highest wear of 0.693mm3 among the three materials at 37°C, followed by XLPE at 0.568mm3 and UHMWPE with the lowest wear of 0.478mm3. At higher synovial fluid temperatures (46°C, 55°C), VE-XLPE still has the largest wear volume among the three materials, while XLPE and UHMWPE have similar wear. The wear cloud pictures showed that the maximum wear volume occurred near the edge of the acetabulum.

Modeling frictional heating effects in triple friction pendulum isolators

AbstractThis paper augments the series spring model for Triple Friction Pendulum (TFP) isolators to predict the relative displacement and velocity at each of its four sliding interfaces. This enables the prediction of the rise in temperature at each sliding interface that results from frictional heating and the introduction of temperature‐dependent friction coefficient. Moreover, the model directly accounts for the velocity‐dependence of the friction coefficient as it can predict the actual velocities at each sliding interface, whereas the original series model only approximately accounted for the velocity effects. It also accounts for the effects of instantaneous bearing pressure on the friction coefficient. The model has been implemented in program OpenSees and has been verified by comparison to results obtained using a much more advanced and complex model that is unsuitable for computations with a large number of isolators.

Electric damage of bearing under AC shaft voltage at different rotation speeds

The breakdown characteristics and the electric damage of bearing were studied at different rotation speeds. The breakdown voltage of bearing could be defined as the instantaneous voltage corresponding to the zero point of the first derivative of equivalent resistance. Under the combined effect of frictional heat and electric heat, the breakdown voltage decreased with the rotation speed. The relationship between lubrication leakage rate and bearing temperature was consistent with the Arrhenius formulation. After breakdown, electric erosion began to form on the raceway and roller. The enrichment of carbide was observed beneath the breakdown surface, indicating a tempering effect of martensite. The hardness analysis suggested that there was a competition between friction-induced hardening and current-induced softening on the bearing surface.

A Comparative Study of Self-Piercing Riveting and Friction Self-Piercing Riveting of Cast Aluminum Alloy Al–Si7Mg

Abstract Cast aluminum alloys are promising materials that can simplify the manufacturing process of automobile body structures. However, the low ductility of cast aluminum poses significant challenges to existing riveting technologies. In the present work, dissimilar AA6061-T6 aluminum alloy and Al–Si7Mg cast aluminum were joined by self-piercing riveting (SPR) and friction self-piercing riveting (F-SPR) processes to reveal the effect of friction heat on rivetability of low-ductility cast aluminum alloys. The joint macro-morphology, microstructure, peak tooling force, microhardness distribution, tensile-shear, and cross-tension performance of the two processes were comparatively studied. Results indicated that the in-situ softening effect of friction heat in the F-SPR process could effectively improve the ductility of cast aluminum, avoid cracking, and reduce the tooling force by 53%, compared to the SPR process. The severe plastic deformation and friction heat induced by rivet rotation results in refined equiaxed grains of aluminum near the rivets and solid-state bonding between aluminum sheets in the rivet cavity. The F-SPR joints are superior to SPR joints in both tensile-shear and cross-tension performance due to the avoidance of cracking, increase of mechanical interlocking, and solid-state bonding of interfaces. Significantly, when Al–Si7Mg is placed on the lower layer, the peak tensile-shear and cross-tension loads of the F-SPR joints are 7.2% and 45.5% higher than the corresponding SPR joints, respectively.

EFFECT OF FRICTIONAL HEATING ON MECHANICALLY MIXED LAYERS DURING DRY SLIDING CONTACT OF Ti-6Al-4V ALLOYS AT HIGH TEMPERATURE IN VACUUM CONDITION

Ti-6Al-4V (an [Formula: see text] titanium alloy) pins were slid against the SS316L disc in a pin-on-disc apparatus at different temperatures under vacuum and ambient conditions. Tribological characterization was performed using a field emission scanning electron microscope (FESEM) equipped with energy dispersive X-ray (EDAX) analysis and X-ray diffraction. The worn pin surfaces of Ti-6Al-4V were investigated in order to identify the effect of frictional heating at the interface of tribo-pair. To investigate the effects of frictional heating on mechanically mixed layer (MML), experiments were performed under vacuum conditions ([Formula: see text] Torr) by varying the temperature from 25°C to 400°C at a constant sliding speed of 0.01[Formula: see text]ms[Formula: see text] and at constant normal load of 137[Formula: see text]N. The material was found to transfer from the counter-face to the worn pin surface of alloy where an MML and tribo-oxide (TO) layer were observed to developed on the worn pin surfaces under both the experimental environments. Moreover, a new mechanism, called the “debris burial mechanism” during the formation of the MML at different temperatures was obtained at the interface. The rate of wear was observed to decreased with the increase in frictional heating at the interface resulting to the progressive formation of thicker MML over the worn pin surface. The wear resistances in Ti–6Al–4V alloy decrease rapidly due to loosening the generated MML on the sliding surface.

Frictional heating and thermal effects of ancient rockslide sedimentology: a case study of the Dora Kamiyama Rockslide and implications for dynamic reconstruction

Frictional heating and thermal effects of ancient rockslide sedimentology: a case study of the Dora Kamiyama Rockslide and implications for dynamic reconstruction

Thermochemical non-equilibrium effects in turbulent hypersonic boundary layers

A hypersonic, spatially evolving turbulent boundary layer at Mach 12.48 with a cooled wall is analysed by means of direct numerical simulations. At the selected conditions, massive kinetic-to-internal energy conversion triggers thermal and chemical non-equilibrium phenomena. Air is assumed to behave as a five-species reacting mixture, and a two-temperature model is adopted to account for vibrational non-equilibrium. Wall cooling partly counteracts the effects of friction heating, and the temperature rise in the boundary layer excites vibrational energy modes while inducing mild chemical dissociation of oxygen. Vibrational non-equilibrium is mostly driven by molecular nitrogen, characterized by slower relaxation rates than the other molecules in the mixture. The results reveal that thermal non-equilibrium is sustained by turbulent mixing: sweep and ejection events efficiently redistribute the gas, contributing to the generation of a vibrationally under-excited state close to the wall, and an over-excited state in the outer region of the boundary layer. The tight coupling between turbulence and thermal effects is quantified by defining an interaction indicator. A modelling strategy for the vibrational energy turbulent flux is proposed, based on the definition of a vibrational turbulent Prandtl number. The validity of the strong Reynolds analogy under thermal non-equilibrium is also evaluated. Strong compressibility effects promote the translational–vibrational energy exchange, but no preferential correlation was detected between expansions/compressions and vibrational over-/under-excitation, as opposed to what has been observed for unconfined turbulent configurations.

Three-dimensional heat transfer of 29 nm CuO-H2O nanoliquid with Joule heating and slip effects over a wedge surface

The three-dimensional magneto-dynamics of viscous fluids have a wide range of applications in engineering and industry, including turbine bodies, heat exchangers, drying technology, and flow on arrow wings. Therefore, the three-dimensional flow of water containing 29 nm cupric nanomaterials on a wedge-shaped surface is studied using the magnetic field, Joule heating, and frictional heating effects. The slip conditions for thermal and solutal fields are taken into account. The Li & Peterson model is considered for the thermal conductivity of the CuO-H2O nanoliquid, which is a function of the temperature and volume of the nanoparticles, while the experimental model of dynamic viscosity is considered. The Modified Buongiorno Model (MBM) is used, which consists of effective thermophysical properties of nanoliquids, and the mechanisms of chaotic movement and thermo-migration of nanoparticles. Nonlinear governing problem is solved by the finite element method (FEM). The heat transfer and mass transfer rates are optimized by applying the response surface methodology (RSM). The thermal boundary layer attempts to adhere to the surface of the wedge surface for a greater magnitude of the shear-strain rate factor. Furthermore, the reduced Nusselt number is greatest in the absence of a friction heating mechanism through the system compared to its presence. The optimum condition for higher heat and mass transfer takes place at Nb = 0.2131, Nt = 0.1 and δT = 0.1 having a maximum heat transfer rate of 2.4658 and a maximum mass transfer rate of 2.8233