Tribological Evaluation for an In-Depth Understanding of Improved Workability of Foamed Asphalt

2019 ◽  
Vol 2673 (4) ◽  
pp. 533-545 ◽  
Author(s):  
Biswajit K. Bairgi ◽  
Umme A. Mannan ◽  
Rafiqul A. Tarefder
Keyword(s):  
Hydrodynamic Lubrication ◽  
Asphalt Binder ◽  
Chemical Properties ◽  
Frictional Resistance ◽  
Frictional Behavior ◽  
Lubrication Regimes ◽  
Foaming Process ◽  
Different Temperatures ◽  
The Coefficient Of Friction ◽  
Tribological Characterization

Asphalt binder acts as a lubricant between two aggregates during mixing and compaction. The frictional behavior of asphalt binder as a lubricant in an asphalt-aggregate system plays an important role in mixing and compaction (workability) of warm-mix asphalt (WMA). This study evaluates the frictional behavior of foamed WMA through tribological characterization using a ball-on-three-plates apparatus assembled inside a dynamic shear rheometer (DSR). The tribological test was conducted on six foamed asphalts with varying foaming water contents (FWCs) and on a controlled unfoamed asphalt binder at four different temperatures: 25°C, 60°C, 100°C, and 135°C. These binders were also characterized for rheological and chemical properties. Test results show that the foaming process alters the frictional resistance of the foamed asphalts; specifically, the foaming process reduces the coefficient of friction in elastohydrodynamic and hydrodynamic lubrication regimes. Reduced frictional resistance helps in the formation of a better coating during mixing and improves the sliding ability between aggregates during compaction at reduced temperature.

The Role of Geometrical Parameters in the Lubrication of the Swiss Lever Escapement

2021 ◽  
Vol 88 (6) ◽  
Author(s):  
Alejandro Roda-Buch ◽  
Valentine A. M. Magnin ◽  
Sandra Guadalupe Maldonado ◽  
Stefano Mischler
Keyword(s):  
Hydrodynamic Lubrication ◽  
Contact Forces ◽  
Geometrical Parameters ◽  
Inverse Dynamic ◽  
Technical Parameters ◽  
Lubrication Regimes ◽  
Multibody Model ◽  
Lubrication Regime ◽  
The Coefficient Of Friction

Abstract The lubrication regimes of a contact pair escapement-ruby pallet of a Swiss lever escapement have been investigated combining the theory of fluid lubrication with a well-established kinematic and inverse dynamic multibody model. The kinematic analytical results have been confronted with experimental measurements. The developed model allows to easily obtain, for the three operating phases of the Swiss lever escapement, the relative speed and the contact forces and, by considering a hydrodynamic lubrication regime, the lubricant minimum film thickness and the coefficient of friction. The presented formulation allows to study the influence of crucial technical parameters in the Swiss lever escapement lubrication. The spout radii of curvature have been identified as the optimal parameters to control the lubrication regimes in the pallet/escapement contacts. In that sense, an interesting result is that the lubrication regime moves away from the boundary lubrication by increasing these radii.

Direct Measurement of the Piston-Assembly Friction Force in a Single Cylinder Engine Under Motoring Conditions

2008 ◽  
Author(s):  
C. Fadel ◽  
N. G. Chalhoub ◽  
G. A. Kfoury ◽  
N. A. Henein
Keyword(s):  
Friction Force ◽  
Direct Measurement ◽  
Engine Speed ◽  
Hydrodynamic Lubrication ◽  
Test Rig ◽  
Oil Viscosity ◽  
Lubrication Regimes ◽  
Lubrication Regime ◽  
The Coefficient Of Friction ◽  
Piston Assembly

Characterization of the lubrication regimes and quantification of the frictional losses are very important factors for the design of durable IC engines with improved fuel economy. Therefore, the current work has focused on the development of a tribology test rig that allows for the direct measurement of the instantaneous piston-assembly friction force under motoring conditions. The test rig was used to examine the effects of oil viscosity and engine speed on both the lubrication regimes and the friction force of the piston-assembly. Furthermore, the experimental data served to generate Stribeck curves for the coefficient of friction at different points in the cycle. Tear-down experiments were conducted to assess the friction contribution of each component in the piston-assembly. The results demonstrated that the magnitude of the friction force decreases with increasing oil grade under both boundary and mixed lubrication regimes. However, it tends to increase with increasing oil viscosity under a hydrodynamic lubrication regime. Moreover, the engine speed above which the hydrodynamic lubrication regime becomes prevalent at the midpoint of the stroke tends to decrease with increasing oil viscosity.

Analysis of the Lubrication Regimes at the Small End and Big End of a Connecting Rod of a High Performance Motorbike Engine

2012 ◽  
Author(s):  
Luca Bertocchi ◽  
Matteo Giacopini ◽  
Daniele Dini
Keyword(s):  
Rotational Speed ◽  
High Speed ◽  
High Performance ◽  
Hydrodynamic Lubrication ◽  
Vertical Axis ◽  
Connecting Rod ◽  
Lubrication Regimes ◽  
High Speed Rotation ◽  
Speed Rotation ◽  
Squeeze Effect

In the present paper, the algorithm proposed by Giacopini et. al. [1], based on a mass-conserving formulation of the Reynolds equation using the concept of complementarity is suitably extended to include the effects of compressibility, piezoviscosity and shear-thinning on the lubricant properties. This improved algorithm is employed to analyse the performance of the lubricated small end and big end bearings of a connecting rod of a high performance motorbike engine. The application of the algorithm proposed to both the small end and the big end of a con-rod is challenging because of the different causes that sustain the hydrodynamic lubrication in the two cases. In the con-rod big end, the fluid film is mainly generated by the relative high speed rotation between the rod and the crankshaft. The relative speed between the two races forms a wedge of fluid that assures appropriate lubrication and avoids undesired direct contacts. On the contrary, at the con-rod small end the relative rotational speed is low and a complete rotation between the mating surfaces does not occurs since the con-rod only oscillates around its vertical axis. Thus, at every revolution of the crankshaft, there are two different moments in which the relative rotational speed between the con-rod and the piston pin is null. Therefore, the dominant effect in the lubrication is the squeeze caused by the high loads transmitted through the piston pin. In particular both combustion forces and inertial forces contribute to the squeeze effect. This work shows how the formulation developed by the authors is capable of predicting the performance of journal bearings in the unsteady regime, where cavitation and reformation occur several times. Moreover, the effects of the pressure and the shear rate on the density and on the viscosity of the lubricant are taken into account.

Hydrodynamic Lubrication of Pocket Bearings and Effect of Contouring the Inner and Outer Regions, and Optimum Design Data

1989 ◽  
Author(s):  
C. Bagci ◽  
C. J. McClure ◽  
S. K. Rajavenkateswaran
Keyword(s):  
Optimum Design ◽  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Load Flow ◽  
Temperature Dependent Viscosity ◽  
Design Data ◽  
Planar Surfaces ◽  
Friction Factors ◽  
The Coefficient Of Friction ◽  
Dependent Viscosity

Abstract The article investigates pocket bearings with contoured profiles of exponential forms on both surfaces inside and outside of the step boundary forming hydro-dynamic action surfaces, and develops optimum design data yielding efficient slider bearings with small pockets with higher load capacities than conventional pocket bearings. In the case of a pocket bearings, in addition to the Reynolds equation used for the regions inside and outside the pocket, the continuity equation along the pocket boundary is satisfied to form the complete model of the bearing. The optimum design data includes dimensionless load-, flow-, temperature rise-, power loss-, stiffness-, and the coefficient of friction factors. Incompressible lubricant with temperature dependent viscosity is considered. Detailed study of conventional pocket bearings with planar surfaces is included. Some optimum exponential pocket bearings yield up to 561 percent increase in load capacity as compared to the conventional tapered bearings.

Tribological Behaviour of GFR Polymer Composites

2005 ◽  
Author(s):  
J. Quintelier ◽  
P. Samyn ◽  
P. De Baets ◽  
J. Degrieck
Keyword(s):  
Polymer Matrix Composites ◽  
Normal Load ◽  
Thin Polymer Film ◽  
Matrix Composites ◽  
Tribological Behaviour ◽  
Frictional Behavior ◽  
Glass Fiber Reinforced ◽  
Thin Polymer ◽  
Pin On Disc ◽  
The Coefficient Of Friction

On a Pin-on-Disc test rig with composite disc and steel pin tribological experiments were done on pultruded glass fiber reinforced polymer matrix composites plates. The wear and frictional behavior strongly depends on the structure. Also the normal load plays an important role in the frictional behavior, which is of greater importance than the speed. The formation of a thin polymer film onto the wear track results in a lowering of the coefficient of friction with 20%.

Investigations on condensation phenomena in mercury vapour

1934 ◽  
Vol 30 (2) ◽  
pp. 216-224
Author(s):  
P. C. Ho
Keyword(s):  
Surface Tension ◽  
Chemical Properties ◽  
Mercury Vapour ◽  
Physical And Chemical Properties ◽  
Critical Supersaturation ◽  
Different Temperatures ◽  
Image Position ◽  
Physical And Chemical ◽  
Theoretical Considerations ◽  
And Chemical Properties

Owing to its physical and chemical properties being greatly different from those of any of the liquids which have hitherto been used in the Wilson cloud chamber, mercury has been used in the experiments described in this paper and the condensation phenomena of its vapour at different temperatures observed. Before constructing the apparatus it was considered necessary to get from theoretical considerations some idea about the magnitude of the critical supersaturation for mercury vapour in equilibrium with a drop carrying unit charge. Assuming that J. J. Thomson's formula.where s is the supersaturation of mercury vapour in equilibrium with a drop of mercury of radius a, charge e, density σ and surface tension T, the value of which is assumed here to be independent of the radius of the drop, K the specific inductive capacity of the dielectric surrounding the drop, and R the gas constant for one gramme of weight, all at temperature θ, can be applied to the present problem, this critical supersaturation sm is given by the formula

scholarly journals ESTUDO DAS PROPRIEDADES QUÍMICAS DO LIGANTE ASFÁLTICO CAP 50/70 MODIFICADO POR ADIÇÃO DE LIGNINA PROVENIENTE DE PINUS E EUCALIPTO / STUDY OF THE CHEMICAL PROPERTIES OF ASPHALT BINDER CAP 50/70 MODIFIED BY THE ADDITION OF LIGNIN FROM PINE AND EUCALYPTUS

2021 ◽  
Vol 7 (3) ◽  
pp. 26888-26902
Author(s):  
Ana Maria G. Duarte Mendonça ◽  
Loredanna Melyssa Costa de Souza ◽  
Yane Coutinho Lira ◽  
Valter Ferreira de Sousa Neto ◽  
Teresa Elane Bezerra Luz ◽  
...  
Keyword(s):  
Asphalt Binder ◽  
Chemical Properties

scholarly journals Influence of Temperature and Heat Treatment Regime on Chemical Properties of Pork Meat

2012 ◽  
Vol 6 (3-4) ◽  
Author(s):  
Dragan Vujadinović ◽  
Željka Marjanović-Balaban
Keyword(s):  
Heat Treatment ◽  
Chemical Properties ◽  
Effect Of Temperature ◽  
Processed Meat ◽  
Pork Meat ◽  
Scientific Publications ◽  
Treatment Processes ◽  
Heat Treatment Regime ◽  
Different Temperatures ◽  
Dry Heat Treatment

The real importance of meat in human nutrition has been defined during the last century. Professional and scientific publications of the twentieth century are often written about the nutritional value of meat. Thermal processing of meat is as old as civilization itself. Meat drying as a procedure for a longer shelf life, probably first appeared as a result of some accident in which the fresh meat has been exposed to heat. The first works about the problems of heat treatment of pork were published in the 1950s.The aim of this paper was to investigate the effect of temperature and different methods of heat treatment on chemical properties of processed pork meat. To determine the optimal conditions for various heat treatment processes, in this paper, meat processing was performed at different temperatures, and set the temperature range from 51 ºC to 100 ºC. Therefore, the meat is processed by dry heat treatment (roasting) and cooking in water (at atmospheric pressure). Then, the change of chemical composition of processed meat was noted (moisture content, ash, fat, protein, micronutrients).

Temperature, osmotic and acidic activity of infusion solutions as an integral part of their mechanism of action

2021 ◽  
Vol 19 (2) ◽  
pp. 175-182
Author(s):  
Natalia A. Urakova
Keyword(s):  
Blood Plasma ◽  
Chemical Properties ◽  
Aerobic Metabolism ◽  
Chemical Action ◽  
Routes Of Administration ◽  
Biological Objects ◽  
Physical Chemical ◽  
Different Temperatures ◽  
Cold Infusion ◽  
And Function

A review of the literature shows that the physical-chemical properties of infusion solutions can be an integral part of the mechanism of their local action on the routes of administration. This new scientific and practical direction in clinical pharmacology was born at the end of the 20th century in Russia. Initially, it was found that isotonic solutions of glucose, mannitol, and sodium chloride with different temperatures have different local effects on the metabolism and viability of isolated biological objects such as mitochondria and blood plasma. At the same time, it was shown that increasing the temperature of solutions from +37 to +45C accelerates the metabolism of these biological objects, increases their reactivity and enhances their response to the action of many drugs-activators of metabolism and function. And vice versa, lowering the temperature of these solutions from +37 to +20C and below (up to 0C) slows down their metabolism, reduces their reactivity, weakens their response to the action of drugs-activators of metabolism and function, and also increases survival in conditions of ischemia and hypoxia. These results allowed us to recommend warm infusion solutions as universal means of activating aerobic metabolism in tissues and the response of tissues to drugs with local physical-chemical action, and cold infusion solutions as universal means of inhibiting aerobic metabolism in tissues and increasing the resistance of tissues to the action of drugs on them. Following this, it was shown that many infusion solutions do not have isoosmotic activity, since the osmotic activity of drugs is not controlled. Therefore, one part of the solutions has hypotonic activity, and the other part has hypertonic activity. Therefore, sometimes the infusion solution can increase the hypoosmotic or hyperosmotic activity of the blood plasma. Then it was shown that the absolute majority of infusion solutions do not have a pH of 7.4. At the same time, very many infusion solutions have acidic activity, so they have an acidifying effect on the blood. The chronology of the development of inventions based on the achievements of the physical-chemical pharmacology of infusion agents is shown.

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