Determination of the boundary of a hydrodynamic contact region

1983 ◽  
Vol 23 (4) ◽  
pp. 491-497
Author(s):  
M. A. Galakhov ◽  
V. P. Kovalev
Keyword(s):  
Contact Region

Impact on Beams

1936 ◽  
Vol 3 (2) ◽  
pp. A55-A61
Author(s):  
H. L. Mason
Keyword(s):  
Historical Development ◽  
Contact Region ◽  
Local Deformation ◽  
Lateral Vibration ◽  
Transverse Impact ◽  
Concentrated Mass ◽  
Impact Theory ◽  
Inelastic Impact ◽  
Maximum Contact

Abstract This paper deals with transverse impact on beams the mass of which is of importance. Experimental results are presented for comparison with theory. Impacts which appear single to the eye are shown to consist in reality of several blows in quick succession. Section 1 of the paper traces the historical development of this subject by discussing the investigations of Young, Hodgkinson, Cox, Saint Venant, and Timoshenko. Section 2 treats a simplified system in which a concentrated mass strikes a smaller concentrated mass having a “soft” spring restraint. For elastic impact, theory predicts for the struck mass a path composed of sinusoidal elements separated by instantaneous blows. For inelastic impact it predicts a joint harmonic motion. Records of the paths of both masses were obtained experimentally. Section 3 of the paper uses Timoshenko’s method of combining local deformation of the contact region with lateral vibration of the beam. An experimental investigation of maximum contact pressure and of blow duration gives what is believed to be the first confirmation of this theory. Section 4 describes an experimental determination of flexural stresses in elastic and inelastic impact on a 3-in. I-beam by the use of a Westinghouse magnetic strain gage. The indication is that stresses may be higher than those calculated by the usual approximations.

An Analytical Description of the Magnetic Conductance Across an Isolated Defect Region in a 1D-Ferromagnetic Lead

SPIN ◽  
2019 ◽  
Vol 09 (01) ◽  
pp. 1950005 ◽  
Author(s):  
Adel Belayadi ◽  
Boualem Bourahla ◽  
Ahmed Mougari
Keyword(s):  
Contact Region ◽  
Analytical Description ◽  
Quantum Scattering ◽  
Defect Region ◽  
Model Calculations ◽  
Adopted Model ◽  
Field Matching ◽  
Ferromagnetic Lead ◽  
Transmission And Reflection

We illustrate in this contribution the determination of the magnetic conductance across a nanocontact region defined by an isolated defect region joined between two mono-atomic leads ferromagnetically ordered. The system is described by the Heisenberg interaction. Additionally, to deal with the lack of symmetry across the contact region defined by the isolated defect, we involve the phase field matching approach. Furthermore, to compute the quantum conductance, we define the quantum scattering of the transmission and reflection probabilities within the framework of Landauer–Büttiker formalism. Based on these approaches, we present an analytical expression of the magnetic conductance. The obtained analytical results based on our adopted procedures confirm the known results adopted for perfect infinite leads (no defect). Our model calculations can be applied numerically when we deal with doping across the defect region. The adopted model could be also used numerically to deal with the impurity configurations that one might encounter in real systems.

On the Analytical Determination of the Nominal Stresses in Dovetail Attachments

2020 ◽  
Author(s):  
Glenn Sinclair
Keyword(s):  
Finite Element ◽  
Closed Form ◽  
Contact Region ◽  
Essential Elements ◽  
Contact Stresses ◽  
Physical Models ◽  
Analytical Determination ◽  
Bending Stress ◽  
Attachment Model

Abstract Simple physical models are developed for the nominal contact stresses in dovetail attachments. These nominal stresses include the pressure, the shear traction, and the bending stress in the contact region, both during loading up and unloading. The models furnish closed-form expressions for these stresses. For a specific dovetail attachment, model values are compared with verified finite element values. As a result of the simplifications introduced to make the models tractable, model values only approximately equal finite element values. Nonetheless, the models capture the essential elements of the response of nominal stresses in dovetail attachments.

Finite Element Analysis of Rolling Contact Problems Using Minimum Dissipation of Energy Principle

1998 ◽  
Vol 65 (1) ◽  
pp. 271-273 ◽  
Author(s):  
S. K. Rathore ◽  
N. N. Kishore
Keyword(s):  
Finite Element ◽  
Contact Region ◽  
Contact Problems ◽  
Rolling Contact ◽  
Element Analysis ◽  
Energy Principle ◽  
Dissipation Of Energy ◽  
Rolling Surface ◽  
Strain Stress

In steady rolling motion, the loads and the fields of strain, stress, and deformations do not change with time at the contact region, as the contact region is continuously being formed by a new rolling surface. The principle of minimum dissipation of energy and the concept of traveling finite elements are made use of in solving such problems and the determination of micro-slips. The conditions of contact are discovered by use of the kinematic constraints and the Coulomb’s law of friction. A two-dimensional plane-strain finite element method along with the iterative procedure is used. The results obtained are in good agreement with expected behavior.

Lateral Distribution of Pressure in Thin Strip Rolling

1970 ◽  
Vol 92 (2) ◽  
pp. 453-459 ◽  
Author(s):  
H. A. Kuhn ◽  
A. S. Weinstein
Keyword(s):  
Rolling Force ◽  
Contact Region ◽  
Three Dimensional ◽  
Work Roll ◽  
Lateral Distribution ◽  
Thin Strip ◽  
Strip Rolling ◽  
Edge Contact ◽  
Strip Shape

A method is presented for the determination of the lateral distribution of pressure in thin strip rolling. A simplified three-dimensional analysis of elastic deformation of the rolls is developed for use in the method. Pressure in the roll edge contact regions (in underface rolling), as well as in the roll-strip contact region, is considered. In the case of four-high, planetary, and Sendzimir-type mills, the lateral distribution of pressure between the work roll and backup rolls is also found. Calculated results indicate lateral pressure distributions which have peak values at each edge of the strip with a minimum at the center. The degree of this nonuniformity depends on roll geometry and configuration. Partition of the total rolling force between roll-strip contact and roll edge contact in underface rolling is also determined. Since interroll heat transfer is dependent on contact area, and hence, pressure, the results can also aid the determination of lateral temperature distributions in the rolls. In addition, the method is potentially useful for a study of the influence of roll geometry and configuration on strip shape.

The Determination of Meshing Force Distribution for Spur Gears

2008 ◽  
Author(s):  
Mohammad Durali ◽  
Maryam Gh. Saryazdi
Keyword(s):  
Reference Data ◽  
Contact Region ◽  
Spur Gear ◽  
Force Distribution ◽  
Element Analysis ◽  
Compliance Matrix ◽  
Operation Conditions ◽  
Reliable Design ◽  
Compliance Matrices

This article presents a method for determination of meshing force distribution on contact region of spur gear teeth. In this method it is assumed that there are inter-connected springs on the teeth profile. These springs treat as capacitive fields. The compliance matrices of these fields are determined from the results of finite element analysis done on 3-D model of a gear. The tooth compliance matrix is used as a reference data to determine the tooth deformations for any meshing situation. The meshing force distribution is calculated using this reference data and Hertz theory for contacting bodies. The results of this analysis help in stress analysis under real operation conditions and more reliable design of gears without needing 3-D contact model. So by this method the volume of the calculations is reduced remarkably. The method is applied to a spur gear pair, and the meshing force distribution and meshing stiffness is determined for two cases of ideal and misaligned contacts.

scholarly journals QUANDO L’INSIEME È MEGLIO DELLA SOMMA: NANOMATERIALI IBRIDI ARGENTO-TITANIA ED ORO-TITANIA PER SENSORI ELETTROANALITICI

2020 ◽  
Author(s):  
Luigi Falciola ◽  
Valentina Pifferi ◽  
Anna Testolin
Keyword(s):  
Titanium Dioxide ◽  
Electrode Surface ◽  
Contact Region ◽  
Volume Ratio ◽  
Dominant Factor ◽  
Material Transport ◽  
Subsequent Increase ◽  
Intimate Contact ◽  
Wide Range

The interest of the scientific community for nanotechnologies and nanomaterials was born in 1959, on the occasion of the annual meeting of the American Physical Society, when a new approach began with which to consider and manipulate matter on a micro- and nano-metric scale. The subsequent increase in the use of nanomaterials in scientific research is due to their peculiar characteristics: increased surface / volume ratio, new optical and physical properties, high active surface, increased or modified material transport, increased selectivity. All these features make nanomaterials extremely suitable for a wide range of applications, from energy, to catalysis and sensors. In recent decades, apart from the application of nanomaterials characterized by a single component, the use of “hybrid” nanomaterials, composed of two or more components in “intimate” contact, is also rapidly growing. This is connected to the fact that, since in a hybrid material the establishment of synergistic properties is confined to the contact region between the different components, in nanomaterials, given the small size, these effects can become a dominant factor of the entire structure. The result is precisely the establishment of new and unexpected properties (often desired and interesting) which are not the simple sum of the ownership of individual contributions. Given all this, hybrid materials are excellent candidates for applications in the most varied fields, including electroanalysis, which can greatly benefit from these systems. In this context, this work aims to present the construction of devices based on hybrid metal-semiconductor nanomaterials (based on silver or gold nanoparticles and titanium dioxide). In these systems, the presence of metal nanoparticles is exploited for the electroanalytical determination of analytes of medical / diagnostic or environmental interest, while the presence of TiO2 is essential for overcoming the problems of fouling and passivation of the electrode surface following the determination of the molecule under examination. . The possibility of renewing the electrode surface simply by irradiating the device with ultraviolet light, allows you to use the devices remotely for a long time, without their continuous recovery. In the case of the Ag-TiO2 system, an “intimate contact” interphase between the silver nanoparticles and titanium dioxide was also found, which makes the hybrid a real new material, with different characteristics and with interesting applications compared to its precursors.

The Minimum Gauge Problem in Thin Strip Rolling

1971 ◽  
Vol 93 (3) ◽  
pp. 331-340 ◽  
Author(s):  
H. A. Kuhn ◽  
A. S. Weinstein
Keyword(s):  
Sliding Friction ◽  
Contact Region ◽  
Three Dimensional ◽  
Thin Strip ◽  
Theoretical Treatment ◽  
Plastic Yielding ◽  
Strip Rolling ◽  
Basic Assumptions ◽  
Traction Distribution

All previous analyses of the minimum gauge problem either fail to arrive at a criterion for determination of the minimum gauge or result in predictions which are grossly in error. The basic assumptions utilized in these analyses are investigated in the present work with a view toward improving the existing theories. Those assumptions whose validity appears questionable are considered in detail through appropriate analysis. In particular, these assumptions are: (i) the strip and rolls deform uniformly across the width of the strip; (ii) Coulomb (sliding) friction occurs between the rolls and strip. Theoretical treatment of the complex three-dimensional behavior of the rolls and strip is made tenable through simplifications to suitable two-dimensional problems. The primary result of the investigation indicates that the assumption of sliding friction is completely without justification in rolling at the limiting conditions. A new shear traction distribution is postulated which is consistent with the fundamental laws of friction and results in sticking friction (zero slip) over most of the contact region. Incorporating this shear distribution, limiting rolling conditions can be shown to exist theoretically and the minimum gauge can be predicted. It is also found that the Poisson’s ratio must be one-half in the regions of incipient plastic yielding in the strip if a minimum gauge is to be predicted.

Interferometric Determination of Elastohydrodynamic Lubrication Contact Pressures

1969 ◽  
Vol 184 (1) ◽  
pp. 633-646 ◽  
Author(s):  
D. L. Cope ◽  
D. J. Haines
Keyword(s):  
Steady State ◽  
Principal Stress ◽  
Contact Region ◽  
Elastohydrodynamic Lubrication ◽  
Optical Quality ◽  
Stress Difference ◽  
Dynamic Stresses ◽  
Rolling Elements ◽  
Contact Pressures

A study has been made of the stress distribution in optical quality glass rolling elements operating under conditions of elastohydrodynamic lubrication, and the pressure distribution in the lubricant film has been inferred from interferometric measurements of the distribution of principal stress sum and principal stress difference on the boundary of the contact region. The absolute retardation method of stress analysis which permits these evaluations has been developed and extended to the measurement of steady-state dynamic stresses, for this purpose. The techniques in use are also amenable to use in the analysis of plasto-elastic elastohydrodynamic lubrication problems.

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

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