Friction Force Research Articles

Study on cutting temperatures of SiCp ∕ Al composites for ultrasonic vibration-assisted cutting

Abstract. In order to deeply understand the cutting mechanism of SiCp / Al in ultrasonic vibration-assisted turning, a prediction model of a cutting temperature field of SiCp / Al composites in UVAC (ultrasonic vibration-assisted cutting) was established. A theoretical model of instantaneous cutting depth and transient shear angle was established considering the real-time changing cutting depth, tool front angle and shear angle characteristics of UVAC. The relationship between cutting speed, shear speed and chip flow speed in UVAC processes is revealed, as well as the shear force and the front cutter friction force. Finally, the influence of heat generated by the heat source zone and shear heat source zone on the temperature rise was calculated, and the temperature field model was established. The experiment of processing SiCp / Al composites by UVAC was carried out. SiCp / Al composites with 25 % volume fraction were turned, and the cutting temperature data were measured and recorded by an infrared thermal imaging device. The cutting speed, cutting depth and feed rate were tested by a single factor, and the changes in cutting temperature under different parameters were compared. Finally, the experimental data were compared with the theoretical values to verify the validity of the theoretical model.

Development and characterization of self-centering friction dampers with confined shape memory alloy bars

This study proposes a new self-centering, shape memory alloy bar-based device to address the tension-compression asymmetry and limited energy dissipation capacity of similar SMA bar-based devices. The proposed device, named the Confined Superelastic Friction Damper (CSFD), employs buckling-restrained SMA bars to maintain symmetry in force-displacement responses and enhance effectiveness in both tension and compression. The device also integrates a frictional damping mechanism, contributing to increased energy dissipation capacity. First, an optimal annealing condition is investigated for as-received SMA bars to achieve a satisfactory superelastic response. Then, the working and design principles of the CSFD are outlined. The experimental characterization of CSFD devices in various configurations is conducted under an increasing amplitude loading protocol. The devices are tested with different levels of frictional damping to assess the effects of the added frictional forces on device characteristics. Analysis of test results considers parameters such as hysteresis curves, maximum force, equivalent viscous damping, and self-centering efficiency to provide a comprehensive performance evaluation of each device. Findings reveal that while a single buckling-restrained SMA bar device exhibits up to 90 % higher forces in compression than in tension, a CSFD device with two such bars nearly eliminates this asymmetry. Compared to tension-only SMA devices, capable of symmetric response, the proposed CSFD device demonstrates a 2.6 times higher force-resisting capacity. For all devices, the addition of some frictional damping improves the energy dissipation and equivalent viscous damping capacity, while leading to some reduction in self-centering efficiency.

SIMULATION OF FLAME PROPAGATION IN A COAL-METHANE-AIR MIXTURE IN A CYLINDRICAL CHANNEL TAKEN INTO ACCOUNT OF GAS VISCOSITY

The paper presents the results of a numerical study of the patterns of flame propagation of a coal-methane-air mixture in a narrow cylindrical channel in the presence of viscous friction forces. The formulation of the problem is based on the approaches of the mechanics of two-phase reacting media. The method for solving the problem is based on an arbitrary discontinuity decay algorithm. The numerical study carried out made it possible to determine the speed of flame propagation of a coal-methane-air mixture in an axisymmetric channel. It is shown that at the initial stage, when the combustion front reaches the side walls of the channel, the flame speed increases. This effect was obtained previously for an inviscid gas. It was found that the flame front of a gas suspension with a low content of coal dust, as it moves along an open channel, tends to be flat, independent of the coordinate along the radius of the channel.

Structural factors influencing the clinical performance of 0.025-inch guidewires for pancreatobiliary endoscopy: An experimental study.

Background and study aims To develop a pancreatobiliary endoscopic guidewire with good clinical performance, an understanding of its structure is necessary. This study aimed to investigate the structural factors influencing the clinical performance of pancreatobiliary endoscopic guidewires. Methods Eight types of 0.025-inch guidewires were evaluated. The following structural properties were measured: tip length, tip deflection height, tip weight (TW), ratio of tip core weight to TW, shaft coating type (flat or uneven), outer diameter, and core wire diameter (CWD). Four performance tests were conducted to evaluate shaft stiffness as bending force (BF), shaft lubricity as friction force (FF), torque response as torque response rate (TRR), and seeking ability as total insertion success (TIS) in a technical test using a 3D bile duct model. The correlation coefficients of each variable were analyzed. Results The BF and CWDs were strongly correlated, as well as the FF and CWDs and BF. Among the guidewires with similar CWDs, the guidewires with uneven coating had significantly lower FF than those with flat coating. The TRR was strongly correlated with the CWDs; furthermore, guidewires with lower FF had better TRR. TIS was strongly correlated with the TRR, TWs, and ratio of the tip core weight to TW. Conclusions CWD affects shaft stiffness; CWD and coating type affect shaft lubricity and torque response. Because TRR and TW are correlated with seeking ability, an appropriate combination of core wire thickness, TW, and coating design is required to develop a guidewire with good seeking ability.

Ion kinetic effects on the formation of intense laser-driven shock waves

The ion kinetic effect on the formation of intense laser-driven collisional shock waves is investigated via hybrid fluid-particle-in-cell simulations. It is found that the ion heat flux dominates the shock formation, which is considerably larger than the electron heat flux in the shock region. The rise of the temperature due to the laser energy deposition drives a heatwave into the overdense plasma, creating an electron–ion energy exchange zone between the critical surface and heat wave front. The heated ions, which are generated at the electron–ion energy exchange zone via the friction force, are found to travel to the high-density region and cause a tail distribution gain. Despite the small quantity, the heated tail ions contribute most of the ion heat flux during the shock formation. Additionally, as the electron heat flux decreases, the population of the heated tail ions is reduced, leading to a fall in the ion heat flux. This results in the delay or even suppression of the shock formation, because the ions are in a non-equilibrium state in the vicinity of the shock region, the ratio of the downstream ion temperature to the upstream ion temperature tends to a modestly decrease in comparison to the theory. The study provides a clear picture of the formation process of laser-driven shock waves.

Rotation of a ring around a horizontal rod

A simple experiment is described where a metal ring was rotated in a vertical plane on a horizontal rod. The ring rotated about 100 times before coming to a stop, so the friction force on the ring remained very small. However, measurements of the rotation frequencies of the ring around the rod and around its centre of mass indicated that the ring was sliding rather than rolling, with an unusually low coefficient of sliding friction.

Electrical measurement method of static friction force on rough surface

Friction plays a key role in the assessment of the safety and stability of mechanical systems (such as superconducting magnet quench explosion, aerospace vehicle bearing wear, etc.). Due to the closeness of the interfaces in engineering structures and the randomness of the contact surfaces, existing methods for measuring static friction force are unable to measure it at the contact interfaces of engineering structures under service conditions. In this paper, a new method for measuring the static friction force at the interface based on electrical signals is proposed. This method enables the measurement of the static friction force at interfaces of complex engineering structures under service conditions solely through electrical signals. The results indicate that the contact resistance gradually decreases with the increase in tangential load during the static friction stage until a monotonic behavior of macroscopic sliding occurs. The evolution of contact resistance is linked to the evolution of the real contact area, and this monotonic behavior can be explained as the deformation form of contact points. The accuracy of the proposed electrical measurement method is verified by comparison with experimental results (with an error of less than 9%). The indirect measurement method of friction force proposed in this paper can effectively measure the static friction force at the interfaces of engineering structures under service conditions, and it is expected to be applied to the detection of friction performance at engineering structure interfaces in extreme service environments.

Cryogenic Deep Drawing Tool Design for Reduced Heat Transfer

Subject of this study is the usage of macro-structured tools for deep drawing of aluminum alloys at cryogenic temperatures in order to increase the drawing depth. The advantage of the macro-structure is the reduced contact area, which primarily leads to a reduction in frictional forces in the flange area and also minimizes the heat transfer from the tool to the cooled sheet metal. In addition to the geometry of the tools, the heat transfer is also influenced by the thermal properties of the tool materials. Therefore, the tool must be designed to reduce heat flux and thermal diffusivity. In this regard, substitute materials for the tools, specifically polymer, and steel-shielded polymer, were investigated. In this context, the heat transfer coefficients between the tool material and the aluminum blank are determined experimentally. The influence of thermal conditions on the cryogenic deep drawing process are investigated numerically and experimentally. The result of the study is an improved process understanding to ensure the blank temperature in a cryogenic range and increase the resistance against bottom cracks.

Study on shallow configuration preparation and macroscopic and microscopic properties of cemented carbide surface

This study aimed to reduce surface configuration defects and improve the service performance of the configuration surface. The configuration was prepared using the principle of preset powder feeding laser cladding. Macroscopic and microscopic properties of the shallow configuration were tested to understand the mechanism behind the preset cladding material's ability to repair defects and improve surface hardness, and the preparation process of the shallow configuration was obtained. Finally, the method's potential for improving the wear resistance of the configuration surface was evaluated through friction and wear tests. The results indicate that the flow of molten preset powder can fill in pores, leading to the formation of a dense cladding layer on the configuration surface. This process also minimizes the generation of defects and holes. The incorporation of hard phases, such as TiN, Ti2N, and the solid solution (Ti, W)C1-X, positively influences the improvement of surface hardness and wear resistance of shallow configuration. When the average laser energy density ranges from 70 to 120 W·cm−2, the average microhardness of the shallow configuration surface is elevated by 13.4% compared to that of the conventional configuration surface. The friction force on the shallow configuration surface is 13.1% lower than that on the conventional configuration surface when the laser power is set to 80%, the scanning speed is maintained at 1500 mm/s, the scanning passes are 9, the spacing between configurations is 130 μm, and the configuration diameter is 50 μm. This technique presents a novel approach to producing configuration surfaces with enhanced quality.

Implant Texture and Capsular Contracture: A Review of Cellular and Molecular Pathways.

Capsular contracture (CC) is a leading cause of morbidity in implant-based breast surgery. Implant surface texture has been implicated in CC development, yet its etiopathogenesis remains unclear. We conducted a systematic review to determine the influence of implant surface texture on cellular and molecular mechanisms involved in the etiopathogenesis of CC. A systematic review of the MEDLINE, Embase, Web of Science, and Scopus databases was completed to examine the influence of implant texture on cellular and molecular pathways leading to CC. Excluded articles were reviews and those examining solely the clinical presentation of CC. Development of CC includes prolonged inflammation, increased myofibroblast density, parallel arrangement of collagen fibers, and biofilm formation. When compared with textured implants, smooth implants are associated with reduction in parallel collagen, capsule thickness, and sheer frictional force. Microtextured implants trigger a reduced macrophage response and decreased fibroblast activation as compared with smooth and macrotextured surfaces. Bacterial counts on microtextured and smooth surfaces are significantly lower than that of macrotextured surfaces. Both micro- and macrotextured implants have increased matrix metalloproteinases and activation of tumor necrosis factor α pathway, with increased activation of the transforming growth factor β1 pathway relative to smooth implants. Implant surface texture alters the cellular and molecular mechanisms in the chronic inflammatory process leading to CC. Given the complex biological system of cellular and molecular events in CC, a mathematical model integrating these influences may be optimal to deduce the etiopathogenesis.

Numerical study on the interface characteristics of gas–liquid falling film flow considering the interface forces

As an energy quality improvement device, an air source heat pump plays an important role in clean heating applications. When operating in a cold and wet environment in winter, the outdoor evaporator will have the problem of frost, which affects the operation efficiency. To solve the frosting problem, the development of frost-free evaporators has attracted more and more attention. The fluctuation characteristics of the gas–liquid interface are the key factors affecting the intensity of gas–liquid heat transfer on the air side of this kind of heat exchanger. Therefore, a mathematical model is established to describe the falling film flow on the surface of the flat finned tube heat exchanger in a closed-type heat source tower. The model takes into account the interfacial tension and interphase friction force between the air flow and the liquid film. On this basis, the fluctuation intensity of the central channel interface during falling film flow with different inlet parameters is studied. It is found that there is a critical value of 1.5 m/s (i.e., Reg = 1643.0) in the air flow rate under the study conditions. When the air flow rate is higher than this velocity, the interface near the gas–liquid outlet fluctuates more frequently and the stability is poor. The distributions of interfacial velocity and pressure are also studied, and the relationship between them and interface fluctuation is analyzed. This paper aims to provide theoretical support for enhanced heat and mass transfer on the air side of finned tube heat exchangers in the closed-type heat source tower.

The effects of polycrystalline 3 C-SiC with different roughness coefficients on the crystal structure of nano-grin ding based on molecular dynamics

To investigate the effect of different roughness subsurface on the crystal structure and grain boundary changes during polycrystalline 3 C-SiC nanocrystalline grinding. Polycrystalline 3 C-SiC with different roughness subsurface is constructed by Voronoi method, the stress, crystal structure change and grain boundary crossing mechanism of polycrystalline 3 C-SiC are analyzed by molecular dynamics method. Three different roughness surfaces (Ry=0.02 um, Ry=0.04 um and Ry=0.045 um) are selected for analysis, before the nano-grinding process, the polycrystalline 3 C-SiC is first annealed to make the atoms closely arranged and eliminate the vacancy defects inside the grains. Different roughness affects the friction force of polycrystalline 3 C-SiC and changes the deformation of its subsurface. Consequently, affecting the elastoplastic properties of polycrystalline 3 C-SiC. Different roughness will affect the shear force on the polycrystalline 3 C-SiC subsurface, the smaller the roughness, the greater the shear stress on the subsurface. The polycrystalline 3 C-SiC crystal structure with a roughness of Ry=0.04um is most obviously affected, the length of the dislocations it produces is relatively small, and the situation is more obvious at the boundary, fewer internal dislocations indicating internal dislocation slip phenomenon is less and more favorable for processing.

Dynamic Simulation Analysis of Aviation Gear Transmission Based on Rough Tooth Surface

In order to explore the influence of tooth surface microstructure on the dynamics of aviation gear transmission, this paper describes the profile of aviation gear considering rough surface based on fractal theory. With the help of the established gear fractal contact model, the dynamic parameters such as time-varying friction coefficient, time-varying meshing stiffness and transmission error of rough tooth surface are characterized. The nonlinear dynamic model of aviation gear is established to solve the dynamic response of smooth and rough tooth surface. The dynamic meshing force, dynamic friction force, vibration time domain and frequency domain diagram are obtained, and the corresponding experiments are carried out. The simulation and experimental results show that the fluctuation range of the dynamic simulation results of aviation gear transmission based on rough tooth surface will be larger, and it has a certain degree of disorder, which is closer to the experimental results.

Badania turbulentnego przepływu płynu w pompach głębinowych w celu poprawy bezpieczeństwa środowiskowego

When the plunger moves downwards, the local hydraulic resistance in the injection system causes a hydraulic force from the bottom upwards, which prevents the plunger from falling freely in the cylinder and is the source of the bending of the pump rod column. For this reason, the plunger takes an eccentric position in the cylinder and presses against it, delaying the plunger fall from the head of the balancer of the rocking machine and disturbing coaxial connection of the stock-discharge valve-plunger. These complications lead to increased wear of the plunger-cylinder pair, breakage of the injection valve cell, broken pump rod column, loss of the plunger stroke, etc. It should be noted, however, that in these tests, the flow factor μ is taken as the hydraulic resistance for determining the pressure loss in the valve assembly, and the valve seat cross-section is calculated. When calculating the friction force in the plunger-pressure valve system, the loss of pressure in it is taken to be equal to the loss of pressure of the valve unit. As is known, the downhole pump suction and injection system is a complex system of local resistance, as it consists of different combinations of elements that strongly affect the overall hydraulic resistance of the unit. It is therefore advisable to adopt the local hydraulic resistance coefficient as the hydraulic resistance of the respective unit. The reliability of downhole pumps in general and their individual components is ensured during their design and manufacture and depends on the design features, the quality of manufacturing of components thereof, assembly of the downhole pump in general and their components, as well as a number of other process indicators.

Phonon energy dissipation in friction between black phosphorus layers.

Herein, we employ molecular dynamics simulations to decode the friction properties and phonon energy dissipation between black phosphorus layers. The observations reveal the influence of three factors, temperature, velocity, and normal load, on the friction force of monolayer/bilayer black phosphorus. Specifically, friction is negatively correlated with layer thickness and temperature, and positively correlated with velocity and normal load. The change in friction force is further explained in terms of frictional energy dissipation, and supplemented by the height of potential barriers as well as the number of excited phonons. From the phonon spectrum analysis, the phonon number at the contact interface is found to be higher than that at the non-contact interface. This is due to the larger distance of the contact interface atoms deviate from their equilibrium positions, resulting in higher total energy generated by more intense oscillations, and therefore contributes greater to friction.

Corrosion, wear and machinability studies on scrap aluminium alloy wheel based metal matrix composite

Recycled materials, especially scrap aluminum alloy wheels with reinforcement castings, are gaining applications in various fields such as aerospace, naval, military, and automobile. In this research, Honda car alloy wheels are stir-cast with 5% alumina as reinforcement and subjected to corrosion, wear, and machinability studies. Corrosion studies were conducted to evaluate the corrosion current density (ICorr), corrosion potential (ECorr), and corrosion rate for the cast aluminum metal matrix composite. The wear studies with different loads, i.e., 50 N, 60 N, 70 N, and 80 N, were performed on the specimen and investigated the coefficient of friction, frictional force, and pin temperature. The sliding load has a significant effect on wear performance, and for the sliding load of 80 N, the wear recorded was 2574.83 µm. The electrochemical machinability studies with voltage, duty cycle, and concentration of citric acid electrolyte are performed on the machining rate and surface corrosion factor. Analysis of the electrochemical machining process with PROMETHEE-II shows that 7 V, 60% duty cycle, and 30 g/L electrolyte concentration are estimated to be the best combination for a higher machining rate and a lower surface corrosion factor. KEY WORDS: Alumina, Machining rate, Nyquist plot, Electrochemical machining, PROMETHEE-II Bull. Chem. Soc. Ethiop. 2024, 38(4), 1163-1175. DOI: https://dx.doi.org/10.4314/bcse.v38i4.27

Inversion of Stabilized Large Droplet Clusters.

We investigate the spontaneous rearrangement of microdroplets in a self-assembled droplet cluster levitating over a thin locally heated water layer. The center-to-periphery droplet diameter ratio (the "inversion coefficient") controls the onset of the inversion. Larger droplets can squeeze between smaller ones due to increased drag force on them from the air-vapor flow. In smaller clusters, the rotation of the droplets plays an important role since larger droplets rotating with the same angular velocity (dependent on the rotor of the airflow field) have higher viscous friction force with the liquid layer. It is desirable to avoid cluster inversion in experiments where individual droplet positions should be traced.

Orthogonal array and artificial neural network approach for sustainable cutting optimization machining of 17-4 PH steel under CNC wet turning operations

Sustainable manufacturing strives to increase output while minimizing resource usage, costs, and environmental impact. Tool longevity is crucial, considering material, power, and resource consumption. Challenges like chip removal, heat, and friction necessitate effective solutions. Cutting fluids, like rice bran oil, reduce temperatures, friction, and enhance tool life and surface quality. Research focuses on using rice bran oil with a TiAlN tipped tool to minimize friction and cutting forces. Taguchi's robust design and L-9 orthogonal array reduce experimental trials. Controllable factors include speed, feed, depth of cut, and rice bran oil flow rate, with surface roughness as the performance metric. Taguchi analysis improves turning performance, particularly with 17-4 PH stainless steel. Rice bran oil reduces frictional forces, enabling improved surface quality across all samples, promoting sustainability. Surface roughness (Ra) is notably influenced by feed rate and rice bran oil, contributing 58.06% and 49.5%, respectively. This research underscores the potential of optimizing cutting fluid and process parameters to enhance sustainability in manufacturing.

Study on Stress Distribution Law of Anchorage Body

In order to reveal the stress distribution law of the anchorage body during the drawing process, through the analysis and research on the anchoring mechanism of the anchor rod, it is found that the bonding mechanism of the interface between the anchor rod and the anchoring material is mainly determined by three factors : bonding force, mechanical interlocking and friction force. The bonding mechanism of the anchorage material-surrounding rock interface is mainly determined by two factors : bonding force and friction force. Then, the mechanical model of anchorage body is established, and the distribution equations of axial force and interfacial shear stress of anchorage body are obtained by theoretical analysis. The axial force and shear stress curves are obtained by substituting the relevant parameters. It is found that the axial force and interfacial shear stress curves are exponentially decreasing. The axial force of the bolt is approximately equal to the load applied on the bolt, and at the end of the anchorage, the axial force approaches zero.

Scientific calculation and application of safety marking principles

In today's era, trains have become an indispensable mode of transportation for people, yet safety hazards are inevitable during the process of trains entering stations. To study these safety hazards and the principles behind the design of safety markings, we combine the Bernoulli Effect and the conservation of mechanical energy in fluids, taking into account factors such as a person's weight, volume, and distance from the train. We derive an expression that relates the pressure experienced by individuals to the train's speed, the train's cross-sectional area, the distance between the individual and the train, and the area of the individual subjected to force. By comparing this with the general friction force that corresponds to real-life situations, we find that the distances for safety markings provided by the national "Railway Technical Management Regulations" for high-speed train and dynamic train stations are reasonable: for speeds not exceeding 120km/h, the distance is 1000mm; for speeds over 120km/h but not exceeding 160km/h, the distance is 1500mm; and for speeds over 160km/h up to 200km/h, the distance is 2000mm, regardless of the platform height. Based on the factors affecting the safety markings on railway platforms, four practical safety recommendations are proposed.