Experimental and Numerical Investigation of Fretting Wear at High Temperature for Aeronautical Alloys

2010 ◽  
Author(s):  
D. Botto ◽  
A. Campagna ◽  
M. Lavella ◽  
M. M. Gola
Keyword(s):  
Three Dimensional ◽  
Experimental Tests ◽  
Fretting Wear ◽  
Numerical Code ◽  
Dissipated Energy ◽  
Hysteresis Cycle ◽  
Set Up ◽  
Wear Law ◽  
Low Amplitude ◽  
The Given

Fretting wear is a complex phenomenon that occurs at component interfaces that undergo low amplitude oscillation under high contact pressure. The aim of this paper is to investigate the fretting behavior of contact interfaces both with experiments and numerical code. The hysteresis cycles have been measured through the experiment and, at the end of the test, the worn volume has been determined. A numerical code has been developed to predict worn volume. The three-dimensional elastic contact problem has been solved by using a semi-analytical half space model. The numerical code uses a wear law for which the worn volume is proportional to the dissipated energy during the hysteresis cycle. The wear coefficient has been iteratively determined by comparing the theoretical results with the experimental tests. The main results of this work is the set up of a wear model for the given geometry and materials.

On Three and Two-Dimensional Disturbances of Pipe Flow

1960 ◽  
Vol 27 (3) ◽  
pp. 381-389 ◽  
Author(s):  
Kurt Spielberg ◽  
Hans Timan
Keyword(s):  
Order Differential Equation ◽  
Three Dimensional ◽  
Circular Cross Section ◽  
Main Flow ◽  
Two Dimensional ◽  
Straight Pipe ◽  
Special Cases ◽  
Set Up ◽  
The Stability ◽  
The Given

A system of ordinary, coupled differential equations is set up for three-dimensional disturbances of Poiseuille flow in a straight pipe of circular cross section. The commonly treated equations are shown to be special cases arising from particular assumptions. It is shown that in the nonviscous, and therefore also in the general case, there exists, in contrast to the analogous problem in Cartesian co-ordinates, no transformation reducing the given problem to a two-dimensional one. A fourth-order differential equation is derived for disturbances independent of the direction of the main flow. The solutions, which are obtained, show that those two-dimensional disturbances, termed cross disturbances, decay with time and do therefore not disturb the stability of the main flow. Explicit expressions for the cross disturbances are obtained and a discussion of their nature is given.

scholarly journals Crystal structure of an unknown tetrahydrofuran solvate of tetrakis(μ3-cyanato-κ3N:N:N)tetrakis[(triphenylphosphane-κP)silver(I)]

2015 ◽  
Vol 71 (10) ◽  
pp. 1262-1265
Author(s):  
Peter Frenzel ◽  
Dieter Schaarschmidt ◽  
Alexander Jakob ◽  
Heinrich Lang
Keyword(s):  
Crystal Structure ◽  
Three Dimensional ◽  
Acta Cryst ◽  
Compound C ◽  
Hydrogen Bonding Interactions ◽  
Dimensional Network ◽  
Solvent Molecules ◽  
Set Up ◽  
The Given ◽  
Triphenylphosphine Ligand

In the title compound, [{[(C6H5)3P]Ag}4{NCO}4], a distorted Ag4N4-heterocubane core is set up by four AgIions being coordinated by the N atoms of the cyanato anions in aμ3-bridging mode. In addition, a triphenylphosphine ligand is datively bonded to each of the AgIions. Intramolecular Ag...Ag distances as short as 3.133 (9) Å suggest the presence of argentophilic (d10...d10) interactions. Five moderate-to-weak C—H...O hydrogen-bonding interactions are observed in the crystal structure, spanning a three-dimensional network. A region of electron density was treated with the SQUEEZE procedure inPLATON[Spek (2015).Acta Cryst.C71, 9–18] following unsuccessful attempts to model it as being part of disordered tetrahydrofuran solvent molecules. The given chemical formula and other crystal data do not take into account these solvent molecules.

Modeling of Fretting Wear Under Gross Slip and Partial Slip Conditions

2007 ◽  
Vol 129 (3) ◽  
pp. 528-535 ◽  
Author(s):  
L. Gallego ◽  
D. Nélias
Keyword(s):  
Contact Problem ◽  
Three Dimensional ◽  
Fretting Wear ◽  
Contact Model ◽  
Partial Slip ◽  
Tangential Displacement ◽  
Normal Contact ◽  
Slip Conditions ◽  
Static Contact ◽  
Wear Law

The paper presents a numerical model to investigate fretting wear either under partial or gross slip conditions. An efficient three-dimensional elastic–static contact model to solve both the normal contact problem and the tangential contact problem is presented. The contact model is validated with analytical solutions for a sphere on flat geometry. A wear law issued from the literature and based on the friction energy is used to simulate surface wear. Numerical friction logs are obtained and the wear rate evolution is found to be highly dependent on the tangential displacement.

scholarly journals Effect of infill density and pattern on the specific load capacity of FDM 3D-printed PLA multi-layer sandwich

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
József Dobos ◽  
Muammel M. Hanon ◽  
István Oldal
Keyword(s):  
Load Capacity ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Bending Test ◽  
Material Structure ◽  
Specific Load ◽  
3D Printed ◽  
Plastic Parts ◽  
The Given ◽  
Manufacturing Time

Abstract Three-dimensional (3D) printing settings allow the existence of differently filled sections together within a piece. That means the use of inhomogeneous internal material structure. Knowing the load capacity that 3D printed plastic parts can withstand leads to the reduction of the filling degree, thus the amount of the used material in certain places. This approach has two advantages during production: (i) less material use and (ii) reduced manufacturing time, both being cost-reducing factors. The present research aims to find the optimal proportions for fabricating a bending test piece with varying filling degrees. To achieve this goal, experimental tests were performed for obtaining tensile strength and modulus of elasticity using different pairs of infill density and pattern. This provided a basis for creating a working mechanical model based on accurate and realistic material properties. Hence, a series of virtual bending test experiments were conducted on a sandwich structure specimen employing Ansys Workbench software. By doing so, the optimal thickness (of the sandwich’s inner layer) with the highest specific load capacity for the given filling patterns and densities were determined. To the best of our knowledge, the current procedure of experiments and method of settings optimization were not discussed elsewhere.

scholarly journals Companion-launched jets and their effect on the dynamics of common envelope interaction simulations

2019 ◽  
Vol 488 (4) ◽  
pp. 5615-5632 ◽  
Author(s):  
Sagiv Shiber ◽  
Roberto Iaconi ◽  
Orsola De Marco ◽  
Noam Soker
Keyword(s):  
Three Dimensional ◽  
Gravitational Energy ◽  
Numerical Code ◽  
Binary Interaction ◽  
Giant Star ◽  
Common Envelope ◽  
The Common ◽  
Red Giant ◽  
Set Up ◽  
First Time

Abstract We conduct three-dimensional hydrodynamic simulations of the common envelope binary interaction and show that if the companion were to launch jets while interacting with the giant primary star’s envelope, the jets would remove a substantial fraction of the envelope’s gas. We use the set-up and numerical code of an earlier common envelope study that did not include jets, with a 0.88-M⊙, 83-R⊙ red giant star and a 0.3-M⊙ companion. The assumption is that the companion star accretes mass via an accretion disc that is responsible for launching the jets which, in the simulations, are injected numerically. For the first time we conduct simulations that include jets as well as the gravitational energy released by the inspiralling core-companion system. We find that simulations with jets unbind approximately three times as much envelope mass than identical simulations that do not include jets, though the total fraction of unbound gas remains below 50 per cent for these particular simulations. The jets generate high-velocity outflows in the polar directions. The jets also increase the final core-companion orbital separation and lead to a kick velocity of the core-companion binary system. Our results show that, if able to form, jets could play a crucial role in ejecting the envelope and in shaping the outflow.

Experiments and Finite Element Simulation of Ultrasonic Assisted Drilling

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Hossein Paktinat ◽  
Saeid Amini
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Advanced Technique ◽  
Burr Height ◽  
Exit Surface ◽  
Element Simulation ◽  
Ultrasonic Assisted ◽  
Low Amplitude

In this study, ultrasonic assisted drilling (UAD) is performed to investigate the effect of ultrasonic vibrations on common difficulties existed in conventional drilling (CD). UAD is a promising and advanced technique by which a harmonic movement with high frequency and low amplitude is superimposed on the movement of work material or cutting tool. The study is conducted both experimentally and numerically; at first, a UAD system is designed, manufactured, and carried out on a milling machine and then experimental tests are accomplished. In the following, experimental results are supported by the help of three-dimensional (3D) finite element simulation. Finally, the dependent parameters such as the burr height and cylindricity of the ultrasonically and conventionally drilled workpiece are measured and compared. Briefly, it was proved that the intermittent movement of drill bit in the direction of feed rate results in broken and discontinuous chips by which built-up-edge (BUE) is reduced and hole quality is improved. In addition, the burr height, which is known as unwanted projection of material at the exit surface of pieces, can notably decrease, if UAD is considered.

Influence of Stick-Slip Behavior on Friction and Wear under Fretting Conditions

2006 ◽  
Vol 326-328 ◽  
pp. 1189-1192
Author(s):  
Sung Hoon Jeong ◽  
Seok Ju Yong ◽  
Tae Shik Ahn ◽  
Young Ze Lee
Keyword(s):  
Friction And Wear ◽  
Fretting Wear ◽  
Partial Slip ◽  
Dissipated Energy ◽  
Stick Slip ◽  
Steel Surfaces ◽  
Low Amplitude ◽  
Fretting Damage ◽  
Friction And Wear Characteristics ◽  
Slip Phenomenon

Friction and wear characteristics between two steel surfaces under fretting condition are investigated experimentally. The fretting damage caused by low-amplitude oscillatory sliding can be classified into three regimes of gross-slip, mixed-slip and partial-slip due to stick-slip phenomenon. One of the most important characteristics of fretting wear is the transition from gross-slip to mixed-slip. This study was focused on getting the degree of stick-slip out of the friction transition under fretting condition. Fretting wear is divided into three conditions of gross-slip/mixed-slip/ partial-slip. The criteria for the division are friction and displacement amplitude, wear scar morphology and dissipated energy. In this test, friction force and displacement were measured for detecting the transition from mixed-slip to gross-slip and qualitatively predicting the degree of the wear.

scholarly journals WAVE PROPAGATION ON A FLUME: NUMERICAL SIMULATION

2015 ◽  
Vol 14 (1) ◽  
pp. 95
Author(s):  
J. M. P. Conde ◽  
P. T. S. Roberto ◽  
C. J. E. M. Fortes
Keyword(s):  
Time Series ◽  
Water Column ◽  
Wave Height ◽  
Stokes Equations ◽  
National Laboratory ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Numerical Code ◽  
Wave Transformation ◽  
Wide Range

This paper presents the numerical simulations done by using the waves2Foam, an OpenFOAM® library, to simulate the propagation of regular waves without breaking in a three-dimensional flume. The numerical code solves the unsteady Navier-Stokes equations and uses a Volume-of-Fluid (VoF) method to identify the free-surface. A regular incident wave with a 1.5s period and 0.1m wave height was considered. This is one of the conditions, from the wide range of wave flume tests conducted at the National Laboratory for Civil Engineering (LNEC), whose objective was to analyze the hydrodynamics of wave transformation and wave breaking for different incident conditions over a variable bathymetry. Comparisons are made between the numerical and the experimental results. These comparisons include time-series of wave-gauges records at several locations along the flume and the corresponding amplitude spectra; significant wave height and average period evolution along the flume; time-series of the velocity components at one section of the flume, measured at the middle of the water column; and hodograph representation of the velocity components, in the middle of the water column, in the xy, xz, and yz planes, along the flume. It was found that the numerical results obtained are close to the experimental data. The observed differences are attributable to numerical inaccuracies as well as the differences between the wave generation method in the numerical and experimental tests.

Prediction of root damaging during mechanical shaking of fruit trees

2014 ◽  
Vol 10 (1) ◽  
pp. 1-15
Author(s):  
Z. Láng
Keyword(s):  
Field Experiments ◽  
Calculated Data ◽  
Fruit Trees ◽  
List Type ◽  
Structure Model ◽  
Root Damage ◽  
Set Up ◽  
Simple Tree ◽  
The Given ◽  
Cherry Trees

The possible effect of shaker harvest on root damage of 10-year-old cherry trees was studied on a simple tree structure model. The model was composed of elastic trunk and rigid main roots, the ends of which were connected to the surrounding soil via springs and dumping elements. Equations were set up to be able to calculate the relation between shaking height on the trunk and strain in the roots. To get the data for root break and their elongation at different shaking heights on the trunk, laboratory and field experiments were carried out on cherry trees and on their roots. Having evaluated the measured and calculated data it could be concluded that root damage is to be expected even at 3.6% strain and the risk of it increases with increased trunk amplitudes, i.e.with the decrease of shaking heightat smaller stem diameters (i.e. in younger plantation), andif the unbalanced mass of the shaker machine is too large for the given tree size.

scholarly journals Vibration characteristics of triple-gear-rotor system in compressed air energy storage under variable torque load

2021 ◽  
Vol 104 (1) ◽  
pp. 003685042098705
Author(s):  
Xinran Wang ◽  
Yangli Zhu ◽  
Wen Li ◽  
Dongxu Hu ◽  
Xuehui Zhang ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Element Model ◽  
Rotor System ◽  
Dynamic Responses ◽  
System Response ◽  
Rotating Speed ◽  
Torque Load ◽  
Set Up ◽  
Two Stages

This paper focuses on the effects of the off-design operation of CAES on the dynamic characteristics of the triple-gear-rotor system. A finite element model of the system is set up with unbalanced excitations, torque load excitations, and backlash which lead to variations of tooth contact status. An experiment is carried out to verify the accuracy of the mathematical model. The results show that when the system is subjected to large-scale torque load lifting at a high rotating speed, it has two stages of relatively strong periodicity when the torque load is light, and of chaotic when the torque load is heavy, with the transition between the two states being relatively quick and violent. The analysis of the three-dimensional acceleration spectrum and the meshing force shows that the variation in the meshing state and the fluctuation of the meshing force is the basic reasons for the variation in the system response with the torque load. In addition, the three rotors in the triple-gear-rotor system studied show a strong similarity in the meshing states and meshing force fluctuations, which result in the similarity in the dynamic responses of the three rotors.

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