scholarly journals Determination of the coefficient of restitution upon contact of a steel ball with aluminum and steel surfaces

2021 ◽  
Vol 2131 (3) ◽  
pp. 032087
Author(s):  
V G Gusev ◽  
A V Sobolkov ◽  
A V Aborkin
Keyword(s):  
Experimental Studies ◽  
Three Dimensional ◽  
Calculated Data ◽  
High Energy ◽  
Complex Model ◽  
Steel Ball ◽  
Restitution Coefficient ◽  
Discrete Elements ◽  
Three Dimensional Model ◽  
Steel Surfaces

Abstract In this work, experimental studies on the rebound of a steel ball from aluminum and steel surfaces have been carried out. Using the ideology of the method of discrete elements, a three-dimensional model of the process was built. By carrying out multivariate calculations with varying the restitution coefficient and subsequent comparison of experimental and calculated data on the ball rebound height, the actual restitution coefficient for contact pairs “steel - steel” and “steel - aluminum” was determined. The results of the work will be used in the development of a complex model of high-energy ball milling.

Three-dimensional analysis of anchored wall with concrete bearing pads

2020 ◽  
Vol 18 (6) ◽  
pp. 1469-1486
Author(s):  
Hamed Arefizadeh ◽  
Hadi Shahir
Keyword(s):  
Design Methodology ◽  
Three Dimensional ◽  
Bending Moments ◽  
Dimensional Model ◽  
Discrete Elements ◽  
Three Dimensional Model ◽  
Content Type ◽  
Finite Element Software ◽  
Internal Forces ◽  
Soldier Pile

Purpose Anchorage with concrete bearing pad is commonly used in Iran for stabilization of excavations because of the ease of construction, less costs and less time consumption than the soldier pile method. In this method, a wall facing which includes the concrete bearing pads at the location of the anchors and a shotcrete layer between the bearing pads is constructed parallel to the excavation operation similar to the nailing method. Design/methodology/approach In this paper, using the finite element software Abaqus, a three-dimensional model of the above-mentioned type of wall is constructed, and the effect of spacing and size of bearing pads on the wall behavior is discussed. Findings According to the obtained results, the size of the concrete bearing pads has little effect on wall deformations, but the internal forces and bending moments developed in the shotcrete layer between the bearing pads are greatly influenced by the bearing pads dimensions and spacing. Originality/value Owing to the discrete elements of the wall facing, the behavior of this system is completely three-dimensional.

Model of local temperature changes in brain upon functional activation

2004 ◽  
Vol 97 (6) ◽  
pp. 2051-2055 ◽  
Author(s):  
Christopher M. Collins ◽  
Michael B. Smith ◽  
Robert Turner
Keyword(s):  
Brain Temperature ◽  
Human Subjects ◽  
Potential Temperature ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Human Head ◽  
Bioheat Equation ◽  
Three Dimensional Model ◽  
Temperature Changes ◽  
Blood Temperature

Experimental results for changes in brain temperature during functional activation show large variations. It is, therefore, desirable to develop a careful numerical model for such changes. Here, a three-dimensional model of temperature in the human head using the bioheat equation, which includes effects of metabolism, perfusion, and thermal conduction, is employed to examine potential temperature changes due to functional activation in brain. It is found that, depending on location in brain and corresponding baseline temperature relative to blood temperature, temperature may increase or decrease on activation and concomitant increases in perfusion and rate of metabolism. Changes in perfusion are generally seen to have a greater effect on temperature than are changes in metabolism, and hence active brain is predicted to approach blood temperature from its initial temperature. All calculated changes in temperature for reasonable physiological parameters have magnitudes <0.12°C and are well within the range reported in recent experimental studies involving human subjects.

Modelling of the electron beam scattering by fine-dispersed structures and calculation of topographical contrast of cathodoluminescent images in the SEM

1990 ◽  
Vol 48 (4) ◽  
pp. 890-891
Author(s):  
M.V. Viskov ◽  
A.G. Nikolaev ◽  
S.K. Obyden ◽  
G.V. Saparin ◽  
S.M. Meleshkin
Keyword(s):  
Electron Beam ◽  
Secondary Electron Emission ◽  
Three Dimensional ◽  
High Energy ◽  
Volume Distribution ◽  
Beam Diameter ◽  
Three Dimensional Model ◽  
Experimental Conditions ◽  
Angular Aperture ◽  
Black And White

A three-dimensional model of the scattering of a high-energy electron beam in a fine-dispersed structure (FDS) is developed. The model is intended for calculating, by the Monte-Carlo method, the color and black-and-white contrast of the image formed in the course of investigations of powdered structures in the cathodoluminescence (CL) mode in the SEM. The theory is developed in the approximation of an infinitely thin electron beam, which limits the minimum sizes of FDS crystals by the value of the order of 10μm under the experimental conditions (the electron beam diameter of 0.8 to 1.0 μm).The model takes account of: 1) elastic and inelastic interactions, and the absorption of the electrons of the primary beam scattered during the whole succession of the acts of interaction with FDS crystals; 2) secondary electron emission: the “birth”, elastic and inelastic scattering, and the absorption of secondary electrons during the whole succession of the acts of interaction with FDS crystals; 3) a change in the intensity and wavelength of the detected monochromatic CL-radiation of each of the FDS crystals with allowance made for the elastic and Raman scattering and the absorption of CL photons; 4) a stochastic character of the volume distribution of the FDS crystals, as well as their random orientation and possible defects of their shape; the requirement of the identical size of the crystals being kept in force; 5) the geometry of the light-collecting system, namely, the angular aperture of the luminescence collector.

Towards a Three-Dimensional Model of Planning Behaviour

1971 ◽  
Vol 3 (3) ◽  
pp. 253-266 ◽  
Author(s):  
A Faludi
Keyword(s):  
Decision Making ◽  
Three Dimensional ◽  
Complex Model ◽  
Learning Systems ◽  
Three Dimensions ◽  
Dimensional Model ◽  
Planning Systems ◽  
Three Dimensional Model ◽  
Disjointed Incrementalism ◽  
Planning Problems

This paper develops conceptual tools for the analysis of planning behaviour. These are, firstly, a model of planning systems as learning systems, and then three dimensions of planning behaviour, each described by defining a pair of dichotomous concepts at their far ends: ‘blueprint’ versus ‘process’ modes of planning; ‘rational-deductive’ decision-making versus ‘disjointed incrementalism’; ‘normative’ versus ‘functional’ planning. Each of these concepts is discussed in detail, and some indicators for the analysis of planning behaviour are suggested. Finally, a more complex model is constructed which combines the three dimensions. Elements of this model are firstly the level at which planning is conducted within a hierarchy of planning systems, and secondly, the ‘planning sub-structurel, that is the technology-image reflecting the nature of planning problems and available planning technologies. From this model one can derive a number of researchable hypotheses about planning behaviour.

Numerical Analysis of Crack Propagation in Silicon Nitride

2011 ◽  
Vol 490 ◽  
pp. 216-225 ◽  
Author(s):  
Waldemar Karaszewski
Keyword(s):  
Numerical Analysis ◽  
Crack Propagation ◽  
Coefficient Of Thermal Expansion ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Contact Fatigue ◽  
High Hardness ◽  
Rolling Contact ◽  
Three Dimensional Model ◽  
Ring Crack

The properties of ceramics, specifically low density, high hardness, high temperature capability and low coefficient of thermal expansion are of most interest to rolling element manufacturers. The influence of ring crack size on rolling contact fatigue failure has been studied using numerical fracture analysis. Such cracks are very often found on ceramic bearing balls and decrease fatigue life rapidly. The numerical calculation are based on a three dimensional model for the ring crack propagation. The stress intensity factors along crack front are analyzed using a three-dimensional boundary element model. The numerical analysis is verified by experimental studies.

Experimental Investigation of a Generic Compressor Bleed System

2006 ◽  
Author(s):  
Reinaldo A. Gomes ◽  
Carsten Schwarz ◽  
Michael Pfitzner
Keyword(s):  
Flow Field ◽  
Annular Flow ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Complex Flow ◽  
Pressure Losses ◽  
Aero Engines

Extensive experimental studies on axial compressor bleed-flow systems have been carried out on a three dimensional model of a generic bleed-flow configuration typical for aero engines. The compressor flow is modeled as a clean annular flow. One row of stator vanes is used to impart a constant swirl upstream of the bleed system. The rig is designed modularly in order to allow for inexpensive changes in all of its components and therefore to enlarge the variability of the model. The research is focused onto the generation of an experimental data base, which can be used to derive correlations for the calculation of effective areas and pressure losses. Those data are gained using steady pneumatic measurement technique. In addition, the highly complex flow field in the manifold, which has an important effect onto the bleed-flow, is analyzed using Doppler-Global-Velocimetry (DGV). These measurements were conducted in collaboration with DLR Cologne, who have developed the DGV technique. In this paper the flow field in the manifold is analyzed in detail for two different configurations featuring two and four bleed ducts, respectively. Furthermore the use of a flush design of the slot is compared with a lip design. These data are compared to results from the literature achieved using 2-dimensional configurations.

scholarly journals Angular Divergence of Electrons in Generating Two Ribbon Beams in a Single Accelerating Diode (Simulation, Experiment)

2020 ◽  
Vol 15 (1) ◽  
pp. 24-41
Author(s):  
Andrey V. Arzhannikov ◽  
Denis A. Samtsov ◽  
Stanislav L. Sinitsky ◽  
Vasily D. Stepanov
Keyword(s):  
Distribution Function ◽  
Simulation Experiment ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Calculated Data ◽  
Measurement Results ◽  
Recording Channels ◽  
Processing Measurement ◽  
Diode Voltage ◽  
A Current

The paper presents the results of numerical simulation and experimental studies of the generation of two ribbon beams in an accelerating diode with magnetic insulation at a diode voltage of ~ 0.7 MeV and a current of 10 kA in it. Model-ing is implemented using the Particle CST Studio package. The experiments were conducted on the U-3 accelerator of the ELMI installation. In calculations with three-dimensional geometry corresponding to the experiments, the distribu-tion of electron velocities over the pitch angle at the exit of the beams from the diode under the conditions of an inho-mogeneous magnetic field with an induction of about 1 T was obtained. These calculated data were confirmed in an experiment in which, using a sensor with seven recording channels, a distribution function of the velocity of electrons with a characteristic width at half maximum of 0.03 rad was obtained. Using the GEANT4 software package in processing measurement results with this sensor gives confidence in the correctness of the obtained distribution function.

Analysis of Ceramic Elements with Ring-Crack Defects in Lubricated Rolling Contact

2016 ◽  
Vol 250 ◽  
pp. 43-49 ◽  
Author(s):  
Waldemar Karaszewski
Keyword(s):  
Coefficient Of Thermal Expansion ◽  
Rolling Contact Fatigue ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Contact Fatigue ◽  
High Hardness ◽  
Rolling Contact ◽  
Three Dimensional Model ◽  
Element Analysis ◽  
Ring Crack

The properties of ceramics, specifically low density, high hardness, high temperature capability and low coefficient of thermal expansion are of most interest to rolling element manufacturers. Surface ring cracks on lubricating rolling contact fatigue failure has been studied using numerical fracture analysis. Such cracks are very often found on ceramic bearing balls and decrease fatigue life rapidly. The numerical calculations are based on a three-dimensional model of the ring crack. The stress intensity factors along crack front are analyzed using a finite element analysis. The numerical analysis is verified by experimental studies.

TEHD Lubrication of Mechanical Face Seals in Stable Tracking Mode: Part 1—Numerical Model and Experiments

2003 ◽  
Vol 125 (3) ◽  
pp. 608-616 ◽  
Author(s):  
Noe¨l Brunetie`re ◽  
Bernard Tournerie ◽  
Jean Fre^ne
Keyword(s):  
Numerical Model ◽  
Thermal Behavior ◽  
Stokes Equations ◽  
Numerical Models ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Computer Code ◽  
Three Dimensional Model ◽  
Face Seals ◽  
Improved Model

After a short presentation of state-of-the-art experimental studies on the thermal behavior of non-contacting face seals, the literature about numerical models for thermal effects is investigated. Next, the geometry, kinematics and dynamics of a steady state three-dimensional model are developed. Simplified Navier-Stokes equations, a generalized Reynolds equation and an energy equation with proper boundary conditions are established for flow regimes, varying from laminar to turbulent. The numerical computer code for solving the governing equations is presented and representative results are shown. It is demonstrated that face distortions strongly modify the seals’ thermal behavior. An original test rig has been developed in order to ensure full fluid film conditions. This apparatus and the experimental procedure are described. The ability of the numerical model to simulate real configurations is also illustrated. Theoretical and experimental results are in good agreement. Yet an improved model of heat transfer on boundaries is still needed.

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