Kinetic Friction Coefficient Research Articles

Friction characteristics of preventative wound dressings under clinically‐relevant conditions

Wound dressings can be used prophylactically or during actual treatment. Preventative dressings have become a standard of care to prevent pressure ulcers in patients while in bed. While the mechanism of the preventative benefit has not been completely explained, the friction between the dressing and linen is hypothesized as being a key performance factor. The objective of this project was to quantify the static and kinetic coefficients of friction (COF) of various brands of prophylactic dressings under the stresses experienced in situ, while the dressings are in contact with bed linen materials. The COF of six commercial dressings were calculated using tribometer measurements. The ranges of static COF were 0.333-0.542 and kinetic COF were 0.333-0.513. Four dressings exhibited COF that were consistent with skin-linen values reported in the literature and all dressing COF appear to be lower than the COF of moist skin against linen.

Experimental Studies on the Friction Parameters of Polyurethane Elastomers Used for Cup-Type Sealing

An experimental setup for studying the friction and wear of elastomeric samples in frictional contact with a ground steel surface is described. An empirical relationship for determining the kinetic friction coefficient of elastomeric materials as a function of pressure, slipping velocity, and hardness is presented.

The calculation of kinetic and static friction coefficient and friction graph analysis using Arduino

In this study, with the help of the Arduino UNO and load-cell force sensor, a simple experimental material has been developed to calculate kinetic and static friction coefficients and analyse the friction force in detail. The system with a force sensor mounted on it is placed on the plane. With the help of the rope attached to the force sensor, a force, whose magnitude increased over time, was applied on the sensor. After the force applied was large enough to move the system, the force was applied to move the system at a constant speed. Since the net force acting on the system is zero while the system is stationary and moving with a constant speed, in these cases the magnitudes of force read through the sensor are equal to the static and kinetic friction forces acting on the object. Using these static and kinetic friction forces values, the maximum value of the static friction coefficient and the kinetic friction coefficient were calculated as 0.484 and 0.313, respectively.

ANALYSIS OF THE TRIBOLOGICAL PROPERTIES OF Cu-aTiO2 COMPOSITE COATINGS APPLIED BY THE COLD SPRAY METHOD

The properties of copper have been known and used for a very long time, and research has also been carried out for a long time to expand the applications of this material. One of the methods increasing the bactericidal and bacteriostatic effect of copper is modification by means of the TiO2 phase. The research was conducted in order to determine the impact of modification of copper coatings with TiO2 titanium dioxide on their tribological properties. The paper presents the results of studies on tribological wear of composite coatings applied on steel using the method of low-pressure cold gas spraying (LPCS). The tests of resistance to abrasive wear were carried out in a ball-disc combination in reciprocating motion. The analysis of the resistance to abrasive wear of the tested coatings included the determination of the impact of the pressure force on the intensity of wear and the kinetic friction coefficient of the tested friction pairs. It was found that the samples covered only with copper coatings were characterized by a higher value of friction coefficient in relation to the substrate made of AISI 316l steel. The modification of copper with the submicron particles TiO2 fraction does not increase the value of friction coefficient. The value of this parameter is maintained at a similar level regardless of the applied counterspecimen.

(Invited) Friction Processing and Application to High Strength Hydrogel Surface

In the medical field and food manufacturing process, labor costs and manufacturing costs are reduced, delivery times are shortened, and production is streamlined in all aspects. In particular, the slider part uses many consumables that have a negative effect on the human body and the environment. In this research, we aim at the low friction surface of the functional gel that realizes human safety and cost reduction by replacing a part of the functional gel with the functional gel. This technique involves laser cutting the gel, and the method of creating the sliding and gel surfaces comes from the method of creating a low friction surface by texturing. The textured surface swells uniformly and the coefficient of kinetic friction was measured by the ball-on-disk friction test.The friction force was measured and the coefficient of friction of the untreated and laser treated DN gel surface was calculated. The results show that laser machining (finishing) can reduce the coefficient of friction. Observation of the gel surface suggests that the cause of friction reduction is a change in the roughness of the gel surface due to laser processing. This finding is expected to guide us to a better understanding of the physicochemical properties of hydrogels. We will introduce an example of using this technology as a machine element.The dynamic friction coefficient of the low friction gel surface prepared by this method was about 1/3 of that of the untreated gel surface. It was also confirmed that wear marks disappeared depending on the degree of texturing.Using this technique, it can be easily applied to gel surfaces with low friction. We also designed and developed a unique friction tester for machines. Furthermore, by replacing the metal sliding part with a gel mechanical material, we succeeded in miniaturizing the ultrasonic diagnostic equipment. Figure 1

A novel fiber-fretting test for tribological characterization of the fiber/matrix interface

Ceramic matrix composites exhibit excellent high temperature properties and are candidate materials for structural applications from jet engines to nuclear fuel cladding. The strength and deformation behavior of these composites are intrinsically tied to the properties of the fiber/matrix interface. This research introduces a novel technique to evaluate the fundamental friction and wear characteristics of these interfaces. A case study on SiCf/PyC/SiCm composites applies in situ fiber fretting to investigate the kinetic friction coefficient and cyclic wear characteristics of the interphase. The experimental methodology is presented in explicit detail to encourage other researchers to explore the capabilities of this technique. Testing was carried out as a function of fiber roughness, PyC thickness (≈10, 500, 1200 nm), cycle count (10, 100, 1000), and frequency (1, 5, and 10 Hz). The friction coefficient and wear behavior changed with cycle length due to a transition from adhesive to abrasive mechanisms. SEM fractography provided insights to tribological evolution from adhesive sliding to three-body abrasive wear. The structural disorder at the tribo-surface relating to graphitic content and dangling bond density was investigated using Raman spectroscopy. Properties are contextualized with comparison to uniaxial tensile behavior of the parent composite.

Determination of kinetic friction coefficient using an Arduino

In this study, a kinetic friction coefficient was determined using an Arduino microcontroller. For this purpose, we used an Arduino UNO, an HC-SR04 ultrasonic distance sensor, two wooden blocks, a pulley system and connecting cables. In the experimental process, one wooden block was attached to another wooden block that was able move in the vertical direction with the help of a pulley. The acceleration was calculated by taking the change of the position of the object per unit of time with the help of a distance sensor throughout the movement. Then, using Newton’s second law, the friction coefficient between the wooden block and the surface was calculated as 0.426. In order to test the accuracy of the study result, a widely used method was also used and the kinetic friction coefficient was found to be 0.384, which is close to the result determined in this study.

Development of Static and Kinetic Friction Coefficient Experiment Device Based on Arduino Uno

The concept of friction makes physics more realistic. Based on research, physics education students are still experiencing misconceptions or do not understand the concept of the friction coefficient. Experimental tools commonly used in practicum have not been able to measure the coefficient of friction properly. The purpose of this research is to design a static and kinetic friction coefficient experiment that can be used in basic physics practicum. This study uses the ADDIE model which is carried out to the stage of develop or media development. The experiment was developed using the principle of sliding beams in an inclined plane by using an Arduino Uno microcontroller and sensors as a time and angle measurement device. The experiments designed to observe the effect of differences in mass and surface roughness on the friction coefficient. this device can measure the value of μs and μk simultaneously. The time measurement precision value of the tool is 93% and the angle measurement precision is 98.0%. The experiment succeeded in proving that μs > μk , surface roughness affects the value of the coefficient of friction and the mass does not affect the value of the coefficient of friction.

THEORETICAL AND EXPERIMENTAL STUDIES ON SLIDING AT LOW SPEEDS WITH INTERMITTENCIES

The guides of the machine tools, brakes, clutches there is the possibility of the intermittent movement of stick-slip. This opens in the case of frictional couples with sliding motion, due to the low sliding speeds. Intermittent slip introduces vibrational phenomena and influences the uniformity of movement and the state of the surface of the couples due to their use. In this respect, the concerns related to the study of this phenomenon represent an interest in the machine building industry. The paper aims to achieve an original theoretical model for calculating the static and kinetic friction coefficients and its experimental verification on a stick-slip stand. The proposed theoretical model establishes the calculation relations of the static and kinetic friction coefficient and the connection between them taking into account the surface processing method. The originality of the approach is that the model is considered friction between the conical penetrator (steel material) and a polymer material. In the literature, the stick-slip phenomenon is approached only in terms of the analysis of flat surfaces. The torques of said materials is frequently used on the parts of sliding machines where this phenomenon is possible. The paper highlights the influence of exploitation factors (load, speed), the processing of surfaces, and the quality of the lubricating liquid on the stick-slip phenomenon, for a friction coupling of polymeric material / metallic material.

Multidrum Stone Columns at the Pompeii Archaeological Site: Analysis of Geometrical Properties and State of Preservation

The seismic vulnerability of ancient free-standing multidrum stone columns is an important issue for the preservation of Greek and Roman archaeological sites. Such elements show a complex and highly non-linear dynamic behavior, requiring specific and sophisticated structural analysis. Different numerical studies on the dynamic behavior of ancient multidrum stone columns found that their seismic response is sensitive to their geometrical parameters, as well as to the material elastic properties, the kinetic coefficient of friction and the amplitude and frequency of the seismic action. Therefore, in the present research, a detailed survey of free-standing multidrum stone columns representative of a wide range of elements at the Pompeii Archaeological site was developed to provide a primary evaluation of the seismic vulnerability of such elements based on their geometrical properties. The study focuses on 103 multidrum grey-tuff columns, from four areas at the site: tetrastyle atrium of Casa del Fauno at Regio VI and Quadriportico dei Teatri, Foro Triangolare and Palestra Sannitica at Regio VIII. Grey tuff was a typically locally sourced natural stone, used as a building material in ancient Pompeii. The research areas included both private (Casa del Fauno) and public buildings (Quadriportico dei Teatri, Foro Triangolare and Palestra Sannitica). The mean overall geometrical properties affecting the seismic behavior of the columns in each research area and the discussion of the collected results are herein presented.

Aggregate micro tribological properties of sponge city permeable pavement base layer under vehicle loading

Macro mechanical behavior of open-graded permeable pavement base layer of sponge city is mainly determined by the micro contact interface properties among aggregates. Understanding the micro tribological properties among aggregates interfaces is critical in order to optimize the design of permeable pavement base layer based on its macro performance. A micro tribological experiment was developed to simulate the tribological behavior among aggregates contact interfaces of base layer. Aggregate wear scar surface micro-texture levels and their distribution at each octave spectrum bands were calculated based on the spectral analysis method. The surface micro-texture levels and their distribution at each octave spectrum bands can detect the detailed micro-texture wavelength scales which greatly influence the micro tribology behavior of aggregate. A ball-aggregate finite element model was developed to calculate the contact stress between ball and aggregate, when there were different depths contact pit on the surface of aggregate. The results show that kinetic friction coefficients of fifteen types of commonly used rock aggregates in engineering increase briefly and then maintain steady condition continuously as the accumulating of sliding cycles except for limestone aggregate. High correlation coefficients between kinetic friction coefficients and each octave band micro-texture levels at different wear stages demonstrate that the aggregate surface micro-texture levels of 32 μm & 2 μm wavelengths greatly influence its micro tribology behavior (i.e. kinetic friction coefficients). Significant correlations between aggregate wear volumes and contact stress indicate that the contact stress among aggregates significantly influences the aggregate wear property.

Investigation of Piezoelectric Energy Harvesting via Nonlinear Friction-Induced Vibration

In this work, piezoelectric energy harvesting (PEH) performance via friction-induced vibration (FIV) is studied numerically. A nonlinear two-degree-of-freedom friction system (mass-on-belt) with piezoelectric elements, which simultaneously considers the stick-slip motion, model coupling instability, separation, and reattachment between the mass and belt, is proposed. Both complex eigenvalue analyses and transient dynamic analysis of this nonlinear system are carried out. Results show that it is feasible to convert FIV energy to electrical energy when the friction system is operating in the unstable vibration region. There exists a critical friction coefficient (μc) for the system to generate FIV and output visible voltage. The friction coefficient plays a significant role in affecting the dynamics and PEH performance of the friction system. The friction system is able to generate stronger vibration and higher voltage in the case that both the kinetic friction coefficient and static friction coefficient are larger thanμc. Moreover, it is seen that the separation behavior between contact pair can result in overestimating or underestimating the vibration magnitude and output voltage amplitude, and the overestimate or underestimate phenomenon is determined by the located range of friction coefficient. Furthermore, it is confirmed that an appropriate value of external resistance is beneficial for the friction system to achieve the highest output voltage. The obtained results will be beneficial for the design of PEH device by means of FIV.

Frictionally coupled sliding and spinning on an inclined plane

The frictionally coupled sliding and spinning of a disk on an inclined plane is considered. The main results of the paper are: (i) The exact solution of the problem can be obtained by quadratures (i.e. in terms of integrals). It includes the kinematical steepness S=σ(tanϕ)∕μ of the plane, with ϕ the declination angle, μ the kinetic friction coefficient, with σ=+1 for downward and σ=−1 for upward motion, respectively. (ii) The phenomenon of the simultaneous stopping of the two motions known from the case of horizontal plane (S=0) is only possible for −0.0804632≤S<1∕2. For example, the choice μ=0.3 leads to an upper bound of ϕmax=8.53o and ϕmax=1.38o for the downhill and uphill motions, respectively. (iii) In the range −0.0804632≤S<0 of the kinematical steepness dual solutions for the uphill motions exist. (iv) When the initial state coincides with one of the fixed points of the system (which only exist in the range −0.0804632≤S<1∕2), the exact solution reduces to a simple elementary form which describes the uniformly decelerated sliding and spinning of the disk until the simultaneous stopping of the two motions. This is a universal phenomenon in the sense that it occurs in all the frictionally coupled sliding and spinning motions considered to date in the literature.

Evaluation of kinetic friction coefficients between single carbon fibers

A device for assessing the kinetic friction between carbon fibers (CFs) was developed. It enabled precise load measurement, in the order of a few mN, upon detection of the extraction movement of a single CF from a CF bundle. The coefficients of friction were evaluated by considering the packing states of the CF bundle. It was found that the packing states strongly affected the kinetic friction coefficient and were largely changed due to compression stress. Stable measurement of the kinetic friction coefficient was achieved when the volume fraction of the CF bundle was within 0.4.–0.5, with a measured kinetic friction coefficient of 0.13 ± 0.1.

Dry Friction Camouflaged in Viscous Drag

Here is presented an interesting problem that can be used to introduce students to a variety of physics topics including non-inertial frames and frictional forces, rotational dynamics, and damped oscillations; the normal force also appears, but not in its usual guises. The problem is a generalized version of problem 3.34 presented in the “Oscillations and Waves,” part of the collection of problems in general physics by I. E. Irodov. The formulation of the problem, now extended by the kinetic friction inclusion, is given in what follows. In the setup shown in Fig. 1, a massive sleeve is fixed between two long identical massless springs. The sleeve can slide over a long horizontal bar against the dry friction of kinetic friction coefficient μ, which emerges to oppose to the relative lateral motion of the two solid surfaces in contact. The horizontal bar rotates at a constant angular velocity about a vertical axis passing through the middle. Above what critical value of the angular velocity (ωC* = ?) will there no longer be oscillations of the sleeve if in the absence of the friction that value amounts to ωC? Initially, the sleeve is given a velocity to start its motion from the center along the rotating bar. Gravitational effects are considered negligible here, but we do use N for the normal force of contact that the bar exerts on the sleeve in the x-y plane. The original problem by Irodov illustrates the same example in order to determine the critical value of angular velocity ωC, but specifically disregards friction (μ = 0).

Controlling Mechanism of Temperature Dependence of Kinetic Friction of Ice

AbstractIce friction is one of the major technical issues in almost every application involving ice as one of the moving parts. Very few studies have placed emphasis on the effects of temperature on ice friction at low velocities, although this is important in the transportation of heavy loads in cold regions using sleds, particularly at the onset of sled movement. In this study, a linear tribometer was designed to move a surface of ice over the test surfaces under constant sliding velocity and load. We present new experimental results of the kinetic friction of ice on stainless steel and polytetrafluoroethylene (PTFE) substrates at low velocities and a wide range of temperatures to a minimum of −60 °C. The results show a strong reduction in friction with increase in temperature. Low friction at low velocities and high temperatures may be owing to the thicker quasi-liquid water from pre-melting at the points of sliding contact, while high friction at low velocities and low temperatures can be caused by the low mobility of the surface molecules. The huge difference between the thermal conductivities of stainless steel and PTFE as well as the relatively high glass transition temperature of PTFE most likely account for the divergence of their coefficient of kinetic friction (COF) curves.

Energy lab practicum: It’s all about the system

This article describes an AP Physics-level lab practicum to determine the coefficient of kinetic friction between a wooden block and a surface in a modified Atwood’s machine setup. The students may not use a dynamics approach to complete the task, only energy concepts. The only equipment they are allowed to use is a meterstick and a digital balance.

Measurement of Kinetic Friction Coefficient through Magnetic Induction Using Audacity Application in Physics Learning

This study is designed to produce an experimental device for the measurement of the kinetic friction coefficient of material through magnetic induction using Audacity application. The objects of material the kinetic friction coefficient of which is going to be measured is rough acrylic with rough acrylic and wood with rough acrylic. The experimental setup was performed on the motion system of the mass of objects m1 and m2 that were connected through a pulley on a table and three solenoids are put under a table as the Electromagnetic Field (EMF) sensor. Analysis of the calculation of kinetic friction coefficient used two concepts, i.e. the kinematics concept to identify the load acceleration and the concept of the dynamic to find the kinetic friction coefficient. The results of the measurement of kinetic friction coefficient in this study have a match with the results obtained in the other studies. Hence, the tools and experimental approaches generated in this study are excellent for use in the learning activities so that teachers can teach physics applicatively.

Measuring the Coefficient of Kinetic Friction by Exploring Dynamics of Rotational Motion

Measuring the coefficients of static, kinetic, and rolling friction are typical experimental tasks for physics students. These coefficients depend on many factors that are difficult to control and so results may vary depending on the method used. We present a novel method of measuring the coefficient of kinetic friction. This method is based on the exploration of the dynamics of rotational motion and makes use of standard physics lab apparatus and procedures. We will focus on the coefficient of kinetic friction and will show that there is good agreement between the values of the coefficient when measured by either the traditional linear motion method or this new rotational technique.

Examining the Frictional Behavior of Primitive Contact Geometries for use as Robotic Finger Pads

Prosthetic and robotic grippers rely on soft finger pads to better acquire objects of varying size, shape and surface. However, the frictional behavior of soft finger pads of different designs and geometries have yet to be quantitatively compared, in large part due to the difficulty in modeling soft contact mechanics. In this letter, we experimentally examine the frictional behavior of several common primitive contact geometries in terms of their performance under shear loads that would tend to cause the contact to slip and the grasp to potentially fail. The effective static and kinetic coefficients of friction were recorded for each finger pad under a range of common grasping loads. The results show that the variance in contact curvature, contact patch geometry and pressure distribution have influences on key parameters for grasping at low forces. The advantages and disadvantages of these simple geometries are discussed for design of single finger, multi-finger and manipulation-based robotic hands.