Experimental Investigation Of Friction Research Articles

Giovanni Canestrini’s models of Leonardo da Vinci’s friction experiments

Among the exhibits at the 2016 Leonardo da Vinci exhibition at the Science Museum, London, was one that purported to illustrate Leonardo’s experiments on friction. The models involved were the work of Giovanni Canestrini (1893–1975) who contributed to the 1939 and 1953 Leonardo exhibitions in Milan. This article discusses the original sources and history of these models, in the light of recent research into Leonardo’s work on friction. It concludes that, while being relevant to Leonardo’s study of mechanics, these models seriously misrepresent his experimental investigations of friction.

Experimental Investigation of Friction and Wear Behavior of AL7075-TiO2-B4C using RSM, ANN and Desirability Function

Metal Matrix Composites (MMC) are widely used in high strength and light weight applications. AL7075 featuring high fatigue strength, good corrosion and wear resistance makes it to employ as a good vehicle building material and also finds it usage in some important engine components which are subjected to constant wear. In this study, dry sliding wear behaviour of hybrid MMC formed by reinforcement of aluminium 7075 with B4C and TiO2 at 3% and 3% weight fraction respectively is investigated. Reinforced particles are powdered using ball mill, reduced to nano size and uniformly dispersed in aluminium matrix using stir casting method. Specimen was prepared according to ASTM standards and wear tests were conducted. Experiments were conducted with keeping force, speed and distance as input parameters while Coefficient of Friction (CoF) and average wear rate as the output parameters. RSM and ANN models were developed to simulate the experiments. The surface which was subjected to test evidenced that presence of TiO2 and B4C particles protected the material to a certain extent. The tests revealed that wear rate and CoF were greatly influenced by force and distance followed by the speed of the rotating disc. The predictions from RSM and ANN models are also correlated well with the experimental data. ANN model also showed better accuracy and capability for predicting the wear rate and CoF. By desirability function, it was found that the material performed well at a keeping force of 38.9 N, speed of 300rpm and distance of 1000 rpm.

Experimental investigation of friction in compliant contact: The effect of configuration, viscoelasticity and operating conditions

This work investigates the effects of kinematic conditions, configuration, viscoelasticity, and lubricant viscosity on friction in lubricated compliant contacts. Experimental data were also used to develop a numerical simulation capable of predicting fluid friction in compliant contacts. Mini Traction Machine (MTM) in the ball-on-disc configuration was used to successfully gain insight into the behaviour of compliant contacts, allowing the investigation of the mentioned effects. The findings have confirmed that viscoelastic effects are present in all configurations, being soft-on-hard (S/H), hard-on-soft (H/S) and soft-on-soft (S/S), where they seem to be more profound in the configurations using compliant discs. The experimental data also suggest that the slide-to-roll ratio affects rolling friction in all configurations which is contrary to current literature.

Analytical and experimental investigations of friction between synthetic fiber ropes and grooved pulleys

Analytical and experimental investigations of friction between synthetic fiber ropes and grooved pulleys

Experimental Investigation of Friction and Slip at the Traction Interface of Rope and Sheave

In this paper, an exclusive testing rig was built to experimentally investigate the friction and slip at elevator traction interface under different traction conditions. The experimental results indicated that slipping occurs at both ends of contact arc first and then expands to the middle region gradually until the full slip along the sheave occurs. In addition, the full slip occurs earlier under lower rope pretension. Meanwhile, by setting similar boundary and loading conditions as in the experiments, the finite element analysis was performed. The simulation results agree with the experiments very well but reveal more details about traction behavior.

Experimental investigation of friction in deep drawing

Investigation of friction is carried out in the radial drawing region between the die and blank holder and also in the stretching zone over the punch in deep drawing. Two methods are developed to calculate the coefficient of friction in each zone using the experimentally determined data such as punch force diagrams and strain distributions obtained by an optical scanning system. The current methods differ from the existing techniques which are obtained in simulative tests. The proposed methods can be applied in room temperature and at elevated temperatures. Comparisons of friction coefficients are made with those obtained by other techniques.

Experimental Investigation of Friction and Wear Properties for Glass/Carbon Hybrid Fiber Reinforced with Epoxy Resin

Friction and wear properties of glass/carbon hybrid fiber weave reinforced with epoxy resin are reported in this experimental study. The tribological properties are investigated using a pin-on-disk test apparatus which measures coefficient friction and wear rate. The experiments are conducted at various loads and sliding distance at constant velocity 5m/s, the purpose is to compare the performance at different sliding conditions. It is found that the wear rate is increased by increasing the carbon content, but the co-efficient of friction decreases by increasing the carbon percentage in the composite.

Generalized law of friction between elastomers and differently shaped rough bodies

In this paper, we study theoretically and experimentally the friction between a rough parabolic or conical profile and a flat elastomer beyond the validity region of Amontons' law. The roughness is assumed to be randomly self-affine with a Hurst exponent H in the range from 0 to 1. We first consider a simple Kelvin body and then generalize the results to media with arbitrary linear rheology. The resulting frictional force as a function of velocity shows the same qualitative behavior as in the case of planar surfaces: it increases monotonically before reaching a plateau. However, the dependencies on normal force, sliding velocity, shear modulus, viscosity, rms roughness, rms surface gradient and the Hurst exponent are different for different macroscopic shapes. We suggest analytical relations describing the coefficient of friction in a wide range of loading conditions and suggest a master curve procedure for the dependence on the normal force. Experimental investigation of friction between a steel ball and a polyurethane rubber for different velocities and normal forces confirms the proposed master curve procedure.

Experimental Investigation of Friction and Wear Behavior at the Interface of Aluminium and Mild Steel

The Paper incorporates the experimental studies carried out for assessing the tribological performance of Aluminium at the sliding contacts with mild steel plate, using a pin-on-disk tribometer as per ASTM-G 99. The study has been done in order to explore the friction and wear behaviors at the interface of tribo-pair. The tribological properties as coefficient of friction and specific wear rate of aluminium 6061are investigated. The Tribological tests are carried out at 500, 1000, 1500 rpm for 1000 meters in dry condition based on Response Surface Methodology. Track diameter, rotating speed and normal load are considered as the design parameters. Using central composite design, the problem is converted into single response optimization problem and the optimum combination of design parameters are found as 50mm track diameter, 500 rpm of rotating speed and 0.5 kg of normal load. The ANOVA result shows that the rotational speed is the most significant factor, followed by load and Track diameter for co-efficient of friction. Whereas the Track diameter is the most significant factor, followed by rotating speed and normal load for specific wear rate. Finally, microscopic images are investigated to identify the wear mechanism.

Experimental Investigations of Friction Carried out with the Tribo-Torsion-Test and Frictional Modelling

Complex frictional effects occur during the extrusion process between the extrusion die and the extruded material. The recently developed Tribo-Torsion-Test is used to measure friction under thermo-mechanical conditions similar to the extrusion process. Investigations have not been carried out only with nitrided but also with two different chemical vapour deposited CVD coated samples. In the context of this study the Tribo-Torsion-Test is introduced and laboratory results are presented.

Experimental investigation of friction in entrapped elastohydrodynamic contacts

Start-up friction is a performance-limiting aspect of hydraulic motor operation. This study was conducted to gain a better understanding of the roles played by contact pressure, speed, and oil type to start-up friction behavior for contacts containing trapped pockets of highly pressurized oil, also known as elastohydrodynamic lubrication (EHL) entrapments. An apparatus was built to measure the start up friction response for ball-on-plane sliding contact with simultaneous observation of the contact region by optical interferometry. Baseline trials for all cases were conducted in the absence of any entrapment and then repeated after forming an entrapment. An impact, activated by solenoids, was used to create a small separation whereby oil would fill the gap and then become trapped as the load rapidly brought the surfaces back into contact. In all cases, entrapment substantially decreased the start-up friction. Additionally, the short-lived entrapments provide the greatest reduction in start-up friction. Therefore, the method of entrapment that may be implemented with least delay before the initiation of sliding has the greatest potential.

Investigation of friction in warm forging of AA6082

This paper presents an experimental investigation of friction in hot forging of AA6082, which is a standard forging alloy in automotive engineering, mechanical engineering and in naval architecture, by employing a modified ring-on-disc test. The experiments were performed with three different commercial graphite-based lubricants and at various loads, sliding velocities and specimen surface conditions. In addition, some tests were performed without lubrication.

Analysis, finite element simulation and experimental investigation of friction in tube hydroforming

The purpose of this work is to present a new analytical method for determination of the coefficient of friction in hydroforming of tubes, based upon the tube-upsetting test. According to the developed method, the friction coefficient can be calculated by using the geometrical data from the deformed tube and material properties without force measurement. Influence of different process parameters on the tribological phenomena has been observed and analyzed. The proposed method has been verified by comparison with the results obtained by FE-simulation and by experiment.

Experimental investigation of friction on low-temperature ice

Using a unique technique, we formed a thin layer of ice on steel surface at temperature as low as 123 K in an ultra-high vacuum. We investigated the frictional behavior of such a thin ice layer in the same UHV using a pin-on-disk friction tester. The sample surfaces were monitored in situ using X-ray Photoelectron Spectroscopy (XPS). Testing data showed that the friction coefficient was a linear function of temperature. This study indicates that the sliding motion is lubricated by a frictionally melted liquid layer.

Experimental Investigation of Friction and Electrical Characteristics of the Porous Bearings with Axial Grooves for Laser Scanner

The electrical and frictional properties of axially grooved oil-impregnated sintered-metal bearing (porous metal bearing) with varying loads and speeds were measured. The results were compared with the performance of bearings without grooves and conventionally used ball bearings. The test results showed that the frictional values of the porous bearings were lower than those of ungrooved bearings and ball bearings, and that the porous bearings operated in a full-hydrodynamic lubrication regime. The values of rating current, starting time and jitter revealed that the grooved-bearing had better electrical characteristics than the ungrooved bearing as well as the ball bearing. From the endurance tests on start-stop and continuous operating, it was confirmed that this bearing could be mass-produced for use in a laser scanner unit. Presented at the 54th Annual Meeting Las Vegas, Nevada May 23–27, 1999

Pressure drop for rib-roughened scalene triangular duct having two rounded corners

An experimental investigation of friction in a scalene triangular passage having two and three rib-roughened sides was made. The parametric study included variations of pitch-to-height and height-to-hydraulic diameter ratio over the ranges 4–20 and 0.065–0.149, respectively. The Reynolds number was varied between 2,000 and 30,000. Generalized correlations of the data are provided. With three roughened sides, the analysis indicates that good estimates of friction factor can be obtained using existing friction relations for cylindrical or plane geometry.

Heated turbulent flow of helium—argon mixtures in tubes

The results of a numerical and experimental investigation of friction and heat-transfer parameters for turbulent flow of helium-argon mixtures in smooth, electrically heated, vertical circular tubes are presented. Mixtures with molecular weights between 15.3 and 29.7 are used; these values correspond to molecular Prandtl numbers between 0.42 and 0.49. Inlet Reynolds numbers range from 31 200 to 102 000, maximum wall temperatures from 392 to 828 K, maximum wall-to-bulk temperature ratios to 1.82, and pressures from 4.7 to 9.7 atm. Popular existing experimental correlations, developed using gases with Prandtl numbers of the order of 0.7, are found to overpredict the observed Nusselt numbers. By comparison of numerical calculations and measured constant property Nusselt numbers, turbulent Prandtl numbers are determined in the wall region. The validity of using these deduced turbulent Prandtl numbers is examined for conditions where the properties vary significantly.