Influence of Hydrodynamic Fluid Pressure and Shoe Tread Depth on Available Coefficient of Friction

2012 ◽  
Author(s):  
Gurjeet Singh ◽  
Kurt Beschorner
Keyword(s):  
Coefficient Of Friction ◽  
Hydrodynamic Lubrication ◽  
Fluid Pressure ◽  
Hydrodynamic Pressure ◽  
High Viscosity ◽  
Health Concern ◽  
Fluid Viscosity ◽  
Low Viscosity ◽  
The Coefficient Of Friction ◽  
Lubrication Mechanisms

Slip and fall accidents are a major occupational health concern. Identifying the lubrication mechanisms affecting shoe-floor-contaminant friction under biofidelic (testing conditions that mimic human slipping) conditions is critical to identifying unsafe surfaces and designing a slip-resistant work environment. The purpose of this study is to measure the effects of varying tread design, tread depth and fluid viscosity on underfoot hydrodynamic pressure, the load supported by the fluid (i.e. load carrying capacity), and the coefficient of friction (COF) during a simulated slip. A single vinyl floor material and two shoe types (work shoe and sportswear shoe) with three different tread depths (no tread, half tread and full tread) were tested under two lubrication conditions: 1) 90% glycerol and 10% water (219 cP) and 2) 1.5% Detergent-98.5% (1.8cP) water solutions. Hydrodynamic pressures were measured with a fluid pressure sensor embedded in the floor and a forceplate was used to measure the friction and normal forces used to calculate coefficient of friction. The study showed that hydrodynamic pressure developed when high viscosity fluids were combined with no tread and resulted in a major reduction of COF (0.005). Peak hydrodynamic pressures (and load supported by the fluid) for the no tread-high viscous conditions were 234 kPa (200.5 N) and 87.63 kPa (113.3 N) for the work and sportswear shoe, respectively. Hydrodynamic pressures were negligible when at least half the tread was present or when a low viscosity fluid was used despite the fact that many of these conditions also resulted in dangerously low COF values. The study suggests that hydrodynamic lubrication is only relevant when high viscous fluids are combined with little or no tread and that other lubrication mechanisms besides hydrodynamic effects are relevant to slipping like boundary lubrication.

Hydrodynamic Lubrication of a Porous Slider

1973 ◽  
Vol 15 (3) ◽  
pp. 232-234 ◽  
Author(s):  
J. Prakash ◽  
S. K. Vij
Keyword(s):  
Drag Coefficient ◽  
Closed Form ◽  
Coefficient Of Friction ◽  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Centre Of Pressure ◽  
Slider Bearing ◽  
Frictional Drag ◽  
Pressure Load ◽  
The Coefficient Of Friction

A plane porous slider bearing is analysed and closed form expressions for pressure, load, frictional drag, coefficient of friction and centre of pressure are obtained. The effect of porosity is to decrease the load capacity and friction. However, the coefficient of friction is increased.

scholarly journals Energy dissipation in microfluidic beam resonators

2010 ◽  
Vol 650 ◽  
pp. 215-250 ◽  
Author(s):  
JOHN E. SADER ◽  
THOMAS P. BURG ◽  
SCOTT R. MANALIS
Keyword(s):  
Energy Dissipation ◽  
Boundary Layers ◽  
Environmental Changes ◽  
Signal To Noise Ratio ◽  
Fluid Motion ◽  
Microfluidic Channel ◽  
Direct Consequence ◽  
High Viscosity ◽  
Fluid Viscosity ◽  
Low Viscosity

The fluid–structure interaction of resonating microcantilevers immersed in fluid has been widely studied and is a cornerstone in nanomechanical sensor development. In many applications, fluid damping imposes severe limitations by strongly degrading the signal-to-noise ratio of measurements. Recently, Burg et al. (Nature, vol. 446, 2007, pp. 1066–1069) proposed an alternative type of microcantilever device whereby a microfluidic channel was embedded inside the cantilever with vacuum outside. Remarkably, it was observed that energy dissipation in these systems was almost identical when air or liquid was passed through the channel and was 4 orders of magnitude lower than that in conventional microcantilever systems. Here, we study the fluid dynamics of these devices and present a rigorous theoretical model corroborated by experimental measurements to explain these observations. In so doing, we elucidate the dominant physical mechanisms giving rise to the unique features of these devices. Significantly, it is found that energy dissipation is not a monotonic function of fluid viscosity, but exhibits oscillatory behaviour, as fluid viscosity is increased/decreased. In the regime of low viscosity, inertia dominates the fluid motion inside the cantilever, resulting in thin viscous boundary layers – this leads to an increase in energy dissipation with increasing viscosity. In the high-viscosity regime, the boundary layers on all surfaces merge, leading to a decrease in dissipation with increasing viscosity. Effects of fluid compressibility also become significant in this latter regime and lead to rich flow behaviour. A direct consequence of these findings is that miniaturization does not necessarily result in degradation in the quality factor, which may indeed be enhanced. This highly desirable feature is unprecedented in current nanomechanical devices and permits direct miniaturization to enhance sensitivity to environmental changes, such as mass variations, in liquid.

scholarly journals Viscophobic turning regulates microalgae transport in viscosity gradients

2020 ◽  
Author(s):  
Michael R. Stehnach ◽  
Nicolas Waisbord ◽  
Derek M. Walkama ◽  
Jeffrey S. Guasto
Keyword(s):  
Cell Motility ◽  
High Viscosity ◽  
Force Model ◽  
Fluid Viscosity ◽  
Protective Effects ◽  
Microbial Transport ◽  
Cell Transport ◽  
Physical Mechanisms ◽  
Low Viscosity ◽  
Population Scale

Gradients in fluid viscosity characterize microbiomes ranging from mucus layers on marine organisms1 and human viscera2,3 to biofilms4. While such environments are widely recognized for their protective effects against pathogens and their ability to influence cell motility2,5, the physical mechanisms controlling cell transport in viscosity gradients remain elusive6–8, primarily due to a lack of quantitative observations. Through microfluidic experiments with a model biflagellated microalga (Chlamydomonas reinhardtii), we show that cells accumulate in high viscosity regions of weak gradients as expected, stemming from their locally reduced swimming speed. However, this expectation is subverted in strong viscosity gradients, where a novel viscophobic turning motility – consistent with a flagellar thrust imbalance9,10 – reorients the swimmers down the gradient and causes striking accumulation in low viscosity zones. Corroborated by Langevin simulations and a three-point force model of cell propulsion, our results illustrate how the competition between viscophobic turning and viscous slowdown ultimately dictates the fate of population scale microbial transport in viscosity gradients.

scholarly journals Slug Translational Velocity for Highly Viscous Oil and Gas Flows in Horizontal Pipes

Fluids ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 170 ◽  
Author(s):  
Baba ◽  
Archibong-Eso ◽  
Aliyu ◽  
Ribeiro ◽  
Lao ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Prediction Models ◽  
High Viscosity ◽  
Internal Diameter ◽  
Viscosity Data ◽  
Fluid Viscosity ◽  
Liquid Viscosity ◽  
Translational Velocity ◽  
Two Phase ◽  
Low Viscosity

Slug translational velocity, described as the velocity of slug units, is the summation of the maximum mixture velocity in the slug body and the drift velocity. Existing prediction models in literature were developed based on observation from low viscosity liquids, neglecting the effects of fluid properties (i.e., viscosity). However, slug translational velocity is expected to be affected by the fluid viscosity. Here, we investigate the influence of high liquid viscosity on slug translational velocity in a horizontal pipeline of 76.2-mm internal diameter. Air and mineral oil with viscosities within the range of 1.0–5.5 Pa·s were used in this investigation. Measurement was by means of a pair of gamma densitometer with fast sampling frequencies (up to 250 Hz). The results obtained show that slug translational velocity increases with increase in liquid viscosity. Existing slug translational velocity prediction models in literature were assessed based on the present high viscosity data for which statistical analysis revealed discrepancies. In view of this, a new empirical correlation for the calculation of slug translational velocity in highly viscous two-phase flow is proposed. A comparison study and validation of the new correlation showed an improved prediction performance.

Droplet Behavior on a Rotating Surface for Atomization-Based Cutting Fluid Application in Micromachining

2010 ◽  
Vol 132 (1) ◽  
Author(s):  
Isha Ghai ◽  
John Wentz ◽  
Richard E. DeVor ◽  
Shiv G. Kapoor ◽  
Johnson Samuel
Keyword(s):  
Surface Tension ◽  
Evaporation Rate ◽  
High Viscosity ◽  
Cutting Fluid ◽  
Fluid Viscosity ◽  
Droplet Shape ◽  
Low Viscosity ◽  
Droplet Behavior ◽  
Rotating Surface ◽  
Cutting Zone

The droplet behavior on a rotating surface has been studied to better understand the physics underlying atomized cutting fluid application. To this end, microturning experiments are carried out and the cutting performance evaluated for varying cutting fluids and at different droplet speeds. Microturning experiments indicate that a cutting fluid with low surface tension and low viscosity generates lower cutting temperatures, whereas a fluid with low surface tension and high viscosity generates lower cutting forces. Single-droplet impingement experiments are also conducted on a rotating surface using fluids with different surface tension and viscosity values. Upon impact, the droplet shape is observed to be a function of both the droplet speed and the surface speed. The spreading increases with increased surface speed owing to the tangential momentum added by the rotating surface. Spreading is observed to also increase with a decrease in fluid surface tension and does not change with the fluid viscosity. The evaporation rate is observed to increase for a rotating surface owing to convective heat transfer. Low surface tension and low viscosity are observed to increase the evaporation rate. It is concluded that a fluid with low surface tension and low viscosity is an effective coolant of the cutting zone, whereas a fluid with low surface tension and high viscosity is effective for lubrication.

scholarly journals Evaluating the effect of drill string rotation and change in drilling fluid viscosity on hole cleaning

2021 ◽  
Author(s):  
Samuel Bright Olawale ◽  
Promise O. Longe ◽  
Samuel Felix Ofesi
Keyword(s):  
Drilling Fluid ◽  
High Viscosity ◽  
Drill String ◽  
Rheological Parameters ◽  
Fluid Viscosity ◽  
Hole Cleaning ◽  
Low Viscosity ◽  
Cutting Bed ◽  
Viscosity Fluid ◽  
Deviated Wells

AbstractThe most primitive hole challenge is cleaning the hole, which is more severe in deviated wells. This problem was tackled in this research via experimental analysis and graphical evaluations. To hit this aim, rheological parameters were experimentally obtained, and Noah’s model was used to determine cutting bed erosion time at varying heights. A graphical evaluation was done using a case study of deviated wells X and Y from a Niger Delta field. The result shows that low-viscosity fluid, KCL polymer fluid and high-viscosity fluid take 124, 283 and 342 min, respectively, to erode equal height as graphical evaluation shows that hole cleaning will grow complex on deviation. Thus, the deduction from this work in reducing non-productive time (NPT) related to hole cleaning in drilling operation is first, prior to making a trip, pumping low-viscosity fluid at a high flow rate. Secondly, during drilling, increasing drill string rotation in deviated wells can effectively stir the cuttings into the annulus above the low session of the hole.

Experimental study on the coefficient of friction of the ball screw

2021 ◽  
pp. 1-18
Author(s):  
Lu-Chao Zhang ◽  
Chang-Guang Zhou
Keyword(s):  
Experimental Study ◽  
Coefficient Of Friction ◽  
Hydrodynamic Lubrication ◽  
Friction Torque ◽  
Measuring System ◽  
Ball Screw ◽  
Stribeck Curve ◽  
Key Factor ◽  
The Coefficient Of Friction ◽  
Curve Fitting Method

Abstract The coefficient of friction (COF) is a key factor to estimate the performance of ball screws. Pieces of research focus on the experimental study of the COF, leading to the COF chosen empirically in many studies. To acquire the COF of the HJG-4010, a measuring system is conducted to detect the friction torque under different preloads and rotational speeds and the effects of the applied axial load and rotational speed on the COF are analyzed. By the curve fitting method, the Stribeck curve of the ball screw is obtained. The experimental results show that the lubricating state can be divided into two categories: the mixed lubrication state, and the hydrodynamic lubrication state. This study is beneficial to choose a suitable working condition for a different performance of the ball screw.

scholarly journals Formulation, Development and Evaluation of Bilayer Floating Tablets of Antihypertensive Drug Bosentan

2021 ◽  
Vol 11 (6) ◽  
pp. 167-172
Author(s):  
Abadhesh Kumar Niranjan ◽  
Alka Singh
Keyword(s):  
High Viscosity ◽  
Health Concern ◽  
Large Contribution ◽  
Dissolution Profile ◽  
Formulation Development ◽  
Bilayer Tablets ◽  
Low Viscosity ◽  
Viscosity Grade ◽  
Viscosity Polymer

Hypertension, or high blood pressure, is a major public health concern around the world because of its large contribution to the global health burden and its function as a major risk factor for a variety of disease processes. Bosentan SR Floating Bilayer Tablets were made with HPMC K4M, HPMC E-15, and HPMC E-15 alone (80%) and in combination with varying percentages of polymer (20&60 percent, 40&40 percent, and 60&20 percent ). The hydrophilic polymer HPMC is used to make three different formulations (M4, M8, and M12) of floating Bosentan SR tablets, each with a viscosity grade of 80 percent. M12 formulation was shown to be suitable for SR tablet formulation. From the M12 formulation. It's based on the M12 formula. The fraction of high viscosity polymer can be lowered by adding low viscosity polymer, as demonstrated in the C3 formulation. It was clear from the dissolution profile of formulation C3 that by mixing the low and high viscosity polymers, the drug release from the formulation may be improved as compared to manufacturing M12 high viscosity polymer alone. According to the findings of this investigation, as floating duration increases, the release rate drops. As a result, it's appropriate for long-term formulation. Keywords: Bosentan, Floating Bilayer Tablets, Hypertension, SR Tablets, HPMC K4M, E-15

A Mixed-Lubrication Model for Shoe-Floor Friction Applied to Pin-on-Disk Apparatus

2008 ◽  
Author(s):  
K. E. Beschorner ◽  
M. R. Lovell ◽  
C. Fred Higgs ◽  
M. S. Redfern
Keyword(s):  
Material Properties ◽  
Normal Force ◽  
Hydrodynamic Lubrication ◽  
Contact Region ◽  
Hydrodynamic Pressure ◽  
Mixed Lubrication ◽  
Health Concern ◽  
Peak Contact Pressure ◽  
Pin On Disk ◽  
Floor Material

Despite the serious health concern associated with slip and fall accidents and the numerous slip testing devices that have been developed, few studies have attempted to tribologically model the shoe-floor interface. To this end, a mixed-lubrication model for shoe-floor interfaces is proposed. The model is applied to a pin-on-disk apparatus and uses contact mechanics and hydrodynamic lubrication modeling with iterative methods to solve the mixed lubrication problem. Outputs of the model are load supported by the fluid and load supported by the contacting asperities. Measurable parameters input to the model are: curvature of the shoe material (pin), material properties of the shoe material, roughness of the shoe and floor material, viscosity of the fluid, sliding speed and normal force. COF estimates are generated as a function of the proportional load borne by the fluid and the contacting asperities. The model COF values replicate the experimental data for the two different shoe materials tested. The peak hydrodynamic pressure was found just outside the contact region and peak contact pressure was at the center of the pin. The model represents a first step towards developing a mixed-lubrication model for an entire shoe-floor surface.

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